Introduce cgit-rs, a Rust wrapper around libgit.a

Later on in the series we add an INCLUDE_LIBGIT_RS variable to control builds and tests; I don't see any reason why we can't move that earlier in the series, so I'll do so in V7 and then look at what we need to do to make things more portable.

Yes, GCC and clang both handle this the same way.

Yes, in V7 this will only be built if INCLUDE_LIBGIT_RS is set.

In preparation for implementing a higher-level Rust API for accessing Git configs, export some of the upstream configset API via libgitpub and libgit-sys. Since this will be exercised as part of the higher-level API in the next commit, no tests have been added for libgit-sys.

While we're at it, add git_configset_alloc() and git_configset_free() functions in libgitpub so that callers can manage config_set structs on the heap. This also allows non-C external consumers to treat config_sets as opaque structs.

---
 contrib/libgit-sys/public_symbol_export.c | 29 +++++++++++++++++++++
 contrib/libgit-sys/public_symbol_export.h | 10 ++++++++
 contrib/libgit-sys/src/lib.rs             | 31 ++++++++++++++++++++++-
 3 files changed, 69 insertions(+), 1 deletion(-)

index 7cd5007902..1799fc6fde 100644
@@ -3,11 +3,40 @@
 // avoids conflicts with other libraries such as libgit2.
 
 #include "git-compat-util.h"
+#include "config.h"
 #include "contrib/libgit-sys/public_symbol_export.h"
 #include "version.h"
 
 #pragma GCC visibility push(default)
 
+struct libgit_config_set *libgit_configset_alloc(void)
+{
+	struct config_set *cs = xmalloc(sizeof(struct config_set));
+	git_configset_init(cs);
+	return (struct libgit_config_set *) cs;
+}
+
+void libgit_configset_free(struct libgit_config_set *cs)
+{
+	git_configset_clear((struct config_set *) cs);
+	free((struct config_set *) cs);
+}
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
+{
+	return git_configset_add_file((struct config_set *) cs, filename);
+}
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest)
+{
+	return git_configset_get_int((struct config_set *) cs, key, dest);
+}
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest)
+{
+	return git_configset_get_string((struct config_set *) cs, key, dest);
+}
+
 const char *libgit_user_agent(void)
 {
 	return git_user_agent();

index a3372f93fa..701db92d53 100644
@@ -1,6 +1,16 @@
 #ifndef PUBLIC_SYMBOL_EXPORT_H
 #define PUBLIC_SYMBOL_EXPORT_H
 
+struct libgit_config_set *libgit_configset_alloc(void);
+
+void libgit_configset_free(struct libgit_config_set *cs);
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename);
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest);
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest);
+
 const char *libgit_user_agent(void);
 
 const char *libgit_user_agent_sanitized(void);

index d4853f3074..dadb4e5f40 100644
@@ -1,15 +1,44 @@
 #[cfg(has_std__ffi__c_char)]
-use std::ffi::c_char;
+use std::ffi::{c_char, c_int};
 
 #[cfg(not(has_std__ffi__c_char))]
 #[allow(non_camel_case_types)]
 pub type c_char = i8;
 
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
+pub type c_int = i32;
+
 extern crate libz_sys;
 
+#[allow(non_camel_case_types)]
+#[repr(C)]
+pub struct libgit_config_set {
+    _data: [u8; 0],
+    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
+}
+
 extern "C" {
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
+
+    pub fn libgit_configset_alloc() -> *mut libgit_config_set;
+    pub fn libgit_configset_free(cs: *mut libgit_config_set);
+
+    pub fn libgit_configset_add_file(cs: *mut libgit_config_set, filename: *const c_char) -> c_int;
+
+    pub fn libgit_configset_get_int(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        int: *mut c_int,
+    ) -> c_int;
+
+    pub fn libgit_configset_get_string(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        dest: *mut *mut c_char,
+    ) -> c_int;
+
 }
 
 #[cfg(test)]

2.48.0.rc2.279.g1de40edade-goog

From: Calvin Wan <[email protected]>

The C functions exported by libgit-sys do not provide an idiomatic Rust interface. To make it easier to use these functions via Rust, add a higher-level "libgit" crate, that wraps the lower-level configset API with an interface that is more Rust-y.

This combination of $X and $X-sys crates is a common pattern for FFI in Rust, as documented in "The Cargo Book" [1].

[1] https://doc.rust-lang.org/cargo/reference/build-scripts.html#-sys-packages

---
 .gitignore                         |  1 +
 Makefile                           |  2 +-
 contrib/libgit-rs/Cargo.lock       | 77 ++++++++++++++++++++++++
 contrib/libgit-rs/Cargo.toml       | 15 +++++
 contrib/libgit-rs/README.md        | 13 ++++
 contrib/libgit-rs/build.rs         |  4 ++
 contrib/libgit-rs/src/lib.rs       | 95 ++++++++++++++++++++++++++++++
 contrib/libgit-rs/testdata/config1 |  2 +
 contrib/libgit-rs/testdata/config2 |  2 +
 contrib/libgit-rs/testdata/config3 |  2 +
 contrib/libgit-sys/src/lib.rs      |  4 ++
 11 files changed, 216 insertions(+), 1 deletion(-)
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3

index 31d7e64287..acdd8ce7c7 100644
@@ -250,4 +250,5 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-rs/target
 /contrib/libgit-sys/target

index 47e864a861..230d366457 100644
@@ -3729,7 +3729,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
 	$(MAKE) -C Documentation/ clean
 	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
-	$(RM) -r contrib/libgit-sys/target
+	$(RM) -r contrib/libgit-rs/target contrib/libgit-sys/target
 	$(RM) -r contrib/libgit-sys/partial_symbol_export.o
 	$(RM) -r contrib/libgit-sys/hidden_symbol_export.o
 	$(RM) -r contrib/libgit-sys/libgitpub.a

new file mode 100644
index 0000000000..634435cd6c
@@ -0,0 +1,15 @@
+[package]
+name = "libgit"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+rust-version = "1.63"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libgit-sys = { version = "0.1.0", path = "../libgit-sys" }
+
+[build-dependencies]
+autocfg = "1.4.0"

new file mode 100644
index 0000000000..ff945e1ce2
@@ -0,0 +1,13 @@
+# libgit-rs
+
+Proof-of-concept Git bindings for Rust.
+
+```toml
+[dependencies]
+libgit = "0.1.0"
+```
+
+## Rust version requirements
+
+libgit-rs should support Rust versions at least as old as the version included
+in Debian stable (currently 1.63).

new file mode 100644
index 0000000000..f8bd01a690
@@ -0,0 +1,4 @@
+pub fn main() {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+}

new file mode 100644
index 0000000000..4e9a9d25d1
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 1

new file mode 100644
index 0000000000..b8d1eca423
@@ -0,0 +1,2 @@
+[trace2]
+	eventTarget = 1

new file mode 100644
index 0000000000..ca7b9a7c38
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 3

index dadb4e5f40..4bfc650450 100644
@@ -1,3 +1,5 @@
+use std::ffi::c_void;
+
 #[cfg(has_std__ffi__c_char)]
 use std::ffi::{c_char, c_int};
 

@@ -19,6 +21,8 @@ pub struct libgit_config_set {
 }
 
 extern "C" {
+    pub fn free(ptr: *mut c_void);
+
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
 

2.48.0.rc2.279.g1de40edade-goog

OK, I'll add a TODO comment in Cargo.toml.

Fixed for V7.

Hmm, I guess we'd need to do that for libgit-sys as well? Or maybe not, since they're part of the API and thus we should just keep the current pub type ... setup?

ACK, will do for V7.

ACK.

Thanks for the review and advice (both for this round and all the previous ones), it's much appreciated.

From: Calvin Wan <[email protected]>

Add libgitrs, libgitrs-sys, libgitrs-test, and libgitrs-sys-test targets to their respective Makefiles so they can be built and tested without having to run cargo build/test.

Add build variable, INCLUDE_LIBGIT_RS, that when set, automatically builds and tests libgit-rs and libgit-rs-sys when make all is run.

---
 Makefile                    | 26 ++++++++++++++++++++++++++
 contrib/libgit-sys/build.rs |  2 +-
 t/Makefile                  | 16 ++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

index 230d366457..133090a145 100644
@@ -416,6 +416,9 @@ include shared.mak
 # Define LINK_FUZZ_PROGRAMS if you want `make all` to also build the fuzz test
 # programs in oss-fuzz/.
 #
+# Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
+# test the Rust crates in contrib/libgit-rs/ and contrib/libgit-rs/libgit-sys/.
+#
 # === Optional library: libintl ===
 #
 # Define NO_GETTEXT if you don't want Git output to be translated.

@@ -2238,6 +2241,13 @@ ifdef FSMONITOR_OS_SETTINGS
 	COMPAT_OBJS += compat/fsmonitor/fsm-path-utils-$(FSMONITOR_OS_SETTINGS).o
 endif
 
+ifdef INCLUDE_LIBGIT_RS
+	# Enable symbol hiding in contrib/libgit-rs/libgit-sys/libgitpub.a
+	# without making us rebuild the whole tree every time we run a Rust
+	# build.
+	BASIC_CFLAGS += -fvisibility=hidden
+endif
+
 ifeq ($(TCLTK_PATH),)
 NO_TCLTK = NoThanks
 endif

@@ -3895,6 +3905,22 @@ build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
 unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests
 
+.PHONY: libgit-sys
+libgit-sys:
+	$(QUIET)(\
+		cd contrib/libgit-sys && \
+		cargo build \
+	)
+.PHONY: libgit-rs
+libgit-rs:
+	$(QUIET)(\
+		cd contrib/libgit-rs && \
+		cargo build \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-rs
+endif
+
 contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
 	$(LD) -r $^ -o $@
 

index b6c65193bc..3ffd80ad91 100644
@@ -14,7 +14,7 @@ pub fn main() -> std::io::Result<()> {
         .env_remove("PROFILE")
         .current_dir(git_root.clone())
         .args([
-            "CFLAGS=-fvisibility=hidden",
+            "INCLUDE_LIBGIT_RS=YesPlease",
             "contrib/libgit-sys/libgitpub.a",
         ])
         .output()

index daa5fcae86..45fe6089b2 100644
@@ -177,3 +177,19 @@ perf:
 
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
+
+.PHONY: libgit-sys-test
+libgit-sys-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-sys && \
+		cargo test \
+	)
+.PHONY: libgit-rs-test
+libgit-rs-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-rs && \
+		cargo test \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-sys-test libgit-rs-test
+endif

2.48.0.rc2.279.g1de40edade-goog

Thanks and welcome back ;-)

Given the lack of feedback on the previous round, I hope we will see enthused support on the topic. Otherwise it is hard to tell if the previous lack of feedback was merely lack of interest, or lack of anything lacking in the series.

OK. Let's see what people find out.

It looks like we're building a general Rust lib crate and a static library here, so symbol versioning isn't an issue. I expect in the future we may want to provide a shared library, in which case we will indeed want to do that, but I agree that can wait until later.

In any event, I overall think this series is a nice improvement, and I am very enthusiastic about it. (This is mostly for the benefit of Junio, since I think the authors of this series already know that.) Once it lands, I do plan to build on it somewhat.

brian m. carlson (they/them or he/him)
Toronto, Ontario, CA

;-) Thanks, I heard you.

This series provides two small Rust wrapper libraries around parts of
Git: "libgit-sys", which exposes a few functions from libgit.a, and "libgit", which provides a more Rust-friendly interface to some of those functions. In addition to included unit tests, at $DAYJOB we have tested building JJ[1] with our library and used it to replace some of the libgit2-rs uses.

[1] https://github.com/jj-vcs/jj

There is known NEEDSWORK, but I feel that they can be addressed in follow-up changes, rather than in this series. If you feel otherwise, please let me know:

* Investigate alternative methods of managing symbol visibility & renaming.

* Figure out symbol versioning

Changes in V7:
* Moved the ConfigSet implementation in libgit-rs to a config module.

* Added doc comments for ConfigSet and its methods.

* Fix meson builds by adding new object files to libgit_sources

* Moved INCLUDE_LIBGIT_RS Makefile changes earlier in the series, so that we can make it optional to compile some of the libgitpub sources. Squashed V6 patch 5/5 into this series' patch 4/4.

* Don't publicly export FFI types in libgit-rs.

* Removed extraneous -r argument to $(RM) in the clean rules.

* Added TODO reminder in Cargo.toml about removing Cargo.lock once we hit a certain minimum supported Rust version.

* Style cleanup in public_symbol_export.c

Changes in V6:
* Rebased onto current master, since V5 was several months old.

* Move libgit-sys out of libgit-rs; while this sort of nesting is common in Rust crates with standalone repositories, it doesn't make as much sense when they're contained in the larger Git project's repo.

* Standardize the naming of some of the Makefile targets to always include a dash in the "-rs" or "-sys" suffixes.

* Clean up READMEs and crate descriptions in preparation for uploading to crates.io.

Changes in V5:
* When building with INCLUDE_LIBGIT_RS defined, add "-fvisibility=hidden" to CFLAGS. This allows us to manage symbol visibility in libgitpub.a without causing make all to rebuild from scratch due to changing CFLAGS.

* Avoid using c_int in the higher-level Rust API.

* Remove libgitpub.a and intermediate files with make clean.

Changes in V4:
* Drop V3 patch #3, which added wrappers around repository initialization and config access. These are not well-libified, and they are not necessary for JJ's proof-of-concept use case, so let's avoid exporting them for now.

* Set a minimum supported Rust version of 1.63. Autodetect whether our Rust version has c_int and c_char types; if not, define them ourselves.

* When building libgitpub.a via build.rs, set DEVELOPER=1 to catch additional errors at build time.

* In build.rs, use the make_cmd crate to portable select the correct invocation of GNU Make.

* Follow naming standards for _alloc() and _free() functions.

* Use String instead of CString in higher-level API.

* Move libgit_configset_alloc() and libgit_configset_free() out of upstream Git, to the libgitpub shim library.

* In libgitpub, initialize libgit_config_set structs in the _alloc() function rather than with a separate _init() function.

* Remove unnecessary comments in libgit-sys showing where the wrapped functions were originally defined.

* Fix clippy lint: don't reborrow configfile path references.

* Various typo fixes and cargo fmt fixes.

Changes in V3:
* Renamed cgit-rs to libgit-rs and cgit-sys to libgit-sys

* Makefile cleanup, particularly adding config.mak options that developers can set to run Rust builds and tests by default (Patch 6)

* Provide testdata configs for unit tests

* ConfigSet API now uses &Path instead of &str -- more ergonomic for Rust users to pass in and errors out if the path string isn't UTF-8

* Fixed unresolved dependency on libz in Cargo.toml

Calvin Wan (1):
libgit: add higher-level libgit crate

Josh Steadmon (3):
common-main: split init and exit code into new files
libgit-sys: introduce Rust wrapper for libgit.a
libgit-sys: also export some config_set functions

 .gitignore                                |   2 +
 Makefile                                  |  45 +++++++++
 common-exit.c                             |  26 ++++++
 common-init.c                             |  63 +++++++++++++
 common-init.h                             |   6 ++
 common-main.c                             |  83 +----------------
 contrib/libgit-rs/Cargo.lock              |  77 ++++++++++++++++
 contrib/libgit-rs/Cargo.toml              |  17 ++++
 contrib/libgit-rs/README.md               |  13 +++
 contrib/libgit-rs/build.rs                |   4 +
 contrib/libgit-rs/src/config.rs           | 106 ++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs              |   1 +
 contrib/libgit-rs/testdata/config1        |   2 +
 contrib/libgit-rs/testdata/config2        |   2 +
 contrib/libgit-rs/testdata/config3        |   2 +
 contrib/libgit-sys/Cargo.lock             |  69 ++++++++++++++
 contrib/libgit-sys/Cargo.toml             |  19 ++++
 contrib/libgit-sys/README.md              |   4 +
 contrib/libgit-sys/build.rs               |  35 +++++++
 contrib/libgit-sys/public_symbol_export.c |  51 +++++++++++
 contrib/libgit-sys/public_symbol_export.h |  18 ++++
 contrib/libgit-sys/src/lib.rs             |  79 ++++++++++++++++
 meson.build                               |   2 +
 t/Makefile                                |  15 +++
 24 files changed, 660 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

Range-diff against v6:
1: ff6cd62397 ! 1: cd0cb9aa04 common-main: split init and exit code into new files
@@ common-main.c
-
- return code;
-}
+
+ ## meson.build ##
+@@ meson.build: libgit_sources = [
+ 'commit-graph.c',
+ 'commit-reach.c',
+ 'commit.c',
++ 'common-exit.c',
++ 'common-init.c',
+ 'compat/nonblock.c',
+ 'compat/obstack.c',
+ 'compat/terminal.c',
2: 5fc66cdb16 ! 2: f1502b8590 libgit-sys: introduce Rust wrapper for libgit.a

    @@ .gitignore: Release/
     +/contrib/libgit-sys/target
     
      ## Makefile ##
    +@@ Makefile: include shared.mak
    + # Define LINK_FUZZ_PROGRAMS if you want `make all` to also build the fuzz test
    + # programs in oss-fuzz/.
    + #
    ++# Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
    ++# test the Rust crate in contrib/libgit-sys.
    ++#
    + # === Optional library: libintl ===
    + #
    + # Define NO_GETTEXT if you don't want Git output to be translated.
     @@ Makefile: CURL_CONFIG = curl-config
      GCOV = gcov
      STRIP = strip
    @@ Makefile: CURL_CONFIG = curl-config
      
      export TCL_PATH TCLTK_PATH
      
    -@@ Makefile: OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
    - OBJECTS += $(UNIT_TEST_OBJS)
    +@@ Makefile: ifdef FSMONITOR_OS_SETTINGS
    + 	COMPAT_OBJS += compat/fsmonitor/fsm-path-utils-$(FSMONITOR_OS_SETTINGS).o
    + endif
    + 
    ++ifdef INCLUDE_LIBGIT_RS
    ++	# Enable symbol hiding in contrib/libgit-sys/libgitpub.a without making
    ++	# us rebuild the whole tree every time we run a Rust build.
    ++	BASIC_CFLAGS += -fvisibility=hidden
    ++endif
    ++
    + ifeq ($(TCLTK_PATH),)
    + NO_TCLTK = NoThanks
    + endif
    +@@ Makefile: OBJECTS += $(UNIT_TEST_OBJS)
      OBJECTS += $(CLAR_TEST_OBJS)
      OBJECTS += $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
    -+OBJECTS += contrib/libgit-sys/public_symbol_export.o
      
    ++ifdef INCLUDE_LIBGIT_RS
    ++	OBJECTS += contrib/libgit-sys/public_symbol_export.o
    ++endif
    ++
      ifndef NO_CURL
      	OBJECTS += http.o http-walker.o remote-curl.o
    + endif
     @@ Makefile: clean: profile-clean coverage-clean cocciclean
      	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
      	$(MAKE) -C Documentation/ clean
      	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
     +	$(RM) -r contrib/libgit-sys/target
    -+	$(RM) -r contrib/libgit-sys/partial_symbol_export.o
    -+	$(RM) -r contrib/libgit-sys/hidden_symbol_export.o
    -+	$(RM) -r contrib/libgit-sys/libgitpub.a
    ++	$(RM) contrib/libgit-sys/partial_symbol_export.o
    ++	$(RM) contrib/libgit-sys/hidden_symbol_export.o
    ++	$(RM) contrib/libgit-sys/libgitpub.a
      ifndef NO_PERL
      	$(RM) -r perl/build/
      endif
    @@ Makefile: $(CLAR_TEST_PROG): $(UNIT_TEST_DIR)/clar.suite $(CLAR_TEST_OBJS) $(GIT
      unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
      	$(MAKE) -C t/ unit-tests
     +
    ++.PHONY: libgit-sys
    ++libgit-sys:
    ++	$(QUIET)(\
    ++		cd contrib/libgit-sys && \
    ++		cargo build \
    ++	)
    ++ifdef INCLUDE_LIBGIT_RS
    ++all:: libgit-sys
    ++endif
    ++
     +contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
     +	$(LD) -r $^ -o $@
     +
    @@ contrib/libgit-sys/Cargo.toml (new)
     +edition = "2021"
     +build = "build.rs"
     +links = "gitpub"
    -+rust-version = "1.63"
    ++rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
    ++                      # version control. See https://lore.kernel.org/git/[email protected]/
     +description = "Native bindings to a portion of libgit"
     +
     +[lib]
    @@ contrib/libgit-sys/build.rs (new)
     +        .env_remove("PROFILE")
     +        .current_dir(git_root.clone())
     +        .args([
    -+            "CFLAGS=-fvisibility=hidden",
    ++            "INCLUDE_LIBGIT_RS=YesPlease",
     +            "contrib/libgit-sys/libgitpub.a",
     +        ])
     +        .output()
    @@ contrib/libgit-sys/build.rs (new)
     
      ## contrib/libgit-sys/public_symbol_export.c (new) ##
     @@
    -+// Shim to publicly export Git symbols. These must be renamed so that the
    -+// original symbols can be hidden. Renaming these with a "libgit_" prefix also
    -+// avoids conflicts with other libraries such as libgit2.
    ++/* Shim to publicly export Git symbols. These must be renamed so that the
    ++ * original symbols can be hidden. Renaming these with a "libgit_" prefix also
    ++ * avoids conflicts with other libraries such as libgit2.
    ++ */
     +
     +#include "git-compat-util.h"
     +#include "contrib/libgit-sys/public_symbol_export.h"
    @@ contrib/libgit-sys/src/lib.rs (new)
     +        );
     +    }
     +}
    +
    + ## t/Makefile ##
    +@@ t/Makefile: perf:
    + 
    + .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
    + 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
    ++
    ++.PHONY: libgit-sys-test
    ++libgit-sys-test:
    ++	$(QUIET)(\
    ++		cd ../contrib/libgit-sys && \
    ++		cargo test \
    ++	)
    ++ifdef INCLUDE_LIBGIT_RS
    ++all:: libgit-sys-test
    ++endif
3:  03f39b6c3a < -:  ---------- libgit-sys: also export some config_set functions
5:  84706f0db7 ! 3:  d67d3648d1 Makefile: add option to build and test libgit-rs and libgit-rs-sys
    @@
      ## Metadata ##
    -Author: Calvin Wan <[email protected]>
    +Author: Josh Steadmon <[email protected]>
     
      ## Commit message ##
    -    Makefile: add option to build and test libgit-rs and libgit-rs-sys
    +    libgit-sys: also export some config_set functions
     
    -    Add libgitrs, libgitrs-sys, libgitrs-test, and libgitrs-sys-test targets
    -    to their respective Makefiles so they can be built and tested without
    -    having to run cargo build/test.
    +    In preparation for implementing a higher-level Rust API for accessing
    +    Git configs, export some of the upstream configset API via libgitpub and
    +    libgit-sys. Since this will be exercised as part of the higher-level API
    +    in the next commit, no tests have been added for libgit-sys.
     
    -    Add build variable, INCLUDE_LIBGIT_RS, that when set, automatically
    -    builds and tests libgit-rs and libgit-rs-sys when `make all` is run.
    +    While we're at it, add git_configset_alloc() and git_configset_free()
    +    functions in libgitpub so that callers can manage config_set structs on
    +    the heap. This also allows non-C external consumers to treat config_sets
    +    as opaque structs.
     
    -    Co-authored-by: Josh Steadmon <[email protected]>
    +    Co-authored-by: Calvin Wan <[email protected]>
         Signed-off-by: Calvin Wan <[email protected]>
    +    Signed-off-by: Josh Steadmon <[email protected]>
     
    - ## Makefile ##
    -@@ Makefile: include shared.mak
    - # Define LINK_FUZZ_PROGRAMS if you want `make all` to also build the fuzz test
    - # programs in oss-fuzz/.
    - #
    -+# Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
    -+# test the Rust crates in contrib/libgit-rs/ and contrib/libgit-rs/libgit-sys/.
    -+#
    - # === Optional library: libintl ===
    - #
    - # Define NO_GETTEXT if you don't want Git output to be translated.
    -@@ Makefile: ifdef FSMONITOR_OS_SETTINGS
    - 	COMPAT_OBJS += compat/fsmonitor/fsm-path-utils-$(FSMONITOR_OS_SETTINGS).o
    - endif
    + ## contrib/libgit-sys/public_symbol_export.c ##
    +@@
    +  */
      
    -+ifdef INCLUDE_LIBGIT_RS
    -+	# Enable symbol hiding in contrib/libgit-rs/libgit-sys/libgitpub.a
    -+	# without making us rebuild the whole tree every time we run a Rust
    -+	# build.
    -+	BASIC_CFLAGS += -fvisibility=hidden
    -+endif
    -+
    - ifeq ($(TCLTK_PATH),)
    - NO_TCLTK = NoThanks
    - endif
    -@@ Makefile: build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
    - unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
    - 	$(MAKE) -C t/ unit-tests
    + #include "git-compat-util.h"
    ++#include "config.h"
    + #include "contrib/libgit-sys/public_symbol_export.h"
    + #include "version.h"
      
    -+.PHONY: libgit-sys
    -+libgit-sys:
    -+	$(QUIET)(\
    -+		cd contrib/libgit-sys && \
    -+		cargo build \
    -+	)
    -+.PHONY: libgit-rs
    -+libgit-rs:
    -+	$(QUIET)(\
    -+		cd contrib/libgit-rs && \
    -+		cargo build \
    -+	)
    -+ifdef INCLUDE_LIBGIT_RS
    -+all:: libgit-rs
    -+endif
    -+
    - contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
    - 	$(LD) -r $^ -o $@
    + #pragma GCC visibility push(default)
      
    ++struct libgit_config_set *libgit_configset_alloc(void)
    ++{
    ++	struct config_set *cs = xmalloc(sizeof(struct config_set));
    ++	git_configset_init(cs);
    ++	return (struct libgit_config_set *) cs;
    ++}
    ++
    ++void libgit_configset_free(struct libgit_config_set *cs)
    ++{
    ++	git_configset_clear((struct config_set *) cs);
    ++	free((struct config_set *) cs);
    ++}
    ++
    ++int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
    ++{
    ++	return git_configset_add_file((struct config_set *) cs, filename);
    ++}
    ++
    ++int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest)
    ++{
    ++	return git_configset_get_int((struct config_set *) cs, key, dest);
    ++}
    ++
    ++int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest)
    ++{
    ++	return git_configset_get_string((struct config_set *) cs, key, dest);
    ++}
    ++
    + const char *libgit_user_agent(void)
    + {
    + 	return git_user_agent();
     
    - ## contrib/libgit-sys/build.rs ##
    -@@ contrib/libgit-sys/build.rs: pub fn main() -> std::io::Result<()> {
    -         .env_remove("PROFILE")
    -         .current_dir(git_root.clone())
    -         .args([
    --            "CFLAGS=-fvisibility=hidden",
    -+            "INCLUDE_LIBGIT_RS=YesPlease",
    -             "contrib/libgit-sys/libgitpub.a",
    -         ])
    -         .output()
    + ## contrib/libgit-sys/public_symbol_export.h ##
    +@@
    + #ifndef PUBLIC_SYMBOL_EXPORT_H
    + #define PUBLIC_SYMBOL_EXPORT_H
    + 
    ++struct libgit_config_set *libgit_configset_alloc(void);
    ++
    ++void libgit_configset_free(struct libgit_config_set *cs);
    ++
    ++int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename);
    ++
    ++int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest);
    ++
    ++int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest);
    ++
    + const char *libgit_user_agent(void);
    + 
    + const char *libgit_user_agent_sanitized(void);
     
    - ## t/Makefile ##
    -@@ t/Makefile: perf:
    + ## contrib/libgit-sys/src/lib.rs ##
    +@@
    + #[cfg(has_std__ffi__c_char)]
    +-use std::ffi::c_char;
    ++use std::ffi::{c_char, c_int};
    + 
    + #[cfg(not(has_std__ffi__c_char))]
    + #[allow(non_camel_case_types)]
    + pub type c_char = i8;
    + 
    ++#[cfg(not(has_std__ffi__c_char))]
    ++#[allow(non_camel_case_types)]
    ++pub type c_int = i32;
    ++
    + extern crate libz_sys;
    + 
    ++#[allow(non_camel_case_types)]
    ++#[repr(C)]
    ++pub struct libgit_config_set {
    ++    _data: [u8; 0],
    ++    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
    ++}
    ++
    + extern "C" {
    +     pub fn libgit_user_agent() -> *const c_char;
    +     pub fn libgit_user_agent_sanitized() -> *const c_char;
    ++
    ++    pub fn libgit_configset_alloc() -> *mut libgit_config_set;
    ++    pub fn libgit_configset_free(cs: *mut libgit_config_set);
    ++
    ++    pub fn libgit_configset_add_file(cs: *mut libgit_config_set, filename: *const c_char) -> c_int;
    ++
    ++    pub fn libgit_configset_get_int(
    ++        cs: *mut libgit_config_set,
    ++        key: *const c_char,
    ++        int: *mut c_int,
    ++    ) -> c_int;
    ++
    ++    pub fn libgit_configset_get_string(
    ++        cs: *mut libgit_config_set,
    ++        key: *const c_char,
    ++        dest: *mut *mut c_char,
    ++    ) -> c_int;
    ++
    + }
      
    - .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
    - 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
    -+
    -+.PHONY: libgit-sys-test
    -+libgit-sys-test:
    -+	$(QUIET)(\
    -+		cd ../contrib/libgit-sys && \
    -+		cargo test \
    -+	)
    -+.PHONY: libgit-rs-test
    -+libgit-rs-test:
    -+	$(QUIET)(\
    -+		cd ../contrib/libgit-rs && \
    -+		cargo test \
    -+	)
    -+ifdef INCLUDE_LIBGIT_RS
    -+all:: libgit-sys-test libgit-rs-test
    -+endif
    + #[cfg(test)]

4: 65166ea0c0 ! 4: 88425bb0b1 libgit: add higher-level libgit crate
@@ .gitignore: Release/
/contrib/libgit-sys/target

## Makefile ##
+@@ Makefile: include shared.mak
+ # programs in oss-fuzz/.
+ #
+ # Define INCLUDE_LIBGIT_RS if you want make all and make test to build and
+-# test the Rust crate in contrib/libgit-sys.
++# test the Rust crates in contrib/libgit-sys and contrib/libgit-rs.
+ #
+ # === Optional library: libintl ===
+ #
@@ Makefile: clean: profile-clean coverage-clean cocciclean
$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
$(MAKE) -C Documentation/ clean
$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
- $(RM) -r contrib/libgit-sys/target
-+ $(RM) -r contrib/libgit-rs/target contrib/libgit-sys/target
- $(RM) -r contrib/libgit-sys/partial_symbol_export.o
- $(RM) -r contrib/libgit-sys/hidden_symbol_export.o
- $(RM) -r contrib/libgit-sys/libgitpub.a
++ $(RM) -r contrib/libgit-sys/target contrib/libgit-rs/target
+ $(RM) contrib/libgit-sys/partial_symbol_export.o
+ $(RM) contrib/libgit-sys/hidden_symbol_export.o
+ $(RM) contrib/libgit-sys/libgitpub.a
+@@ Makefile: build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
+ unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
+ $(MAKE) -C t/ unit-tests
+
+-.PHONY: libgit-sys
++.PHONY: libgit-sys libgit-rs
+ libgit-sys:
+ $(QUIET)(\
+ cd contrib/libgit-sys && \
+ cargo build \
+ )
++libgit-rs:
++ $(QUIET)(\
++ cd contrib/libgit-rs && \
++ cargo build \
++ )
+ ifdef INCLUDE_LIBGIT_RS
+-all:: libgit-sys
++all:: libgit-sys libgit-rs
+ endif
+
+ contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a

## contrib/libgit-rs/Cargo.lock (new) ##
@@
@@ contrib/libgit-rs/Cargo.toml (new)
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
-+rust-version = "1.63"
++rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
++ # version control. See https://lore.kernel.org/git/[email protected]/
++
+
+[lib]
+path = "src/lib.rs"
@@ contrib/libgit-rs/build.rs (new)
+ ac.emit_has_path("std::ffi::c_char");
+}

- ## contrib/libgit-rs/src/lib.rs (new) ##
+ ## contrib/libgit-rs/src/config.rs (new) ##
@@
+use std::ffi::{c_void, CStr, CString};
+use std::path::Path;
@@ contrib/libgit-rs/src/lib.rs (new)
+
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
-+pub type c_char = i8;
++type c_char = i8;
+
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
-+pub type c_int = i32;
++type c_int = i32;
+
+use libgit_sys::*;
+
++/// A ConfigSet is an in-memory cache for config-like files such as .gitmodules or .gitconfig. ++/// It does not support all config directives; notably, it will not process include or ++/// includeIf directives (but it will store them so that callers can choose whether and how to ++/// handle them).
+pub struct ConfigSet(*mut libgit_config_set);
+impl ConfigSet {
++ /// Allocate a new ConfigSet
+ pub fn new() -> Self {
+ unsafe { ConfigSet(libgit_configset_alloc()) }
+ }
+
++ /// Load the given files into the ConfigSet; conflicting directives in later files will
++ /// override those given in earlier files.
+ pub fn add_files(&mut self, files: &[&Path]) {
+ for file in files {
+ let pstr = file.to_str().expect("Invalid UTF-8");
@@ contrib/libgit-rs/src/lib.rs (new)
+ }
+ }
+
++ /// Load the value for the given key and attempt to parse it as an i32. Dies with a fatal error
++ /// if the value cannot be parsed. Returns None if the key is not present.
+ pub fn get_int(&mut self, key: &str) -> Option<i32> {
+ let key = CString::new(key).expect("Couldn't convert to CString");
+ let mut val: c_int = 0;
@@ contrib/libgit-rs/src/lib.rs (new)
+ Some(val.into())
+ }
+
++ /// Clones the value for the given key. Dies with a fatal error if the value cannot be
++ /// converted to a String. Returns None if the key is not present.
+ pub fn get_string(&mut self, key: &str) -> Option<String> {
+ let key = CString::new(key).expect("Couldn't convert key to CString");
+ let mut val: *mut c_char = std::ptr::null_mut();
@@ contrib/libgit-rs/src/lib.rs (new)
+ }
+}

+ ## contrib/libgit-rs/src/lib.rs (new) ##
+@@
++pub mod config;
+
## contrib/libgit-rs/testdata/config1 (new) ##
@@
+[trace2]
@@ contrib/libgit-sys/src/lib.rs: pub struct libgit_config_set {
pub fn libgit_user_agent() -> *const c_char; pub fn libgit_user_agent_sanitized() -> *const c_char;

+
+ ## t/Makefile ##
+@@ t/Makefile: perf:
+ .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
+ check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
+
+-.PHONY: libgit-sys-test
++.PHONY: libgit-sys-test libgit-rs-test
+ libgit-sys-test:
+ $(QUIET)(\
+ cd ../contrib/libgit-sys && \
+ cargo test \
+ )
++libgit-rs-test:
++ $(QUIET)(\
++ cd ../contrib/libgit-rs && \
++ cargo test \
++ )
+ ifdef INCLUDE_LIBGIT_RS
+-all:: libgit-sys-test
++all:: libgit-sys-test libgit-rs-test
+ endif

base-commit: 757161efcca150a9a96b312d9e780a071e601a03

2.48.1.262.g85cc9f2d1e-goog

Currently, object files in libgit.a reference common_exit(), which is contained in common-main.o. However, common-main.o also includes main(), which references cmd_main() in git.o, which in turn depends on all the builtin/*.o objects.

We would like to allow external users to link libgit.a without needing to include so many extra objects. Enable this by splitting common_exit() and check_bug_if_BUG() into a new file common-exit.c, and add common-exit.o to LIB_OBJS so that these are included in libgit.a.

This split has previously been proposed ([1], [2]) to support fuzz tests and unit tests by avoiding conflicting definitions for main(). However, both of those issues were resolved by other methods of avoiding symbol conflicts. Now we are trying to make libgit.a more self-contained, so hopefully we can revisit this approach.

Additionally, move the initialization code out of main() into a new init_git() function in its own file. Include this in libgit.a as well, so that external users can share our setup code without calling our main().

[1] https://lore.kernel.org/git/[email protected]/
[2] https://lore.kernel.org/git/[email protected]/

---
 Makefile      |  2 ++
 common-exit.c | 26 ++++++++++++++++
 common-init.c | 63 ++++++++++++++++++++++++++++++++++++++
 common-init.h |  6 ++++
 common-main.c | 83 ++-------------------------------------------------
 meson.build   |  2 ++
 6 files changed, 101 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h

index 97e8385b66..27e68ac039 100644
@@ -981,6 +981,8 @@ LIB_OBJS += combine-diff.o
 LIB_OBJS += commit-graph.o
 LIB_OBJS += commit-reach.o
 LIB_OBJS += commit.o
+LIB_OBJS += common-exit.o
+LIB_OBJS += common-init.o
 LIB_OBJS += compat/nonblock.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o

new file mode 100644
index 0000000000..1aaa538be3
@@ -0,0 +1,26 @@
+#include "git-compat-util.h"
+#include "trace2.h"
+
+static void check_bug_if_BUG(void)
+{
+	if (!bug_called_must_BUG)
+		return;
+	BUG("on exit(): had bug() call(s) in this process without explicit BUG_if_bug()");
+}
+
+/* We wrap exit() to call common_exit() in git-compat-util.h */
+int common_exit(const char *file, int line, int code)
+{
+	/*
+	 * For non-POSIX systems: Take the lowest 8 bits of the "code"
+	 * to e.g. turn -1 into 255. On a POSIX system this is
+	 * redundant, see exit(3) and wait(2), but as it doesn't harm
+	 * anything there we don't need to guard this with an "ifdef".
+	 */
+	code &= 0xff;
+
+	check_bug_if_BUG();
+	trace2_cmd_exit_fl(file, line, code);
+
+	return code;
+}

new file mode 100644
index 0000000000..3e6db20cae
@@ -0,0 +1,6 @@
+#ifndef COMMON_INIT_H
+#define COMMON_INIT_H
+
+void init_git(const char **argv);
+
+#endif /* COMMON_INIT_H */

index 0064eb64f5..e5ba28b47f 100644
@@ -245,6 +245,8 @@ libgit_sources = [
   'commit-graph.c',
   'commit-reach.c',
   'commit.c',
+  'common-exit.c',
+  'common-init.c',
   'compat/nonblock.c',
   'compat/obstack.c',
   'compat/terminal.c',

2.48.1.262.g85cc9f2d1e-goog

Introduce libgit-sys, a Rust wrapper crate that allows Rust code to call functions in libgit.a. This initial patch defines build rules and an interface that exposes user agent string getter functions as a proof of concept. This library can be tested with cargo test. In later commits, a higher-level library containing a more Rust-friendly interface will be added at contrib/libgit-rs.

Symbols in libgit can collide with symbols from other libraries such as libgit2. We avoid this by first exposing library symbols in public_symbol_export.[ch]. These symbols are prepended with "libgit_" to avoid collisions and set to visible using a visibility pragma. In build.rs, Rust builds contrib/libgit-rs/libgit-sys/libgitpub.a, which also contains libgit.a and other dependent libraries, with -fvisibility=hidden to hide all symbols within those libraries that haven't been exposed with a visibility pragma.

---
 .gitignore                                |  1 +
 Makefile                                  | 38 +++++++++++++
 contrib/libgit-sys/Cargo.lock             | 69 +++++++++++++++++++++++
 contrib/libgit-sys/Cargo.toml             | 19 +++++++
 contrib/libgit-sys/README.md              |  4 ++
 contrib/libgit-sys/build.rs               | 35 ++++++++++++
 contrib/libgit-sys/public_symbol_export.c | 22 ++++++++
 contrib/libgit-sys/public_symbol_export.h |  8 +++
 contrib/libgit-sys/src/lib.rs             | 46 +++++++++++++++
 t/Makefile                                | 10 ++++
 10 files changed, 252 insertions(+)
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

index e82aa19df0..31d7e64287 100644
@@ -250,3 +250,4 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-sys/target

index 27e68ac039..92989d3311 100644
@@ -416,6 +416,9 @@ include shared.mak
 # Define LINK_FUZZ_PROGRAMS if you want `make all` to also build the fuzz test
 # programs in oss-fuzz/.
 #
+# Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
+# test the Rust crate in contrib/libgit-sys.
+#
 # === Optional library: libintl ===
 #
 # Define NO_GETTEXT if you don't want Git output to be translated.

@@ -657,6 +660,8 @@ CURL_CONFIG = curl-config
 GCOV = gcov
 STRIP = strip
 SPATCH = spatch
+LD = ld
+OBJCOPY = objcopy
 
 export TCL_PATH TCLTK_PATH
 

@@ -2236,6 +2241,12 @@ ifdef FSMONITOR_OS_SETTINGS
 	COMPAT_OBJS += compat/fsmonitor/fsm-path-utils-$(FSMONITOR_OS_SETTINGS).o
 endif
 
+ifdef INCLUDE_LIBGIT_RS
+	# Enable symbol hiding in contrib/libgit-sys/libgitpub.a without making
+	# us rebuild the whole tree every time we run a Rust build.
+	BASIC_CFLAGS += -fvisibility=hidden
+endif
+
 ifeq ($(TCLTK_PATH),)
 NO_TCLTK = NoThanks
 endif

@@ -2732,6 +2743,10 @@ OBJECTS += $(UNIT_TEST_OBJS)
 OBJECTS += $(CLAR_TEST_OBJS)
 OBJECTS += $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
 
+ifdef INCLUDE_LIBGIT_RS
+	OBJECTS += contrib/libgit-sys/public_symbol_export.o
+endif
+
 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
 endif

@@ -3726,6 +3741,10 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
 	$(MAKE) -C Documentation/ clean
 	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
+	$(RM) -r contrib/libgit-sys/target
+	$(RM) contrib/libgit-sys/partial_symbol_export.o
+	$(RM) contrib/libgit-sys/hidden_symbol_export.o
+	$(RM) contrib/libgit-sys/libgitpub.a
 ifndef NO_PERL
 	$(RM) -r perl/build/
 endif

@@ -3887,3 +3906,22 @@ $(CLAR_TEST_PROG): $(UNIT_TEST_DIR)/clar.suite $(CLAR_TEST_OBJS) $(GITLIBS) GIT-
 build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
 unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests
+
+.PHONY: libgit-sys
+libgit-sys:
+	$(QUIET)(\
+		cd contrib/libgit-sys && \
+		cargo build \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-sys
+endif
+
+contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
+	$(LD) -r $^ -o $@
+
+contrib/libgit-sys/hidden_symbol_export.o: contrib/libgit-sys/partial_symbol_export.o
+	$(OBJCOPY) --localize-hidden $^ $@
+
+contrib/libgit-sys/libgitpub.a: contrib/libgit-sys/hidden_symbol_export.o
+	$(AR) $(ARFLAGS) $@ $^

new file mode 100644
index 0000000000..e0623022c3
@@ -0,0 +1,19 @@
+[package]
+name = "libgit-sys"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+links = "gitpub"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+description = "Native bindings to a portion of libgit"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libz-sys = "1.1.19"
+
+[build-dependencies]
+autocfg = "1.4.0"
+make-cmd = "0.1.0"

new file mode 100644
index 0000000000..c061cfcaf5
@@ -0,0 +1,4 @@
+# libgit-sys
+
+A small proof-of-concept crate showing how to provide a Rust FFI to Git
+internals.

new file mode 100644
index 0000000000..3ffd80ad91
@@ -0,0 +1,35 @@
+use std::env;
+use std::path::PathBuf;
+
+pub fn main() -> std::io::Result<()> {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+
+    let crate_root = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let git_root = crate_root.join("../..");
+    let dst = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    let make_output = make_cmd::gnu_make()
+        .env("DEVELOPER", "1")
+        .env_remove("PROFILE")
+        .current_dir(git_root.clone())
+        .args([
+            "INCLUDE_LIBGIT_RS=YesPlease",
+            "contrib/libgit-sys/libgitpub.a",
+        ])
+        .output()
+        .expect("Make failed to run");
+    if !make_output.status.success() {
+        panic!(
+            "Make failed:\n  stdout = {}\n  stderr = {}\n",
+            String::from_utf8(make_output.stdout).unwrap(),
+            String::from_utf8(make_output.stderr).unwrap()
+        );
+    }
+    std::fs::copy(crate_root.join("libgitpub.a"), dst.join("libgitpub.a"))?;
+    println!("cargo:rustc-link-search=native={}", dst.display());
+    println!("cargo:rustc-link-lib=gitpub");
+    println!("cargo:rerun-if-changed={}", git_root.display());
+
+    Ok(())
+}

new file mode 100644
index 0000000000..cd1602206e
@@ -0,0 +1,22 @@
+/* Shim to publicly export Git symbols. These must be renamed so that the
+ * original symbols can be hidden. Renaming these with a "libgit_" prefix also
+ * avoids conflicts with other libraries such as libgit2.
+ */
+
+#include "git-compat-util.h"
+#include "contrib/libgit-sys/public_symbol_export.h"
+#include "version.h"
+
+#pragma GCC visibility push(default)
+
+const char *libgit_user_agent(void)
+{
+	return git_user_agent();
+}
+
+const char *libgit_user_agent_sanitized(void)
+{
+	return git_user_agent_sanitized();
+}
+
+#pragma GCC visibility pop

new file mode 100644
index 0000000000..a3372f93fa
@@ -0,0 +1,8 @@
+#ifndef PUBLIC_SYMBOL_EXPORT_H
+#define PUBLIC_SYMBOL_EXPORT_H
+
+const char *libgit_user_agent(void);
+
+const char *libgit_user_agent_sanitized(void);
+
+#endif /* PUBLIC_SYMBOL_EXPORT_H */

index daa5fcae86..53ba01c21b 100644
@@ -177,3 +177,13 @@ perf:
 
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
+
+.PHONY: libgit-sys-test
+libgit-sys-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-sys && \
+		cargo test \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-sys-test
+endif

2.48.1.262.g85cc9f2d1e-goog

It's great to see some tests. This is looking good, I've left a couple of small comments below.

Done for V8.

Whoops, fixed, thanks.

The series is looking good and it seems that we'll be expecting a hopefully small and final reroll? I'll mark the topic in the "What's cooking" draft as such.

Thanks, all.

In preparation for implementing a higher-level Rust API for accessing Git configs, export some of the upstream configset API via libgitpub and libgit-sys. Since this will be exercised as part of the higher-level API in the next commit, no tests have been added for libgit-sys.

While we're at it, add git_configset_alloc() and git_configset_free() functions in libgitpub so that callers can manage config_set structs on the heap. This also allows non-C external consumers to treat config_sets as opaque structs.

---
 contrib/libgit-sys/public_symbol_export.c | 29 +++++++++++++++++++++
 contrib/libgit-sys/public_symbol_export.h | 10 ++++++++
 contrib/libgit-sys/src/lib.rs             | 31 ++++++++++++++++++++++-
 3 files changed, 69 insertions(+), 1 deletion(-)

index cd1602206e..a0297cb1a5 100644
@@ -4,11 +4,40 @@
  */
 
 #include "git-compat-util.h"
+#include "config.h"
 #include "contrib/libgit-sys/public_symbol_export.h"
 #include "version.h"
 
 #pragma GCC visibility push(default)
 
+struct libgit_config_set *libgit_configset_alloc(void)
+{
+	struct config_set *cs = xmalloc(sizeof(struct config_set));
+	git_configset_init(cs);
+	return (struct libgit_config_set *) cs;
+}
+
+void libgit_configset_free(struct libgit_config_set *cs)
+{
+	git_configset_clear((struct config_set *) cs);
+	free((struct config_set *) cs);
+}
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
+{
+	return git_configset_add_file((struct config_set *) cs, filename);
+}
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest)
+{
+	return git_configset_get_int((struct config_set *) cs, key, dest);
+}
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest)
+{
+	return git_configset_get_string((struct config_set *) cs, key, dest);
+}
+
 const char *libgit_user_agent(void)
 {
 	return git_user_agent();

index a3372f93fa..701db92d53 100644
@@ -1,6 +1,16 @@
 #ifndef PUBLIC_SYMBOL_EXPORT_H
 #define PUBLIC_SYMBOL_EXPORT_H
 
+struct libgit_config_set *libgit_configset_alloc(void);
+
+void libgit_configset_free(struct libgit_config_set *cs);
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename);
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest);
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest);
+
 const char *libgit_user_agent(void);
 
 const char *libgit_user_agent_sanitized(void);

index d4853f3074..dadb4e5f40 100644
@@ -1,15 +1,44 @@
 #[cfg(has_std__ffi__c_char)]
-use std::ffi::c_char;
+use std::ffi::{c_char, c_int};
 
 #[cfg(not(has_std__ffi__c_char))]
 #[allow(non_camel_case_types)]
 pub type c_char = i8;
 
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
+pub type c_int = i32;
+
 extern crate libz_sys;
 
+#[allow(non_camel_case_types)]
+#[repr(C)]
+pub struct libgit_config_set {
+    _data: [u8; 0],
+    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
+}
+
 extern "C" {
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
+
+    pub fn libgit_configset_alloc() -> *mut libgit_config_set;
+    pub fn libgit_configset_free(cs: *mut libgit_config_set);
+
+    pub fn libgit_configset_add_file(cs: *mut libgit_config_set, filename: *const c_char) -> c_int;
+
+    pub fn libgit_configset_get_int(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        int: *mut c_int,
+    ) -> c_int;
+
+    pub fn libgit_configset_get_string(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        dest: *mut *mut c_char,
+    ) -> c_int;
+
 }
 
 #[cfg(test)]

2.48.1.262.g85cc9f2d1e-goog

Hi Josh

This interface is looks nice, I've left a couple of comments below

struct libgit_config_set {
	struct config_set cs;
}

{
	struct libget_config_set *cs =
		xmalloc(sizeof(struct libgit_config_set));
	git_configset_init(&cs->cs);
	return cs;
}

Hmm yeah I remember this feedback from (checks Lore) back in V2. I think you're right, we should have gone this way from the beginning. Done in V8.

Fixed.

From: Calvin Wan <[email protected]>

The C functions exported by libgit-sys do not provide an idiomatic Rust interface. To make it easier to use these functions via Rust, add a higher-level "libgit" crate, that wraps the lower-level configset API with an interface that is more Rust-y.

This combination of $X and $X-sys crates is a common pattern for FFI in Rust, as documented in "The Cargo Book" [1].

[1] https://doc.rust-lang.org/cargo/reference/build-scripts.html#-sys-packages

---
 .gitignore                         |   1 +
 Makefile                           |  13 ++--
 contrib/libgit-rs/Cargo.lock       |  77 +++++++++++++++++++++
 contrib/libgit-rs/Cargo.toml       |  17 +++++
 contrib/libgit-rs/README.md        |  13 ++++
 contrib/libgit-rs/build.rs         |   4 ++
 contrib/libgit-rs/src/config.rs    | 106 +++++++++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs       |   1 +
 contrib/libgit-rs/testdata/config1 |   2 +
 contrib/libgit-rs/testdata/config2 |   2 +
 contrib/libgit-rs/testdata/config3 |   2 +
 contrib/libgit-sys/src/lib.rs      |   4 ++
 t/Makefile                         |   9 ++-
 13 files changed, 245 insertions(+), 6 deletions(-)
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3

index 31d7e64287..acdd8ce7c7 100644
@@ -250,4 +250,5 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-rs/target
 /contrib/libgit-sys/target

index 92989d3311..37b63de079 100644
@@ -417,7 +417,7 @@ include shared.mak
 # programs in oss-fuzz/.
 #
 # Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
-# test the Rust crate in contrib/libgit-sys.
+# test the Rust crates in contrib/libgit-sys and contrib/libgit-rs.
 #
 # === Optional library: libintl ===
 #

@@ -3741,7 +3741,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
 	$(MAKE) -C Documentation/ clean
 	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
-	$(RM) -r contrib/libgit-sys/target
+	$(RM) -r contrib/libgit-sys/target contrib/libgit-rs/target
 	$(RM) contrib/libgit-sys/partial_symbol_export.o
 	$(RM) contrib/libgit-sys/hidden_symbol_export.o
 	$(RM) contrib/libgit-sys/libgitpub.a

@@ -3907,14 +3907,19 @@ build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
 unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests
 
-.PHONY: libgit-sys
+.PHONY: libgit-sys libgit-rs
 libgit-sys:
 	$(QUIET)(\
 		cd contrib/libgit-sys && \
 		cargo build \
 	)
+libgit-rs:
+	$(QUIET)(\
+		cd contrib/libgit-rs && \
+		cargo build \
+	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys
+all:: libgit-sys libgit-rs
 endif
 
 contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a

new file mode 100644
index 0000000000..c3289e69db
@@ -0,0 +1,17 @@
+[package]
+name = "libgit"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libgit-sys = { version = "0.1.0", path = "../libgit-sys" }
+
+[build-dependencies]
+autocfg = "1.4.0"

new file mode 100644
index 0000000000..ff945e1ce2
@@ -0,0 +1,13 @@
+# libgit-rs
+
+Proof-of-concept Git bindings for Rust.
+
+```toml
+[dependencies]
+libgit = "0.1.0"
+```
+
+## Rust version requirements
+
+libgit-rs should support Rust versions at least as old as the version included
+in Debian stable (currently 1.63).

new file mode 100644
index 0000000000..f8bd01a690
@@ -0,0 +1,4 @@
+pub fn main() {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+}

new file mode 100644
index 0000000000..ef68c36943
@@ -0,0 +1 @@
+pub mod config;

new file mode 100644
index 0000000000..4e9a9d25d1
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 1

new file mode 100644
index 0000000000..b8d1eca423
@@ -0,0 +1,2 @@
+[trace2]
+	eventTarget = 1

new file mode 100644
index 0000000000..ca7b9a7c38
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 3

index dadb4e5f40..4bfc650450 100644
@@ -1,3 +1,5 @@
+use std::ffi::c_void;
+
 #[cfg(has_std__ffi__c_char)]
 use std::ffi::{c_char, c_int};
 

@@ -19,6 +21,8 @@ pub struct libgit_config_set {
 }
 
 extern "C" {
+    pub fn free(ptr: *mut c_void);
+
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
 

index 53ba01c21b..2994eb5fa9 100644
@@ -178,12 +178,17 @@ perf:
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
 
-.PHONY: libgit-sys-test
+.PHONY: libgit-sys-test libgit-rs-test
 libgit-sys-test:
 	$(QUIET)(\
 		cd ../contrib/libgit-sys && \
 		cargo test \
 	)
+libgit-rs-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-rs && \
+		cargo test \
+	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys-test
+all:: libgit-sys-test libgit-rs-test
 endif

2.48.1.262.g85cc9f2d1e-goog

Fixed since I'm sending out a V8 for Phillip's feedback anyway. Thanks.

It would be a "fix" only if we anticipate that we will add in the future more Rust things to contrib/ and all of them would follow the same pattern. Otherwise, it does not really matter, and as I said, what you posted is just fine.

Thanks.

This series provides two small Rust wrapper libraries around parts of
Git: "libgit-sys", which exposes a few functions from libgit.a, and "libgit", which provides a more Rust-friendly interface to some of those functions. In addition to included unit tests, at $DAYJOB we have tested building JJ[1] with our library and used it to replace some of the libgit2-rs uses.

[1] https://github.com/jj-vcs/jj

There is known NEEDSWORK, but I feel that they can be addressed in follow-up changes, rather than in this series. If you feel otherwise, please let me know:

* Investigate alternative methods of managing symbol visibility & renaming.

* Figure out symbol versioning

Changes in V8:
* Define a private libgit_config_set struct to avoid excessive casting in public_symbol_export.c.

* Style fixes: merge some Makefile rules, limit rule line length by defining intermediate variables, add initial empty comment line, add linebreaks in function definitions.

Changes in V7:
* Moved the ConfigSet implementation in libgit-rs to a config module.

* Added doc comments for ConfigSet and its methods.

* Fix meson builds by adding new object files to libgit_sources

* Moved INCLUDE_LIBGIT_RS Makefile changes earlier in the series, so that we can make it optional to compile some of the libgitpub sources. Squashed V6 patch 5/5 into this series' patch 4/4.

* Don't publicly export FFI types in libgit-rs.

* Removed extraneous -r argument to $(RM) in the clean rules.

* Added TODO reminder in Cargo.toml about removing Cargo.lock once we hit a certain minimum supported Rust version.

* Style cleanup in public_symbol_export.c

Changes in V6:
* Rebased onto current master, since V5 was several months old.

* Move libgit-sys out of libgit-rs; while this sort of nesting is common in Rust crates with standalone repositories, it doesn't make as much sense when they're contained in the larger Git project's repo.

* Standardize the naming of some of the Makefile targets to always include a dash in the "-rs" or "-sys" suffixes.

* Clean up READMEs and crate descriptions in preparation for uploading to crates.io.

Changes in V5:
* When building with INCLUDE_LIBGIT_RS defined, add "-fvisibility=hidden" to CFLAGS. This allows us to manage symbol visibility in libgitpub.a without causing make all to rebuild from scratch due to changing CFLAGS.

* Avoid using c_int in the higher-level Rust API.

* Remove libgitpub.a and intermediate files with make clean.

Changes in V4:
* Drop V3 patch #3, which added wrappers around repository initialization and config access. These are not well-libified, and they are not necessary for JJ's proof-of-concept use case, so let's avoid exporting them for now.

* Set a minimum supported Rust version of 1.63. Autodetect whether our Rust version has c_int and c_char types; if not, define them ourselves.

* When building libgitpub.a via build.rs, set DEVELOPER=1 to catch additional errors at build time.

* In build.rs, use the make_cmd crate to portable select the correct invocation of GNU Make.

* Follow naming standards for _alloc() and _free() functions.

* Use String instead of CString in higher-level API.

* Move libgit_configset_alloc() and libgit_configset_free() out of upstream Git, to the libgitpub shim library.

* In libgitpub, initialize libgit_config_set structs in the _alloc() function rather than with a separate _init() function.

* Remove unnecessary comments in libgit-sys showing where the wrapped functions were originally defined.

* Fix clippy lint: don't reborrow configfile path references.

* Various typo fixes and cargo fmt fixes.

Changes in V3:
* Renamed cgit-rs to libgit-rs and cgit-sys to libgit-sys

* Makefile cleanup, particularly adding config.mak options that developers can set to run Rust builds and tests by default (Patch 6)

* Provide testdata configs for unit tests

* ConfigSet API now uses &Path instead of &str -- more ergonomic for Rust users to pass in and errors out if the path string isn't UTF-8

* Fixed unresolved dependency on libz in Cargo.toml

Calvin Wan (1):
libgit: add higher-level libgit crate

Josh Steadmon (3):
common-main: split init and exit code into new files
libgit-sys: introduce Rust wrapper for libgit.a
libgit-sys: also export some config_set functions

 .gitignore                                |   2 +
 Makefile                                  |  49 ++++++++++
 common-exit.c                             |  26 ++++++
 common-init.c                             |  63 +++++++++++++
 common-init.h                             |   6 ++
 common-main.c                             |  83 +----------------
 contrib/libgit-rs/Cargo.lock              |  77 ++++++++++++++++
 contrib/libgit-rs/Cargo.toml              |  17 ++++
 contrib/libgit-rs/README.md               |  13 +++
 contrib/libgit-rs/build.rs                |   4 +
 contrib/libgit-rs/src/config.rs           | 106 ++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs              |   1 +
 contrib/libgit-rs/testdata/config1        |   2 +
 contrib/libgit-rs/testdata/config2        |   2 +
 contrib/libgit-rs/testdata/config3        |   2 +
 contrib/libgit-sys/Cargo.lock             |  69 ++++++++++++++
 contrib/libgit-sys/Cargo.toml             |  19 ++++
 contrib/libgit-sys/README.md              |   4 +
 contrib/libgit-sys/build.rs               |  35 +++++++
 contrib/libgit-sys/public_symbol_export.c |  59 ++++++++++++
 contrib/libgit-sys/public_symbol_export.h |  18 ++++
 contrib/libgit-sys/src/lib.rs             |  79 ++++++++++++++++
 meson.build                               |   2 +
 t/Makefile                                |  15 +++
 24 files changed, 672 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

Range-diff against v7:

1:  cd0cb9aa04 = 1:  cd0cb9aa04 common-main: split init and exit code into new files
2:  f1502b8590 ! 2:  3588a3c3fc libgit-sys: introduce Rust wrapper for libgit.a
    @@ Makefile: $(CLAR_TEST_PROG): $(UNIT_TEST_DIR)/clar.suite $(CLAR_TEST_OBJS) $(GIT
     +all:: libgit-sys
     +endif
     +
    -+contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
    ++LIBGIT_PUB_OBJS = contrib/libgit-sys/public_symbol_export.o
    ++LIBGIT_PUB_OBJS += libgit.a
    ++LIBGIT_PUB_OBJS += reftable/libreftable.a
    ++LIBGIT_PUB_OBJS += xdiff/lib.a
    ++
    ++LIBGIT_PARTIAL_EXPORT = contrib/libgit-sys/partial_symbol_export.o
    ++
    ++LIBGIT_HIDDEN_EXPORT = contrib/libgit-sys/hidden_symbol_export.o
    ++
    ++$(LIBGIT_PARTIAL_EXPORT): $(LIBGIT_PUB_OBJS)
     +	$(LD) -r $^ -o $@
     +
    -+contrib/libgit-sys/hidden_symbol_export.o: contrib/libgit-sys/partial_symbol_export.o
    ++$(LIBGIT_HIDDEN_EXPORT): $(LIBGIT_PARTIAL_EXPORT)
     +	$(OBJCOPY) --localize-hidden $^ $@
     +
    -+contrib/libgit-sys/libgitpub.a: contrib/libgit-sys/hidden_symbol_export.o
    ++contrib/libgit-sys/libgitpub.a: $(LIBGIT_HIDDEN_EXPORT)
     +	$(AR) $(ARFLAGS) $@ $^
     
      ## contrib/libgit-sys/Cargo.lock (new) ##
    @@ contrib/libgit-sys/build.rs (new)
     
      ## contrib/libgit-sys/public_symbol_export.c (new) ##
     @@
    -+/* Shim to publicly export Git symbols. These must be renamed so that the
    ++/*
    ++ * Shim to publicly export Git symbols. These must be renamed so that the
     + * original symbols can be hidden. Renaming these with a "libgit_" prefix also
     + * avoids conflicts with other libraries such as libgit2.
     + */
3:  d67d3648d1 ! 3:  f4452fffe6 libgit-sys: also export some config_set functions
    @@ contrib/libgit-sys/public_symbol_export.c
      
      #pragma GCC visibility push(default)
      
    ++struct libgit_config_set {
    ++	struct config_set cs;
    ++};
    ++
     +struct libgit_config_set *libgit_configset_alloc(void)
     +{
    -+	struct config_set *cs = xmalloc(sizeof(struct config_set));
    -+	git_configset_init(cs);
    -+	return (struct libgit_config_set *) cs;
    ++	struct libgit_config_set *cs =
    ++			xmalloc(sizeof(struct libgit_config_set));
    ++	git_configset_init(&cs->cs);
    ++	return cs;
     +}
     +
     +void libgit_configset_free(struct libgit_config_set *cs)
     +{
    -+	git_configset_clear((struct config_set *) cs);
    -+	free((struct config_set *) cs);
    ++	git_configset_clear(&cs->cs);
    ++	free(&cs->cs);
     +}
     +
     +int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
     +{
    -+	return git_configset_add_file((struct config_set *) cs, filename);
    ++	return git_configset_add_file(&cs->cs, filename);
     +}
     +
    -+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest)
    ++int libgit_configset_get_int(struct libgit_config_set *cs, const char *key,
    ++			     int *dest)
     +{
    -+	return git_configset_get_int((struct config_set *) cs, key, dest);
    ++	return git_configset_get_int(&cs->cs, key, dest);
     +}
     +
    -+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest)
    ++int libgit_configset_get_string(struct libgit_config_set *cs, const char *key,
    ++				char **dest)
     +{
    -+	return git_configset_get_string((struct config_set *) cs, key, dest);
    ++	return git_configset_get_string(&cs->cs, key, dest);
     +}
     +
      const char *libgit_user_agent(void)
4:  88425bb0b1 ! 4:  ada9fc0a13 libgit: add higher-level libgit crate
    @@ Makefile: build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
      	$(MAKE) -C t/ unit-tests
      
     -.PHONY: libgit-sys
    +-libgit-sys:
     +.PHONY: libgit-sys libgit-rs
    - libgit-sys:
    ++libgit-sys libgit-rs:
      	$(QUIET)(\
    - 		cd contrib/libgit-sys && \
    +-		cd contrib/libgit-sys && \
    ++		cd contrib/$@ && \
      		cargo build \
      	)
    -+libgit-rs:
    -+	$(QUIET)(\
    -+		cd contrib/libgit-rs && \
    -+		cargo build \
    -+	)
      ifdef INCLUDE_LIBGIT_RS
     -all:: libgit-sys
     +all:: libgit-sys libgit-rs
      endif
      
    - contrib/libgit-sys/partial_symbol_export.o: contrib/libgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
    + LIBGIT_PUB_OBJS = contrib/libgit-sys/public_symbol_export.o
     
      ## contrib/libgit-rs/Cargo.lock (new) ##
     @@

base-commit: 757161efcca150a9a96b312d9e780a071e601a03

2.48.1.262.g85cc9f2d1e-goog

Currently, object files in libgit.a reference common_exit(), which is contained in common-main.o. However, common-main.o also includes main(), which references cmd_main() in git.o, which in turn depends on all the builtin/*.o objects.

We would like to allow external users to link libgit.a without needing to include so many extra objects. Enable this by splitting common_exit() and check_bug_if_BUG() into a new file common-exit.c, and add common-exit.o to LIB_OBJS so that these are included in libgit.a.

This split has previously been proposed ([1], [2]) to support fuzz tests and unit tests by avoiding conflicting definitions for main(). However, both of those issues were resolved by other methods of avoiding symbol conflicts. Now we are trying to make libgit.a more self-contained, so hopefully we can revisit this approach.

Additionally, move the initialization code out of main() into a new init_git() function in its own file. Include this in libgit.a as well, so that external users can share our setup code without calling our main().

[1] https://lore.kernel.org/git/[email protected]/
[2] https://lore.kernel.org/git/[email protected]/

---
 Makefile      |  2 ++
 common-exit.c | 26 ++++++++++++++++
 common-init.c | 63 ++++++++++++++++++++++++++++++++++++++
 common-init.h |  6 ++++
 common-main.c | 83 ++-------------------------------------------------
 meson.build   |  2 ++
 6 files changed, 101 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h

index 97e8385b66..27e68ac039 100644
@@ -981,6 +981,8 @@ LIB_OBJS += combine-diff.o
 LIB_OBJS += commit-graph.o
 LIB_OBJS += commit-reach.o
 LIB_OBJS += commit.o
+LIB_OBJS += common-exit.o
+LIB_OBJS += common-init.o
 LIB_OBJS += compat/nonblock.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o

new file mode 100644
index 0000000000..1aaa538be3
@@ -0,0 +1,26 @@
+#include "git-compat-util.h"
+#include "trace2.h"
+
+static void check_bug_if_BUG(void)
+{
+	if (!bug_called_must_BUG)
+		return;
+	BUG("on exit(): had bug() call(s) in this process without explicit BUG_if_bug()");
+}
+
+/* We wrap exit() to call common_exit() in git-compat-util.h */
+int common_exit(const char *file, int line, int code)
+{
+	/*
+	 * For non-POSIX systems: Take the lowest 8 bits of the "code"
+	 * to e.g. turn -1 into 255. On a POSIX system this is
+	 * redundant, see exit(3) and wait(2), but as it doesn't harm
+	 * anything there we don't need to guard this with an "ifdef".
+	 */
+	code &= 0xff;
+
+	check_bug_if_BUG();
+	trace2_cmd_exit_fl(file, line, code);
+
+	return code;
+}

new file mode 100644
index 0000000000..3e6db20cae
@@ -0,0 +1,6 @@
+#ifndef COMMON_INIT_H
+#define COMMON_INIT_H
+
+void init_git(const char **argv);
+
+#endif /* COMMON_INIT_H */

index 0064eb64f5..e5ba28b47f 100644
@@ -245,6 +245,8 @@ libgit_sources = [
   'commit-graph.c',
   'commit-reach.c',
   'commit.c',
+  'common-exit.c',
+  'common-init.c',
   'compat/nonblock.c',
   'compat/obstack.c',
   'compat/terminal.c',

2.48.1.262.g85cc9f2d1e-goog

Introduce libgit-sys, a Rust wrapper crate that allows Rust code to call functions in libgit.a. This initial patch defines build rules and an interface that exposes user agent string getter functions as a proof of concept. This library can be tested with cargo test. In later commits, a higher-level library containing a more Rust-friendly interface will be added at contrib/libgit-rs.

Symbols in libgit can collide with symbols from other libraries such as libgit2. We avoid this by first exposing library symbols in public_symbol_export.[ch]. These symbols are prepended with "libgit_" to avoid collisions and set to visible using a visibility pragma. In build.rs, Rust builds contrib/libgit-rs/libgit-sys/libgitpub.a, which also contains libgit.a and other dependent libraries, with -fvisibility=hidden to hide all symbols within those libraries that haven't been exposed with a visibility pragma.

---
 .gitignore                                |  1 +
 Makefile                                  | 47 +++++++++++++++
 contrib/libgit-sys/Cargo.lock             | 69 +++++++++++++++++++++++
 contrib/libgit-sys/Cargo.toml             | 19 +++++++
 contrib/libgit-sys/README.md              |  4 ++
 contrib/libgit-sys/build.rs               | 35 ++++++++++++
 contrib/libgit-sys/public_symbol_export.c | 23 ++++++++
 contrib/libgit-sys/public_symbol_export.h |  8 +++
 contrib/libgit-sys/src/lib.rs             | 46 +++++++++++++++
 t/Makefile                                | 10 ++++
 10 files changed, 262 insertions(+)
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

index e82aa19df0..31d7e64287 100644
@@ -250,3 +250,4 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-sys/target

new file mode 100644
index 0000000000..e0623022c3
@@ -0,0 +1,19 @@
+[package]
+name = "libgit-sys"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+links = "gitpub"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+description = "Native bindings to a portion of libgit"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libz-sys = "1.1.19"
+
+[build-dependencies]
+autocfg = "1.4.0"
+make-cmd = "0.1.0"

new file mode 100644
index 0000000000..c061cfcaf5
@@ -0,0 +1,4 @@
+# libgit-sys
+
+A small proof-of-concept crate showing how to provide a Rust FFI to Git
+internals.

new file mode 100644
index 0000000000..3ffd80ad91
@@ -0,0 +1,35 @@
+use std::env;
+use std::path::PathBuf;
+
+pub fn main() -> std::io::Result<()> {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+
+    let crate_root = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let git_root = crate_root.join("../..");
+    let dst = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    let make_output = make_cmd::gnu_make()
+        .env("DEVELOPER", "1")
+        .env_remove("PROFILE")
+        .current_dir(git_root.clone())
+        .args([
+            "INCLUDE_LIBGIT_RS=YesPlease",
+            "contrib/libgit-sys/libgitpub.a",
+        ])
+        .output()
+        .expect("Make failed to run");
+    if !make_output.status.success() {
+        panic!(
+            "Make failed:\n  stdout = {}\n  stderr = {}\n",
+            String::from_utf8(make_output.stdout).unwrap(),
+            String::from_utf8(make_output.stderr).unwrap()
+        );
+    }
+    std::fs::copy(crate_root.join("libgitpub.a"), dst.join("libgitpub.a"))?;
+    println!("cargo:rustc-link-search=native={}", dst.display());
+    println!("cargo:rustc-link-lib=gitpub");
+    println!("cargo:rerun-if-changed={}", git_root.display());
+
+    Ok(())
+}

new file mode 100644
index 0000000000..4c153c6f0d
@@ -0,0 +1,23 @@
+/*
+ * Shim to publicly export Git symbols. These must be renamed so that the
+ * original symbols can be hidden. Renaming these with a "libgit_" prefix also
+ * avoids conflicts with other libraries such as libgit2.
+ */
+
+#include "git-compat-util.h"
+#include "contrib/libgit-sys/public_symbol_export.h"
+#include "version.h"
+
+#pragma GCC visibility push(default)
+
+const char *libgit_user_agent(void)
+{
+	return git_user_agent();
+}
+
+const char *libgit_user_agent_sanitized(void)
+{
+	return git_user_agent_sanitized();
+}
+
+#pragma GCC visibility pop

new file mode 100644
index 0000000000..a3372f93fa
@@ -0,0 +1,8 @@
+#ifndef PUBLIC_SYMBOL_EXPORT_H
+#define PUBLIC_SYMBOL_EXPORT_H
+
+const char *libgit_user_agent(void);
+
+const char *libgit_user_agent_sanitized(void);
+
+#endif /* PUBLIC_SYMBOL_EXPORT_H */

index daa5fcae86..53ba01c21b 100644
@@ -177,3 +177,13 @@ perf:
 
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
+
+.PHONY: libgit-sys-test
+libgit-sys-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-sys && \
+		cargo test \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-sys-test
+endif

2.48.1.262.g85cc9f2d1e-goog

Ack, will send a V9 soon with this & a fix for Phillip's feedback. Thanks.

In preparation for implementing a higher-level Rust API for accessing Git configs, export some of the upstream configset API via libgitpub and libgit-sys. Since this will be exercised as part of the higher-level API in the next commit, no tests have been added for libgit-sys.

While we're at it, add git_configset_alloc() and git_configset_free() functions in libgitpub so that callers can manage config_set structs on the heap. This also allows non-C external consumers to treat config_sets as opaque structs.

---
 contrib/libgit-sys/public_symbol_export.c | 36 +++++++++++++++++++++++
 contrib/libgit-sys/public_symbol_export.h | 10 +++++++
 contrib/libgit-sys/src/lib.rs             | 31 ++++++++++++++++++-
 3 files changed, 76 insertions(+), 1 deletion(-)

index 4c153c6f0d..dbb7948104 100644
@@ -5,11 +5,47 @@
  */
 
 #include "git-compat-util.h"
+#include "config.h"
 #include "contrib/libgit-sys/public_symbol_export.h"
 #include "version.h"
 
 #pragma GCC visibility push(default)
 
+struct libgit_config_set {
+	struct config_set cs;
+};
+
+struct libgit_config_set *libgit_configset_alloc(void)
+{
+	struct libgit_config_set *cs =
+			xmalloc(sizeof(struct libgit_config_set));
+	git_configset_init(&cs->cs);
+	return cs;
+}
+
+void libgit_configset_free(struct libgit_config_set *cs)
+{
+	git_configset_clear(&cs->cs);
+	free(&cs->cs);
+}
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
+{
+	return git_configset_add_file(&cs->cs, filename);
+}
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key,
+			     int *dest)
+{
+	return git_configset_get_int(&cs->cs, key, dest);
+}
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key,
+				char **dest)
+{
+	return git_configset_get_string(&cs->cs, key, dest);
+}
+
 const char *libgit_user_agent(void)
 {
 	return git_user_agent();

index a3372f93fa..701db92d53 100644
@@ -1,6 +1,16 @@
 #ifndef PUBLIC_SYMBOL_EXPORT_H
 #define PUBLIC_SYMBOL_EXPORT_H
 
+struct libgit_config_set *libgit_configset_alloc(void);
+
+void libgit_configset_free(struct libgit_config_set *cs);
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename);
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest);
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest);
+
 const char *libgit_user_agent(void);
 
 const char *libgit_user_agent_sanitized(void);

index d4853f3074..dadb4e5f40 100644
@@ -1,15 +1,44 @@
 #[cfg(has_std__ffi__c_char)]
-use std::ffi::c_char;
+use std::ffi::{c_char, c_int};
 
 #[cfg(not(has_std__ffi__c_char))]
 #[allow(non_camel_case_types)]
 pub type c_char = i8;
 
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
+pub type c_int = i32;
+
 extern crate libz_sys;
 
+#[allow(non_camel_case_types)]
+#[repr(C)]
+pub struct libgit_config_set {
+    _data: [u8; 0],
+    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
+}
+
 extern "C" {
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
+
+    pub fn libgit_configset_alloc() -> *mut libgit_config_set;
+    pub fn libgit_configset_free(cs: *mut libgit_config_set);
+
+    pub fn libgit_configset_add_file(cs: *mut libgit_config_set, filename: *const c_char) -> c_int;
+
+    pub fn libgit_configset_get_int(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        int: *mut c_int,
+    ) -> c_int;
+
+    pub fn libgit_configset_get_string(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        dest: *mut *mut c_char,
+    ) -> c_int;
+
 }
 
 #[cfg(test)]

2.48.1.262.g85cc9f2d1e-goog

From: Calvin Wan <[email protected]>

The C functions exported by libgit-sys do not provide an idiomatic Rust interface. To make it easier to use these functions via Rust, add a higher-level "libgit" crate, that wraps the lower-level configset API with an interface that is more Rust-y.

This combination of $X and $X-sys crates is a common pattern for FFI in Rust, as documented in "The Cargo Book" [1].

[1] https://doc.rust-lang.org/cargo/reference/build-scripts.html#-sys-packages

---
 .gitignore                         |   1 +
 Makefile                           |  12 ++--
 contrib/libgit-rs/Cargo.lock       |  77 +++++++++++++++++++++
 contrib/libgit-rs/Cargo.toml       |  17 +++++
 contrib/libgit-rs/README.md        |  13 ++++
 contrib/libgit-rs/build.rs         |   4 ++
 contrib/libgit-rs/src/config.rs    | 106 +++++++++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs       |   1 +
 contrib/libgit-rs/testdata/config1 |   2 +
 contrib/libgit-rs/testdata/config2 |   2 +
 contrib/libgit-rs/testdata/config3 |   2 +
 contrib/libgit-sys/src/lib.rs      |   4 ++
 t/Makefile                         |   9 ++-
 13 files changed, 242 insertions(+), 8 deletions(-)
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3

index 31d7e64287..acdd8ce7c7 100644
@@ -250,4 +250,5 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-rs/target
 /contrib/libgit-sys/target

index f2c08df4cb..f883d310aa 100644
@@ -417,7 +417,7 @@ include shared.mak
 # programs in oss-fuzz/.
 #
 # Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
-# test the Rust crate in contrib/libgit-sys.
+# test the Rust crates in contrib/libgit-sys and contrib/libgit-rs.
 #
 # === Optional library: libintl ===
 #

@@ -3741,7 +3741,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
 	$(MAKE) -C Documentation/ clean
 	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
-	$(RM) -r contrib/libgit-sys/target
+	$(RM) -r contrib/libgit-sys/target contrib/libgit-rs/target
 	$(RM) contrib/libgit-sys/partial_symbol_export.o
 	$(RM) contrib/libgit-sys/hidden_symbol_export.o
 	$(RM) contrib/libgit-sys/libgitpub.a

@@ -3907,14 +3907,14 @@ build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
 unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests
 
-.PHONY: libgit-sys
-libgit-sys:
+.PHONY: libgit-sys libgit-rs
+libgit-sys libgit-rs:
 	$(QUIET)(\
-		cd contrib/libgit-sys && \
+		cd contrib/$@ && \
 		cargo build \
 	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys
+all:: libgit-sys libgit-rs
 endif
 
 LIBGIT_PUB_OBJS = contrib/libgit-sys/public_symbol_export.o

new file mode 100644
index 0000000000..c3289e69db
@@ -0,0 +1,17 @@
+[package]
+name = "libgit"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libgit-sys = { version = "0.1.0", path = "../libgit-sys" }
+
+[build-dependencies]
+autocfg = "1.4.0"

new file mode 100644
index 0000000000..ff945e1ce2
@@ -0,0 +1,13 @@
+# libgit-rs
+
+Proof-of-concept Git bindings for Rust.
+
+```toml
+[dependencies]
+libgit = "0.1.0"
+```
+
+## Rust version requirements
+
+libgit-rs should support Rust versions at least as old as the version included
+in Debian stable (currently 1.63).

new file mode 100644
index 0000000000..f8bd01a690
@@ -0,0 +1,4 @@
+pub fn main() {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+}

new file mode 100644
index 0000000000..ef68c36943
@@ -0,0 +1 @@
+pub mod config;

new file mode 100644
index 0000000000..4e9a9d25d1
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 1

new file mode 100644
index 0000000000..b8d1eca423
@@ -0,0 +1,2 @@
+[trace2]
+	eventTarget = 1

new file mode 100644
index 0000000000..ca7b9a7c38
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 3

index dadb4e5f40..4bfc650450 100644
@@ -1,3 +1,5 @@
+use std::ffi::c_void;
+
 #[cfg(has_std__ffi__c_char)]
 use std::ffi::{c_char, c_int};
 

@@ -19,6 +21,8 @@ pub struct libgit_config_set {
 }
 
 extern "C" {
+    pub fn free(ptr: *mut c_void);
+
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
 

index 53ba01c21b..2994eb5fa9 100644
@@ -178,12 +178,17 @@ perf:
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
 
-.PHONY: libgit-sys-test
+.PHONY: libgit-sys-test libgit-rs-test
 libgit-sys-test:
 	$(QUIET)(\
 		cd ../contrib/libgit-sys && \
 		cargo test \
 	)
+libgit-rs-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-rs && \
+		cargo test \
+	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys-test
+all:: libgit-sys-test libgit-rs-test
 endif

2.48.1.262.g85cc9f2d1e-goog

Hi Josh

On 28/01/2025 22:01, Josh Steadmon wrote:

Thanks for re-rolling, the range-diff looks good to me apart from

Which I think should be "free(cs)". In practice it does not matter because we pass the same value to free() but it seems a bit odd to pass the address of the first member of the struct rather than the address of the struct itself.

I'm looking forward to seeing this merged soon

Best Wishes

Phillip

Yep sorry, got a bit careless with search-and-replace. Thanks for the catch!

This series provides two small Rust wrapper libraries around parts of
Git: "libgit-sys", which exposes a few functions from libgit.a, and "libgit", which provides a more Rust-friendly interface to some of those functions. In addition to included unit tests, at $DAYJOB we have tested building JJ[1] with our library and used it to replace some of the libgit2-rs uses.

[1] https://github.com/jj-vcs/jj

There is known NEEDSWORK, but I feel that they can be addressed in follow-up changes, rather than in this series. If you feel otherwise, please let me know:

* Investigate alternative methods of managing symbol visibility & renaming.

* Figure out symbol versioning

Changes in V9:
* Properly initialize Makefile var LIBGIT_PUB_OBJS.

* Pass the correct pointer to free in libgit_configset_free().

Changes in V8:
* Define a private libgit_config_set struct to avoid excessive casting in public_symbol_export.c.

* Style fixes: merge some Makefile rules, limit rule line length by defining intermediate variables, add initial empty comment line, add linebreaks in function definitions.

Changes in V7:
* Moved the ConfigSet implementation in libgit-rs to a config module.

* Added doc comments for ConfigSet and its methods.

* Fix meson builds by adding new object files to libgit_sources

* Moved INCLUDE_LIBGIT_RS Makefile changes earlier in the series, so that we can make it optional to compile some of the libgitpub sources. Squashed V6 patch 5/5 into this series' patch 4/4.

* Don't publicly export FFI types in libgit-rs.

* Removed extraneous -r argument to $(RM) in the clean rules.

* Added TODO reminder in Cargo.toml about removing Cargo.lock once we hit a certain minimum supported Rust version.

* Style cleanup in public_symbol_export.c

Changes in V6:
* Rebased onto current master, since V5 was several months old.

* Move libgit-sys out of libgit-rs; while this sort of nesting is common in Rust crates with standalone repositories, it doesn't make as much sense when they're contained in the larger Git project's repo.

* Standardize the naming of some of the Makefile targets to always include a dash in the "-rs" or "-sys" suffixes.

* Clean up READMEs and crate descriptions in preparation for uploading to crates.io.

Changes in V5:
* When building with INCLUDE_LIBGIT_RS defined, add "-fvisibility=hidden" to CFLAGS. This allows us to manage symbol visibility in libgitpub.a without causing make all to rebuild from scratch due to changing CFLAGS.

* Avoid using c_int in the higher-level Rust API.

* Remove libgitpub.a and intermediate files with make clean.

Changes in V4:
* Drop V3 patch #3, which added wrappers around repository initialization and config access. These are not well-libified, and they are not necessary for JJ's proof-of-concept use case, so let's avoid exporting them for now.

* Set a minimum supported Rust version of 1.63. Autodetect whether our Rust version has c_int and c_char types; if not, define them ourselves.

* When building libgitpub.a via build.rs, set DEVELOPER=1 to catch additional errors at build time.

* In build.rs, use the make_cmd crate to portable select the correct invocation of GNU Make.

* Follow naming standards for _alloc() and _free() functions.

* Use String instead of CString in higher-level API.

* Move libgit_configset_alloc() and libgit_configset_free() out of upstream Git, to the libgitpub shim library.

* In libgitpub, initialize libgit_config_set structs in the _alloc() function rather than with a separate _init() function.

* Remove unnecessary comments in libgit-sys showing where the wrapped functions were originally defined.

* Fix clippy lint: don't reborrow configfile path references.

* Various typo fixes and cargo fmt fixes.

Changes in V3:
* Renamed cgit-rs to libgit-rs and cgit-sys to libgit-sys

* Makefile cleanup, particularly adding config.mak options that developers can set to run Rust builds and tests by default (Patch 6)

* Provide testdata configs for unit tests

* ConfigSet API now uses &Path instead of &str -- more ergonomic for Rust users to pass in and errors out if the path string isn't UTF-8

* Fixed unresolved dependency on libz in Cargo.toml

Calvin Wan (1):
libgit: add higher-level libgit crate

Josh Steadmon (3):
common-main: split init and exit code into new files
libgit-sys: introduce Rust wrapper for libgit.a
libgit-sys: also export some config_set functions

 .gitignore                                |   2 +
 Makefile                                  |  50 ++++++++++
 common-exit.c                             |  26 ++++++
 common-init.c                             |  63 +++++++++++++
 common-init.h                             |   6 ++
 common-main.c                             |  83 +----------------
 contrib/libgit-rs/Cargo.lock              |  77 ++++++++++++++++
 contrib/libgit-rs/Cargo.toml              |  17 ++++
 contrib/libgit-rs/README.md               |  13 +++
 contrib/libgit-rs/build.rs                |   4 +
 contrib/libgit-rs/src/config.rs           | 106 ++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs              |   1 +
 contrib/libgit-rs/testdata/config1        |   2 +
 contrib/libgit-rs/testdata/config2        |   2 +
 contrib/libgit-rs/testdata/config3        |   2 +
 contrib/libgit-sys/Cargo.lock             |  69 ++++++++++++++
 contrib/libgit-sys/Cargo.toml             |  19 ++++
 contrib/libgit-sys/README.md              |   4 +
 contrib/libgit-sys/build.rs               |  35 +++++++
 contrib/libgit-sys/public_symbol_export.c |  59 ++++++++++++
 contrib/libgit-sys/public_symbol_export.h |  18 ++++
 contrib/libgit-sys/src/lib.rs             |  79 ++++++++++++++++
 meson.build                               |   2 +
 t/Makefile                                |  15 +++
 24 files changed, 673 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

Range-diff against v8:

1:  cd0cb9aa04 = 1:  cd0cb9aa04 common-main: split init and exit code into new files
2:  3588a3c3fc ! 2:  8793ff64a7 libgit-sys: introduce Rust wrapper for libgit.a
    @@ Makefile: $(CLAR_TEST_PROG): $(UNIT_TEST_DIR)/clar.suite $(CLAR_TEST_OBJS) $(GIT
     +all:: libgit-sys
     +endif
     +
    -+LIBGIT_PUB_OBJS = contrib/libgit-sys/public_symbol_export.o
    ++LIBGIT_PUB_OBJS =
    ++LIBGIT_PUB_OBJS += contrib/libgit-sys/public_symbol_export.o
     +LIBGIT_PUB_OBJS += libgit.a
     +LIBGIT_PUB_OBJS += reftable/libreftable.a
     +LIBGIT_PUB_OBJS += xdiff/lib.a
3:  f4452fffe6 ! 3:  ab32bd1d07 libgit-sys: also export some config_set functions
    @@ contrib/libgit-sys/public_symbol_export.c
     +void libgit_configset_free(struct libgit_config_set *cs)
     +{
     +	git_configset_clear(&cs->cs);
    -+	free(&cs->cs);
    ++	free(cs);
     +}
     +
     +int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)

4: ada9fc0a13 ! 4: 1bf8c5392c libgit: add higher-level libgit crate
@@ Makefile: build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
+all:: libgit-sys libgit-rs
endif

- LIBGIT_PUB_OBJS = contrib/libgit-sys/public_symbol_export.o
+ LIBGIT_PUB_OBJS =

## contrib/libgit-rs/Cargo.lock (new) ##
@@

base-commit: 757161efcca150a9a96b312d9e780a071e601a03

2.48.1.362.g079036d154-goog

Currently, object files in libgit.a reference common_exit(), which is contained in common-main.o. However, common-main.o also includes main(), which references cmd_main() in git.o, which in turn depends on all the builtin/*.o objects.

We would like to allow external users to link libgit.a without needing to include so many extra objects. Enable this by splitting common_exit() and check_bug_if_BUG() into a new file common-exit.c, and add common-exit.o to LIB_OBJS so that these are included in libgit.a.

This split has previously been proposed ([1], [2]) to support fuzz tests and unit tests by avoiding conflicting definitions for main(). However, both of those issues were resolved by other methods of avoiding symbol conflicts. Now we are trying to make libgit.a more self-contained, so hopefully we can revisit this approach.

Additionally, move the initialization code out of main() into a new init_git() function in its own file. Include this in libgit.a as well, so that external users can share our setup code without calling our main().

[1] https://lore.kernel.org/git/[email protected]/
[2] https://lore.kernel.org/git/[email protected]/

---
 Makefile      |  2 ++
 common-exit.c | 26 ++++++++++++++++
 common-init.c | 63 ++++++++++++++++++++++++++++++++++++++
 common-init.h |  6 ++++
 common-main.c | 83 ++-------------------------------------------------
 meson.build   |  2 ++
 6 files changed, 101 insertions(+), 81 deletions(-)
 create mode 100644 common-exit.c
 create mode 100644 common-init.c
 create mode 100644 common-init.h

index 97e8385b66..27e68ac039 100644
@@ -981,6 +981,8 @@ LIB_OBJS += combine-diff.o
 LIB_OBJS += commit-graph.o
 LIB_OBJS += commit-reach.o
 LIB_OBJS += commit.o
+LIB_OBJS += common-exit.o
+LIB_OBJS += common-init.o
 LIB_OBJS += compat/nonblock.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o

new file mode 100644
index 0000000000..1aaa538be3
@@ -0,0 +1,26 @@
+#include "git-compat-util.h"
+#include "trace2.h"
+
+static void check_bug_if_BUG(void)
+{
+	if (!bug_called_must_BUG)
+		return;
+	BUG("on exit(): had bug() call(s) in this process without explicit BUG_if_bug()");
+}
+
+/* We wrap exit() to call common_exit() in git-compat-util.h */
+int common_exit(const char *file, int line, int code)
+{
+	/*
+	 * For non-POSIX systems: Take the lowest 8 bits of the "code"
+	 * to e.g. turn -1 into 255. On a POSIX system this is
+	 * redundant, see exit(3) and wait(2), but as it doesn't harm
+	 * anything there we don't need to guard this with an "ifdef".
+	 */
+	code &= 0xff;
+
+	check_bug_if_BUG();
+	trace2_cmd_exit_fl(file, line, code);
+
+	return code;
+}

new file mode 100644
index 0000000000..3e6db20cae
@@ -0,0 +1,6 @@
+#ifndef COMMON_INIT_H
+#define COMMON_INIT_H
+
+void init_git(const char **argv);
+
+#endif /* COMMON_INIT_H */

index 0064eb64f5..e5ba28b47f 100644
@@ -245,6 +245,8 @@ libgit_sources = [
   'commit-graph.c',
   'commit-reach.c',
   'commit.c',
+  'common-exit.c',
+  'common-init.c',
   'compat/nonblock.c',
   'compat/obstack.c',
   'compat/terminal.c',

2.48.1.362.g079036d154-goog

Introduce libgit-sys, a Rust wrapper crate that allows Rust code to call functions in libgit.a. This initial patch defines build rules and an interface that exposes user agent string getter functions as a proof of concept. This library can be tested with cargo test. In later commits, a higher-level library containing a more Rust-friendly interface will be added at contrib/libgit-rs.

Symbols in libgit can collide with symbols from other libraries such as libgit2. We avoid this by first exposing library symbols in public_symbol_export.[ch]. These symbols are prepended with "libgit_" to avoid collisions and set to visible using a visibility pragma. In build.rs, Rust builds contrib/libgit-rs/libgit-sys/libgitpub.a, which also contains libgit.a and other dependent libraries, with -fvisibility=hidden to hide all symbols within those libraries that haven't been exposed with a visibility pragma.

---
 .gitignore                                |  1 +
 Makefile                                  | 48 ++++++++++++++++
 contrib/libgit-sys/Cargo.lock             | 69 +++++++++++++++++++++++
 contrib/libgit-sys/Cargo.toml             | 19 +++++++
 contrib/libgit-sys/README.md              |  4 ++
 contrib/libgit-sys/build.rs               | 35 ++++++++++++
 contrib/libgit-sys/public_symbol_export.c | 23 ++++++++
 contrib/libgit-sys/public_symbol_export.h |  8 +++
 contrib/libgit-sys/src/lib.rs             | 46 +++++++++++++++
 t/Makefile                                | 10 ++++
 10 files changed, 263 insertions(+)
 create mode 100644 contrib/libgit-sys/Cargo.lock
 create mode 100644 contrib/libgit-sys/Cargo.toml
 create mode 100644 contrib/libgit-sys/README.md
 create mode 100644 contrib/libgit-sys/build.rs
 create mode 100644 contrib/libgit-sys/public_symbol_export.c
 create mode 100644 contrib/libgit-sys/public_symbol_export.h
 create mode 100644 contrib/libgit-sys/src/lib.rs

index e82aa19df0..31d7e64287 100644
@@ -250,3 +250,4 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-sys/target

new file mode 100644
index 0000000000..e0623022c3
@@ -0,0 +1,19 @@
+[package]
+name = "libgit-sys"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+links = "gitpub"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+description = "Native bindings to a portion of libgit"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libz-sys = "1.1.19"
+
+[build-dependencies]
+autocfg = "1.4.0"
+make-cmd = "0.1.0"

new file mode 100644
index 0000000000..c061cfcaf5
@@ -0,0 +1,4 @@
+# libgit-sys
+
+A small proof-of-concept crate showing how to provide a Rust FFI to Git
+internals.

new file mode 100644
index 0000000000..3ffd80ad91
@@ -0,0 +1,35 @@
+use std::env;
+use std::path::PathBuf;
+
+pub fn main() -> std::io::Result<()> {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+
+    let crate_root = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let git_root = crate_root.join("../..");
+    let dst = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    let make_output = make_cmd::gnu_make()
+        .env("DEVELOPER", "1")
+        .env_remove("PROFILE")
+        .current_dir(git_root.clone())
+        .args([
+            "INCLUDE_LIBGIT_RS=YesPlease",
+            "contrib/libgit-sys/libgitpub.a",
+        ])
+        .output()
+        .expect("Make failed to run");
+    if !make_output.status.success() {
+        panic!(
+            "Make failed:\n  stdout = {}\n  stderr = {}\n",
+            String::from_utf8(make_output.stdout).unwrap(),
+            String::from_utf8(make_output.stderr).unwrap()
+        );
+    }
+    std::fs::copy(crate_root.join("libgitpub.a"), dst.join("libgitpub.a"))?;
+    println!("cargo:rustc-link-search=native={}", dst.display());
+    println!("cargo:rustc-link-lib=gitpub");
+    println!("cargo:rerun-if-changed={}", git_root.display());
+
+    Ok(())
+}

new file mode 100644
index 0000000000..4c153c6f0d
@@ -0,0 +1,23 @@
+/*
+ * Shim to publicly export Git symbols. These must be renamed so that the
+ * original symbols can be hidden. Renaming these with a "libgit_" prefix also
+ * avoids conflicts with other libraries such as libgit2.
+ */
+
+#include "git-compat-util.h"
+#include "contrib/libgit-sys/public_symbol_export.h"
+#include "version.h"
+
+#pragma GCC visibility push(default)
+
+const char *libgit_user_agent(void)
+{
+	return git_user_agent();
+}
+
+const char *libgit_user_agent_sanitized(void)
+{
+	return git_user_agent_sanitized();
+}
+
+#pragma GCC visibility pop

new file mode 100644
index 0000000000..a3372f93fa
@@ -0,0 +1,8 @@
+#ifndef PUBLIC_SYMBOL_EXPORT_H
+#define PUBLIC_SYMBOL_EXPORT_H
+
+const char *libgit_user_agent(void);
+
+const char *libgit_user_agent_sanitized(void);
+
+#endif /* PUBLIC_SYMBOL_EXPORT_H */

index daa5fcae86..53ba01c21b 100644
@@ -177,3 +177,13 @@ perf:
 
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
+
+.PHONY: libgit-sys-test
+libgit-sys-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-sys && \
+		cargo test \
+	)
+ifdef INCLUDE_LIBGIT_RS
+all:: libgit-sys-test
+endif

2.48.1.362.g079036d154-goog

In preparation for implementing a higher-level Rust API for accessing Git configs, export some of the upstream configset API via libgitpub and libgit-sys. Since this will be exercised as part of the higher-level API in the next commit, no tests have been added for libgit-sys.

While we're at it, add git_configset_alloc() and git_configset_free() functions in libgitpub so that callers can manage config_set structs on the heap. This also allows non-C external consumers to treat config_sets as opaque structs.

---
 contrib/libgit-sys/public_symbol_export.c | 36 +++++++++++++++++++++++
 contrib/libgit-sys/public_symbol_export.h | 10 +++++++
 contrib/libgit-sys/src/lib.rs             | 31 ++++++++++++++++++-
 3 files changed, 76 insertions(+), 1 deletion(-)

index 4c153c6f0d..dfbb257115 100644
@@ -5,11 +5,47 @@
  */
 
 #include "git-compat-util.h"
+#include "config.h"
 #include "contrib/libgit-sys/public_symbol_export.h"
 #include "version.h"
 
 #pragma GCC visibility push(default)
 
+struct libgit_config_set {
+	struct config_set cs;
+};
+
+struct libgit_config_set *libgit_configset_alloc(void)
+{
+	struct libgit_config_set *cs =
+			xmalloc(sizeof(struct libgit_config_set));
+	git_configset_init(&cs->cs);
+	return cs;
+}
+
+void libgit_configset_free(struct libgit_config_set *cs)
+{
+	git_configset_clear(&cs->cs);
+	free(cs);
+}
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename)
+{
+	return git_configset_add_file(&cs->cs, filename);
+}
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key,
+			     int *dest)
+{
+	return git_configset_get_int(&cs->cs, key, dest);
+}
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key,
+				char **dest)
+{
+	return git_configset_get_string(&cs->cs, key, dest);
+}
+
 const char *libgit_user_agent(void)
 {
 	return git_user_agent();

index a3372f93fa..701db92d53 100644
@@ -1,6 +1,16 @@
 #ifndef PUBLIC_SYMBOL_EXPORT_H
 #define PUBLIC_SYMBOL_EXPORT_H
 
+struct libgit_config_set *libgit_configset_alloc(void);
+
+void libgit_configset_free(struct libgit_config_set *cs);
+
+int libgit_configset_add_file(struct libgit_config_set *cs, const char *filename);
+
+int libgit_configset_get_int(struct libgit_config_set *cs, const char *key, int *dest);
+
+int libgit_configset_get_string(struct libgit_config_set *cs, const char *key, char **dest);
+
 const char *libgit_user_agent(void);
 
 const char *libgit_user_agent_sanitized(void);

index d4853f3074..dadb4e5f40 100644
@@ -1,15 +1,44 @@
 #[cfg(has_std__ffi__c_char)]
-use std::ffi::c_char;
+use std::ffi::{c_char, c_int};
 
 #[cfg(not(has_std__ffi__c_char))]
 #[allow(non_camel_case_types)]
 pub type c_char = i8;
 
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
+pub type c_int = i32;
+
 extern crate libz_sys;
 
+#[allow(non_camel_case_types)]
+#[repr(C)]
+pub struct libgit_config_set {
+    _data: [u8; 0],
+    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
+}
+
 extern "C" {
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
+
+    pub fn libgit_configset_alloc() -> *mut libgit_config_set;
+    pub fn libgit_configset_free(cs: *mut libgit_config_set);
+
+    pub fn libgit_configset_add_file(cs: *mut libgit_config_set, filename: *const c_char) -> c_int;
+
+    pub fn libgit_configset_get_int(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        int: *mut c_int,
+    ) -> c_int;
+
+    pub fn libgit_configset_get_string(
+        cs: *mut libgit_config_set,
+        key: *const c_char,
+        dest: *mut *mut c_char,
+    ) -> c_int;
+
 }
 
 #[cfg(test)]

2.48.1.362.g079036d154-goog

From: Calvin Wan <[email protected]>

The C functions exported by libgit-sys do not provide an idiomatic Rust interface. To make it easier to use these functions via Rust, add a higher-level "libgit" crate, that wraps the lower-level configset API with an interface that is more Rust-y.

This combination of $X and $X-sys crates is a common pattern for FFI in Rust, as documented in "The Cargo Book" [1].

[1] https://doc.rust-lang.org/cargo/reference/build-scripts.html#-sys-packages

---
 .gitignore                         |   1 +
 Makefile                           |  12 ++--
 contrib/libgit-rs/Cargo.lock       |  77 +++++++++++++++++++++
 contrib/libgit-rs/Cargo.toml       |  17 +++++
 contrib/libgit-rs/README.md        |  13 ++++
 contrib/libgit-rs/build.rs         |   4 ++
 contrib/libgit-rs/src/config.rs    | 106 +++++++++++++++++++++++++++++
 contrib/libgit-rs/src/lib.rs       |   1 +
 contrib/libgit-rs/testdata/config1 |   2 +
 contrib/libgit-rs/testdata/config2 |   2 +
 contrib/libgit-rs/testdata/config3 |   2 +
 contrib/libgit-sys/src/lib.rs      |   4 ++
 t/Makefile                         |   9 ++-
 13 files changed, 242 insertions(+), 8 deletions(-)
 create mode 100644 contrib/libgit-rs/Cargo.lock
 create mode 100644 contrib/libgit-rs/Cargo.toml
 create mode 100644 contrib/libgit-rs/README.md
 create mode 100644 contrib/libgit-rs/build.rs
 create mode 100644 contrib/libgit-rs/src/config.rs
 create mode 100644 contrib/libgit-rs/src/lib.rs
 create mode 100644 contrib/libgit-rs/testdata/config1
 create mode 100644 contrib/libgit-rs/testdata/config2
 create mode 100644 contrib/libgit-rs/testdata/config3

index 31d7e64287..acdd8ce7c7 100644
@@ -250,4 +250,5 @@ Release/
 /git.VC.db
 *.dSYM
 /contrib/buildsystems/out
+/contrib/libgit-rs/target
 /contrib/libgit-sys/target

index a772bff186..7681ec9a3d 100644
@@ -417,7 +417,7 @@ include shared.mak
 # programs in oss-fuzz/.
 #
 # Define INCLUDE_LIBGIT_RS if you want `make all` and `make test` to build and
-# test the Rust crate in contrib/libgit-sys.
+# test the Rust crates in contrib/libgit-sys and contrib/libgit-rs.
 #
 # === Optional library: libintl ===
 #

@@ -3741,7 +3741,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
 	$(MAKE) -C Documentation/ clean
 	$(RM) Documentation/GIT-EXCLUDED-PROGRAMS
-	$(RM) -r contrib/libgit-sys/target
+	$(RM) -r contrib/libgit-sys/target contrib/libgit-rs/target
 	$(RM) contrib/libgit-sys/partial_symbol_export.o
 	$(RM) contrib/libgit-sys/hidden_symbol_export.o
 	$(RM) contrib/libgit-sys/libgitpub.a

@@ -3907,14 +3907,14 @@ build-unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG)
 unit-tests: $(UNIT_TEST_PROGS) $(CLAR_TEST_PROG) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests
 
-.PHONY: libgit-sys
-libgit-sys:
+.PHONY: libgit-sys libgit-rs
+libgit-sys libgit-rs:
 	$(QUIET)(\
-		cd contrib/libgit-sys && \
+		cd contrib/$@ && \
 		cargo build \
 	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys
+all:: libgit-sys libgit-rs
 endif
 
 LIBGIT_PUB_OBJS =

new file mode 100644
index 0000000000..c3289e69db
@@ -0,0 +1,17 @@
+[package]
+name = "libgit"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+                      # version control. See https://lore.kernel.org/git/[email protected]/
+
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libgit-sys = { version = "0.1.0", path = "../libgit-sys" }
+
+[build-dependencies]
+autocfg = "1.4.0"

new file mode 100644
index 0000000000..ff945e1ce2
@@ -0,0 +1,13 @@
+# libgit-rs
+
+Proof-of-concept Git bindings for Rust.
+
+```toml
+[dependencies]
+libgit = "0.1.0"
+```
+
+## Rust version requirements
+
+libgit-rs should support Rust versions at least as old as the version included
+in Debian stable (currently 1.63).

new file mode 100644
index 0000000000..f8bd01a690
@@ -0,0 +1,4 @@
+pub fn main() {
+    let ac = autocfg::new();
+    ac.emit_has_path("std::ffi::c_char");
+}

new file mode 100644
index 0000000000..ef68c36943
@@ -0,0 +1 @@
+pub mod config;

new file mode 100644
index 0000000000..4e9a9d25d1
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 1

new file mode 100644
index 0000000000..b8d1eca423
@@ -0,0 +1,2 @@
+[trace2]
+	eventTarget = 1

new file mode 100644
index 0000000000..ca7b9a7c38
@@ -0,0 +1,2 @@
+[trace2]
+	eventNesting = 3

index dadb4e5f40..4bfc650450 100644
@@ -1,3 +1,5 @@
+use std::ffi::c_void;
+
 #[cfg(has_std__ffi__c_char)]
 use std::ffi::{c_char, c_int};
 

@@ -19,6 +21,8 @@ pub struct libgit_config_set {
 }
 
 extern "C" {
+    pub fn free(ptr: *mut c_void);
+
     pub fn libgit_user_agent() -> *const c_char;
     pub fn libgit_user_agent_sanitized() -> *const c_char;
 

index 53ba01c21b..2994eb5fa9 100644
@@ -178,12 +178,17 @@ perf:
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
 	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
 
-.PHONY: libgit-sys-test
+.PHONY: libgit-sys-test libgit-rs-test
 libgit-sys-test:
 	$(QUIET)(\
 		cd ../contrib/libgit-sys && \
 		cargo test \
 	)
+libgit-rs-test:
+	$(QUIET)(\
+		cd ../contrib/libgit-rs && \
+		cargo test \
+	)
 ifdef INCLUDE_LIBGIT_RS
-all:: libgit-sys-test
+all:: libgit-sys-test libgit-rs-test
 endif

2.48.1.362.g079036d154-goog

Hi Josh

The range-diff looks good. It's really nice to see this being added to git.

Best Wishes

Phillip