fuzz: port OSS-Fuzz tests back to Git

Git's fuzz tests are run continuously as part of OSS-Fuzz [1]. Several additional fuzz tests have been contributed directly to OSS-Fuzz; however, these tests are vulnerable to bitrot because they are not built during Git's CI runs, and thus breaking changes are much less likely to be noticed by Git contributors.

OSS-Fuzz's recommended setup is for tests to live in the repository of the code they test and to be built along with other tests [1].

Port some of these tests back to the Git project, so that they can be built and tested during our normal development workflow and CI, and as such avoid future bitrot.

[1] https://google.github.io/oss-fuzz/advanced-topics/ideal-integration/

Changes in V2:
* Remove an errant echo in ci/run-build-and-minimal-fuzzers.sh
* Fix some style nits in ci/run-build-and-minimal-fuzzers.sh
* Fix whitespace errors in attr.{h,c}

Eric Sesterhenn (3):
fuzz: port fuzz-credential-from-url-gently from OSS-Fuzz
fuzz: port fuzz-parse-attr-line from OSS-Fuzz
fuzz: port fuzz-url-decode-mem from OSS-Fuzz

 Makefile                                   |  3 ++
 attr.c                                     | 40 +-------------------
 attr.h                                     | 43 ++++++++++++++++++++++
 ci/run-build-and-minimal-fuzzers.sh        | 13 ++++++-
 oss-fuzz/.gitignore                        |  3 ++
 oss-fuzz/fuzz-credential-from-url-gently.c | 32 ++++++++++++++++
 oss-fuzz/fuzz-parse-attr-line.c            | 39 ++++++++++++++++++++
 oss-fuzz/fuzz-url-decode-mem.c             | 43 ++++++++++++++++++++++
 8 files changed, 177 insertions(+), 39 deletions(-)
 create mode 100644 oss-fuzz/fuzz-credential-from-url-gently.c
 create mode 100644 oss-fuzz/fuzz-parse-attr-line.c
 create mode 100644 oss-fuzz/fuzz-url-decode-mem.c

Range-diff against v1:
1: 625b8d607e ! 1: 04225dd421 fuzz: port fuzz-credential-from-url-gently from OSS-Fuzz

    @@ ci/run-build-and-minimal-fuzzers.sh: group "Build fuzzers" make \
      
     -for fuzzer in commit-graph config date pack-headers pack-idx ; do
     +fuzzers="
    -+commit-graph \
    -+config \
    -+credential-from-url-gently \
    -+date \
    -+pack-headers \
    -+pack-idx \
    ++commit-graph
    ++config
    ++credential-from-url-gently
    ++date
    ++pack-headers
    ++pack-idx
     +"
     +
    -+for fuzzer in $fuzzers ; do
    ++for fuzzer in $fuzzers; do
      	begin_group "fuzz-$fuzzer"
    --	./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
    -+	echo ./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
    + 	./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
      	end_group "fuzz-$fuzzer"
    - done
     
      ## oss-fuzz/.gitignore ##
     @@

2: 770fe27c67 ! 2: 16c6573190 fuzz: port fuzz-parse-attr-line from OSS-Fuzz
@@ attr.c: static const char *parse_attr(const char *src, int lineno, const char *c
}

-static struct match_attr *parse_attr_line(const char *line, const char *src,
+- int lineno, unsigned flags)
+struct match_attr *parse_attr_line(const char *line, const char *src,
- int lineno, unsigned flags)
++ int lineno, unsigned flags)
{
size_t namelen, num_attr, i;
+ const char *cp, *name, *states;

## attr.h ##
@@ attr.h: int git_attr_system_is_enabled(void);
@@ attr.h: int git_attr_system_is_enabled(void);
+};
+
+struct match_attr *parse_attr_line(const char *line, const char *src,
-+ int lineno, unsigned flags);
++ int lineno, unsigned flags);
+
#endif /* ATTR_H */

## ci/run-build-and-minimal-fuzzers.sh ##
-@@ ci/run-build-and-minimal-fuzzers.sh: credential-from-url-gently \
- date \
- pack-headers \
- pack-idx \
-+parse-attr-line \
+@@ ci/run-build-and-minimal-fuzzers.sh: credential-from-url-gently
+ date
+ pack-headers
+ pack-idx
++parse-attr-line
"

- for fuzzer in $fuzzers ; do
+ for fuzzer in $fuzzers; do

## oss-fuzz/.gitignore ##
@@ oss-fuzz/.gitignore: fuzz-credential-from-url-gently
3: 4c9813313c ! 3: ec6b5eed71 fuzz: port fuzz-url-decode-mem from OSS-Fuzz
@@ Makefile: FUZZ_OBJS += oss-fuzz/fuzz-date.o

## ci/run-build-and-minimal-fuzzers.sh ##
-@@ ci/run-build-and-minimal-fuzzers.sh: date \
- pack-headers \
- pack-idx \
- parse-attr-line \
-+url-decode-mem \
+@@ ci/run-build-and-minimal-fuzzers.sh: date
+ pack-headers
+ pack-idx
+ parse-attr-line
++url-decode-mem
"

- for fuzzer in $fuzzers ; do
+ for fuzzer in $fuzzers; do

## oss-fuzz/.gitignore ##
@@ oss-fuzz/.gitignore: fuzz-date

base-commit: 159f2d50e75c17382c9f4eb7cbda671a6fa612d1

2.47.0.rc1.288.g06298d1525-goog