fsmonitor: option to allow fsmonitor to run against network-mounted repos

Follow-on to the work done to allow Windows to work against network-mounted repos for macOS.

Have macOS take advantage of the same configuration option, 'fsmonitor.allowRemote' that was introduced for Windows. Setting this option to true will override the default behavior (erroring-out) when a network-mounted repo is detected by fsmonitor.

The added wrinkle being that the Unix domain socket (UDS) file used for IPC cannot be created in a network location; instead $HOME is used if the default location is on the network. The user may, optionally, set the 'fsmonitor.socketDir' configuration option to a valid, local directory if $HOME itself is on the network or is simply not the desired location for the UDS file.

An additional issue is that for mount points in the root directory, FSEvents does not report a path that matches the worktree directory due to the introduction of 'synthetic firmlinks'. fsmonitor must map the FSEvents paths to the worktree directory by interrogating the root filesystem for synthetic firmlinks and using that information to translate the path.

v15 differs from v14:

* fix memory leak

v14 differs from v13:

* code review feedback

v13 differs from v12:

* code review feedback

v12 differs from v11:

* bug fixes

v11 differs from v10:

* incorporates code review feedback
* fix memory leak in fsm-listen-darwin.c

v10 differs from v9:

* incorporates code review feedback
* improves error messaging for incompatible socket directory

v9 differs from v8:

* incorporates code review feedback
* check for incompatibility before communicating with fsmonitor

v8 differs from v7:

* incorporates code review feedback
* gets the rebase right

v7 differs from v6:

* incorporates code review feedback

v6 differs from v5:

* incorporates earlier, Windows-specific changes that have not made it back yet to the master branch
* incorporates code review feedback
* adds documentation for 'fsmonitor.allowRemote' and 'fsmonitor.socketDir'

v5 differs significantly from earlier versions:

* redesign of handling 'fsmonitor.allowRemote' and 'fsmonitor.socketDir' such that these options are no longer added to the settings data structure but are rather read from config at point of use
* refactoring of code for handling platform-specific file system checks via a common interface to avoid platform #ifdef in IPC code and be in-model with other platform-specific fsmonitor code
* dealing with 'synthetic firmlinks' on macOS

Eric DeCosta (6):
fsmonitor: refactor filesystem checks to common interface
fsmonitor: relocate socket file if .git directory is remote
fsmonitor: avoid socket location check if using hook
fsmonitor: deal with synthetic firmlinks on macOS
fsmonitor: check for compatability before communicating with fsmonitor
fsmonitor: add documentation for allowRemote and socketDir options

 Documentation/config.txt                   |   2 +
 Documentation/config/fsmonitor--daemon.txt |  11 ++
 Documentation/git-fsmonitor--daemon.txt    |  37 ++++-
 Makefile                                   |   2 +
 builtin/fsmonitor--daemon.c                |  11 +-
 compat/fsmonitor/fsm-ipc-darwin.c          |  52 ++++++
 compat/fsmonitor/fsm-ipc-win32.c           |   9 ++
 compat/fsmonitor/fsm-listen-darwin.c       |  14 +-
 compat/fsmonitor/fsm-path-utils-darwin.c   | 135 ++++++++++++++++
 compat/fsmonitor/fsm-path-utils-win32.c    | 145 +++++++++++++++++
 compat/fsmonitor/fsm-settings-darwin.c     |  77 +++------
 compat/fsmonitor/fsm-settings-win32.c      | 174 +--------------------
 contrib/buildsystems/CMakeLists.txt        |   4 +
 fsmonitor--daemon.h                        |   3 +
 fsmonitor-ipc.c                            |  18 +--
 fsmonitor-ipc.h                            |   4 +-
 fsmonitor-path-utils.h                     |  60 +++++++
 fsmonitor-settings.c                       |  68 +++++++-
 fsmonitor-settings.h                       |   4 +-
 fsmonitor.c                                |   7 +
 20 files changed, 588 insertions(+), 249 deletions(-)
 create mode 100644 Documentation/config/fsmonitor--daemon.txt
 create mode 100644 compat/fsmonitor/fsm-ipc-darwin.c
 create mode 100644 compat/fsmonitor/fsm-ipc-win32.c
 create mode 100644 compat/fsmonitor/fsm-path-utils-darwin.c
 create mode 100644 compat/fsmonitor/fsm-path-utils-win32.c
 create mode 100644 fsmonitor-path-utils.h

base-commit: 3dcec76d9df911ed8321007b1d197c1a206dc164
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1326%2Fedecosta-mw%2Ffsmonitor_macos-v15
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1326/edecosta-mw/fsmonitor_macos-v15
Pull-Request: https://github.com/gitgitgadget/git/pull/1326

Range-diff vs v14:

1: 0b9b64428c5 ! 1: ec49a74086d fsmonitor: refactor filesystem checks to common interface

     @@ compat/fsmonitor/fsm-path-utils-darwin.c (new)
      +	else
      +		fs_info->is_remote = 0;
      +
     -+	fs_info->typename = fs.f_fstypename;
     ++	fs_info->typename = xstrdup(fs.f_fstypename);
      +
      +	trace_printf_key(&trace_fsmonitor,
      +				"'%s' is_remote: %d",
     @@ compat/fsmonitor/fsm-path-utils-darwin.c (new)
      +	struct fs_info fs;
      +	if (fsmonitor__get_fs_info(path, &fs))
      +		return -1;
     ++
     ++	free(fs.typename);
     ++
      +	return fs.is_remote;
      +}
      
     @@ compat/fsmonitor/fsm-settings-darwin.c
      -	trace_printf_key(&trace_fsmonitor,
      -			 "statfs('%s') [type 0x%08x][flags 0x%08x] '%s'",
      -			 r->worktree, fs.f_type, fs.f_flags, fs.f_fstypename);
     -+	strbuf_release(&path);
     - 
     +-
      -	if (!(fs.f_flags & MNT_LOCAL))
     -+	if (fs.is_remote)
     - 		return FSMONITOR_REASON_REMOTE;
     +-		return FSMONITOR_REASON_REMOTE;
     ++	strbuf_release(&path);
       
      -	if (!strcmp(fs.f_fstypename, "msdos")) /* aka FAT32 */
     -+	if (!strcmp(fs.typename, "msdos")) /* aka FAT32 */
     - 		return FSMONITOR_REASON_NOSOCKETS;
     - 
     +-		return FSMONITOR_REASON_NOSOCKETS;
     +-
      -	if (!strcmp(fs.f_fstypename, "ntfs"))
     -+	if (!strcmp(fs.typename, "ntfs"))
     ++	if (fs.is_remote ||
     ++		!strcmp(fs.typename, "msdos") ||
     ++		!strcmp(fs.typename, "ntfs")) {
     ++		free(fs.typename);
       		return FSMONITOR_REASON_NOSOCKETS;
     ++	}
       
     ++	free(fs.typename);
       	return FSMONITOR_REASON_OK;
     + }
     + 
      @@ compat/fsmonitor/fsm-settings-darwin.c: enum fsmonitor_reason fsm_os__incompatible(struct repository *r)
       {
       	enum fsmonitor_reason reason;
     @@ fsmonitor-path-utils.h (new)
      +/*
      + * Get some basic filesystem informtion for the given path
      + *
     ++ * The caller owns the storage that is occupied by fs_info and
     ++ * is responsible for releasing it.
     ++ *
      + * Returns -1 on error, zero otherwise.
      + */
      +int fsmonitor__get_fs_info(const char *path, struct fs_info *fs_info);
 2:  680d4c83f99 = 2:  7bf1cdfe3b2 fsmonitor: relocate socket file if .git directory is remote
 3:  7987d0c1f33 = 3:  c5e8b6cfe5d fsmonitor: avoid socket location check if using hook
 4:  241043b7c15 ! 4:  863063aefee fsmonitor: deal with synthetic firmlinks on macOS
     @@ compat/fsmonitor/fsm-path-utils-darwin.c
       #include <sys/mount.h>
       
      @@ compat/fsmonitor/fsm-path-utils-darwin.c: int fsmonitor__is_fs_remote(const char *path)
     - 		return -1;
     + 
       	return fs.is_remote;
       }
      +
     @@ fsmonitor-path-utils.h
      - * Get some basic filesystem informtion for the given path
      + * Get some basic filesystem information for the given path
        *
     -  * Returns -1 on error, zero otherwise.
     -  */
     +  * The caller owns the storage that is occupied by fs_info and
     +  * is responsible for releasing it.
      @@ fsmonitor-path-utils.h: int fsmonitor__get_fs_info(const char *path, struct fs_info *fs_info);
        */
       int fsmonitor__is_fs_remote(const char *path);

5: d906debba5e ! 5: fa974bfd5ef fsmonitor: check for compatability before communicating with fsmonitor
@@ Commit message

- ## compat/fsmonitor/fsm-settings-darwin.c ##
-@@ compat/fsmonitor/fsm-settings-darwin.c: static enum fsmonitor_reason check_uds_volume(struct repository *r)
- strbuf_release(&path);
-
- if (fs.is_remote)
-- return FSMONITOR_REASON_REMOTE;
-+ return FSMONITOR_REASON_NOSOCKETS;
-
- if (!strcmp(fs.typename, "msdos")) /* aka FAT32 */
- return FSMONITOR_REASON_NOSOCKETS;
-
## fsmonitor-settings.c ##
@@
#include "cache.h"
6: ed14fbd009e = 6: af7309745f7 fsmonitor: add documentation for allowRemote and socketDir options

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