fsmonitor: completing a stale patch that Implements fsmonitor for Linux

Documentation/config/fsmonitor--daemon.txt

@@ -4,8 +4,8 @@ fsmonitor.allowRemote::
     behavior.  Only respected when `core.fsmonitor` is set to `true`.
 
 fsmonitor.socketDir::
-    This Mac OS-specific option, if set, specifies the directory in
+    Mac OS and Linux-specific option. If set, specifies the directory in
     which to create the Unix domain socket used for communication
     between the fsmonitor daemon and various Git commands. The directory must
-    reside on a native Mac OS filesystem.  Only respected when `core.fsmonitor`
+    reside on a native filesystem.  Only respected when `core.fsmonitor`
     is set to `true`.

Documentation/git-fsmonitor--daemon.txt

@@ -76,23 +76,31 @@ repositories; this may be overridden by setting `fsmonitor.allowRemote` to
 correctly with all network-mounted repositories, so such use is considered
 experimental.
 
-On Mac OS, the inter-process communication (IPC) between various Git
+On Linux and Mac OS, the inter-process communication (IPC) between various Git
 commands and the fsmonitor daemon is done via a Unix domain socket (UDS) -- a
-special type of file -- which is supported by native Mac OS filesystems,
-but not on network-mounted filesystems, NTFS, or FAT32.  Other filesystems
-may or may not have the needed support; the fsmonitor daemon is not guaranteed
-to work with these filesystems and such use is considered experimental.
+special type of file -- which is supported by many native Linux and Mac OS
+filesystems, but not on network-mounted filesystems, NTFS, or FAT32.  Other
+filesystems may or may not have the needed support; the fsmonitor daemon is not
+guaranteed to work with these filesystems and such use is considered
+experimental.
 
 By default, the socket is created in the `.git` directory.  However, if the
 `.git` directory is on a network-mounted filesystem, it will instead be
 created at `$HOME/.git-fsmonitor-*` unless `$HOME` itself is on a
-network-mounted filesystem, in which case you must set the configuration
-variable `fsmonitor.socketDir` to the path of a directory on a Mac OS native
+network-mounted filesystem in which case you must set the configuration
+variable `fsmonitor.socketDir` to the path of a directory on a native
 filesystem in which to create the socket file.
 
 If none of the above directories (`.git`, `$HOME`, or `fsmonitor.socketDir`)
-is on a native Mac OS file filesystem the fsmonitor daemon will report an
-error that will cause the daemon and the currently running command to exit.
+is on a native Linux or Mac OS filesystem the fsmonitor daemon will report
+an error that will cause the daemon to exit and the currently running command
+to issue a warning.
+
+On Linux, the fsmonitor daemon registers a watch for each directory in the
+repository.  The default per-user limit for the number of watches on most Linux
+systems is 8192.  This may not be sufficient for large repositories or if
+multiple instances of the fsmonitor daemon are running.
+See https://watchexec.github.io/docs/inotify-limits.html[Linux inotify limits] for more information.
 
 CONFIGURATION
 -------------

Makefile

@@ -2088,6 +2088,10 @@ ifdef HAVE_CLOCK_GETTIME
 	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
 endif
 
+ifdef HAVE_LINUX_MAGIC_H
+	BASIC_CFLAGS += -DHAVE_LINUX_MAGIC_H
+endif
+
 ifdef HAVE_CLOCK_MONOTONIC
 	BASIC_CFLAGS += -DHAVE_CLOCK_MONOTONIC
 endif

compat/fsmonitor/fsm-health-linux.c

@@ -0,0 +1,24 @@
+#include "git-compat-util.h"
+#include "config.h"
+#include "fsmonitor.h"
+#include "fsm-health.h"
+#include "fsmonitor--daemon.h"
+
+int fsm_health__ctor(struct fsmonitor_daemon_state *state)
+{
+	return 0;
+}
+
+void fsm_health__dtor(struct fsmonitor_daemon_state *state)
+{
+	return;
+}
+
+void fsm_health__loop(struct fsmonitor_daemon_state *state)
+{
+	return;
+}
+
+void fsm_health__stop_async(struct fsmonitor_daemon_state *state)
+{
+}

compat/fsmonitor/fsm-ipc-darwin.c

@@ -1,56 +1 @@
-#include "git-compat-util.h"
-#include "config.h"
-#include "gettext.h"
-#include "hex.h"
-#include "path.h"
-#include "repository.h"
-#include "strbuf.h"
-#include "fsmonitor-ll.h"
-#include "fsmonitor-ipc.h"
-#include "fsmonitor-path-utils.h"
-
-static GIT_PATH_FUNC(fsmonitor_ipc__get_default_path, "fsmonitor--daemon.ipc")
-
-const char *fsmonitor_ipc__get_path(struct repository *r)
-{
-	static const char *ipc_path = NULL;
-	git_SHA_CTX sha1ctx;
-	char *sock_dir = NULL;
-	struct strbuf ipc_file = STRBUF_INIT;
-	unsigned char hash[GIT_MAX_RAWSZ];
-
-	if (!r)
-		BUG("No repository passed into fsmonitor_ipc__get_path");
-
-	if (ipc_path)
-		return ipc_path;
-
-
-	/* By default the socket file is created in the .git directory */
-	if (fsmonitor__is_fs_remote(r->gitdir) < 1) {
-		ipc_path = fsmonitor_ipc__get_default_path();
-		return ipc_path;
-	}
-
-	git_SHA1_Init(&sha1ctx);
-	git_SHA1_Update(&sha1ctx, r->worktree, strlen(r->worktree));
-	git_SHA1_Final(hash, &sha1ctx);
-
-	repo_config_get_string(r, "fsmonitor.socketdir", &sock_dir);
-
-	/* Create the socket file in either socketDir or $HOME */
-	if (sock_dir && *sock_dir) {
-		strbuf_addf(&ipc_file, "%s/.git-fsmonitor-%s",
-					sock_dir, hash_to_hex(hash));
-	} else {
-		strbuf_addf(&ipc_file, "~/.git-fsmonitor-%s", hash_to_hex(hash));
-	}
-	free(sock_dir);
-
-	ipc_path = interpolate_path(ipc_file.buf, 1);
-	if (!ipc_path)
-		die(_("Invalid path: %s"), ipc_file.buf);
-
-	strbuf_release(&ipc_file);
-	return ipc_path;
-}
+#include "fsm-ipc-unix.c"

compat/fsmonitor/fsm-ipc-linux.c

@@ -0,0 +1 @@
+#include "fsm-ipc-unix.c"

compat/fsmonitor/fsm-ipc-unix.c

@@ -0,0 +1,55 @@
+#include "git-compat-util.h"
+#include "config.h"
+#include "hex.h"
+#include "strbuf.h"
+#include "fsmonitor.h"
+#include "fsmonitor-ipc.h"
+#include "fsmonitor-path-utils.h"
+#include "gettext.h"
+#include "path.h"
+
+static GIT_PATH_FUNC(fsmonitor_ipc__get_default_path, "fsmonitor--daemon.ipc")
+
+const char *fsmonitor_ipc__get_path(struct repository *r)
+{
+	static const char *ipc_path = NULL;
+	git_SHA_CTX sha1ctx;
+	char *sock_dir = NULL;
+	struct strbuf ipc_file = STRBUF_INIT;
+	unsigned char hash[GIT_MAX_RAWSZ];
+
+	if (!r)
+		BUG("no repository passed into fsmonitor_ipc__get_path");
+
+	if (ipc_path)
+		return ipc_path;
+
+
+	/* By default the socket file is created in the .git directory */
+	if (fsmonitor__is_fs_remote(r->gitdir) < 1) {
+		ipc_path = fsmonitor_ipc__get_default_path();
+		return ipc_path;
+	}
+
+	git_SHA1_Init(&sha1ctx);
+	git_SHA1_Update(&sha1ctx, r->worktree, strlen(r->worktree));
+	git_SHA1_Final(hash, &sha1ctx);
+
+	repo_config_get_string(r, "fsmonitor.socketdir", &sock_dir);
+
+	/* Create the socket file in either socketDir or $HOME */
+	if (sock_dir && *sock_dir) {
+		strbuf_addf(&ipc_file, "%s/.git-fsmonitor-%s",
+					sock_dir, hash_to_hex(hash));
+	} else {
+		strbuf_addf(&ipc_file, "~/.git-fsmonitor-%s", hash_to_hex(hash));
+	}
+	free(sock_dir);
+
+	ipc_path = interpolate_path(ipc_file.buf, 1);
+	if (!ipc_path)
+		die(_("Invalid path: %s"), ipc_file.buf);
+
+	strbuf_release(&ipc_file);
+	return ipc_path;
+}