[PATCH v2 0/4] fsmonitor: option to allow fsmonitor to run against network-mounted repos

["Eric DeCosta via GitGitGadget" <gitgitgadget@gmail.com>]

cc: Johannes Schindelin Johannes.Schindelin@gmx.de cc: Jeff Hostetler
git@jeffhostetler.com cc: Eric Sunshine sunshine@sunshineco.com cc: Torsten
Bögershausen tboegi@web.de

Eric DeCosta (2):
  fsmonitor: option to allow fsmonitor to run against network-mounted
    repos
  fsmonitor: macOS: allow fsmonitor to run against network-mounted repos

edecosta (2):
  Check working directory and Unix domain socket file for compatability
  Minor refactoring and simplification of Windows settings checks

 compat/fsmonitor/fsm-settings-darwin.c | 72 +++++++++++++++++++-------
 compat/fsmonitor/fsm-settings-win32.c  | 47 ++++++++++++++++-
 fsmonitor-ipc.c                        | 40 ++++++++++++--
 fsmonitor-ipc.h                        |  6 +++
 fsmonitor-settings.c                   | 67 +++++++++++++++++++++++-
 fsmonitor-settings.h                   |  4 ++
 6 files changed, 210 insertions(+), 26 deletions(-)


base-commit: 9bf691b78cf906751e65d65ba0c6ffdcd9a5a12c
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1326%2Fedecosta-mw%2Ffsmonitor_macos-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1326/edecosta-mw/fsmonitor_macos-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1326

Range-diff vs v1:

 -:  ----------- > 1:  40ce21e85c9 fsmonitor: option to allow fsmonitor to run against network-mounted repos
 -:  ----------- > 2:  46b4efd96cc fsmonitor: macOS: allow fsmonitor to run against network-mounted repos
 1:  425df16ac0b ! 3:  9b128a98149 fsmonitor: option to allow fsmonitor to run against network-mounted repos
     @@
       ## Metadata ##
     -Author: Eric DeCosta <edecosta@mathworks.com>
     +Author: edecosta <edecosta@mathworks.com>
      
       ## Commit message ##
     -    fsmonitor: option to allow fsmonitor to run against network-mounted repos
     +    Check working directory and Unix domain socket file for compatability
      
     -    Though perhaps not common, there are uses cases where users have large,
     -    network-mounted repos. Having the ability to run fsmonitor against
     -    network paths would benefit those users.
     +    Perform separate checks for the working directory and Unix domain socket
     +    (UDS) file location. The working directory may be located on a
     +    network-mounted file system if 'fsmonitor.allowRemote' is true. The UDS
     +    file may never be located on a network-mounted file system; additionally
     +    it may not be located on FAT32 or NTFS file systems.
      
     -    As a first step towards enabling fsmonitor to work against
     -    network-mounted repos, a configuration option, 'fsmonitor.allowRemote'
     -    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. In order for macOS to have parity with Windows,
     -    the same option is now introduced for macOS.
     -
     -    The the added wrinkle being that the Unix domain socket (UDS) file
     -    used for IPC cannot be created in a network location; instead the
     -    temporary directory is used.
     -
     -    Signed-off-by: Eric DeCosta <edecosta@mathworks.com>
     +    Signed-off-by: edecosta <edecosta@mathworks.com>
      
       ## compat/fsmonitor/fsm-settings-darwin.c ##
      @@
     - #include "config.h"
       #include "repository.h"
       #include "fsmonitor-settings.h"
     -+#include "fsmonitor-ipc.h"
       #include "fsmonitor.h"
     ++#include "fsmonitor-ipc.h"
       #include <sys/param.h>
       #include <sys/mount.h>
       
     -+/*
     -+ * Check if monitoring remote working directories is allowed.
     -+ *
     -+ * By default, monitoring remote working directories is
     -+ * disabled.  Users may override this behavior in enviroments where
     -+ * they have proper support.
     -+ */
     -+static int check_config_allowremote(struct repository *r)
     -+{
     -+	int allow;
     -+
     -+	if (!repo_config_get_bool(r, "fsmonitor.allowremote", &allow))
     -+		return allow;
     -+
     -+	return -1; /* fsmonitor.allowremote not set */
     -+}
     -+
       /*
     -  * [1] Remote working directories are problematic for FSMonitor.
     +- * [1] Remote working directories are problematic for FSMonitor.
     ++ * Remote working directories are problematic for FSMonitor.
        *
     +  * The underlying file system on the server machine and/or the remote
     +  * mount type (NFS, SAMBA, etc.) dictates whether notification events
      @@
        * In theory, the above issues need to be addressed whether we are
        * using the Hook or IPC API.
        *
     -+ * So (for now at least), mark remote working directories as
     -+ * incompatible by default.
     -+ *
     -  * For the builtin FSMonitor, we create the Unix domain socket for the
     +- * For the builtin FSMonitor, we create the Unix domain socket for the
      - * IPC in the .git directory.  If the working directory is remote,
      - * then the socket will be created on the remote file system.  This
      - * can fail if the remote file system does not support UDS file types
     @@ compat/fsmonitor/fsm-settings-darwin.c
      - * well-known local directory on the client machine, but care should
      - * be taken to ensure that $HOME is actually local and not a managed
      - * file share.)
     -+ * IPC in the temporary directory.  If the temporary directory is
     -+ * remote, then the socket will be created on the remote file system.
     -+ * This can fail if the remote file system does not support UDS file
     -+ * types (e.g. smbfs to a Windows server) or if the remote kernel does
     -+ * not allow a non-local process to bind() the socket.
     -  *
     -- * So (for now at least), mark remote working directories as
     +- *
     +  * So (for now at least), mark remote working directories as
      - * incompatible.
     -+ * Therefore remote UDS locations are marked as incompatible.
     -  *
     -  *
     -  * [2] FAT32 and NTFS working directories are problematic too.
     -  *
     +- *
     +- *
     +- * [2] FAT32 and NTFS working directories are problematic too.
     +- *
      - * The builtin FSMonitor uses a Unix domain socket in the .git
     -+ * The builtin FSMonitor uses a Unix domain socket in the temporary
     -  * directory for IPC.  These Windows drive formats do not support
     -  * Unix domain sockets, so mark them as incompatible for the daemon.
     +- * directory for IPC.  These Windows drive formats do not support
     +- * Unix domain sockets, so mark them as incompatible for the daemon.
     ++ * incompatible unless fsmonitor.allowRemote is true.
        *
     +  */
     + static enum fsmonitor_reason check_volume(struct repository *r)
      @@ compat/fsmonitor/fsm-settings-darwin.c: static enum fsmonitor_reason check_volume(struct repository *r)
       			 "statfs('%s') [type 0x%08x][flags 0x%08x] '%s'",
       			 r->worktree, fs.f_type, fs.f_flags, fs.f_fstypename);
       
     -+	if (!(fs.f_flags & MNT_LOCAL)) {
     -+		switch (check_config_allowremote(r)) {
     -+		case 0: /* config overrides and disables */
     ++	if (!(fs.f_flags & MNT_LOCAL)
     ++		&& (fsm_settings__get_allow_remote(r) < 1))
      +			return FSMONITOR_REASON_REMOTE;
     -+		case 1: /* config overrides and enables */
     -+			return FSMONITOR_REASON_OK;
     -+		default:
     -+			break; /* config has no opinion */
     -+		}
     -+
     -+		return FSMONITOR_REASON_REMOTE;
     -+	}
      +
      +	return FSMONITOR_REASON_OK;
      +}
      +
     ++/*
     ++ * For the builtin FSMonitor, we create the Unix domain socket (UDS)
     ++ * for the IPC in the .git directory by default or $HOME if
     ++ * fsmonitor.allowRemote is true.  If the directory is remote,
     ++ * then the socket will be created on the remote file system. This
     ++ * can fail if the remote file system does not support UDS file types
     ++ * (e.g. smbfs to a Windows server) or if the remote kernel does not
     ++ * allow a non-local process to bind() the socket.
     ++ *
     ++ * Therefore remote UDS locations are marked as incompatible.
     ++ *
     ++ * FAT32 and NTFS working directories are problematic too.
     ++ *
     ++ * These Windows drive formats do not support Unix domain sockets, so
     ++ * mark them as incompatible for the location of the UDS file.
     ++ *
     ++ */
      +static enum fsmonitor_reason check_uds_volume(void)
      +{
      +	struct statfs fs;
     -+	const char *path = fsmonitor_ipc__get_path();
     ++	struct strbuf path = STRBUF_INIT;
     ++	const char *ipc_path = fsmonitor_ipc__get_path();
     ++	strbuf_add(&path, ipc_path, strlen(ipc_path));
      +
     -+	if (statfs(path, &fs) == -1) {
     ++	if (statfs(dirname(path.buf), &fs) == -1) {
      +		int saved_errno = errno;
      +		trace_printf_key(&trace_fsmonitor, "statfs('%s') failed: %s",
     -+				 path, strerror(saved_errno));
     ++				 path.buf, strerror(saved_errno));
      +		errno = saved_errno;
     ++		strbuf_release(&path);
      +		return FSMONITOR_REASON_ERROR;
      +	}
      +
      +	trace_printf_key(&trace_fsmonitor,
      +			 "statfs('%s') [type 0x%08x][flags 0x%08x] '%s'",
     -+			 path, fs.f_type, fs.f_flags, fs.f_fstypename);
     ++			 path.buf, fs.f_type, fs.f_flags, fs.f_fstypename);
     ++	strbuf_release(&path);
      +
       	if (!(fs.f_flags & MNT_LOCAL))
       		return FSMONITOR_REASON_REMOTE;
     @@ compat/fsmonitor/fsm-settings-darwin.c: enum fsmonitor_reason fsm_os__incompatib
      +
       	return FSMONITOR_REASON_OK;
       }
     -
     - ## fsmonitor-ipc.c ##
     -@@
     - #include "fsmonitor-ipc.h"
     - #include "run-command.h"
     - #include "strbuf.h"
     -+#include "tempfile.h"
     - #include "trace2.h"
     - 
     - #ifndef HAVE_FSMONITOR_DAEMON_BACKEND
     -@@ fsmonitor-ipc.c: int fsmonitor_ipc__is_supported(void)
     - 	return 1;
     - }
     - 
     --GIT_PATH_FUNC(fsmonitor_ipc__get_path, "fsmonitor--daemon.ipc")
     -+GIT_PATH_FUNC(fsmonitor_ipc__get_pathfile, "fsmonitor--daemon.ipc")
     -+
     -+static char *gen_ipc_file(void)
     -+{
     -+	char *retval = NULL;
     -+	struct tempfile *ipc;
     -+
     -+	const char *ipc_file = fsmonitor_ipc__get_pathfile();
     -+	FILE *fp = fopen(ipc_file, "w");
     -+
     -+	if (!fp)
     -+		die_errno("error opening '%s'", ipc_file);
     -+	ipc = mks_tempfile_t("fsmonitor_ipc_XXXXXX");
     -+	strbuf_write(&ipc->filename, fp);
     -+	fclose(fp);
     -+	retval = strbuf_detach(&ipc->filename, NULL);
     -+	strbuf_release(&ipc->filename);
     -+	return retval;
     -+}
     -+
     -+const char *fsmonitor_ipc__get_path(void)
     -+{
     -+	char *retval = NULL;
     -+	struct strbuf sb = STRBUF_INIT;
     -+
     -+	const char *ipc_file = fsmonitor_ipc__get_pathfile();
     -+	FILE *fp = fopen(ipc_file, "r");
     -+
     -+	if (!fp) {
     -+		return gen_ipc_file();
     -+	} else {
     -+		strbuf_read(&sb, fileno(fp), 0);
     -+		fclose(fp);
     -+		fp = fopen(sb.buf, "r");
     -+		if (!fp) { /* generate new file */
     -+			if (unlink(ipc_file) < 0)
     -+				die_errno("could not remove '%s'", ipc_file);
     -+			return gen_ipc_file();
     -+		}
     -+		fclose(fp);
     -+		retval = strbuf_detach(&sb, NULL);
     -+		strbuf_release(&sb);
     -+		return retval;
     -+	}
     -+}
     - 
     - enum ipc_active_state fsmonitor_ipc__get_state(void)
     - {
     -
     - ## fsmonitor-ipc.h ##
     -@@ fsmonitor-ipc.h: int fsmonitor_ipc__is_supported(void);
     -  */
     - const char *fsmonitor_ipc__get_path(void);
     - 
     -+/*
     -+ * Returns the pathname to the file that contains the pathname to the
     -+ * IPC named pipe or Unix domain socket.
     -+ */
     -+const char *fsmonitor_ipc__get_pathfile(void);
     -+
     - /*
     -  * Try to determine whether there is a `git-fsmonitor--daemon` process
     -  * listening on the IPC pipe/socket.
 -:  ----------- > 4:  15c965801f8 Minor refactoring and simplification of Windows settings checks

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