Merge branch 'jh/builtin-fsmonitor-part3'

More fsmonitor--daemon.

* jh/builtin-fsmonitor-part3: (30 commits)
  t7527: improve implicit shutdown testing in fsmonitor--daemon
  fsmonitor--daemon: allow --super-prefix argument
  t7527: test Unicode NFC/NFD handling on MacOS
  t/lib-unicode-nfc-nfd: helper prereqs for testing unicode nfc/nfd
  t/helper/hexdump: add helper to print hexdump of stdin
  fsmonitor: on macOS also emit NFC spelling for NFD pathname
  t7527: test FSMonitor on case insensitive+preserving file system
  fsmonitor: never set CE_FSMONITOR_VALID on submodules
  t/perf/p7527: add perf test for builtin FSMonitor
  t7527: FSMonitor tests for directory moves
  fsmonitor: optimize processing of directory events
  fsm-listen-darwin: shutdown daemon if worktree root is moved/renamed
  fsm-health-win32: force shutdown daemon if worktree root moves
  fsm-health-win32: add polling framework to monitor daemon health
  fsmonitor--daemon: stub in health thread
  fsmonitor--daemon: rename listener thread related variables
  fsmonitor--daemon: prepare for adding health thread
  fsmonitor--daemon: cd out of worktree root
  fsm-listen-darwin: ignore FSEvents caused by xattr changes on macOS
  unpack-trees: initialize fsmonitor_has_run_once in o->result
  ...

1 files changed, 89 insertions, 0 deletions

diff --git a/compat/fsmonitor/fsm-settings-darwin.c b/compat/fsmonitor/fsm-settings-darwin.c
new file mode 100644
index 0000000000..efc732c0f3
--- /dev/null
+++ b/compat/fsmonitor/fsm-settings-darwin.c
@@ -0,0 +1,89 @@
+#include "cache.h"
+#include "config.h"
+#include "repository.h"
+#include "fsmonitor-settings.h"
+#include "fsmonitor.h"
+#include <sys/param.h>
+#include <sys/mount.h>
+
+/*
+ * [1] 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
+ * are available at all to remote client machines.
+ *
+ * Kernel differences between the server and client machines also
+ * dictate the how (buffering, frequency, de-dup) the events are
+ * delivered to client machine processes.
+ *
+ * A client machine (such as a laptop) may choose to suspend/resume
+ * and it is unclear (without lots of testing) whether the watcher can
+ * resync after a resume.  We might be able to treat this as a normal
+ * "events were dropped by the kernel" event and do our normal "flush
+ * and resync" --or-- we might need to close the existing (zombie?)
+ * notification fd and create a new one.
+ *
+ * In theory, the above issues need to be addressed whether we are
+ * using the Hook or IPC API.
+ *
+ * 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
+ * (e.g. smbfs to a Windows server) or if the remote kernel does not
+ * allow a non-local process to bind() the socket.  (These problems
+ * could be fixed by moving the UDS out of the .git directory and to a
+ * 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.)
+ *
+ * So (for now at least), mark remote working directories as
+ * incompatible.
+ *
+ *
+ * [2] FAT32 and NTFS working directories are problematic too.
+ *
+ * The builtin FSMonitor uses a Unix domain socket in the .git
+ * directory for IPC.  These Windows drive formats do not support
+ * Unix domain sockets, so mark them as incompatible for the daemon.
+ *
+ */
+static enum fsmonitor_reason check_volume(struct repository *r)
+{
+	struct statfs fs;
+
+	if (statfs(r->worktree, &fs) == -1) {
+		int saved_errno = errno;
+		trace_printf_key(&trace_fsmonitor, "statfs('%s') failed: %s",
+				 r->worktree, strerror(saved_errno));
+		errno = saved_errno;
+		return FSMONITOR_REASON_ERROR;
+	}
+
+	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);
+
+	if (!(fs.f_flags & MNT_LOCAL))
+		return FSMONITOR_REASON_REMOTE;
+
+	if (!strcmp(fs.f_fstypename, "msdos")) /* aka FAT32 */
+		return FSMONITOR_REASON_NOSOCKETS;
+
+	if (!strcmp(fs.f_fstypename, "ntfs"))
+		return FSMONITOR_REASON_NOSOCKETS;
+
+	return FSMONITOR_REASON_OK;
+}
+
+enum fsmonitor_reason fsm_os__incompatible(struct repository *r)
+{
+	enum fsmonitor_reason reason;
+
+	reason = check_volume(r);
+	if (reason != FSMONITOR_REASON_OK)
+		return reason;
+
+	return FSMONITOR_REASON_OK;
+}