From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Teach Git to detect remote working directories on Windows and mark them as
incompatible with FSMonitor.
With this `git fsmonitor--daemon run` will error out with a message like it
does for bare repos.
Client commands, such as `git status`, will not attempt to start the daemon.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
compat/fsmonitor/fsm-settings-win32.c | 102 ++++++++++++++++++++++++++
1 file changed, 102 insertions(+)
diff --git a/compat/fsmonitor/fsm-settings-win32.c b/compat/fsmonitor/fsm-settings-win32.c
index ee78bba38e3..907655720bb 100644
--- a/compat/fsmonitor/fsm-settings-win32.c
+++ b/compat/fsmonitor/fsm-settings-win32.c
@@ -2,6 +2,7 @@
#include "config.h"
#include "repository.h"
#include "fsmonitor-settings.h"
+#include "fsmonitor.h"
/*
* VFS for Git is incompatible with FSMonitor.
@@ -23,6 +24,103 @@ static enum fsmonitor_reason check_vfs4git(struct repository *r)
return FSMONITOR_REASON_OK;
}
+/*
+ * Remote working directories are problematic for FSMonitor.
+ *
+ * The underlying file system on the server machine and/or the remote
+ * mount type 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.
+ *
+ * So (for now at least), mark remote working directories as
+ * incompatible.
+ *
+ * Notes for testing:
+ *
+ * (a) Windows allows a network share to be mapped to a drive letter.
+ * (This is the normal method to access it.)
+ *
+ * $ NET USE Z: \\server\share
+ * $ git -C Z:/repo status
+ *
+ * (b) Windows allows a network share to be referenced WITHOUT mapping
+ * it to drive letter.
+ *
+ * $ NET USE \\server\share\dir
+ * $ git -C //server/share/repo status
+ *
+ * (c) Windows allows "SUBST" to create a fake drive mapping to an
+ * arbitrary path (which may be remote)
+ *
+ * $ SUBST Q: Z:\repo
+ * $ git -C Q:/ status
+ *
+ * (d) Windows allows a directory symlink to be created on a local
+ * file system that points to a remote repo.
+ *
+ * $ mklink /d ./link //server/share/repo
+ * $ git -C ./link status
+ */
+static enum fsmonitor_reason check_remote(struct repository *r)
+{
+ wchar_t wpath[MAX_PATH];
+ wchar_t wfullpath[MAX_PATH];
+ size_t wlen;
+ UINT driveType;
+
+ /*
+ * Do everything in wide chars because the drive letter might be
+ * a multi-byte sequence. See win32_has_dos_drive_prefix().
+ */
+ if (xutftowcs_path(wpath, r->worktree) < 0)
+ return FSMONITOR_REASON_ERROR;
+
+ /*
+ * GetDriveTypeW() requires a final slash. We assume that the
+ * worktree pathname points to an actual directory.
+ */
+ wlen = wcslen(wpath);
+ if (wpath[wlen - 1] != L'\\' && wpath[wlen - 1] != L'/') {
+ wpath[wlen++] = L'\\';
+ wpath[wlen] = 0;
+ }
+
+ /*
+ * Normalize the path. If nothing else, this converts forward
+ * slashes to backslashes. This is essential to get GetDriveTypeW()
+ * correctly handle some UNC "\\server\share\..." paths.
+ */
+ if (!GetFullPathNameW(wpath, MAX_PATH, wfullpath, NULL))
+ return FSMONITOR_REASON_ERROR;
+
+ driveType = GetDriveTypeW(wfullpath);
+ trace_printf_key(&trace_fsmonitor,
+ "DriveType '%s' L'%ls' (%u)",
+ r->worktree, wfullpath, driveType);
+
+ if (driveType == DRIVE_REMOTE) {
+ trace_printf_key(&trace_fsmonitor,
+ "check_remote('%s') true",
+ r->worktree);
+ return FSMONITOR_REASON_REMOTE;
+ }
+
+ return FSMONITOR_REASON_OK;
+}
+
enum fsmonitor_reason fsm_os__incompatible(struct repository *r)
{
enum fsmonitor_reason reason;
@@ -31,5 +129,9 @@ enum fsmonitor_reason fsm_os__incompatible(struct repository *r)
if (reason != FSMONITOR_REASON_OK)
return reason;
+ reason = check_remote(r);
+ if (reason != FSMONITOR_REASON_OK)
+ return reason;
+
return FSMONITOR_REASON_OK;
}
--
gitgitgadget
