fsmonitor-settings: remote repos on Windows are incompatible

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@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pull/1271/merge
Jeff Hostetler 4 months ago committed by Junio C Hamano
parent 1e7be10de0
commit d989b266c1
  1. 102
      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;
}

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