diff options
| -rw-r--r-- | compat/fsmonitor/fsm-health-win32.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/compat/fsmonitor/fsm-health-win32.c b/compat/fsmonitor/fsm-health-win32.c index 24fc612..2ea08c1 100644 --- a/compat/fsmonitor/fsm-health-win32.c +++ b/compat/fsmonitor/fsm-health-win32.c @@ -29,8 +29,150 @@ struct fsm_health_data HANDLE hHandles[1]; /* the array does not own these handles */ #define HEALTH_SHUTDOWN 0 int nr_handles; /* number of active event handles */ + + struct wt_moved + { + wchar_t wpath[MAX_PATH + 1]; + BY_HANDLE_FILE_INFORMATION bhfi; + } wt_moved; }; +/* + * Lookup the system unique ID for the path. This is as close as + * we get to an inode number, but this also contains volume info, + * so it is a little stronger. + */ +static int lookup_bhfi(wchar_t *wpath, + BY_HANDLE_FILE_INFORMATION *bhfi) +{ + DWORD desired_access = FILE_LIST_DIRECTORY; + DWORD share_mode = + FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE; + HANDLE hDir; + + hDir = CreateFileW(wpath, desired_access, share_mode, NULL, + OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL); + if (hDir == INVALID_HANDLE_VALUE) { + error(_("[GLE %ld] health thread could not open '%ls'"), + GetLastError(), wpath); + return -1; + } + + if (!GetFileInformationByHandle(hDir, bhfi)) { + error(_("[GLE %ld] health thread getting BHFI for '%ls'"), + GetLastError(), wpath); + CloseHandle(hDir); + return -1; + } + + CloseHandle(hDir); + return 0; +} + +/* + * Compare the relevant fields from two system unique IDs. + * We use this to see if two different handles to the same + * path actually refer to the same *instance* of the file + * or directory. + */ +static int bhfi_eq(const BY_HANDLE_FILE_INFORMATION *bhfi_1, + const BY_HANDLE_FILE_INFORMATION *bhfi_2) +{ + return (bhfi_1->dwVolumeSerialNumber == bhfi_2->dwVolumeSerialNumber && + bhfi_1->nFileIndexHigh == bhfi_2->nFileIndexHigh && + bhfi_1->nFileIndexLow == bhfi_2->nFileIndexLow); +} + +/* + * Shutdown if the original worktree root directory been deleted, + * moved, or renamed? + * + * Since the main thread did a "chdir(getenv($HOME))" and our CWD + * is not in the worktree root directory and because the listener + * thread added FILE_SHARE_DELETE to the watch handle, it is possible + * for the root directory to be moved or deleted while we are still + * watching it. We want to detect that here and force a shutdown. + * + * Granted, a delete MAY cause some operations to fail, such as + * GetOverlappedResult(), but it is not guaranteed. And because + * ReadDirectoryChangesW() only reports on changes *WITHIN* the + * directory, not changes *ON* the directory, our watch will not + * receive a delete event for it. + * + * A move/rename of the worktree root will also not generate an event. + * And since the listener thread already has an open handle, it may + * continue to receive events for events within the directory. + * However, the pathname of the named-pipe was constructed using the + * original location of the worktree root. (Remember named-pipes are + * stored in the NPFS and not in the actual file system.) Clients + * trying to talk to the worktree after the move/rename will not + * reach our daemon process, since we're still listening on the + * pipe with original path. + * + * Furthermore, if the user does something like: + * + * $ mv repo repo.old + * $ git init repo + * + * A new daemon cannot be started in the new instance of "repo" + * because the named-pipe is still being used by the daemon on + * the original instance. + * + * So, detect move/rename/delete and shutdown. This should also + * handle unsafe drive removal. + * + * We use the file system unique ID to distinguish the original + * directory instance from a new instance and force a shutdown + * if the unique ID changes. + * + * Since a worktree move/rename/delete/unmount doesn't happen + * that often (and we can't get an immediate event anyway), we + * use a timeout and periodically poll it. + */ +static int has_worktree_moved(struct fsmonitor_daemon_state *state, + enum interval_fn_ctx ctx) +{ + struct fsm_health_data *data = state->health_data; + BY_HANDLE_FILE_INFORMATION bhfi; + int r; + + switch (ctx) { + case CTX_TERM: + return 0; + + case CTX_INIT: + if (xutftowcs_path(data->wt_moved.wpath, + state->path_worktree_watch.buf) < 0) { + error(_("could not convert to wide characters: '%s'"), + state->path_worktree_watch.buf); + return -1; + } + + /* + * On the first call we lookup the unique sequence ID for + * the worktree root directory. + */ + return lookup_bhfi(data->wt_moved.wpath, &data->wt_moved.bhfi); + + case CTX_TIMER: + r = lookup_bhfi(data->wt_moved.wpath, &bhfi); + if (r) + return r; + if (!bhfi_eq(&data->wt_moved.bhfi, &bhfi)) { + error(_("BHFI changed '%ls'"), data->wt_moved.wpath); + return -1; + } + return 0; + + default: + die(_("unhandled case in 'has_worktree_moved': %d"), + (int)ctx); + } + + return 0; +} + + int fsm_health__ctor(struct fsmonitor_daemon_state *state) { struct fsm_health_data *data; @@ -64,6 +206,7 @@ void fsm_health__dtor(struct fsmonitor_daemon_state *state) * A table of the polling functions. */ static interval_fn *table[] = { + has_worktree_moved, NULL, /* must be last */ }; |