When smbd receives SMB Transact2 SetFileInfo command setting the modification
timestamp of the opened file, it keeps the timestamp in the pending_modtime
field and skips file_utime(). (See call_trans2setfilepathinfo() in
"source/smbd/trans2.c".) Thus, the follow-on SMB Transact2 QueryFileInfo command
(by the same process and others) asking the modtime of this opened file returns
the stale information (despite the fact that SetFileInfo command succeeded). The
modtime is updated when SMB CloseFile command is received, but by that time the
clients may have already cached the last modtime (which is stale!). This
behavior breaks the applications which rely on the modtime to detect the file
change.

smbd should call file_utime() after saving the pending_modtime. (Note: The
pending_modtime is still needed to set it at SMB CloseFile.)

Here is the sample test program.

#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include <stdlib.h>

#ifdef _UNICODE
int wmain(int argc, wchar_t *argv[], wchar_t *envp[])
#else
int main(int argc, char *argv[], char *envp[])
#endif
{
    HANDLE fh = INVALID_HANDLE_VALUE;
    const DWORD da = GENERIC_READ|GENERIC_WRITE;
    const DWORD sm = FILE_SHARE_READ|FILE_SHARE_WRITE;
    TCHAR *fp = NULL;
    DWORD n = 1;
    FILETIME lwt;
    DWORD i;
    BOOL failed = FALSE;

    if (argc < 2) {
	_ftprintf(stderr, _TEXT("Usage: %s pathname [count]\n"), argv[0]);
	exit(2);
    }

    fp = argv[1];

    if (argc > 2)
        n = _tcstoul((const TCHAR *)argv[2], NULL, 0);

    _ftprintf(stdout, _TEXT("%s %u\n"), fp, n);

    if ((fh = CreateFile(fp, da, sm,
                         NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS,
                         NULL)) == INVALID_HANDLE_VALUE) {
        _ftprintf(stderr, _TEXT("CreateFile(%s): %u\n"),
                  fp, GetLastError());
        return 1;
    }

    if (!GetFileTime(fh, NULL, NULL, &lwt)) {
        _ftprintf(stderr, _TEXT("GetFileTime(%s): %u\n"),
                  fp, GetLastError());
        return 1;
    }

    for (i = 0; i < n; i++) {
        FILETIME wt = lwt;
        FILETIME new_t;
        DWORDLONG t;

        t = ((DWORDLONG)(wt.dwHighDateTime) << 32)
            | (DWORDLONG)(wt.dwLowDateTime);
        t += (10*1000*1000);	/* +1 second */

        new_t.dwHighDateTime = (DWORD)((t >> 32) & 0xffffffff);
        new_t.dwLowDateTime = (DWORD)(t & 0xffffffff);

        if (!SetFileTime(fh, NULL, NULL, &new_t)) {
            _ftprintf(stderr, _TEXT("SetFileTime(%s): %u\n"),
                      fp, GetLastError());
            return 1;
        }

        if (!GetFileTime(fh, NULL, NULL, &lwt)) {
            _ftprintf(stderr, _TEXT("GetFileTime(%s): %u\n"),
                      fp, GetLastError());
            return 1;
        }

        if (CompareFileTime(&lwt, &new_t) != 0) {
            _ftprintf(stderr, _TEXT("**** The new time is different!\n"));
            failed = TRUE;
        }

        if (CompareFileTime(&lwt, &wt) == 0) {
            _ftprintf(stderr, _TEXT("**** Not changed from the previous!\n"));
            failed = TRUE;
        }
    }

    if (!CloseHandle(fh)) {
        _ftprintf(stderr, _TEXT("CloseHandle(): %u\n"), GetLastError());
        return 1;
    }

    if (failed) {
        FILETIME wt = lwt;

        if ((fh = CreateFile(fp, da, sm,
                             NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS,
                             NULL)) == INVALID_HANDLE_VALUE) {
            _ftprintf(stderr, _TEXT("CreateFile(%s): %u\n"),
                      fp, GetLastError());
            return 1;
        }

        if (!GetFileTime(fh, NULL, NULL, &lwt)) {
            _ftprintf(stderr, _TEXT("GetFileTime(%s): %u\n"),
                      fp, GetLastError());
            return 1;
        }

        if (CompareFileTime(&lwt, &wt) != 0)
            _ftprintf(stderr, _TEXT("**** Changed after CloseHandle()!\n"));

        if (!CloseHandle(fh)) {
            _ftprintf(stderr, _TEXT("CloseHandle(): %u\n"), GetLastError());
            return 1;
        }
    }

    return 0;
}