Discussion:
fstat: fix time_t values on native Windows
(too old to reply)
Bruno Haible
2017-04-29 20:53:38 UTC
Permalink
Raw Message
Per the discussion in the thread of
<https://lists.gnu.org/archive/html/bug-gnulib/2017-04/msg00134.html>.


2017-04-29 Bruno Haible <***@clisp.org>

fstat: Fix time_t values on native Windows platforms.
* doc/posix-functions/fstat.texi: Mention the problem with st_*time.
* lib/stat-w32.h: New file.
* lib/stat-w32.c: New file.
* lib/fstat.c: Don't include msvc-inval.h. Include msvc-nothrow.h,
stat-w32.h instead.
(fstat_nothrow): Remove function.
(rpl_fstat): Implement by means of _gl_fstat_by_handle.
* m4/fstat.m4 (gl_FUNC_FSTAT): On native Windows, set REPLACE_FSTAT
always.
(gl_PREREQ_FSTAT): Require gl_HEADER_SYS_STAT_H.
* modules/fstat (Files): Add lib/stat-w32.h, lib/stat-w32.c.
(Depends-on): Remove msvc-inval. Add pathmax, msvc-nothrow.
(configure.ac): Also compile lib/stat-w32.c.

diff --git a/doc/posix-functions/fstat.texi b/doc/posix-functions/fstat.texi
index 0f5b860..cb662fc 100644
--- a/doc/posix-functions/fstat.texi
+++ b/doc/posix-functions/fstat.texi
@@ -15,6 +15,11 @@ MSVC 9.
On platforms where @code{off_t} is a 32-bit type, @code{fstat} may not correctly
report the size of files or block devices larger than 2 GB.
(Cf. @code{AC_SYS_LARGEFILE}.)
+@item
+The @code{st_atime}, @code{st_ctime}, @code{st_mtime} field are affected by
+the current time zone and by the DST flag of the current time zone on some
+platforms:
+mingw, MSVC 14 (when the environment variable @code{TZ} is set).
@end itemize

Portability problems not fixed by Gnulib:
diff --git a/lib/fstat.c b/lib/fstat.c
index a5aabc5..a4896e3 100644
--- a/lib/fstat.c
+++ b/lib/fstat.c
@@ -23,20 +23,28 @@
/* Get the original definition of fstat. It might be defined as a macro. */
#include <sys/types.h>
#include <sys/stat.h>
-#if _GL_WINDOWS_64_BIT_ST_SIZE
-# undef stat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
-# define stat _stati64
-# undef fstat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
-# define fstat _fstati64
-#endif
#undef __need_system_sys_stat_h

+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+# define WINDOWS_NATIVE
+# if _GL_WINDOWS_64_BIT_ST_SIZE
+# undef stat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
+# define stat _stati64
+# undef fstat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
+# define fstat _fstati64
+# endif
+#endif
+
+#if !defined WINDOWS_NATIVE
+
static int
orig_fstat (int fd, struct stat *buf)
{
return fstat (fd, buf);
}

+#endif
+
/* Specification. */
/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
eliminates this include because of the preliminary #include <sys/stat.h>
@@ -45,32 +53,11 @@ orig_fstat (int fd, struct stat *buf)

#include <errno.h>
#include <unistd.h>
-
-#if HAVE_MSVC_INVALID_PARAMETER_HANDLER
-# include "msvc-inval.h"
-#endif
-
-#if HAVE_MSVC_INVALID_PARAMETER_HANDLER
-static int
-fstat_nothrow (int fd, struct stat *buf)
-{
- int result;
-
- TRY_MSVC_INVAL
- {
- result = orig_fstat (fd, buf);
- }
- CATCH_MSVC_INVAL
- {
- result = -1;
- errno = EBADF;
- }
- DONE_MSVC_INVAL;
-
- return result;
-}
-#else
-# define fstat_nothrow orig_fstat
+#ifdef WINDOWS_NATIVE
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+# include "msvc-nothrow.h"
+# include "stat-w32.h"
#endif

int
@@ -84,5 +71,20 @@ rpl_fstat (int fd, struct stat *buf)
return stat (name, buf);
#endif

- return fstat_nothrow (fd, buf);
+#ifdef WINDOWS_NATIVE
+ /* Fill the fields ourselves, because the original fstat function returns
+ values for st_atime, st_mtime, st_ctime that depend on the current time
+ zone. See
+ <https://lists.gnu.org/archive/html/bug-gnulib/2017-04/msg00134.html> */
+ HANDLE h = (HANDLE) _get_osfhandle (fd);
+
+ if (h == INVALID_HANDLE_VALUE)
+ {
+ errno = EBADF;
+ return -1;
+ }
+ return _gl_fstat_by_handle (h, NULL, buf);
+#else
+ return orig_fstat (fd, buf);
+#endif
}
diff --git a/lib/stat-w32.c b/lib/stat-w32.c
new file mode 100644
index 0000000..4f4a105
--- /dev/null
+++ b/lib/stat-w32.c
@@ -0,0 +1,293 @@
+/* Core of implementation of fstat and stat for native Windows.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible. */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+# if _GL_WINDOWS_64_BIT_ST_SIZE
+# undef stat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
+# define stat _stati64
+# endif
+# include <errno.h>
+# include <limits.h>
+# include <unistd.h>
+# include <windows.h>
+
+/* Specification. */
+# include "stat-w32.h"
+
+# include "pathmax.h"
+
+/* GetFinalPathNameByHandle was introduced only in Windows Vista. */
+typedef DWORD (WINAPI * GetFinalPathNameByHandleFuncType) (HANDLE hFile,
+ LPTSTR lpFilePath,
+ DWORD lenFilePath,
+ DWORD dwFlags);
+static GetFinalPathNameByHandleFuncType GetFinalPathNameByHandleFunc = NULL;
+static BOOL initialized = FALSE;
+
+static void
+initialize (void)
+{
+ HMODULE kernel32 = LoadLibrary ("kernel32.dll");
+ if (kernel32 != NULL)
+ {
+ GetFinalPathNameByHandleFunc =
+ (GetFinalPathNameByHandleFuncType) GetProcAddress (kernel32, "GetFinalPathNameByHandleA");
+ }
+ initialized = TRUE;
+}
+
+/* Converts a FILETIME to GMT time since 1970-01-01 00:00:00. */
+time_t
+_gl_convert_FILETIME_to_POSIX (const FILETIME *ft)
+{
+ /* FILETIME: <https://msdn.microsoft.com/en-us/library/ms724284.aspx> */
+ unsigned long long since_1601 =
+ ((unsigned long long) ft->dwHighDateTime << 32)
+ | (unsigned long long) ft->dwLowDateTime;
+ if (since_1601 == 0)
+ return 0;
+ /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
+ years, in total 134774 days. */
+ unsigned long long since_1970 =
+ since_1601 - (unsigned long long) 134774 * (unsigned long long) 86400 * (unsigned long long) 10000000;
+ return since_1970 / (unsigned long long) 10000000;
+}
+
+/* Fill *BUF with information about the file designated by H.
+ PATH is the file name, if known, otherwise NULL.
+ Return 0 if successful, or -1 with errno set upon failure. */
+int
+_gl_fstat_by_handle (HANDLE h, const char *path, struct stat *buf)
+{
+ /* GetFileType
+ <https://msdn.microsoft.com/en-us/library/aa364960.aspx> */
+ DWORD type = GetFileType (h);
+ if (type == FILE_TYPE_DISK)
+ {
+ if (!initialized)
+ initialize ();
+
+ /* st_mode can be determined through
+ GetFileAttributesEx
+ <https://msdn.microsoft.com/en-us/library/aa364946.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa365739.aspx>
+ or through
+ GetFileInformationByHandle
+ <https://msdn.microsoft.com/en-us/library/aa364952.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa363788.aspx>
+ or through
+ GetFileInformationByHandleEx with argument FileBasicInfo
+ <https://msdn.microsoft.com/en-us/library/aa364953.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa364217.aspx>
+ The latter requires -D_WIN32_WINNT=_WIN32_WINNT_VISTA or higher. */
+ BY_HANDLE_FILE_INFORMATION info;
+ if (! GetFileInformationByHandle (h, &info))
+ goto failed;
+
+ /* Test for error conditions before starting to fill *buf. */
+ if (sizeof (buf->st_size) <= 4 && info.nFileSizeHigh > 0)
+ {
+ errno = EOVERFLOW;
+ return -1;
+ }
+
+ /* st_ino is not wide enough for identifying a file on a device.
+ Without st_ino, st_dev is pointless. */
+ buf->st_dev = 0;
+ buf->st_ino = 0;
+
+ /* st_mode. */
+ unsigned int mode =
+ /* XXX How to handle FILE_ATTRIBUTE_REPARSE_POINT ? */
+ ((info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ? _S_IFDIR | S_IEXEC_UGO : _S_IFREG)
+ | S_IREAD_UGO
+ | ((info.dwFileAttributes & FILE_ATTRIBUTE_READONLY) ? 0 : S_IWRITE_UGO);
+ if (!(info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
+ {
+ /* Determine whether the file is executable by looking at the file
+ name suffix.
+ If the file name is already known, use it. Otherwise, for
+ non-empty files, it can be determined through
+ GetFinalPathNameByHandle
+ <https://msdn.microsoft.com/en-us/library/aa364962.aspx>
+ or through
+ GetFileInformationByHandleEx with argument FileNameInfo
+ <https://msdn.microsoft.com/en-us/library/aa364953.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa364388.aspx>
+ Both require -D_WIN32_WINNT=_WIN32_WINNT_VISTA or higher. */
+ if (info.nFileSizeHigh > 0 || info.nFileSizeLow > 0)
+ {
+ char fpath[PATH_MAX];
+ if (path != NULL
+ || (GetFinalPathNameByHandleFunc != NULL
+ && GetFinalPathNameByHandleFunc (h, fpath, sizeof (fpath), VOLUME_NAME_NONE)
+ < sizeof (fpath)
+ && (path = fpath, 1)))
+ {
+ const char *last_dot = NULL;
+ const char *p;
+ for (p = path; *p != '\0'; p++)
+ if (*p == '.')
+ last_dot = p;
+ if (last_dot != NULL)
+ {
+ const char *suffix = last_dot + 1;
+ if (_stricmp (suffix, "exe") == 0
+ || _stricmp (suffix, "bat") == 0
+ || _stricmp (suffix, "cmd") == 0
+ || _stricmp (suffix, "com") == 0)
+ mode |= S_IEXEC_UGO;
+ }
+ }
+ else
+ /* Cannot determine file name. Pretend that it is executable. */
+ mode |= S_IEXEC_UGO;
+ }
+ }
+ buf->st_mode = mode;
+
+ /* st_nlink can be determined through
+ GetFileInformationByHandle
+ <https://msdn.microsoft.com/en-us/library/aa364952.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa363788.aspx>
+ or through
+ GetFileInformationByHandleEx with argument FileStandardInfo
+ <https://msdn.microsoft.com/en-us/library/aa364953.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa364401.aspx>
+ The latter requires -D_WIN32_WINNT=_WIN32_WINNT_VISTA or higher. */
+ buf->st_nlink = (info.nNumberOfLinks > SHRT_MAX ? SHRT_MAX : info.nNumberOfLinks);
+
+ /* There's no easy way to map the Windows SID concept to an integer. */
+ buf->st_uid = 0;
+ buf->st_gid = 0;
+
+ /* st_rdev is irrelevant for normal files and directories. */
+ buf->st_rdev = 0;
+
+ /* st_size can be determined through
+ GetFileSizeEx
+ <https://msdn.microsoft.com/en-us/library/aa364957.aspx>
+ or through
+ GetFileAttributesEx
+ <https://msdn.microsoft.com/en-us/library/aa364946.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa365739.aspx>
+ or through
+ GetFileInformationByHandle
+ <https://msdn.microsoft.com/en-us/library/aa364952.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa363788.aspx>
+ or through
+ GetFileInformationByHandleEx with argument FileStandardInfo
+ <https://msdn.microsoft.com/en-us/library/aa364953.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa364401.aspx>
+ The latter requires -D_WIN32_WINNT=_WIN32_WINNT_VISTA or higher. */
+ if (sizeof (buf->st_size) <= 4)
+ /* Range check already done above. */
+ buf->st_size = info.nFileSizeLow;
+ else
+ buf->st_size = ((long long) info.nFileSizeHigh << 32) | (long long) info.nFileSizeLow;
+
+ /* st_atime, st_mtime, st_ctime can be determined through
+ GetFileTime
+ <https://msdn.microsoft.com/en-us/library/ms724320.aspx>
+ or through
+ GetFileAttributesEx
+ <https://msdn.microsoft.com/en-us/library/aa364946.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa365739.aspx>
+ or through
+ GetFileInformationByHandle
+ <https://msdn.microsoft.com/en-us/library/aa364952.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa363788.aspx>
+ or through
+ GetFileInformationByHandleEx with argument FileBasicInfo
+ <https://msdn.microsoft.com/en-us/library/aa364953.aspx>
+ <https://msdn.microsoft.com/en-us/library/aa364217.aspx>
+ The latter requires -D_WIN32_WINNT=_WIN32_WINNT_VISTA or higher. */
+ buf->st_atime = _gl_convert_FILETIME_to_POSIX (&info.ftLastAccessTime);
+ buf->st_mtime = _gl_convert_FILETIME_to_POSIX (&info.ftLastWriteTime);
+ buf->st_ctime = _gl_convert_FILETIME_to_POSIX (&info.ftCreationTime);
+
+ return 0;
+ }
+ else if (type == FILE_TYPE_CHAR || type == FILE_TYPE_PIPE)
+ {
+ buf->st_dev = 0;
+ buf->st_ino = 0;
+ buf->st_mode = (type == FILE_TYPE_PIPE ? _S_IFIFO : _S_IFCHR);
+ buf->st_nlink = 1;
+ buf->st_uid = 0;
+ buf->st_gid = 0;
+ buf->st_rdev = 0;
+ if (type == FILE_TYPE_PIPE)
+ {
+ /* PeekNamedPipe
+ <https://msdn.microsoft.com/en-us/library/aa365779.aspx> */
+ DWORD bytes_available;
+ if (PeekNamedPipe (h, NULL, 0, NULL, &bytes_available, NULL))
+ buf->st_size = bytes_available;
+ else
+ buf->st_size = 0;
+ }
+ else
+ buf->st_size = 0;
+ buf->st_atime = 0;
+ buf->st_mtime = 0;
+ buf->st_ctime = 0;
+ return 0;
+ }
+ else
+ {
+ errno = ENOENT;
+ return -1;
+ }
+
+ failed:
+ {
+ DWORD error = GetLastError ();
+ #if 0
+ fprintf (stderr, "_gl_fstat_by_handle error 0x%x\n", (unsigned int) error);
+ #endif
+ switch (error)
+ {
+ case ERROR_ACCESS_DENIED:
+ case ERROR_SHARING_VIOLATION:
+ errno = EACCES;
+ break;
+
+ case ERROR_OUTOFMEMORY:
+ errno = ENOMEM;
+ break;
+
+ case ERROR_WRITE_FAULT:
+ case ERROR_READ_FAULT:
+ case ERROR_GEN_FAILURE:
+ errno = EIO;
+ break;
+
+ default:
+ errno = EINVAL;
+ break;
+ }
+ return -1;
+ }
+}
+
+#endif
diff --git a/lib/stat-w32.h b/lib/stat-w32.h
new file mode 100644
index 0000000..68cac29
--- /dev/null
+++ b/lib/stat-w32.h
@@ -0,0 +1,33 @@
+/* Core of implementation of fstat and stat for native Windows.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#ifndef _STAT_W32_H
+#define _STAT_W32_H 1
+
+/* Converts a FILETIME to GMT time since 1970-01-01 00:00:00. */
+extern time_t _gl_convert_FILETIME_to_POSIX (const FILETIME *ft);
+
+/* Fill *BUF with information about the file designated by H.
+ PATH is the file name, if known, otherwise NULL.
+ Return 0 if successful, or -1 with errno set upon failure. */
+extern int _gl_fstat_by_handle (HANDLE h, const char *path, struct stat *buf);
+
+/* Bitmasks for st_mode. */
+#define S_IREAD_UGO (_S_IREAD | (_S_IREAD >> 3) | (_S_IREAD >> 6))
+#define S_IWRITE_UGO (_S_IWRITE | (_S_IWRITE >> 3) | (_S_IWRITE >> 6))
+#define S_IEXEC_UGO (_S_IEXEC | (_S_IEXEC >> 3) | (_S_IEXEC >> 6))
+
+#endif /* _STAT_W32_H */
diff --git a/m4/fstat.m4 b/m4/fstat.m4
index 14c871a..14f87be 100644
--- a/m4/fstat.m4
+++ b/m4/fstat.m4
@@ -1,4 +1,4 @@
-# fstat.m4 serial 4
+# fstat.m4 serial 5
dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -8,15 +8,13 @@ AC_DEFUN([gl_FUNC_FSTAT],
[
AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])

- AC_REQUIRE([gl_MSVC_INVAL])
- if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
- REPLACE_FSTAT=1
- fi
-
- AC_REQUIRE([gl_HEADER_SYS_STAT_H])
- if test $WINDOWS_64_BIT_ST_SIZE = 1; then
- REPLACE_FSTAT=1
- fi
+ case "$host_os" in
+ mingw*)
+ dnl On this platform, the original stat() returns st_atime, st_mtime,
+ dnl st_ctime values that are affected by the time zone.
+ REPLACE_FSTAT=1
+ ;;
+ esac

dnl Replace fstat() for supporting the gnulib-defined open() on directories.
m4_ifdef([gl_FUNC_FCHDIR], [
@@ -32,5 +30,8 @@ AC_DEFUN([gl_FUNC_FSTAT],
])
])

-# Prerequisites of lib/fstat.c.
-AC_DEFUN([gl_PREREQ_FSTAT], [:])
+# Prerequisites of lib/fstat.c and lib/stat-w32.c.
+AC_DEFUN([gl_PREREQ_FSTAT], [
+ AC_REQUIRE([gl_HEADER_SYS_STAT_H])
+ :
+])
diff --git a/modules/fstat b/modules/fstat
index 2db555a..3f2357b 100644
--- a/modules/fstat
+++ b/modules/fstat
@@ -3,18 +3,22 @@ fstat() function: return information about an open file.

Files:
lib/fstat.c
+lib/stat-w32.h
+lib/stat-w32.c
m4/fstat.m4

Depends-on:
sys_stat
largefile
+pathmax [test $REPLACE_STAT = 1]
unistd [test $REPLACE_STAT = 1]
-msvc-inval [test $REPLACE_STAT = 1]
+msvc-nothrow [test $REPLACE_STAT = 1]

configure.ac:
gl_FUNC_FSTAT
if test $REPLACE_FSTAT = 1; then
AC_LIBOBJ([fstat])
+ AC_LIBOBJ([stat-w32])
gl_PREREQ_FSTAT
fi
gl_SYS_STAT_MODULE_INDICATOR([fstat])

Loading...