1/* Generic implementation of statx based on fstatat64.
2 Copyright (C) 2018-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <fcntl.h>
21#include <string.h>
22#include <sys/stat.h>
23#include <sys/sysmacros.h>
24
25/* Obtain the original definition of struct statx. */
26#undef __statx_defined
27#define statx original_statx
28#include <bits/types/struct_statx.h>
29#undef statx
30
31static inline struct statx_timestamp
32statx_convert_timestamp (struct timespec tv)
33{
34 return (struct statx_timestamp) { tv.tv_sec, tv.tv_nsec };
35}
36
37/* Approximate emulation of statx. This will always fill in
38 POSIX-mandated attributes even if the underlying file system does
39 not actually support it (for example, GID and UID on file systems
40 without UNIX-style permissions). */
41static __attribute__ ((unused)) int
42statx_generic (int fd, const char *path, int flags,
43 unsigned int mask, struct statx *buf)
44{
45 /* Flags which need to be cleared before passing them to
46 fstatat64. */
47 static const int clear_flags = AT_STATX_SYNC_AS_STAT;
48
49 /* Flags supported by our emulation. */
50 static const int supported_flags
51 = AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW | clear_flags;
52
53 if (__glibc_unlikely ((flags & ~supported_flags) != 0))
54 {
55 __set_errno (EINVAL);
56 return -1;
57 }
58
59 struct stat64 st;
60 int ret = __fstatat64 (fd, path, &st, flags & ~clear_flags);
61 if (ret != 0)
62 return ret;
63
64 /* The interface is defined in such a way that unused (padding)
65 fields have to be cleared. STATX_BASIC_STATS corresponds to the
66 data which is available via fstatat64. */
67 struct original_statx obuf =
68 {
69 .stx_mask = STATX_BASIC_STATS,
70 .stx_blksize = st.st_blksize,
71 .stx_nlink = st.st_nlink,
72 .stx_uid = st.st_uid,
73 .stx_gid = st.st_gid,
74 .stx_mode = st.st_mode,
75 .stx_ino = st.st_ino,
76 .stx_size = st.st_size,
77 .stx_blocks = st.st_blocks,
78 .stx_atime = statx_convert_timestamp (st.st_atim),
79 .stx_ctime = statx_convert_timestamp (st.st_ctim),
80 .stx_mtime = statx_convert_timestamp (st.st_mtim),
81 .stx_rdev_major = major (st.st_rdev),
82 .stx_rdev_minor = minor (st.st_rdev),
83 .stx_dev_major = major (st.st_dev),
84 .stx_dev_minor = minor (st.st_dev),
85 };
86 _Static_assert (sizeof (*buf) >= sizeof (obuf), "struct statx size");
87 memcpy (buf, &obuf, sizeof (obuf));
88
89 return 0;
90}
91