io/statx_generic.c

   1 /* Generic implementation of statx based on fstatat64.
   2    Copyright (C) 2018-2019 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <sys/stat.h>
  22 #include <sys/sysmacros.h>
  23
  24 static inline struct statx_timestamp
  25 statx_convert_timestamp (struct timespec tv)
  26 {
  27   return (struct statx_timestamp) { tv.tv_sec, tv.tv_nsec };
  28 }
  29
  30 /* Approximate emulation of statx.  This will always fill in
  31    POSIX-mandated attributes even if the underlying file system does
  32    not actually support it (for example, GID and UID on file systems
  33    without UNIX-style permissions).  */
  34 static __attribute__ ((unused)) int
  35 statx_generic (int fd, const char *path, int flags,
  36                unsigned int mask, struct statx *buf)
  37 {
  38   /* Flags which need to be cleared before passing them to
  39      fstatat64.  */
  40   static const int clear_flags = AT_STATX_SYNC_AS_STAT;
  41
  42     /* Flags supported by our emulation.  */
  43   static const int supported_flags
  44     = AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW | clear_flags;
  45
  46   if (__glibc_unlikely ((flags & ~supported_flags) != 0))
  47     {
  48       __set_errno (EINVAL);
  49       return -1;
  50     }
  51
  52   struct stat64 st;
  53   int ret = __fstatat64 (fd, path, &st, flags & ~clear_flags);
  54   if (ret != 0)
  55     return ret;
  56
  57   /* The interface is defined in such a way that unused (padding)
  58      fields have to be cleared.  STATX_BASIC_STATS corresponds to the
  59      data which is available via fstatat64.  */
  60   *buf = (struct statx)
  61     {
  62       .stx_mask = STATX_BASIC_STATS,
  63       .stx_blksize = st.st_blksize,
  64       .stx_nlink = st.st_nlink,
  65       .stx_uid = st.st_uid,
  66       .stx_gid = st.st_gid,
  67       .stx_mode = st.st_mode,
  68       .stx_ino = st.st_ino,
  69       .stx_size = st.st_size,
  70       .stx_blocks = st.st_blocks,
  71       .stx_atime = statx_convert_timestamp (st.st_atim),
  72       .stx_ctime = statx_convert_timestamp (st.st_ctim),
  73       .stx_mtime = statx_convert_timestamp (st.st_mtim),
  74       .stx_rdev_major = major (st.st_rdev),
  75       .stx_rdev_minor = minor (st.st_rdev),
  76       .stx_dev_major = major (st.st_dev),
  77       .stx_dev_minor = minor (st.st_dev),
  78     };
  79
  80   return 0;
  81 }