sysdeps/unix/sysv/linux/renameat.c

   1 /* Copyright (C) 2005, 2006 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <kernel-features.h>
  24 #include <sysdep.h>
  25
  26
  27 #ifndef __ASSUME_ATFCTS
  28 void
  29 attribute_hidden
  30 __atfct_seterrno_2 (int errval, int fd1, const char *buf1, int fd2,
  31                     const char *buf2)
  32 {
  33   if (buf1 != NULL || buf2 != NULL)
  34     {
  35       struct stat64 st;
  36
  37       if (errval == ENOTDIR)
  38         {
  39           /* This can mean either the file descriptor is invalid or
  40              /proc is not mounted.  */
  41           if (buf1 != NULL)
  42             {
  43               if (__fxstat64 (_STAT_VER, fd1, &st) != 0)
  44                 /* errno is already set correctly.  */
  45                 return;
  46
  47               /* If /proc is not mounted there is nothing we can do.  */
  48               if (S_ISDIR (st.st_mode)
  49                   && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  50                       || !S_ISDIR (st.st_mode)))
  51                 {
  52                   errval = ENOSYS;
  53                   goto out;
  54                 }
  55             }
  56
  57           if (buf2 != NULL)
  58             {
  59               if (__fxstat64 (_STAT_VER, fd2, &st) != 0)
  60                 /* errno is already set correctly.  */
  61                 return;
  62
  63               /* If /proc is not mounted there is nothing we can do.  */
  64               if (S_ISDIR (st.st_mode)
  65                   && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  66                       || !S_ISDIR (st.st_mode)))
  67                 errval = ENOSYS;
  68             }
  69         }
  70       else if (errval == ENOENT)
  71         {
  72           /* This could mean the file descriptor is not valid.  We
  73              reuse BUF for the stat call.  Find the slash after the
  74              file descriptor number.  */
  75           if (buf1 != NULL)
  76             {
  77               *(char *) strchr (buf1 + sizeof "/proc/self/fd", '/') = '\0';
  78
  79               int e = __lxstat64 (_STAT_VER, buf1, &st);
  80               if ((e == -1 && errno == ENOENT)
  81                   ||(e == 0 && !S_ISLNK (st.st_mode)))
  82                 {
  83                   errval = EBADF;
  84                   goto out;
  85                 }
  86             }
  87
  88           if (buf2 != NULL)
  89             {
  90               *(char *) strchr (buf2 + sizeof "/proc/self/fd", '/') = '\0';
  91
  92               int e = __lxstat64 (_STAT_VER, buf2, &st);
  93               if ((e == -1 && errno == ENOENT)
  94                   ||(e == 0 && !S_ISLNK (st.st_mode)))
  95                 errval = EBADF;
  96             }
  97         }
  98     }
  99
 100  out:
 101   __set_errno (errval);
 102 }
 103 #endif
 104
 105
 106 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
 107 int
 108 renameat (oldfd, old, newfd, new)
 109      int oldfd;
 110      const char *old;
 111      int newfd;
 112      const char *new;
 113 {
 114   int result;
 115
 116 #ifdef __NR_renameat
 117 # ifndef __ASSUME_ATFCTS
 118   if (__have_atfcts >= 0)
 119 # endif
 120     {
 121       result = INLINE_SYSCALL (renameat, 4, oldfd, old, newfd, new);
 122 # ifndef __ASSUME_ATFCTS
 123       if (result == -1 && errno == ENOSYS)
 124         __have_atfcts = -1;
 125       else
 126 # endif
 127         return result;
 128     }
 129 #endif
 130
 131 #ifndef __ASSUME_ATFCTS
 132   static const char procfd[] = "/proc/self/fd/%d/%s";
 133   char *bufold = NULL;
 134
 135   if (oldfd != AT_FDCWD && old[0] != '/')
 136     {
 137       size_t filelen = strlen (old);
 138       /* Buffer for the path name we are going to use.  It consists of
 139          - the string /proc/self/fd/
 140          - the file descriptor number
 141          - the file name provided.
 142          The final NUL is included in the sizeof.   A bit of overhead
 143          due to the format elements compensates for possible negative
 144          numbers.  */
 145       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 146       bufold = alloca (buflen);
 147
 148       __snprintf (bufold, buflen, procfd, oldfd, old);
 149       old = bufold;
 150     }
 151
 152   char *bufnew = NULL;
 153
 154   if (newfd != AT_FDCWD && new[0] != '/')
 155     {
 156       size_t filelen = strlen (new);
 157       /* Buffer for the path name we are going to use.  It consists of
 158          - the string /proc/self/fd/
 159          - the file descriptor number
 160          - the file name provided.
 161          The final NUL is included in the sizeof.   A bit of overhead
 162          due to the format elements compensates for possible negative
 163          numbers.  */
 164       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 165       bufnew = alloca (buflen);
 166
 167       __snprintf (bufnew, buflen, procfd, newfd, new);
 168       new = bufnew;
 169     }
 170
 171   INTERNAL_SYSCALL_DECL (err);
 172
 173   result = INTERNAL_SYSCALL (rename, err, 2, old,  new);
 174
 175   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 176     {
 177       __atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), newfd, bufnew,
 178                           oldfd, bufold);
 179       result = -1;
 180     }
 181
 182   return result;
 183 #endif
 184 }