sysdeps/unix/sysv/linux/renameat.c

   1 /* Copyright (C) 2005 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 <sysdep.h>
  24
  25
  26 void
  27 attribute_hidden
  28 __atfct_seterrno_2 (int errval, int fd1, const char *buf1, int fd2,
  29                     const char *buf2)
  30 {
  31   if (errval == ENOTDIR && (buf1 != NULL || buf2 != NULL))
  32     {
  33       /* This can mean either the file descriptor is invalid or
  34          /proc is not mounted.  */
  35       struct stat64 st;
  36
  37       if (buf1 != NULL)
  38         {
  39           if (__fxstat64 (_STAT_VER, fd1, &st) != 0)
  40             /* errno is already set correctly.  */
  41             return;
  42
  43           /* If /proc is not mounted there is nothing we can do.  */
  44           if (S_ISDIR (st.st_mode)
  45               && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  46                   || !S_ISDIR (st.st_mode)))
  47             {
  48               errval = ENOSYS;
  49               goto out;
  50             }
  51         }
  52
  53       if (buf2 != NULL)
  54         {
  55           if (__fxstat64 (_STAT_VER, fd2, &st) != 0)
  56             /* errno is already set correctly.  */
  57             return;
  58
  59           /* If /proc is not mounted there is nothing we can do.  */
  60           if (S_ISDIR (st.st_mode)
  61               && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
  62                   || !S_ISDIR (st.st_mode)))
  63             errval = ENOSYS;
  64         }
  65     }
  66
  67  out:
  68   __set_errno (errval);
  69 }
  70
  71
  72 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
  73 int
  74 renameat (oldfd, old, newfd, new)
  75      int oldfd;
  76      const char *old;
  77      int newfd;
  78      const char *new;
  79 {
  80   static const char procfd[] = "/proc/self/fd/%d/%s";
  81   char *bufold = NULL;
  82
  83   if (oldfd != AT_FDCWD && old[0] != '/')
  84     {
  85       size_t filelen = strlen (old);
  86       /* Buffer for the path name we are going to use.  It consists of
  87          - the string /proc/self/fd/
  88          - the file descriptor number
  89          - the file name provided.
  90          The final NUL is included in the sizeof.   A bit of overhead
  91          due to the format elements compensates for possible negative
  92          numbers.  */
  93       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
  94       bufold = alloca (buflen);
  95
  96       __snprintf (bufold, buflen, procfd, oldfd, old);
  97       old = bufold;
  98     }
  99
 100   char *bufnew = NULL;
 101
 102   if (newfd != AT_FDCWD && new[0] != '/')
 103     {
 104       size_t filelen = strlen (new);
 105       /* Buffer for the path name we are going to use.  It consists of
 106          - the string /proc/self/fd/
 107          - the file descriptor number
 108          - the file name provided.
 109          The final NUL is included in the sizeof.   A bit of overhead
 110          due to the format elements compensates for possible negative
 111          numbers.  */
 112       size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
 113       bufnew = alloca (buflen);
 114
 115       __snprintf (bufnew, buflen, procfd, newfd, new);
 116       new = bufnew;
 117     }
 118
 119   INTERNAL_SYSCALL_DECL (err);
 120
 121   int result = INTERNAL_SYSCALL (rename, err, 2, old,  new);
 122
 123   if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
 124     {
 125       __atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), newfd, bufnew,
 126                           oldfd, bufold);
 127       result = -1;
 128     }
 129
 130   return result;
 131 }