kc3-lang/gnulib/lib/openat-proc.c

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• Hash : f345edc0
  Author :
  Date : 2014-05-22T00:05:01
  

  fchdir: port 'open' and 'close' redefinitions to AIX 7.1
  
  * lib/chown.c, lib/clean-temp.c, lib/copy-file.c, lib/execute.c:
  * lib/fsusage.c, lib/gc-gnulib.c, lib/javacomp.c, lib/mountlist.c:
  * lib/openat-proc.c, lib/pagealign_alloc.c, lib/progreloc.c:
  * lib/spawn-pipe.c:
  Do not #undef 'open' and 'close'.  AIX 7 does '#define open open64'
  and then 'int open64(const char *, int, ...);', which means the
  declaration for 'open' gets lost if we later '#undef open'.
  Discovered while building grep pretest 2.18.151-1c770 on AIX 7.1,
  where the compilation reported the non-fatal error "In function
  'openat_proc_name' ... warning: implicit declaration of function
  'open'".  In this case the error is relatively harmless, but in
  other cases it might not be so minor.
  

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• lib/openat-proc.c

• /* Create /proc/self/fd-related names for subfiles of open directories.
  
     Copyright (C) 2006, 2009-2014 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 Paul Eggert.  */
  
  #include <config.h>
  
  #include "openat-priv.h"
  
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "intprops.h"
  
  #define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s"
  
  #define PROC_SELF_FD_NAME_SIZE_BOUND(len) \
    (sizeof PROC_SELF_FD_FORMAT - sizeof "%d%s" \
     + INT_STRLEN_BOUND (int) + (len) + 1)
  
  
  /* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
     respectively for %d and %s.  If successful, return BUF if the
     result fits in BUF, dynamically allocated memory otherwise.  But
     return NULL if /proc is not reliable, either because the operating
     system support is lacking or because memory is low.  */
  char *
  openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
  {
    static int proc_status = 0;
  
    /* Make sure the caller gets ENOENT when appropriate.  */
    if (!*file)
      {
        buf[0] = '\0';
        return buf;
      }
  
    if (! proc_status)
      {
        /* Set PROC_STATUS to a positive value if /proc/self/fd is
           reliable, and a negative value otherwise.  Solaris 10
           /proc/self/fd mishandles "..", and any file name might expand
           to ".." after symbolic link expansion, so avoid /proc/self/fd
           if it mishandles "..".  Solaris 10 has openat, but this
           problem is exhibited on code that built on Solaris 8 and
           running on Solaris 10.  */
  
        int proc_self_fd = open ("/proc/self/fd",
                                 O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
        if (proc_self_fd < 0)
          proc_status = -1;
        else
          {
            /* Detect whether /proc/self/fd/%i/../fd exists, where %i is the
               number of a file descriptor open on /proc/self/fd.  On Linux,
               that name resolves to /proc/self/fd, which was opened above.
               However, on Solaris, it may resolve to /proc/self/fd/fd, which
               cannot exist, since all names in /proc/self/fd are numeric.  */
            char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof "../fd" - 1)];
            sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "../fd");
            proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
            close (proc_self_fd);
          }
      }
  
    if (proc_status < 0)
      return NULL;
    else
      {
        size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
        char *result = buf;
        if (OPENAT_BUFFER_SIZE < bufsize)
          {
            result = malloc (bufsize);
            if (! result)
              return NULL;
          }
        sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
        return result;
      }
  }
  

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