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

• Show log

  Commit

• Hash : 2392b180
  Author :
  Date : 2011-01-11T10:42:55
  

  openat, save-cwd: avoid xmalloc
  
  This removes a direct (but undocumented) dependency of openat on
  xalloc, along with an indirect dependency via save-cwd.  It also
  removes a dependency of save-cwd on xgetcwd, and thereby
  indirectly on xalloc.  This change causes the openat substitute
  to fall back on save_cwd when memory is tight, and for save_cwd to
  fail instead of dying when memory is tight, but that's good enough.
  
  * lib/openat-proc.c: Include stdlib.h (for malloc), not
  xalloc.h (for xmalloc).
  (openat_proc_name): Use malloc, not xmalloc.
  * lib/save-cwd.c (save_cwd): Use getcwd, not xgetcwd.
  * modules/save-cwd (Files): Depend on getcwd, not xgetcwd.
  

Download

• lib/openat-proc.c

• /* Create /proc/self/fd-related names for subfiles of open directories.
  
     Copyright (C) 2006, 2009-2011 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 "dirname.h"
  #include "intprops.h"
  #include "same-inode.h"
  
  /* The results of open() in this file are not used with fchdir,
     and we do not leak fds to any single-threaded code that could use stdio,
     therefore save some unnecessary work in fchdir.c.
     FIXME - if the kernel ever adds support for multi-thread safety for
     avoiding standard fds, then we should use open_safer.  */
  #undef open
  #undef close
  
  #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);
        if (proc_self_fd < 0)
          proc_status = -1;
        else
          {
            struct stat proc_self_fd_dotdot_st;
            struct stat proc_self_st;
            char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof ".." - 1)];
            sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "..");
            proc_status =
              ((stat (dotdot_buf, &proc_self_fd_dotdot_st) == 0
                && stat ("/proc/self", &proc_self_st) == 0
                && SAME_INODE (proc_self_fd_dotdot_st, proc_self_st))
               ? 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;
      }
  }
  

Download