shadow/fgetspent.c

   1 /* Copyright (C) 1996, 1997, 1998 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <libc-lock.h>
  21 #include <shadow.h>
  22 #include <stdlib.h>
  23
  24
  25 /* A reasonable size for a buffer to start with.  */
  26 #define BUFLEN_SPWD 1024
  27
  28 /* We need to protect the dynamic buffer handling.  */
  29 __libc_lock_define_initialized (static, lock);
  30
  31 /* Read one shadow entry from the given stream.  */
  32 struct spwd *
  33 fgetspent (FILE *stream)
  34 {
  35   static char *buffer;
  36   static size_t buffer_size;
  37   static struct spwd resbuf;
  38   struct spwd *result;
  39   int save, save_errno;
  40
  41   /* Get lock.  */
  42   __libc_lock_lock (lock);
  43
  44   /* Allocate buffer if not yet available.  */
  45   if (buffer == NULL)
  46     {
  47       buffer_size = BUFLEN_SPWD;
  48       buffer = malloc (buffer_size);
  49     }
  50
  51   /* We don't want to pass errno == 0 or errno == ERANGE back */
  52   save_errno = errno;
  53   while (buffer != NULL
  54          && __fgetspent_r (stream, &resbuf, buffer, buffer_size, &result) != 0
  55          && errno == ERANGE)
  56     {
  57       char *new_buf;
  58       buffer_size += BUFLEN_SPWD;
  59       __set_errno (0);
  60       new_buf = realloc (buffer, buffer_size);
  61       if (new_buf == NULL)
  62         {
  63           /* We are out of memory.  Free the current buffer so that the
  64              process gets a chance for a normal termination.  */
  65           save = errno;
  66           free (buffer);
  67           __set_errno (save);
  68         }
  69       buffer = new_buf;
  70     }
  71
  72   if (errno == 0)
  73     __set_errno (save_errno);
  74
  75   if (buffer == NULL)
  76     result = NULL;
  77
  78   /* Release lock.  Preserve error value.  */
  79   save = errno;
  80   __libc_lock_unlock (lock);
  81   __set_errno (save);
  82
  83   return result;
  84 }