1  /* Copyright (C) 1996-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <libc-lock.h>
      20  #include <shadow.h>
      21  #include <stdlib.h>
      22  
      23  
      24  /* A reasonable size for a buffer to start with.  */
      25  #define BUFLEN_SPWD 1024
      26  
      27  /* We need to protect the dynamic buffer handling.  */
      28  __libc_lock_define_initialized (static, lock);
      29  
      30  /* Read one shadow entry from the given stream.  */
      31  struct spwd *
      32  sgetspent (const char *string)
      33  {
      34    static char *buffer;
      35    static size_t buffer_size;
      36    static struct spwd resbuf;
      37    struct spwd *result;
      38    int save;
      39  
      40    /* Get lock.  */
      41    __libc_lock_lock (lock);
      42  
      43    /* Allocate buffer if not yet available.  */
      44    if (buffer == NULL)
      45      {
      46        buffer_size = BUFLEN_SPWD;
      47        buffer = malloc (buffer_size);
      48      }
      49  
      50    while (buffer != NULL
      51  	 && (__sgetspent_r (string, &resbuf, buffer, buffer_size, &result)
      52  	     == ERANGE))
      53      {
      54        char *new_buf;
      55        buffer_size += BUFLEN_SPWD;
      56        new_buf = realloc (buffer, buffer_size);
      57        if (new_buf == NULL)
      58  	{
      59  	  /* We are out of memory.  Free the current buffer so that the
      60  	     process gets a chance for a normal termination.  */
      61  	  save = errno;
      62  	  free (buffer);
      63  	  __set_errno (save);
      64  	}
      65        buffer = new_buf;
      66      }
      67  
      68    if (buffer == NULL)
      69      result = NULL;
      70  
      71    /* Release lock.  Preserve error value.  */
      72    save = errno;
      73    __libc_lock_unlock (lock);
      74    __set_errno (save);
      75  
      76    return result;
      77  }