kc3-lang/gnulib/lib/getusershell.c

• Show log

  Commit

• Hash : 15d3d56a
  Author :
  Date : 2003-09-09T19:26:25
  

  (readname, default_index, line_size, readname):
  Use size_t, not int, for sizes.
  (readname): If the size overflows, report an error instead of
  looping forever.
  

Download

• lib/getusershell.c

• /* getusershell.c -- Return names of valid user shells.
     Copyright (C) 1991, 1997, 2000, 2001, 2003 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 2, 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, write to the Free Software Foundation,
     Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  
  /* Written by David MacKenzie <djm@gnu.ai.mit.edu> */
  
  #ifdef HAVE_CONFIG_H
  # include <config.h>
  #endif
  
  #ifndef SHELLS_FILE
  # ifndef __DJGPP__
  /* File containing a list of nonrestricted shells, one per line. */
  #  define SHELLS_FILE "/etc/shells"
  # else
  /* This is a horrible kludge.  Isn't there a better way?  */
  #  define SHELLS_FILE "/dev/env/DJDIR/etc/shells"
  # endif
  #endif
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <ctype.h>
  #include "unlocked-io.h"
  #include "xalloc.h"
  
  #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
  # define IN_CTYPE_DOMAIN(c) 1
  #else
  # define IN_CTYPE_DOMAIN(c) isascii(c)
  #endif
  
  #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
  
  static size_t readname (char **, size_t *, FILE *);
  
  #if ! defined ADDITIONAL_DEFAULT_SHELLS && defined __MSDOS__
  # define ADDITIONAL_DEFAULT_SHELLS \
    "c:/dos/command.com", "c:/windows/command.com", "c:/command.com",
  #else
  # define ADDITIONAL_DEFAULT_SHELLS /* empty */
  #endif
  
  /* List of shells to use if the shells file is missing. */
  static char const* const default_shells[] =
  {
    ADDITIONAL_DEFAULT_SHELLS
    "/bin/sh", "/bin/csh", "/usr/bin/sh", "/usr/bin/csh", NULL
  };
  
  /* Index of the next shell in `default_shells' to return.
     0 means we are not using `default_shells'. */
  static size_t default_index = 0;
  
  /* Input stream from the shells file. */
  static FILE *shellstream = NULL;
  
  /* Line of input from the shells file. */
  static char *line = NULL;
  
  /* Number of bytes allocated for `line'. */
  static size_t line_size = 0;
  
  /* Return an entry from the shells file, ignoring comment lines.
     If the file doesn't exist, use the list in DEFAULT_SHELLS (above).
     In any case, the returned string is in memory allocated through malloc.
     Return NULL if there are no more entries.  */
  
  char *
  getusershell (void)
  {
    if (default_index > 0)
      {
        if (default_shells[default_index])
  	/* Not at the end of the list yet.  */
  	return xstrdup (default_shells[default_index++]);
        return NULL;
      }
  
    if (shellstream == NULL)
      {
        shellstream = fopen (SHELLS_FILE, "r");
        if (shellstream == NULL)
  	{
  	  /* No shells file.  Use the default list.  */
  	  default_index = 1;
  	  return xstrdup (default_shells[0]);
  	}
      }
  
    while (readname (&line, &line_size, shellstream))
      {
        if (*line != '#')
  	return line;
      }
    return NULL;			/* End of file. */
  }
  
  /* Rewind the shells file. */
  
  void
  setusershell (void)
  {
    default_index = 0;
    if (shellstream)
      rewind (shellstream);
  }
  
  /* Close the shells file. */
  
  void
  endusershell (void)
  {
    if (shellstream)
      {
        fclose (shellstream);
        shellstream = NULL;
      }
  }
  
  /* Read a line from STREAM, removing any newline at the end.
     Place the result in *NAME, which is malloc'd
     and/or realloc'd as necessary and can start out NULL,
     and whose size is passed and returned in *SIZE.
  
     Return the number of bytes placed in *NAME
     if some nonempty sequence was found, otherwise 0.  */
  
  static size_t
  readname (char **name, size_t *size, FILE *stream)
  {
    int c;
    size_t name_index = 0;
  
    if (*name == NULL)
      {
        /* The initial size must be a power of two, so that the overflow
  	 check works.  */
        *size = 16;
  
        *name = xmalloc (*size);
      }
  
    /* Skip blank space.  */
    while ((c = getc (stream)) != EOF && ISSPACE (c))
      /* Do nothing. */ ;
  
    while (c != EOF && !ISSPACE (c))
      {
        (*name)[name_index++] = c;
        if (*size < name_index)
  	{
  	  *size *= 2;
  	  if (! *size)
  	    xalloc_die ();
  	  *name = xrealloc (*name, *size);
  	}
        c = getc (stream);
      }
    (*name)[name_index] = '\0';
    return name_index;
  }
  
  #ifdef TEST
  int
  main (void)
  {
    char *s;
  
    while (s = getusershell ())
      puts (s);
    exit (0);
  }
  #endif
  

Download