uclibc-ng/libc/pwd_grp/__getgrent.c

/*
 * __getgrent.c - This file is part of the libc-8086/grp package for ELKS,
 * Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>.
 * 
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <grp.h>
#include "config.h"

/*
 * This is the core group-file read function.  It behaves exactly like
 * getgrent() except that it is passed a file descriptor.  getgrent()
 * is just a wrapper for this function.
 */
struct group *
__getgrent(int grp_fd)
{
#ifndef GR_SCALE_DYNAMIC  
  static char line_buff[GR_MAX_LINE_LEN];
  static char * members[GR_MAX_MEMBERS];
#else
  static char * line_buff = NULL;
  static char ** members = NULL;
  short line_index;
  short buff_size;
#endif
  static struct group group;
  register char * ptr;
  char * field_begin;
  short member_num;
  char * endptr;
  int line_len;


  /* We use the restart label to handle malformatted lines */
restart:
#ifdef GR_SCALE_DYNAMIC
  line_index=0;
  buff_size=256;
#endif

#ifndef GR_SCALE_DYNAMIC
  /* Read the line into the static buffer */
  if ((line_len=read(grp_fd, line_buff, GR_MAX_LINE_LEN))<=0)
    return NULL;
  field_begin=strchr(line_buff, '\n');
  if (field_begin!=NULL)
    lseek(grp_fd, (long) (1+field_begin-(line_buff+line_len)), SEEK_CUR);
  else /* The line is too long - skip it :-\ */
    {
      do { if ((line_len=read(grp_fd, line_buff, GR_MAX_LINE_LEN))<=0)
	return NULL;
      } while (!(field_begin=strchr(line_buff, '\n')));
      lseek(grp_fd, (long) ((field_begin-line_buff)-line_len+1), SEEK_CUR);
      goto restart;
    }
  if (*line_buff=='#' || *line_buff==' ' || *line_buff=='\n' ||
      *line_buff=='\t')
    goto restart;
  *field_begin='\0';

#else /* !GR_SCALE_DYNAMIC */
  line_buff=realloc(line_buff, buff_size);
  while (1)
    {
      if ((line_len=read(grp_fd, line_buff+line_index,
			 buff_size-line_index))<=0)
	  return NULL;
      field_begin=strchr(line_buff, '\n');
      if (field_begin!=NULL)
	{
	  lseek(grp_fd, (long) (1+field_begin-(line_len+line_index+line_buff)),
		SEEK_CUR);
	  *field_begin='\0';
	  if (*line_buff=='#' || *line_buff==' ' || *line_buff=='\n' ||
	      *line_buff=='\t')
	    goto restart;
	  break;
	}
      else /* Allocate some more space */
	{
	  line_index=buff_size;
	  buff_size+=256;
	  line_buff=realloc(line_buff, buff_size);
	}
    }
#endif /* GR_SCALE_DYNAMIC */

  /* Now parse the line */
  group.gr_name=line_buff;
  ptr=strchr(line_buff, ':');
  if (ptr==NULL) goto restart;
  *ptr++='\0';

  group.gr_passwd=ptr;
  ptr=strchr(ptr, ':');
  if (ptr==NULL) goto restart;
  *ptr++='\0';

  field_begin=ptr;
  ptr=strchr(ptr, ':');
  if (ptr==NULL) goto restart;
  *ptr++='\0';

  group.gr_gid=(gid_t) strtoul(field_begin, &endptr, 10);
  if (*endptr!='\0') goto restart;

  member_num=0;
  field_begin=ptr;

#ifndef GR_SCALE_DYNAMIC
  while ((ptr=strchr(ptr, ','))!=NULL)
    {
      *ptr='\0';
      ptr++;
      members[member_num]=field_begin;
      field_begin=ptr;
      member_num++;
    }
  if (*field_begin=='\0')
    members[member_num]=NULL;
  else
    {
      members[member_num]=field_begin;
      members[member_num+1]=NULL;
    }
#else /* !GR_SCALE_DYNAMIC */
  if (members!=NULL)
    free (members);
  members=(char **) malloc(1*sizeof(char *));
  while ((ptr=strchr(ptr, ','))!=NULL)
    {
      *ptr='\0';
      ptr++;
      members[member_num]=field_begin;
      field_begin=ptr;
      member_num++;
      members=(char **)realloc((void *)members, (member_num+1)*sizeof(char *));
    }
  if (*field_begin=='\0')
      members[member_num]=NULL;
  else
    {
      members[member_num]=field_begin;
      members[member_num+1]=NULL;
    }
#endif /* GR_SCALE_DYNAMIC */

  group.gr_mem=members;
  return &group;
}