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/*
 * __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.
 * 
 * Sep 2023 Greg Haerr - removed excess unworking code, reduced code and data size
 */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <grp.h>
#include "config-grp.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)
{
    static struct group group;
    register char  *ptr;
    char           *field_begin;
    short           member_num;
    int             line_len;
    static char     line_buff[GR_MAX_LINE_LEN];
    static char    *members[GR_MAX_MEMBERS];

    /* We use the restart label to handle malformatted lines */
restart:
    /* 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';

    /* 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) atoi(field_begin);

    member_num = 0;
    field_begin = ptr;

    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;
    }

    group.gr_mem = members;
    return &group;
}
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