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204 lines
5.6 KiB
C
204 lines
5.6 KiB
C
/*
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* __getgrent.c - This file is part of the libc-8086/grp package for ELKS,
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* Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include "busybox.h"
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#include "grp_.h"
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/*
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* Define GR_SCALE_DYNAMIC if you want grp to dynamically scale its read buffer
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* so that lines of any length can be used. On very very small systems,
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* you may want to leave this undefined becasue it will make the grp functions
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* somewhat larger (because of the inclusion of malloc and the code necessary).
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* On larger systems, you will want to define this, because grp will _not_
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* deal with long lines gracefully (they will be skipped).
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*/
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#undef GR_SCALE_DYNAMIC
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#ifndef GR_SCALE_DYNAMIC
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/*
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* If scaling is not dynamic, the buffers will be statically allocated, and
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* maximums must be chosen. GR_MAX_LINE_LEN is the maximum number of
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* characters per line in the group file. GR_MAX_MEMBERS is the maximum
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* number of members of any given group.
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*/
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#define GR_MAX_LINE_LEN 128
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/* GR_MAX_MEMBERS = (GR_MAX_LINE_LEN-(24+3+6))/9 */
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#define GR_MAX_MEMBERS 11
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#endif /* !GR_SCALE_DYNAMIC */
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/*
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* Define GR_DYNAMIC_GROUP_LIST to make initgroups() dynamically allocate
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* space for it's GID array before calling setgroups(). This is probably
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* unnecessary scalage, so it's undefined by default.
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*/
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#undef GR_DYNAMIC_GROUP_LIST
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#ifndef GR_DYNAMIC_GROUP_LIST
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/*
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* GR_MAX_GROUPS is the size of the static array initgroups() uses for
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* its static GID array if GR_DYNAMIC_GROUP_LIST isn't defined.
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*/
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#define GR_MAX_GROUPS 64
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#endif /* !GR_DYNAMIC_GROUP_LIST */
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/*
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* This is the core group-file read function. It behaves exactly like
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* getgrent() except that it is passed a file descriptor. getgrent()
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* is just a wrapper for this function.
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*/
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struct group *__getgrent(int grp_fd)
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{
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#ifndef GR_SCALE_DYNAMIC
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static char line_buff[GR_MAX_LINE_LEN];
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static char *members[GR_MAX_MEMBERS];
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#else
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static char *line_buff = NULL;
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static char **members = NULL;
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short line_index;
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short buff_size;
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#endif
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static struct group group;
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register char *ptr;
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char *field_begin;
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short member_num;
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char *endptr;
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int line_len;
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/* We use the restart label to handle malformatted lines */
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restart:
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#ifdef GR_SCALE_DYNAMIC
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line_index = 0;
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buff_size = 256;
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#endif
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#ifndef GR_SCALE_DYNAMIC
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/* Read the line into the static buffer */
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if ((line_len = read(grp_fd, line_buff, GR_MAX_LINE_LEN)) <= 0)
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return NULL;
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field_begin = strchr(line_buff, '\n');
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if (field_begin != NULL)
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lseek(grp_fd, (long) (1 + field_begin - (line_buff + line_len)),
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SEEK_CUR);
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else { /* The line is too long - skip it :-\ */
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do {
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if ((line_len = read(grp_fd, line_buff, GR_MAX_LINE_LEN)) <= 0)
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return NULL;
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} while (!(field_begin = strchr(line_buff, '\n')));
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lseek(grp_fd, (long) ((field_begin - line_buff) - line_len + 1),
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SEEK_CUR);
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goto restart;
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}
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if (*line_buff == '#' || *line_buff == ' ' || *line_buff == '\n' ||
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*line_buff == '\t')
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goto restart;
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*field_begin = '\0';
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#else /* !GR_SCALE_DYNAMIC */
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line_buff = realloc(line_buff, buff_size);
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while (1) {
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if ((line_len = read(grp_fd, line_buff + line_index,
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buff_size - line_index)) <= 0)
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return NULL;
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field_begin = strchr(line_buff, '\n');
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if (field_begin != NULL) {
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lseek(grp_fd,
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(long) (1 + field_begin -
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(line_len + line_index + line_buff)), SEEK_CUR);
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*field_begin = '\0';
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if (*line_buff == '#' || *line_buff == ' '
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|| *line_buff == '\n' || *line_buff == '\t')
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goto restart;
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break;
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} else { /* Allocate some more space */
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line_index = buff_size;
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buff_size += 256;
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line_buff = realloc(line_buff, buff_size);
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}
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}
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#endif /* GR_SCALE_DYNAMIC */
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/* Now parse the line */
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group.gr_name = line_buff;
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ptr = strchr(line_buff, ':');
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if (ptr == NULL)
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goto restart;
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*ptr++ = '\0';
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group.gr_passwd = ptr;
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ptr = strchr(ptr, ':');
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if (ptr == NULL)
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goto restart;
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*ptr++ = '\0';
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field_begin = ptr;
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ptr = strchr(ptr, ':');
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if (ptr == NULL)
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goto restart;
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*ptr++ = '\0';
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group.gr_gid = (gid_t) strtoul(field_begin, &endptr, 10);
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if (*endptr != '\0')
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goto restart;
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member_num = 0;
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field_begin = ptr;
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#ifndef GR_SCALE_DYNAMIC
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while ((ptr = strchr(ptr, ',')) != NULL) {
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*ptr = '\0';
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ptr++;
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members[member_num] = field_begin;
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field_begin = ptr;
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member_num++;
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}
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if (*field_begin == '\0')
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members[member_num] = NULL;
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else {
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members[member_num] = field_begin;
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members[member_num + 1] = NULL;
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}
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#else /* !GR_SCALE_DYNAMIC */
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free(members);
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members = (char **) malloc((member_num + 1) * sizeof(char *));
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for ( ; field_begin && *field_begin != '\0'; field_begin = ptr) {
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if ((ptr = strchr(field_begin, ',')) != NULL)
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*ptr++ = '\0';
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members[member_num++] = field_begin;
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members = (char **) realloc(members,
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(member_num + 1) * sizeof(char *));
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}
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members[member_num] = NULL;
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#endif /* GR_SCALE_DYNAMIC */
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group.gr_mem = members;
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return &group;
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}
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