aboutsummaryrefslogtreecommitdiff
path: root/libpwdgrp/__getgrent.c
blob: ed4f59c5b164b5d51ec214b715f381272616bd5c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
/*
 * __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 "busybox.h"
#include "grp_.h"

/*
 * Define GR_SCALE_DYNAMIC if you want grp to dynamically scale its read buffer
 * so that lines of any length can be used.  On very very small systems,
 * you may want to leave this undefined becasue it will make the grp functions
 * somewhat larger (because of the inclusion of malloc and the code necessary).
 * On larger systems, you will want to define this, because grp will _not_
 * deal with long lines gracefully (they will be skipped).
 */
#undef GR_SCALE_DYNAMIC

#ifndef GR_SCALE_DYNAMIC
/*
 * If scaling is not dynamic, the buffers will be statically allocated, and
 * maximums must be chosen.  GR_MAX_LINE_LEN is the maximum number of
 * characters per line in the group file.  GR_MAX_MEMBERS is the maximum
 * number of members of any given group.
 */
#define GR_MAX_LINE_LEN 128
/* GR_MAX_MEMBERS = (GR_MAX_LINE_LEN-(24+3+6))/9 */
#define GR_MAX_MEMBERS 11

#endif /* !GR_SCALE_DYNAMIC */


/*
 * Define GR_DYNAMIC_GROUP_LIST to make initgroups() dynamically allocate
 * space for it's GID array before calling setgroups().  This is probably
 * unnecessary scalage, so it's undefined by default.
 */
#undef GR_DYNAMIC_GROUP_LIST

#ifndef GR_DYNAMIC_GROUP_LIST
/*
 * GR_MAX_GROUPS is the size of the static array initgroups() uses for
 * its static GID array if GR_DYNAMIC_GROUP_LIST isn't defined.
 */
#define GR_MAX_GROUPS 64

#endif /* !GR_DYNAMIC_GROUP_LIST */


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

	group.gr_mem = members;
	return &group;
}