1/* Copyright (C) 1991-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <grp.h>
20#include <libc-lock.h>
21#include <stdio.h>
22#include <stdlib.h>
23#include <set-freeres.h>
24
25
26/* We need to protect the dynamic buffer handling. */
27__libc_lock_define_initialized (static, lock);
28
29static char *buffer;
30
31/* Read one entry from the given stream. */
32struct group *
33fgetgrent (FILE *stream)
34{
35 static size_t buffer_size;
36 static struct group resbuf;
37 fpos_t pos;
38 struct group *result;
39 int save;
40
41 if (__builtin_expect (fgetpos (stream, &pos), 0) != 0)
42 return NULL;
43
44 /* Get lock. */
45 __libc_lock_lock (lock);
46
47 /* Allocate buffer if not yet available. */
48 if (buffer == NULL)
49 {
50 buffer_size = NSS_BUFLEN_GROUP;
51 buffer = malloc (buffer_size);
52 }
53
54 while (buffer != NULL
55 && (__fgetgrent_r (stream, &resbuf, buffer, buffer_size, &result)
56 == ERANGE))
57 {
58 char *new_buf;
59 buffer_size += NSS_BUFLEN_GROUP;
60 new_buf = realloc (buffer, buffer_size);
61 if (__glibc_unlikely (new_buf == NULL))
62 {
63 /* We are out of memory. Free the current buffer so that the
64 process gets a chance for a normal termination. */
65 save = errno;
66 free (buffer);
67 __set_errno (save);
68 }
69 buffer = new_buf;
70
71 /* Reset the stream. */
72 if (fsetpos (stream, &pos) != 0)
73 buffer = NULL;
74 }
75
76 if (buffer == NULL)
77 result = NULL;
78
79 /* Release lock. Preserve error value. */
80 save = errno;
81 __libc_lock_unlock (lock);
82 __set_errno (save);
83
84 return result;
85}
86
87weak_alias (buffer, __libc_fgetgrent_freemem_ptr)
88