1/* Copyright (C) 2009-2023 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 <libc-lock.h>
20#include <gshadow.h>
21#include <stdio.h>
22#include <stdlib.h>
23
24
25/* A reasonable size for a buffer to start with. */
26#define BUFLEN_SPWD 1024
27
28/* We need to protect the dynamic buffer handling. */
29__libc_lock_define_initialized (static, lock);
30
31libc_freeres_ptr (static char *buffer);
32
33/* Read one shadow entry from the given stream. */
34struct sgrp *
35fgetsgent (FILE *stream)
36{
37 static size_t buffer_size;
38 static struct sgrp resbuf;
39 fpos_t pos;
40 struct sgrp *result;
41 int save;
42
43 if (fgetpos (stream, &pos) != 0)
44 return NULL;
45
46 /* Get lock. */
47 __libc_lock_lock (lock);
48
49 /* Allocate buffer if not yet available. */
50 if (buffer == NULL)
51 {
52 buffer_size = BUFLEN_SPWD;
53 buffer = malloc (buffer_size);
54 }
55
56 while (buffer != NULL
57 && (__fgetsgent_r (stream, &resbuf, buffer, buffer_size, &result)
58 == ERANGE))
59 {
60 char *new_buf;
61 buffer_size += BUFLEN_SPWD;
62 new_buf = realloc (buffer, buffer_size);
63 if (new_buf == NULL)
64 {
65 /* We are out of memory. Free the current buffer so that the
66 process gets a chance for a normal termination. */
67 save = errno;
68 free (buffer);
69 __set_errno (save);
70 }
71 buffer = new_buf;
72
73 /* Reset the stream. */
74 if (fsetpos (stream, &pos) != 0)
75 buffer = NULL;
76 }
77
78 if (buffer == NULL)
79 result = NULL;
80
81 /* Release lock. Preserve error value. */
82 save = errno;
83 __libc_lock_unlock (lock);
84 __set_errno (save);
85
86 return result;
87}
88