1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)fgetln.c 8.2 (Berkeley) 1/2/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include "namespace.h"
42 #include <errno.h>
43 #include <limits.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include "un-namespace.h"
48 #include "libc_private.h"
49 #include "local.h"
50
51 /*
52 * Expand the line buffer. Return -1 on error.
53 */
54 int
__slbexpand(FILE * fp,size_t newsize)55 __slbexpand(FILE *fp, size_t newsize)
56 {
57 void *p;
58
59 if (fp->_lb._size >= newsize)
60 return (0);
61 if (newsize > INT_MAX) {
62 errno = ENOMEM;
63 return (-1);
64 }
65 if ((p = realloc(fp->_lb._base, newsize)) == NULL)
66 return (-1);
67 fp->_lb._base = p;
68 fp->_lb._size = newsize;
69 return (0);
70 }
71
72 /*
73 * Get an input line. The returned pointer often (but not always)
74 * points into a stdio buffer. Fgetln does not alter the text of
75 * the returned line (which is thus not a C string because it will
76 * not necessarily end with '\0'), but does allow callers to modify
77 * it if they wish. Thus, we set __SMOD in case the caller does.
78 */
79 char *
fgetln(FILE * fp,size_t * lenp)80 fgetln(FILE *fp, size_t *lenp)
81 {
82 unsigned char *p;
83 char *ret;
84 size_t len;
85 size_t off;
86
87 FLOCKFILE_CANCELSAFE(fp);
88 ORIENT(fp, -1);
89 /* make sure there is input */
90 if (fp->_r <= 0 && __srefill(fp)) {
91 *lenp = 0;
92 ret = NULL;
93 goto end;
94 }
95
96 /* look for a newline in the input */
97 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
98 /*
99 * Found one. Flag buffer as modified to keep fseek from
100 * `optimising' a backward seek, in case the user stomps on
101 * the text.
102 */
103 p++; /* advance over it */
104 ret = (char *)fp->_p;
105 *lenp = len = p - fp->_p;
106 fp->_flags |= __SMOD;
107 fp->_r -= len;
108 fp->_p = p;
109 goto end;
110 }
111
112 /*
113 * We have to copy the current buffered data to the line buffer.
114 * As a bonus, though, we can leave off the __SMOD.
115 *
116 * OPTIMISTIC is length that we (optimistically) expect will
117 * accommodate the `rest' of the string, on each trip through the
118 * loop below.
119 */
120 #define OPTIMISTIC 80
121
122 for (len = fp->_r, off = 0;; len += fp->_r) {
123 size_t diff;
124
125 /*
126 * Make sure there is room for more bytes. Copy data from
127 * file buffer to line buffer, refill file and look for
128 * newline. The loop stops only when we find a newline.
129 */
130 if (__slbexpand(fp, len + OPTIMISTIC))
131 goto error;
132 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
133 len - off);
134 off = len;
135 if (__srefill(fp)) {
136 if (__sfeof(fp))
137 break;
138 goto error;
139 }
140 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
141 continue;
142
143 /* got it: finish up the line (like code above) */
144 p++;
145 diff = p - fp->_p;
146 len += diff;
147 if (__slbexpand(fp, len))
148 goto error;
149 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
150 diff);
151 fp->_r -= diff;
152 fp->_p = p;
153 break;
154 }
155 *lenp = len;
156 ret = (char *)fp->_lb._base;
157 end:
158 FUNLOCKFILE_CANCELSAFE();
159 return (ret);
160
161 error:
162 *lenp = 0; /* ??? */
163 fp->_flags |= __SERR;
164 ret = NULL;
165 goto end;
166 }
167