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 #ifdef notdef
54 * The `new size' does not account for a terminating '\0',
55 * so we add 1 here.
56 #endif
57 */
58 int
__slbexpand(FILE * fp,size_t newsize)59 __slbexpand(FILE *fp, size_t newsize)
60 {
61 void *p;
62
63 #ifdef notdef
64 ++newsize;
65 #endif
66 if (fp->_lb._size >= newsize)
67 return (0);
68 if (newsize > INT_MAX) {
69 errno = ENOMEM;
70 return (-1);
71 }
72 if ((p = realloc(fp->_lb._base, newsize)) == NULL)
73 return (-1);
74 fp->_lb._base = p;
75 fp->_lb._size = newsize;
76 return (0);
77 }
78
79 /*
80 * Get an input line. The returned pointer often (but not always)
81 * points into a stdio buffer. Fgetln does not alter the text of
82 * the returned line (which is thus not a C string because it will
83 * not necessarily end with '\0'), but does allow callers to modify
84 * it if they wish. Thus, we set __SMOD in case the caller does.
85 */
86 char *
fgetln(FILE * fp,size_t * lenp)87 fgetln(FILE *fp, size_t *lenp)
88 {
89 unsigned char *p;
90 char *ret;
91 size_t len;
92 size_t off;
93
94 FLOCKFILE_CANCELSAFE(fp);
95 ORIENT(fp, -1);
96 /* make sure there is input */
97 if (fp->_r <= 0 && __srefill(fp)) {
98 *lenp = 0;
99 ret = NULL;
100 goto end;
101 }
102
103 /* look for a newline in the input */
104 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
105 /*
106 * Found one. Flag buffer as modified to keep fseek from
107 * `optimising' a backward seek, in case the user stomps on
108 * the text.
109 */
110 p++; /* advance over it */
111 ret = (char *)fp->_p;
112 *lenp = len = p - fp->_p;
113 fp->_flags |= __SMOD;
114 fp->_r -= len;
115 fp->_p = p;
116 goto end;
117 }
118
119 /*
120 * We have to copy the current buffered data to the line buffer.
121 * As a bonus, though, we can leave off the __SMOD.
122 *
123 * OPTIMISTIC is length that we (optimistically) expect will
124 * accommodate the `rest' of the string, on each trip through the
125 * loop below.
126 */
127 #define OPTIMISTIC 80
128
129 for (len = fp->_r, off = 0;; len += fp->_r) {
130 size_t diff;
131
132 /*
133 * Make sure there is room for more bytes. Copy data from
134 * file buffer to line buffer, refill file and look for
135 * newline. The loop stops only when we find a newline.
136 */
137 if (__slbexpand(fp, len + OPTIMISTIC))
138 goto error;
139 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
140 len - off);
141 off = len;
142 if (__srefill(fp)) {
143 if (__sfeof(fp))
144 break;
145 goto error;
146 }
147 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
148 continue;
149
150 /* got it: finish up the line (like code above) */
151 p++;
152 diff = p - fp->_p;
153 len += diff;
154 if (__slbexpand(fp, len))
155 goto error;
156 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
157 diff);
158 fp->_r -= diff;
159 fp->_p = p;
160 break;
161 }
162 *lenp = len;
163 #ifdef notdef
164 fp->_lb._base[len] = '\0';
165 #endif
166 ret = (char *)fp->_lb._base;
167 end:
168 FUNLOCKFILE_CANCELSAFE();
169 return (ret);
170
171 error:
172 *lenp = 0; /* ??? */
173 fp->_flags |= __SERR;
174 ret = NULL;
175 goto end;
176 }
177