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 "namespace.h"
39 #include <errno.h>
40 #include <limits.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include "un-namespace.h"
45 #include "libc_private.h"
46 #include "local.h"
47
48 /*
49 * Expand the line buffer. Return -1 on error.
50 */
51 int
__slbexpand(FILE * fp,size_t newsize)52 __slbexpand(FILE *fp, size_t newsize)
53 {
54 void *p;
55
56 if (fp->_lb._size >= newsize)
57 return (0);
58 if (newsize > INT_MAX) {
59 errno = ENOMEM;
60 return (-1);
61 }
62 if ((p = realloc(fp->_lb._base, newsize)) == NULL)
63 return (-1);
64 fp->_lb._base = p;
65 fp->_lb._size = newsize;
66 return (0);
67 }
68
69 /*
70 * Get an input line. The returned pointer often (but not always)
71 * points into a stdio buffer. Fgetln does not alter the text of
72 * the returned line (which is thus not a C string because it will
73 * not necessarily end with '\0'), but does allow callers to modify
74 * it if they wish. Thus, we set __SMOD in case the caller does.
75 */
76 char *
fgetln(FILE * fp,size_t * lenp)77 fgetln(FILE *fp, size_t *lenp)
78 {
79 unsigned char *p;
80 char *ret;
81 size_t len;
82 size_t off;
83
84 FLOCKFILE_CANCELSAFE(fp);
85 ORIENT(fp, -1);
86 /* make sure there is input */
87 if (fp->_r <= 0 && __srefill(fp)) {
88 *lenp = 0;
89 ret = NULL;
90 goto end;
91 }
92
93 /* look for a newline in the input */
94 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
95 /*
96 * Found one. Flag buffer as modified to keep fseek from
97 * `optimising' a backward seek, in case the user stomps on
98 * the text.
99 */
100 p++; /* advance over it */
101 ret = (char *)fp->_p;
102 *lenp = len = p - fp->_p;
103 fp->_flags |= __SMOD;
104 fp->_r -= len;
105 fp->_p = p;
106 goto end;
107 }
108
109 /*
110 * We have to copy the current buffered data to the line buffer.
111 * As a bonus, though, we can leave off the __SMOD.
112 *
113 * OPTIMISTIC is length that we (optimistically) expect will
114 * accommodate the `rest' of the string, on each trip through the
115 * loop below.
116 */
117 #define OPTIMISTIC 80
118
119 for (len = fp->_r, off = 0;; len += fp->_r) {
120 size_t diff;
121
122 /*
123 * Make sure there is room for more bytes. Copy data from
124 * file buffer to line buffer, refill file and look for
125 * newline. The loop stops only when we find a newline.
126 */
127 if (__slbexpand(fp, len + OPTIMISTIC))
128 goto error;
129 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
130 len - off);
131 off = len;
132 if (__srefill(fp)) {
133 if (__sfeof(fp))
134 break;
135 goto error;
136 }
137 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
138 continue;
139
140 /* got it: finish up the line (like code above) */
141 p++;
142 diff = p - fp->_p;
143 len += diff;
144 if (__slbexpand(fp, len))
145 goto error;
146 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
147 diff);
148 fp->_r -= diff;
149 fp->_p = p;
150 break;
151 }
152 *lenp = len;
153 ret = (char *)fp->_lb._base;
154 end:
155 FUNLOCKFILE_CANCELSAFE();
156 return (ret);
157
158 error:
159 *lenp = 0; /* ??? */
160 fp->_flags |= __SERR;
161 ret = NULL;
162 goto end;
163 }
164