fgetln.c - vx32 - Local 9vx git repository for patches.
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---
fgetln.c (4848B)
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1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char *rcsid = "$OpenBSD: fgetln.c,v 1.2 1996/08/19 08:32:29 tholo Exp $";
39 #endif /* LIBC_SCCS and not lint */
40
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include "local.h"
45
46 /*
47 * Expand the line buffer. Return -1 on error.
48 #ifdef notdef
49 * The `new size' does not account for a terminating '\0',
50 * so we add 1 here.
51 #endif
52 */
53 int
54 __slbexpand(fp, newsize)
55 FILE *fp;
56 size_t newsize;
57 {
58 void *p;
59
60 #ifdef notdef
61 ++newsize;
62 #endif
63 if (fp->_lb._size >= newsize)
64 return (0);
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. Fgetline 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 *
80 fgetln(fp, lenp)
81 register FILE *fp;
82 size_t *lenp;
83 {
84 register unsigned char *p;
85 register size_t len;
86 size_t off;
87
88 /* make sure there is input */
89 if (fp->_r <= 0 && __srefill(fp)) {
90 *lenp = 0;
91 return (NULL);
92 }
93
94 /* look for a newline in the input */
95 if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) {
96 register char *ret;
97
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 return (ret);
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 * accomodate 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 register 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 break; /* EOF or error: return partial line */
137 if ((p = memchr((void *)fp->_p, '\n', 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 #ifdef notdef
154 fp->_lb._base[len] = 0;
155 #endif
156 return ((char *)fp->_lb._base);
157
158 error:
159 *lenp = 0; /* ??? */
160 return (NULL); /* ??? */
161 }