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8d2f28ac WJ |
1 | /*- |
2 | * Copyright (c) 1990 The Regents of the University of California. | |
3 | * 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 sccsid[] = "@(#)fgets.c 5.4 (Berkeley) 5/4/91"; | |
39 | #endif /* LIBC_SCCS and not lint */ | |
40 | ||
41 | #include <stdio.h> | |
42 | #include <string.h> | |
43 | ||
44 | /* | |
45 | * Read at most n-1 characters from the given file. | |
46 | * Stop when a newline has been read, or the count runs out. | |
47 | * Return first argument, or NULL if no characters were read. | |
48 | */ | |
49 | char * | |
50 | fgets(buf, n, fp) | |
51 | char *buf; | |
52 | register size_t n; | |
53 | register FILE *fp; | |
54 | { | |
55 | register size_t len; | |
56 | register char *s; | |
57 | register unsigned char *p, *t; | |
58 | ||
59 | if (n < 2) /* sanity check */ | |
60 | return (NULL); | |
61 | ||
62 | s = buf; | |
63 | n--; /* leave space for NUL */ | |
64 | do { | |
65 | /* | |
66 | * If the buffer is empty, refill it. | |
67 | */ | |
68 | if ((len = fp->_r) <= 0) { | |
69 | if (__srefill(fp)) { | |
70 | /* EOF/error: stop with partial or no line */ | |
71 | if (s == buf) | |
72 | return (NULL); | |
73 | break; | |
74 | } | |
75 | len = fp->_r; | |
76 | } | |
77 | p = fp->_p; | |
78 | ||
79 | /* | |
80 | * Scan through at most n bytes of the current buffer, | |
81 | * looking for '\n'. If found, copy up to and including | |
82 | * newline, and stop. Otherwise, copy entire chunk | |
83 | * and loop. | |
84 | */ | |
85 | if (len > n) | |
86 | len = n; | |
87 | t = memchr((void *)p, '\n', len); | |
88 | if (t != NULL) { | |
89 | len = ++t - p; | |
90 | fp->_r -= len; | |
91 | fp->_p = t; | |
92 | (void) bcopy((void *)p, (void *)s, len); | |
93 | s[len] = 0; | |
94 | return (buf); | |
95 | } | |
96 | fp->_r -= len; | |
97 | fp->_p += len; | |
98 | (void) bcopy((void *)p, (void *)s, len); | |
99 | s += len; | |
100 | } while ((n -= len) != 0); | |
101 | *s = 0; | |
102 | return (buf); | |
103 | } |