Sync libc/stdio with FreeBSD:
[dragonfly.git] / lib / libc / stdio / fread.c
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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.
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16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
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31 *
32 * @(#)fread.c 8.2 (Berkeley) 12/11/93
e0f95098 33 * $FreeBSD: src/lib/libc/stdio/fread.c,v 1.15 2008/12/01 14:33:34 ru Exp $
5b10ca29 34 * $DragonFly: src/lib/libc/stdio/fread.c,v 1.8 2005/12/20 00:21:53 davidxu Exp $
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35 */
36
17ea2221 37#include "namespace.h"
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38#include <stdio.h>
39#include <string.h>
17ea2221 40#include "un-namespace.h"
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41#include "local.h"
42#include "libc_private.h"
55b5af84 43#include "priv_stdio.h"
984263bc 44
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45/*
46 * MT-safe version
47 */
48
984263bc 49size_t
e0f95098 50fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
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51{
52 size_t ret;
53
54 FLOCKFILE(fp);
55 ret = __fread(buf, size, count, fp);
56 FUNLOCKFILE(fp);
57 return (ret);
58}
59
60size_t
e0f95098 61__fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
984263bc 62{
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63 size_t resid;
64 char *p;
65 int r;
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66 size_t total;
67
68 /*
69 * The ANSI standard requires a return value of 0 for a count
70 * or a size of 0. Peculiarily, it imposes no such requirements
71 * on fwrite; it only requires fread to be broken.
72 */
73 if ((resid = count * size) == 0)
74 return (0);
e0f95098 75 ORIENT(fp, -1);
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76 if (fp->pub._r < 0)
77 fp->pub._r = 0;
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78 total = resid;
79 p = buf;
55b5af84 80 while (resid > (r = fp->pub._r)) {
54a0004d 81 memcpy((void *)p, (void *)fp->pub._p, (size_t)r);
55b5af84 82 fp->pub._p += r;
e0f95098 83 /* fp->pub._r = 0 ... done in __srefill */
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84 p += r;
85 resid -= r;
86 if (__srefill(fp)) {
87 /* no more input: return partial result */
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88 return ((total - resid) / size);
89 }
90 }
54a0004d 91 memcpy((void *)p, (void *)fp->pub._p, resid);
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92 fp->pub._r -= resid;
93 fp->pub._p += resid;
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94 return (count);
95}