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 * 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.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)fread.c	8.2 (Berkeley) 12/11/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: src/lib/libc/stdio/fread.c,v 1.16 2009/07/12 13:09:43 ed Exp $");
38
39#include "namespace.h"
40#include <stdio.h>
41#include <string.h>
42#include "un-namespace.h"
43#include "local.h"
44#include "libc_private.h"
45
46/*
47 * MT-safe version
48 */
49
50size_t
51fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
52{
53	size_t ret;
54
55	FLOCKFILE(fp);
56	ret = __fread(buf, size, count, fp);
57	FUNLOCKFILE(fp);
58	return (ret);
59}
60
61/*
62 * The maximum amount to read to avoid integer overflow.  INT_MAX is odd,
63 * so it make sense to make it even.  We subtract (BUFSIZ - 1) to get a
64 * whole number of BUFSIZ chunks.
65 */
66#define MAXREAD	(INT_MAX - (BUFSIZ - 1))
67
68/* __fread0: int sized, with size = 1 */
69static inline int
70__fread0(void * __restrict buf, int count, FILE * __restrict fp)
71{
72	int resid;
73	char *p;
74	int r, ret;
75
76	resid = count;
77	p = buf;
78	/* first deal with anything left in buffer, plus any ungetc buffers */
79	while (resid > (r = fp->_r)) {
80		(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
81		fp->_p += r;
82		/* fp->_r = 0 ... done in __srefill */
83		p += r;
84		resid -= r;
85		if ((ret = __srefill0(fp)) > 0)
86			break;
87		else if (ret) {
88			/* no more input: return partial result */
89			return (count - resid);
90		}
91	}
92	/*
93	 * 5980080: don't use optimization if __SMBF not set (meaning setvbuf
94	 * was called, and the buffer belongs to the user).
95	 * 6180417: but for unbuffered (__SMBF is not set), so specifically
96	 * test for it.
97	 */
98	if ((fp->_flags & (__SMBF | __SNBF)) && resid > fp->_bf._size) {
99		struct __sbuf save;
100		size_t n;
101
102		save = fp->_bf;
103		fp->_bf._base = (unsigned char *)p;
104		fp->_bf._size = resid;
105		while (fp->_bf._size > 0) {
106			if ((ret = __srefill1(fp)) != 0) {
107				/* no more input: return partial result */
108				resid = fp->_bf._size;
109				fp->_bf = save;
110				fp->_p = fp->_bf._base;
111				/* fp->_r = 0;  already set in __srefill1 */
112				return (count - resid);
113			}
114			fp->_bf._base += fp->_r;
115			fp->_bf._size -= fp->_r;
116		}
117		fp->_bf = save;
118		n = fp->_bf._size * ((resid - 1) / fp->_bf._size);
119		r = resid - n;
120		(void)memcpy((void *)fp->_bf._base, (void *)(p + n), (size_t)r);
121		fp->_p = fp->_bf._base + r;
122		fp->_r = 0;
123	} else {
124		while (resid > (r = fp->_r)) {
125			(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
126			fp->_p += r;
127			/* fp->_r = 0 ... done in __srefill */
128			p += r;
129			resid -= r;
130			if (__srefill1(fp)) {
131				/* no more input: return partial result */
132				return (count - resid);
133			}
134		}
135		(void)memcpy((void *)p, (void *)fp->_p, resid);
136		fp->_r -= resid;
137		fp->_p += resid;
138	}
139	return (count);
140}
141
142size_t
143__fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
144{
145	size_t resid;
146	int r, ret;
147	size_t total;
148
149	/*
150	 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
151	 */
152	if ((resid = count * size) == 0)
153		return (0);
154	ORIENT(fp, -1);
155	if (fp->_r < 0)
156		fp->_r = 0;
157
158	for (total = resid; resid > 0; buf += r, resid -= r) {
159		r = resid > INT_MAX ? MAXREAD : (int)resid;
160		if ((ret = __fread0(buf, r, fp)) != r) {
161			count = (total - resid + ret) / size;
162			break;
163		}
164	}
165	return (count);
166}
167