fread.c revision 5d54f3d8999eac1762fe0a8c7177d20f1f201fae
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 1986 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
/*LINTLIBRARY*/
/*
* This version reads directly from the buffer rather than looping on getc.
* Ptr args aren't checked for NULL because the program would be a
* catastrophic mess anyway. Better to abort than just to return NULL.
*/
#include <stdio.h>
#include "stdiom.h"
#include <memory.h>
#define MIN(x, y) (x < y ? x : y)
extern int _filbuf();
int
fread(char *ptr, int size, int count, FILE *iop)
{
unsigned int nleft;
int n;
if (size <= 0 || count <= 0) return 0;
nleft = count * size;
/* Put characters in the buffer */
/* note that the meaning of n when just starting this loop is
irrelevant. It is defined in the loop */
for ( ; ; ) {
if (iop->_cnt <= 0) { /* empty buffer */
if (_filbuf(iop) == EOF)
return (count - (nleft + size - 1)/size);
iop->_ptr--;
iop->_cnt++;
}
n = MIN(nleft, iop->_cnt);
ptr = memcpy(ptr, (char *) iop->_ptr, n) + n;
iop->_cnt -= n;
iop->_ptr += n;
_BUFSYNC(iop);
if ((nleft -= n) == 0)
return (count);
}
}