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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1988 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     31 
     32 #include "lint.h"
     33 #include "file64.h"
     34 #include "mtlib.h"
     35 #include <stdio.h>
     36 #include <stddef.h>
     37 #include <values.h>
     38 #include <memory.h>
     39 #include <thread.h>
     40 #include <synch.h>
     41 #include <errno.h>
     42 #include <sys/types.h>
     43 #include "stdiom.h"
     44 #include "mse.h"
     45 
     46 size_t
     47 fread(void *ptr, size_t size, size_t count, FILE *iop)
     48 {
     49 	ssize_t s;
     50 	int c;
     51 	char *dptr = (char *)ptr;
     52 	rmutex_t *lk;
     53 
     54 	FLOCKFILE(lk, iop);
     55 
     56 	_SET_ORIENTATION_BYTE(iop);
     57 
     58 	/* is it a readable stream */
     59 	if (!(iop->_flag & (_IOREAD | _IORW))) {
     60 		iop->_flag |= _IOERR;
     61 		errno = EBADF;
     62 		FUNLOCKFILE(lk);
     63 		return (0);
     64 	}
     65 
     66 	if (iop->_flag & _IOEOF) {
     67 		FUNLOCKFILE(lk);
     68 		return (0);
     69 	}
     70 
     71 	/* These checks are here to avoid the multiply */
     72 	if (count == 1)
     73 		s = size;
     74 	else if (size == 1)
     75 		s = count;
     76 	else
     77 		s = size * count;
     78 
     79 	while (s > 0) {
     80 		if (iop->_cnt < s) {
     81 			if (iop->_cnt > 0) {
     82 				(void) memcpy((void*)dptr, iop->_ptr,
     83 				    iop->_cnt);
     84 				dptr += iop->_cnt;
     85 				s -= iop->_cnt;
     86 			}
     87 			/*
     88 			 * filbuf clobbers _cnt & _ptr,
     89 			 * so don't waste time setting them.
     90 			 */
     91 			if ((c = __filbuf(iop)) == EOF)
     92 				break;
     93 			*dptr++ = (char)c;
     94 			s--;
     95 		}
     96 		if (iop->_cnt >= s) {
     97 			char *tmp = (char *)iop->_ptr;
     98 			switch (s) {
     99 			case 8:
    100 				*dptr++ = *tmp++;
    101 				/*FALLTHRU*/
    102 			case 7:
    103 				*dptr++ = *tmp++;
    104 				/*FALLTHRU*/
    105 			case 6:
    106 				*dptr++ = *tmp++;
    107 				/*FALLTHRU*/
    108 			case 5:
    109 				*dptr++ = *tmp++;
    110 				/*FALLTHRU*/
    111 			case 4:
    112 				*dptr++ = *tmp++;
    113 				/*FALLTHRU*/
    114 			case 3:
    115 				*dptr++ = *tmp++;
    116 				/*FALLTHRU*/
    117 			case 2:
    118 				*dptr++ = *tmp++;
    119 				/*FALLTHRU*/
    120 			case 1:
    121 				*dptr++ = *tmp++;
    122 				break;
    123 			default:
    124 				(void) memcpy((void*)dptr, iop->_ptr,
    125 				    (size_t)s);
    126 			}
    127 			iop->_ptr += s;
    128 			iop->_cnt -= s;
    129 			FUNLOCKFILE(lk);
    130 			return (count);
    131 		}
    132 	}
    133 	FUNLOCKFILE(lk);
    134 	return (size != 0 ? count - ((s + size - 1) / size) : 0);
    135 }
    136