stdio/fread-fbsd.c

   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  * 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[] = "@(#)fread.c     8.2 (Berkeley) 12/11/93";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdio/fread.c,v 1.12 2002/10/12 16:13:37 mike Exp $");
  42
  43 #include "namespace.h"
  44 #include <stdio.h>
  45 #include <string.h>
  46 #include "un-namespace.h"
  47 #include "local.h"
  48 #include "libc_private.h"
  49
  50 size_t
  51 fread(buf, size, count, fp)
  52         void * __restrict buf;
  53         size_t size, count;
  54         FILE * __restrict fp;
  55 {
  56         size_t resid;
  57         char *p;
  58         int r, ret;
  59         size_t total;
  60
  61         /*
  62          * The ANSI standard requires a return value of 0 for a count
  63          * or a size of 0.  Peculiarily, it imposes no such requirements
  64          * on fwrite; it only requires fread to be broken.
  65          */
  66         if ((resid = count * size) == 0)
  67                 return (0);
  68         FLOCKFILE(fp);
  69         ORIENT(fp, -1);
  70         if (fp->_r < 0)
  71                 fp->_r = 0;
  72         total = resid;
  73         p = buf;
  74         /* first deal with anything left in buffer, plus any ungetc buffers */
  75         while (resid > (r = fp->_r)) {
  76                 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
  77                 fp->_p += r;
  78                 /* fp->_r = 0 ... done in __srefill */
  79                 p += r;
  80                 resid -= r;
  81                 if ((ret = __srefill0(fp)) > 0)
  82                         break;
  83                 else if (ret) {
  84                         /* no more input: return partial result */
  85                         FUNLOCKFILE(fp);
  86                         return ((total - resid) / size);
  87                 }
  88         }
  89         /*
  90          * 5980080: don't use optimization if __SMBF not set (meaning setvbuf
  91          * was called, and the buffer belongs to the user).
  92          * 6180417: but for unbuffered (__SMBF is not set), so specifically
  93          * test for it.
  94          */
  95         if ((fp->_flags & (__SMBF | __SNBF)) && resid > fp->_bf._size) {
  96                 struct __sbuf save;
  97                 size_t n;
  98
  99                 save = fp->_bf;
 100                 fp->_bf._base = p;
 101                 fp->_bf._size = resid;
 102                 while (fp->_bf._size > 0) {
 103                         if ((ret = __srefill1(fp)) != 0) {
 104                                 /* no more input: return partial result */
 105                                 resid = fp->_bf._size;
 106                                 fp->_bf = save;
 107                                 fp->_p = fp->_bf._base;
 108                                 /* fp->_r = 0;  already set in __srefill1 */
 109                                 FUNLOCKFILE(fp);
 110                                 return ((total - resid) / size);
 111                         }
 112                         fp->_bf._base += fp->_r;
 113                         fp->_bf._size -= fp->_r;
 114                 }
 115                 fp->_bf = save;
 116                 n = fp->_bf._size * ((resid - 1) / fp->_bf._size);
 117                 r = resid - n;
 118                 (void)memcpy((void *)fp->_bf._base, (void *)(p + n), (size_t)r);
 119                 fp->_p = fp->_bf._base + r;
 120                 fp->_r = 0;
 121         } else {
 122                 while (resid > (r = fp->_r)) {
 123                         (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
 124                         fp->_p += r;
 125                         /* fp->_r = 0 ... done in __srefill */
 126                         p += r;
 127                         resid -= r;
 128                         if (__srefill1(fp)) {
 129                                 /* no more input: return partial result */
 130                                 FUNLOCKFILE(fp);
 131                                 return ((total - resid) / size);
 132                         }
 133                 }
 134                 (void)memcpy((void *)p, (void *)fp->_p, resid);
 135                 fp->_r -= resid;
 136                 fp->_p += resid;
 137         }
 138         FUNLOCKFILE(fp);
 139         return (count);
 140 }