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Annotation of src/lib/libc/stdio/fread.c, Revision 1.16

1.16    ! agc         1: /*     $NetBSD: fread.c,v 1.15 2003/01/18 11:29:53 thorpej Exp $       */
1.6       jtc         2:
1.1       cgd         3: /*-
1.6       jtc         4:  * Copyright (c) 1990, 1993
                      5:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         6:  *
                      7:  * This code is derived from software contributed to Berkeley by
                      8:  * Chris Torek.
                      9:  *
                     10:  * Redistribution and use in source and binary forms, with or without
                     11:  * modification, are permitted provided that the following conditions
                     12:  * are met:
                     13:  * 1. Redistributions of source code must retain the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer.
                     15:  * 2. Redistributions in binary form must reproduce the above copyright
                     16:  *    notice, this list of conditions and the following disclaimer in the
                     17:  *    documentation and/or other materials provided with the distribution.
1.16    ! agc        18:  * 3. Neither the name of the University nor the names of its contributors
1.1       cgd        19:  *    may be used to endorse or promote products derived from this software
                     20:  *    without specific prior written permission.
                     21:  *
                     22:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     23:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     24:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     25:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     26:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     27:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     28:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     29:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     30:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     31:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     32:  * SUCH DAMAGE.
                     33:  */
                     34:
1.7       christos   35: #include <sys/cdefs.h>
1.1       cgd        36: #if defined(LIBC_SCCS) && !defined(lint)
1.6       jtc        37: #if 0
                     38: static char sccsid[] = "@(#)fread.c    8.2 (Berkeley) 12/11/93";
1.7       christos   39: #else
1.16    ! agc        40: __RCSID("$NetBSD: fread.c,v 1.15 2003/01/18 11:29:53 thorpej Exp $");
1.6       jtc        41: #endif
1.1       cgd        42: #endif /* LIBC_SCCS and not lint */
                     43:
1.10      lukem      44: #include <assert.h>
                     45: #include <errno.h>
1.1       cgd        46: #include <stdio.h>
                     47: #include <string.h>
1.15      thorpej    48: #include "reentrant.h"
1.7       christos   49: #include "local.h"
1.1       cgd        50:
1.4       jtc        51: size_t
1.1       cgd        52: fread(buf, size, count, fp)
                     53:        void *buf;
                     54:        size_t size, count;
1.9       perry      55:        FILE *fp;
1.1       cgd        56: {
1.9       perry      57:        size_t resid;
                     58:        char *p;
                     59:        int r;
1.1       cgd        60:        size_t total;
1.10      lukem      61:
                     62:        _DIAGASSERT(fp != NULL);
1.6       jtc        63:        /*
                     64:         * The ANSI standard requires a return value of 0 for a count
1.14      lukem      65:         * or a size of 0.  Whilst ANSI imposes no such requirements on
                     66:         * fwrite, the SUSv2 does.
1.6       jtc        67:         */
1.1       cgd        68:        if ((resid = count * size) == 0)
1.5       jtc        69:                return (0);
1.14      lukem      70:
                     71:        _DIAGASSERT(buf != NULL);
                     72:
1.8       jtc        73:        FLOCKFILE(fp);
1.1       cgd        74:        if (fp->_r < 0)
                     75:                fp->_r = 0;
                     76:        total = resid;
                     77:        p = buf;
                     78:        while (resid > (r = fp->_r)) {
1.6       jtc        79:                (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
1.1       cgd        80:                fp->_p += r;
                     81:                /* fp->_r = 0 ... done in __srefill */
                     82:                p += r;
                     83:                resid -= r;
                     84:                if (__srefill(fp)) {
                     85:                        /* no more input: return partial result */
1.8       jtc        86:                        FUNLOCKFILE(fp);
1.1       cgd        87:                        return ((total - resid) / size);
                     88:                }
                     89:        }
1.6       jtc        90:        (void)memcpy((void *)p, (void *)fp->_p, resid);
1.1       cgd        91:        fp->_r -= resid;
                     92:        fp->_p += resid;
1.8       jtc        93:        FUNLOCKFILE(fp);
1.1       cgd        94:        return (count);
                     95: }