/* $NetBSD: fread.c,v 1.22.34.1 2021/02/07 17:41:02 martin Exp $ */ /*- * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Chris Torek. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #if defined(LIBC_SCCS) && !defined(lint) #if 0 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; #else __RCSID("$NetBSD: fread.c,v 1.22.34.1 2021/02/07 17:41:02 martin Exp $"); #endif #endif /* LIBC_SCCS and not lint */ #include #include #include #include #include "reentrant.h" #include "local.h" size_t fread(void *buf, size_t size, size_t count, FILE *fp) { size_t resid; char *p; int r; size_t total; _DIAGASSERT(fp != NULL); /* * The ANSI standard requires a return value of 0 for a count * or a size of 0. Whilst ANSI imposes no such requirements on * fwrite, the SUSv2 does. */ if ((resid = count * size) == 0) return 0; _DIAGASSERT(buf != NULL); FLOCKFILE(fp); if (fp->_r < 0) fp->_r = 0; total = resid; p = buf; /* * If we're unbuffered we know that the buffer in fp is empty so * we can read directly into buf. This is much faster than a * series of one byte reads into fp->_nbuf. */ if ((fp->_flags & __SNBF) != 0) { while (resid > 0) { /* set up the buffer */ fp->_bf._base = fp->_p = (unsigned char *)p; fp->_bf._size = resid; if (__srefill(fp)) { /* no more input: return partial result */ count = (total - resid) / size; break; } p += fp->_r; resid -= fp->_r; } /* restore the old buffer (see __smakebuf) */ fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; fp->_r = 0; FUNLOCKFILE(fp); return (count); } while (resid > (size_t)(r = fp->_r)) { (void)memcpy(p, fp->_p, (size_t)r); fp->_p += r; /* fp->_r = 0 ... done in __srefill */ p += r; resid -= r; if (__srefill(fp)) { /* no more input: return partial result */ FUNLOCKFILE(fp); return (total - resid) / size; } } (void)memcpy(p, fp->_p, resid); _DIAGASSERT(__type_fit(int, fp->_r - resid)); fp->_r -= (int)resid; fp->_p += resid; FUNLOCKFILE(fp); return count; }