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 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 #include <stdio.h> 16 #include <string.h> 17 18 size_t 19 fread(buf, size, count, fp) 20 void *buf; 21 size_t size, count; 22 register FILE *fp; 23 { 24 register size_t resid; 25 register char *p; 26 register int r; 27 size_t total; 28 29 /* 30 * The ANSI standard requires a return value of 0 for a count 31 * or a size of 0. Peculiarily, it imposes no such requirements 32 * on fwrite; it only requires fread to be broken. 33 */ 34 if ((resid = count * size) == 0) 35 return (0); 36 if (fp->_r < 0) 37 fp->_r = 0; 38 total = resid; 39 p = buf; 40 while (resid > (r = fp->_r)) { 41 (void)memcpy((void *)p, (void *)fp->_p, (size_t)r); 42 fp->_p += r; 43 /* fp->_r = 0 ... done in __srefill */ 44 p += r; 45 resid -= r; 46 if (__srefill(fp)) { 47 /* no more input: return partial result */ 48 return ((total - resid) / size); 49 } 50 } 51 (void)memcpy((void *)p, (void *)fp->_p, resid); 52 fp->_r -= resid; 53 fp->_p += resid; 54 return (count); 55 } 56