146084Sbostic /*-
261180Sbostic * Copyright (c) 1990, 1993
361180Sbostic * The Regents of the University of California. All rights reserved.
446084Sbostic *
546084Sbostic * This code is derived from software contributed to Berkeley by
646084Sbostic * Chris Torek.
746084Sbostic *
846084Sbostic * %sccs.include.redist.c%
921406Sdist */
1021406Sdist
1126651Sdonn #if defined(LIBC_SCCS) && !defined(lint)
12*65097Storek static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93";
1346084Sbostic #endif /* LIBC_SCCS and not lint */
1421406Sdist
1546084Sbostic #include <stdio.h>
1646084Sbostic #include <string.h>
1716549Skarels
1850964Sbostic size_t
fread(buf,size,count,fp)1946084Sbostic fread(buf, size, count, fp)
2046084Sbostic void *buf;
2146084Sbostic size_t size, count;
2246084Sbostic register FILE *fp;
2316549Skarels {
2446084Sbostic register size_t resid;
2546084Sbostic register char *p;
2646084Sbostic register int r;
2746084Sbostic size_t total;
2816549Skarels
29*65097Storek /*
30*65097Storek * The ANSI standard requires a return value of 0 for a count
31*65097Storek * or a size of 0. Peculiarily, it imposes no such requirements
32*65097Storek * on fwrite; it only requires fread to be broken.
33*65097Storek */
3446084Sbostic if ((resid = count * size) == 0)
35*65097Storek return (0);
3646084Sbostic if (fp->_r < 0)
3746084Sbostic fp->_r = 0;
3846084Sbostic total = resid;
3946084Sbostic p = buf;
4046084Sbostic while (resid > (r = fp->_r)) {
4158451Storek (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
4246084Sbostic fp->_p += r;
4346084Sbostic /* fp->_r = 0 ... done in __srefill */
4446084Sbostic p += r;
4546084Sbostic resid -= r;
4646084Sbostic if (__srefill(fp)) {
4746084Sbostic /* no more input: return partial result */
4846084Sbostic return ((total - resid) / size);
4916549Skarels }
5016549Skarels }
5158451Storek (void)memcpy((void *)p, (void *)fp->_p, resid);
5246084Sbostic fp->_r -= resid;
5346084Sbostic fp->_p += resid;
5446084Sbostic return (count);
5516549Skarels }
56