bcopy => memcpy (safe in all these cases) for ANSI (sigh)

[unix-history] / usr / src / lib / libc / stdio / fgets.c

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* %sccs.include.redist.c%
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fgets.c     5.5 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <stdio.h>
#include <string.h>

/*
* Read at most n-1 characters from the given file.
* Stop when a newline has been read, or the count runs out.
* Return first argument, or NULL if no characters were read.
*/
char *
fgets(buf, n, fp)
       char *buf;
       register size_t n;
       register FILE *fp;
{
       register size_t len;
       register char *s;
       register unsigned char *p, *t;

       if (n < 2)              /* sanity check */
               return (NULL);

       s = buf;
       n--;                    /* leave space for NUL */
       do {
               /*
                * If the buffer is empty, refill it.
                */
               if ((len = fp->_r) <= 0) {
                       if (__srefill(fp)) {
                               /* EOF/error: stop with partial or no line */
                               if (s == buf)
                                       return (NULL);
                               break;
                       }
                       len = fp->_r;
               }
               p = fp->_p;

               /*
                * Scan through at most n bytes of the current buffer,
                * looking for '\n'.  If found, copy up to and including
                * newline, and stop.  Otherwise, copy entire chunk
                * and loop.
                */
               if (len > n)
                       len = n;
               t = memchr((void *)p, '\n', len);
               if (t != NULL) {
                       len = ++t - p;
                       fp->_r -= len;
                       fp->_p = t;
                       (void)memcpy((void *)s, (void *)p, len);
                       s[len] = 0;
                       return (buf);
               }
               fp->_r -= len;
               fp->_p += len;
               (void)memcpy((void *)s, (void *)p, len);
               s += len;
       } while ((n -= len) != 0);
       *s = 0;
       return (buf);
}