usr/src/lib/libbc/libc/stdio/common/gets.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*      Copyright (c) 1984 AT&T */
  23 /*        All Rights Reserved   */
  24
  25 #pragma ident   "%Z%%M% %I%     %E% SMI"
  26
  27 /*LINTLIBRARY*/
  28 /*
  29  * This version reads directly from the buffer rather than looping on getc.
  30  * Ptr args aren't checked for NULL because the program would be a
  31  * catastrophic mess anyway.  Better to abort than just to return NULL.
  32  */
  33 #include <stdio.h>
  34 #include "stdiom.h"
  35 #include <memory.h>
  36
  37 extern int _filbuf();
  38
  39 char *
  40 gets(char *ptr)
  41 {
  42         char *p, *ptr0 = ptr;
  43         int n;
  44
  45         for ( ; ; ) {
  46                 if (stdin->_cnt <= 0) { /* empty buffer */
  47                         if (_filbuf(stdin) == EOF) {
  48                                 if (ptr0 == ptr)
  49                                         return (NULL);
  50                                 break; /* no more data */
  51                         }
  52                         stdin->_ptr--;
  53                         stdin->_cnt++;
  54                 }
  55                 n = stdin->_cnt;
  56                 if ((p = memccpy(ptr, (char *) stdin->_ptr, '\n', n)) != NULL)
  57                         n = p - ptr;
  58                 ptr += n;
  59                 stdin->_cnt -= n;
  60                 stdin->_ptr += n;
  61                 _BUFSYNC(stdin);
  62                 if (p != NULL) { /* found '\n' in buffer */
  63                         ptr--; /* step back over '\n' */
  64                         break;
  65                 }
  66         }
  67         *ptr = '\0';
  68         return (ptr0);
  69 }