usr/src/lib/libbc/libc/stdio/common/fgets.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 /*
  23  * Copyright 1989 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"  /* from S5R2 3.3 */
  31
  32 /*LINTLIBRARY*/
  33 /*
  34  * This version reads directly from the buffer rather than looping on getc.
  35  * Ptr args aren't checked for NULL because the program would be a
  36  * catastrophic mess anyway.  Better to abort than just to return NULL.
  37  */
  38 #include <stdio.h>
  39 #include "stdiom.h"
  40
  41 #define MIN(x, y)       (x < y ? x : y)
  42
  43 extern int _filbuf();
  44 extern char *memccpy();
  45
  46 char *
  47 fgets(ptr, size, iop)
  48 char *ptr;
  49 register int size;
  50 register FILE *iop;
  51 {
  52         char *p, *ptr0 = ptr;
  53         register int n;
  54
  55         if ( !(iop->_flag & (_IOREAD|_IORW)) ) {
  56                 iop->_flag |= _IOERR;
  57                 return (NULL);
  58         }
  59
  60         for (size--; size > 0; size -= n) {
  61                 if (iop->_cnt <= 0) { /* empty buffer */
  62                         if (_filbuf(iop) == EOF) {
  63                                 if (ptr0 == ptr)
  64                                         return (NULL);
  65                                 break; /* no more data */
  66                         }
  67                         iop->_ptr--;
  68                         iop->_cnt++;
  69                 }
  70                 n = MIN(size, iop->_cnt);
  71                 if ((p = memccpy(ptr, (char *) iop->_ptr, '\n', n)) != NULL)
  72                         n = p - ptr;
  73                 ptr += n;
  74                 iop->_cnt -= n;
  75                 iop->_ptr += n;
  76                 _BUFSYNC(iop);
  77                 if (p != NULL)
  78                         break; /* found '\n' in buffer */
  79         }
  80         *ptr = '\0';
  81         return (ptr0);
  82 }