usr/src/lib/libc/port/stdio/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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #include "lint.h"
  33 #include "file64.h"
  34 #include "mtlib.h"
  35 #include <stdio.h>
  36 #include <memory.h>
  37 #include <errno.h>
  38 #include <thread.h>
  39 #include <synch.h>
  40 #include <sys/types.h>
  41 #include "stdiom.h"
  42 #include "mse.h"
  43
  44 /* read size-max line from stream, including '\n' */
  45 char *
  46 fgets(char *buf, int size, FILE *iop)
  47 {
  48         char *ptr = buf;
  49         int n;
  50         Uchar *bufend;
  51         char *p;
  52         rmutex_t *lk;
  53
  54         FLOCKFILE(lk, iop);
  55
  56         _SET_ORIENTATION_BYTE(iop);
  57
  58         if (!(iop->_flag & (_IOREAD | _IORW))) {
  59                 errno = EBADF;
  60                 FUNLOCKFILE(lk);
  61                 return (NULL);
  62         }
  63
  64         if (iop->_base == NULL) {
  65                 if ((bufend = _findbuf(iop)) == NULL) {
  66                         FUNLOCKFILE(lk);
  67                         return (NULL);
  68                 }
  69         }
  70         else
  71                 bufend = _bufend(iop);
  72
  73         size--;         /* room for '\0' */
  74         while (size > 0) {
  75                 /* empty buffer */
  76                 if (iop->_cnt <= 0) {
  77                         if (__filbuf(iop) != EOF) {
  78                                 iop->_ptr--;    /* put back the character */
  79                                 iop->_cnt++;
  80                         } else if (ptr == buf) {  /* never read anything */
  81                                 FUNLOCKFILE(lk);
  82                                 return (NULL);
  83                         } else
  84                                 break;          /* nothing left to read */
  85                 }
  86                 n = (int)(size < iop->_cnt ? size : iop->_cnt);
  87                 if ((p = memccpy(ptr, (char *)iop->_ptr, '\n',
  88                     (size_t)n)) != NULL)
  89                         n = (int)(p - ptr);
  90                 ptr += n;
  91                 iop->_cnt -= n;
  92                 iop->_ptr += n;
  93                 if (_needsync(iop, bufend))
  94                         _bufsync(iop, bufend);
  95                 if (p != NULL)
  96                         break; /* newline found */
  97                 size -= n;
  98         }
  99         FUNLOCKFILE(lk);
 100         *ptr = '\0';
 101         return (buf);
 102 }