Home | History | Annotate | Download | only in stdio 
      1 /*	$OpenBSD: refill.c,v 1.8 2005/08/08 08:05:36 espie Exp $ */
      2 /*-
      3  * Copyright (c) 1990, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * This code is derived from software contributed to Berkeley by
      7  * Chris Torek.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #include <errno.h>
     35 #include <stdio.h>
     36 #include <stdlib.h>
     37 #include "local.h"
     38 
     39 static int
     40 lflush(FILE *fp)
     41 {
     42 	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
     43 		return (__sflush_locked(fp)); /* ignored... */
     44 	return (0);
     45 }
     46 
     47 /*
     48  * Refill a stdio buffer.
     49  * Return EOF on eof or error, 0 otherwise.
     50  */
     51 int
     52 __srefill(FILE *fp)
     53 {
     54 
     55 	/* make sure stdio is set up */
     56 	if (!__sdidinit)
     57 		__sinit();
     58 
     59 	fp->_r = 0;		/* largely a convenience for callers */
     60 
     61 	/* SysV does not make this test; take it out for compatibility */
     62 	if (fp->_flags & __SEOF)
     63 		return (EOF);
     64 
     65 	/* if not already reading, have to be reading and writing */
     66 	if ((fp->_flags & __SRD) == 0) {
     67 		if ((fp->_flags & __SRW) == 0) {
     68 			errno = EBADF;
     69 			fp->_flags |= __SERR;
     70 			return (EOF);
     71 		}
     72 		/* switch to reading */
     73 		if (fp->_flags & __SWR) {
     74 			if (__sflush(fp))
     75 				return (EOF);
     76 			fp->_flags &= ~__SWR;
     77 			fp->_w = 0;
     78 			fp->_lbfsize = 0;
     79 		}
     80 		fp->_flags |= __SRD;
     81 	} else {
     82 		/*
     83 		 * We were reading.  If there is an ungetc buffer,
     84 		 * we must have been reading from that.  Drop it,
     85 		 * restoring the previous buffer (if any).  If there
     86 		 * is anything in that buffer, return.
     87 		 */
     88 		if (HASUB(fp)) {
     89 			FREEUB(fp);
     90 			if ((fp->_r = fp->_ur) != 0) {
     91 				fp->_p = fp->_up;
     92 				return (0);
     93 			}
     94 		}
     95 	}
     96 
     97 	if (fp->_bf._base == NULL)
     98 		__smakebuf(fp);
     99 
    100 	/*
    101 	 * Before reading from a line buffered or unbuffered file,
    102 	 * flush all line buffered output files, per the ANSI C
    103 	 * standard.
    104 	 */
    105 	if (fp->_flags & (__SLBF|__SNBF)) {
    106 		/* Ignore this file in _fwalk to avoid potential deadlock. */
    107 		fp->_flags |= __SIGN;
    108 		(void) _fwalk(lflush);
    109 		fp->_flags &= ~__SIGN;
    110 
    111 		/* Now flush this file without locking it. */
    112 		if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
    113 		    __sflush(fp);
    114 	}
    115 	fp->_p = fp->_bf._base;
    116 	fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
    117 	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
    118 	if (fp->_r <= 0) {
    119 		if (fp->_r == 0)
    120 			fp->_flags |= __SEOF;
    121 		else {
    122 			fp->_r = 0;
    123 			fp->_flags |= __SERR;
    124 		}
    125 		return (EOF);
    126 	}
    127 	return (0);
    128 }
    129