src/system/libroot/posix/stdio/refill.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37
  38 #include <errno.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41
  42 #include <errno_private.h>
  43
  44 #include "local.h"
  45
  46 static int
  47 lflush(fp)
  48         FILE *fp;
  49 {
  50
  51         if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
  52                 return (__sflush(fp));
  53         return (0);
  54 }
  55
  56 /*
  57  * Refill a stdio buffer.
  58  * Return EOF on eof or error, 0 otherwise.
  59  */
  60 int
  61 __srefill(fp)
  62         register FILE *fp;
  63 {
  64
  65         /* make sure stdio is set up */
  66         if (!__sdidinit)
  67                 __sinit();
  68
  69         fp->_r = 0;             /* largely a convenience for callers */
  70
  71         /* SysV does not make this test; take it out for compatibility */
  72         if (fp->_flags & __SEOF)
  73                 return (EOF);
  74
  75         /* if not already reading, have to be reading and writing */
  76         if ((fp->_flags & __SRD) == 0) {
  77                 if ((fp->_flags & __SRW) == 0) {
  78                         __set_errno(EBADF);
  79                         fp->_flags |= __SERR;
  80                         return (EOF);
  81                 }
  82                 /* switch to reading */
  83                 if (fp->_flags & __SWR) {
  84                         if (__sflush(fp))
  85                                 return (EOF);
  86                         fp->_flags &= ~__SWR;
  87                         fp->_w = 0;
  88                         fp->_lbfsize = 0;
  89                 }
  90                 fp->_flags |= __SRD;
  91         } else {
  92                 /*
  93                  * We were reading.  If there is an ungetc buffer,
  94                  * we must have been reading from that.  Drop it,
  95                  * restoring the previous buffer (if any).  If there
  96                  * is anything in that buffer, return.
  97                  */
  98                 if (HASUB(fp)) {
  99                         FREEUB(fp);
 100                         if ((fp->_r = fp->_ur) != 0) {
 101                                 fp->_p = fp->_up;
 102                                 return (0);
 103                         }
 104                 }
 105         }
 106
 107         if (fp->_bf._base == NULL)
 108                 __smakebuf(fp);
 109
 110         /*
 111          * Before reading from a line buffered or unbuffered file,
 112          * flush all line buffered output files, per the ANSI C
 113          * standard.
 114          */
 115         if (fp->_flags & (__SLBF|__SNBF))
 116                 (void) _fwalk(lflush);
 117         fp->_p = fp->_bf._base;
 118         fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
 119         fp->_flags &= ~__SMOD;  /* buffer contents are again pristine */
 120         if (fp->_r <= 0) {
 121                 if (fp->_r == 0)
 122                         fp->_flags |= __SEOF;
 123                 else {
 124                         fp->_r = 0;
 125                         fp->_flags |= __SERR;
 126                 }
 127                 return (EOF);
 128         }
 129         return (0);
 130 }