StdLib/LibC/Stdio/freopen.c

   1 /** @file
   2     Implementation of freopen as declared in <stdio.h>.
   3
   4     Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
   5     This program and the accompanying materials are licensed and made available
   6     under the terms and conditions of the BSD License that accompanies this
   7     distribution.  The full text of the license may be found at
   8     http://opensource.org/licenses/bsd-license.
   9
  10     THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11     WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13     Copyright (c) 1990, 1993
  14     The Regents of the University of California.  All rights reserved.
  15
  16     This code is derived from software contributed to Berkeley by
  17     Chris Torek.
  18
  19     Redistribution and use in source and binary forms, with or without
  20     modification, are permitted provided that the following conditions
  21     are met:
  22       - Redistributions of source code must retain the above copyright
  23         notice, this list of conditions and the following disclaimer.
  24       - Redistributions in binary form must reproduce the above copyright
  25         notice, this list of conditions and the following disclaimer in the
  26         documentation and/or other materials provided with the distribution.
  27       - Neither the name of the University nor the names of its contributors
  28         may be used to endorse or promote products derived from this software
  29         without specific prior written permission.
  30
  31     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  32     AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  33     IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  34     ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
  35     LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  36     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  37     SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  38     INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  39     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  40     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41     POSSIBILITY OF SUCH DAMAGE.
  42
  43     NetBSD: freopen.c,v 1.14 2003/08/07 16:43:25 agc Exp
  44     freopen.c 8.1 (Berkeley) 6/4/93
  45 **/
  46 #include  <LibConfig.h>
  47 #include  <sys/EfiCdefs.h>
  48
  49 #include  <sys/types.h>
  50 #include  <sys/stat.h>
  51
  52 #include  <assert.h>
  53 #include  <errno.h>
  54 #include  <fcntl.h>
  55 #include  <sys/EfiSysCall.h>
  56 #include  <stdio.h>
  57 #include  <stdlib.h>
  58 #include  <wchar.h>
  59 #include  "reentrant.h"
  60 #include  "local.h"
  61
  62 /*
  63  * Re-direct an existing, open (probably) file to some other file.
  64  * ANSI is written such that the original file gets closed if at
  65  * all possible, no matter what.
  66  */
  67 FILE *
  68 freopen(const char *file, const char *mode, FILE *fp)
  69 {
  70   int f;
  71   int flags, isopen, oflags, sverrno, wantfd;
  72
  73   _DIAGASSERT(file != NULL);
  74   _DIAGASSERT(mode != NULL);
  75   _DIAGASSERT(fp != NULL);
  76   if(fp == NULL) {
  77     errno = EINVAL;
  78     return (NULL);
  79   }
  80
  81   if ((flags = __sflags(mode, &oflags)) == 0) {
  82     (void) fclose(fp);
  83     return (NULL);
  84   }
  85
  86   if (!__sdidinit)
  87     __sinit();
  88
  89   /*
  90    * There are actually programs that depend on being able to "freopen"
  91    * descriptors that weren't originally open.  Keep this from breaking.
  92    * Remember whether the stream was open to begin with, and which file
  93    * descriptor (if any) was associated with it.  If it was attached to
  94    * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
  95    * should work.  This is unnecessary if it was not a Unix file.
  96    */
  97   if (fp->_flags == 0) {
  98     fp->_flags = __SEOF;  /* hold on to it */
  99     isopen = 0;
 100     wantfd = -1;
 101   } else {
 102     /* flush the stream; ANSI doesn't require this. */
 103     if (fp->_flags & __SWR)
 104       (void) __sflush(fp);
 105     /* if close is NULL, closing is a no-op, hence pointless */
 106     isopen = fp->_close != NULL;
 107     if (((wantfd = fp->_file) >= 0) && isopen) {
 108       (void) (*fp->_close)(fp->_cookie);
 109       isopen = 0;
 110     }
 111   }
 112
 113   /* Get a new descriptor to refer to the new file. */
 114   f = open(file, oflags, DEFFILEMODE);
 115   if (f < 0 && isopen) {
 116     /* If out of fd's close the old one and try again. */
 117     if (errno == ENFILE || errno == EMFILE) {
 118       (void) (*fp->_close)(fp->_cookie);
 119       isopen = 0;
 120       f = open(file, oflags, DEFFILEMODE);
 121     }
 122   }
 123   sverrno = errno;
 124
 125   /*
 126    * Finish closing fp.  Even if the open succeeded above, we cannot
 127    * keep fp->_base: it may be the wrong size.  This loses the effect
 128    * of any setbuffer calls, but stdio has always done this before.
 129    */
 130   if (isopen && (f != wantfd))
 131     (void) (*fp->_close)(fp->_cookie);
 132   if (fp->_flags & __SMBF)
 133     free((char *)fp->_bf._base);
 134   fp->_w = 0;
 135   fp->_r = 0;
 136   fp->_p = NULL;
 137   fp->_bf._base = NULL;
 138   fp->_bf._size = 0;
 139   fp->_lbfsize = 0;
 140   if (HASUB(fp))
 141     FREEUB(fp);
 142   WCIO_FREE(fp);
 143   _UB(fp)._size = 0;
 144   if (HASLB(fp))
 145     FREELB(fp);
 146   fp->_lb._size = 0;
 147
 148   if (f < 0) {      /* did not get it after all */
 149     fp->_flags = 0;   /* set it free */
 150     errno = sverrno;  /* restore in case _close clobbered */
 151     return (NULL);
 152   }
 153
 154   if (oflags & O_NONBLOCK) {
 155     struct stat st;
 156     if (fstat(f, &st) == -1) {
 157       sverrno = errno;
 158       (void)close(f);
 159       errno = sverrno;
 160       return (NULL);
 161     }
 162     if (!S_ISREG(st.st_mode)) {
 163       (void)close(f);
 164       errno = EFTYPE;
 165       return (NULL);
 166     }
 167   }
 168
 169   /*
 170    * If reopening something that was open before on a real file, try
 171    * to maintain the descriptor.  Various C library routines (perror)
 172    * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
 173    */
 174   if (wantfd >= 0 && f != wantfd) {
 175     if (dup2(f, wantfd) >= 0) {
 176       (void) close(f);
 177       f = wantfd;
 178     }
 179   }
 180
 181   fp->_flags = (unsigned short)flags;
 182   fp->_file = (short)f;
 183   fp->_cookie = fp;
 184   fp->_read = __sread;
 185   fp->_write = __swrite;
 186   fp->_seek = __sseek;
 187   fp->_close = __sclose;
 188
 189   /*
 190    * When reopening in append mode, even though we use O_APPEND,
 191    * we need to seek to the end so that ftell() gets the right
 192    * answer.  If the user then alters the seek pointer, or
 193    * the file extends, this will fail, but there is not much
 194    * we can do about this.  (We could set __SAPP and check in
 195    * fseek and ftell.)
 196    */
 197   if (oflags & O_APPEND)
 198     (void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
 199   return (fp);
 200 }