StdLib/LibC/Stdio/freopen.c

   1 /** @file
   2     Implementation of freopen as declared in <stdio.h>.
   3
   4     Copyright (c) 2010, 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.php.
   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
  77   if ((flags = __sflags(mode, &oflags)) == 0) {
  78     (void) fclose(fp);
  79     return (NULL);
  80   }
  81
  82   if (!__sdidinit)
  83     __sinit();
  84
  85   /*
  86    * There are actually programs that depend on being able to "freopen"
  87    * descriptors that weren't originally open.  Keep this from breaking.
  88    * Remember whether the stream was open to begin with, and which file
  89    * descriptor (if any) was associated with it.  If it was attached to
  90    * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
  91    * should work.  This is unnecessary if it was not a Unix file.
  92    */
  93   if (fp->_flags == 0) {
  94     fp->_flags = __SEOF;  /* hold on to it */
  95     isopen = 0;
  96     wantfd = -1;
  97   } else {
  98     /* flush the stream; ANSI doesn't require this. */
  99     if (fp->_flags & __SWR)
 100       (void) __sflush(fp);
 101     /* if close is NULL, closing is a no-op, hence pointless */
 102     isopen = fp->_close != NULL;
 103     if ((wantfd = fp->_file) < 0 && isopen) {
 104       (void) (*fp->_close)(fp->_cookie);
 105       isopen = 0;
 106     }
 107   }
 108
 109   /* Get a new descriptor to refer to the new file. */
 110   f = open(file, oflags, DEFFILEMODE);
 111   if (f < 0 && isopen) {
 112     /* If out of fd's close the old one and try again. */
 113     if (errno == ENFILE || errno == EMFILE) {
 114       (void) (*fp->_close)(fp->_cookie);
 115       isopen = 0;
 116       f = open(file, oflags, DEFFILEMODE);
 117     }
 118   }
 119   sverrno = errno;
 120
 121   /*
 122    * Finish closing fp.  Even if the open succeeded above, we cannot
 123    * keep fp->_base: it may be the wrong size.  This loses the effect
 124    * of any setbuffer calls, but stdio has always done this before.
 125    */
 126   if (isopen && f != wantfd)
 127     (void) (*fp->_close)(fp->_cookie);
 128   if (fp->_flags & __SMBF)
 129     free((char *)fp->_bf._base);
 130   fp->_w = 0;
 131   fp->_r = 0;
 132   fp->_p = NULL;
 133   fp->_bf._base = NULL;
 134   fp->_bf._size = 0;
 135   fp->_lbfsize = 0;
 136   if (HASUB(fp))
 137     FREEUB(fp);
 138   WCIO_FREE(fp);
 139   _UB(fp)._size = 0;
 140   if (HASLB(fp))
 141     FREELB(fp);
 142   fp->_lb._size = 0;
 143
 144   if (f < 0) {      /* did not get it after all */
 145     fp->_flags = 0;   /* set it free */
 146     errno = sverrno;  /* restore in case _close clobbered */
 147     return (NULL);
 148   }
 149
 150   if (oflags & O_NONBLOCK) {
 151     struct stat st;
 152     if (fstat(f, &st) == -1) {
 153       sverrno = errno;
 154       (void)close(f);
 155       errno = sverrno;
 156       return (NULL);
 157     }
 158     if (!S_ISREG(st.st_mode)) {
 159       (void)close(f);
 160       errno = EFTYPE;
 161       return (NULL);
 162     }
 163   }
 164
 165   /*
 166    * If reopening something that was open before on a real file, try
 167    * to maintain the descriptor.  Various C library routines (perror)
 168    * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
 169    */
 170   if (wantfd >= 0 && f != wantfd) {
 171     if (dup2(f, wantfd) >= 0) {
 172       (void) close(f);
 173       f = wantfd;
 174     }
 175   }
 176
 177   fp->_flags = (unsigned short)flags;
 178   fp->_file = (short)f;
 179   fp->_cookie = fp;
 180   fp->_read = __sread;
 181   fp->_write = __swrite;
 182   fp->_seek = __sseek;
 183   fp->_close = __sclose;
 184
 185   /*
 186    * When reopening in append mode, even though we use O_APPEND,
 187    * we need to seek to the end so that ftell() gets the right
 188    * answer.  If the user then alters the seek pointer, or
 189    * the file extends, this will fail, but there is not much
 190    * we can do about this.  (We could set __SAPP and check in
 191    * fseek and ftell.)
 192    */
 193   if (oflags & O_APPEND)
 194     (void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
 195   return (fp);
 196 }