toolchain/gcc/newlib/libc/stdio/freopen.c

   1 /*
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * advertising materials, and other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19 FUNCTION
  20 <<freopen>>---open a file using an existing file descriptor
  21
  22 INDEX
  23         freopen
  24 INDEX
  25         _freopen_r
  26
  27 ANSI_SYNOPSIS
  28         #include <stdio.h>
  29         FILE *freopen(const char *<[file]>, const char *<[mode]>,
  30                       FILE *<[fp]>);
  31         FILE *_freopen_r(struct _reent *<[ptr]>, const char *<[file]>,
  32                       const char *<[mode]>, FILE *<[fp]>);
  33
  34 TRAD_SYNOPSIS
  35         #include <stdio.h>
  36         FILE *freopen(<[file]>, <[mode]>, <[fp]>)
  37         char *<[file]>;
  38         char *<[mode]>;
  39         FILE *<[fp]>;
  40
  41         FILE *_freopen_r(<[ptr]>, <[file]>, <[mode]>, <[fp]>)
  42         struct _reent *<[ptr]>;
  43         char *<[file]>;
  44         char *<[mode]>;
  45         FILE *<[fp]>;
  46
  47 DESCRIPTION
  48 Use this variant of <<fopen>> if you wish to specify a particular file
  49 descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for
  50 the file.
  51
  52 If <[fp]> was associated with another file or stream, <<freopen>>
  53 closes that other file or stream (but ignores any errors while closing
  54 it).
  55
  56 <[file]> and <[mode]> are used just as in <<fopen>>.
  57
  58 RETURNS
  59 If successful, the result is the same as the argument <[fp]>.  If the
  60 file cannot be opened as specified, the result is <<NULL>>.
  61
  62 PORTABILITY
  63 ANSI C requires <<freopen>>.
  64
  65 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  66 <<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.
  67 */
  68
  69 #include <time.h>
  70 #include <stdio.h>
  71 #include <fcntl.h>
  72 #include <stdlib.h>
  73 #include "local.h"
  74 #include <sys/lock.h>
  75
  76 /*
  77  * Re-direct an existing, open (probably) file to some other file.
  78  */
  79
  80 FILE *
  81 _DEFUN (_freopen_r, (ptr, file, mode, fp),
  82         struct _reent *ptr _AND
  83         _CONST char *file _AND
  84         _CONST char *mode _AND
  85         register FILE *fp)
  86 {
  87   register int f;
  88   int flags, oflags, e;
  89
  90   _flockfile(fp);
  91
  92   CHECK_INIT (fp);
  93
  94   if ((flags = __sflags (ptr, mode, &oflags)) == 0)
  95     {
  96       (void) fclose (fp);
  97       _funlockfile(fp);
  98       return NULL;
  99     }
 100
 101   /*
 102    * Remember whether the stream was open to begin with, and
 103    * which file descriptor (if any) was associated with it.
 104    * If it was attached to a descriptor, defer closing it,
 105    * so that, e.g., freopen("/dev/stdin", "r", stdin) works.
 106    * This is unnecessary if it was not a Unix file.
 107    */
 108
 109   if (fp->_flags == 0)
 110     fp->_flags = __SEOF;        /* hold on to it */
 111   else
 112     {
 113       if (fp->_flags & __SWR)
 114         (void) fflush (fp);
 115       /* if close is NULL, closing is a no-op, hence pointless */
 116       if (fp->_close != NULL)
 117         (void) (*fp->_close) (fp->_cookie);
 118     }
 119
 120   /*
 121    * Now get a new descriptor to refer to the new file.
 122    */
 123
 124   f = _open_r (ptr, (char *) file, oflags, 0666);
 125   e = ptr->_errno;
 126
 127   /*
 128    * Finish closing fp.  Even if the open succeeded above,
 129    * we cannot keep fp->_base: it may be the wrong size.
 130    * This loses the effect of any setbuffer calls,
 131    * but stdio has always done this before.
 132    */
 133
 134   if (fp->_flags & __SMBF)
 135     _free_r (ptr, (char *) fp->_bf._base);
 136   fp->_w = 0;
 137   fp->_r = 0;
 138   fp->_p = NULL;
 139   fp->_bf._base = NULL;
 140   fp->_bf._size = 0;
 141   fp->_lbfsize = 0;
 142   if (HASUB (fp))
 143     FREEUB (fp);
 144   fp->_ub._size = 0;
 145   if (HASLB (fp))
 146     FREELB (fp);
 147   fp->_lb._size = 0;
 148
 149   if (f < 0)
 150     {                           /* did not get it after all */
 151       ptr->_errno = e;          /* restore in case _close clobbered */
 152       _funlockfile(fp);
 153 #ifndef __SINGLE_THREAD__
 154       __lock_close_recursive (*(_LOCK_RECURSIVE_T *)&fp->_lock);
 155 #endif
 156       fp->_flags = 0;           /* set it free */
 157       return NULL;
 158     }
 159
 160   fp->_flags = flags;
 161   fp->_file = f;
 162   fp->_cookie = (_PTR) fp;
 163   fp->_read = __sread;
 164   fp->_write = __swrite;
 165   fp->_seek = __sseek;
 166   fp->_close = __sclose;
 167
 168 #ifdef __SCLE
 169   if (__stextmode(fp->_file))
 170     fp->_flags |= __SCLE;
 171 #endif
 172
 173   _funlockfile(fp);
 174   return fp;
 175 }
 176
 177 #ifndef _REENT_ONLY
 178
 179 FILE *
 180 _DEFUN (freopen, (file, mode, fp),
 181         _CONST char *file _AND
 182         _CONST char *mode _AND
 183         register FILE *fp)
 184 {
 185   return _freopen_r (_REENT, file, mode, fp);
 186 }
 187
 188 #endif /*!_REENT_ONLY */