diff options
Diffstat (limited to 'newlib/libc/stdio/freopen.c')
| -rw-r--r-- | newlib/libc/stdio/freopen.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/newlib/libc/stdio/freopen.c b/newlib/libc/stdio/freopen.c new file mode 100644 index 0000000..a4ab965 --- /dev/null +++ b/newlib/libc/stdio/freopen.c @@ -0,0 +1,151 @@ +/* + * Copyright (c) 1990 The Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms are permitted + * provided that the above copyright notice and this paragraph are + * duplicated in all such forms and that any documentation, + * advertising materials, and other materials related to such + * distribution and use acknowledge that the software was developed + * by the University of California, Berkeley. The name of the + * University may not be used to endorse or promote products derived + * from this software without specific prior written permission. + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + */ + +/* +FUNCTION +<<freopen>>---open a file using an existing file descriptor + +INDEX + freopen + +ANSI_SYNOPSIS + #include <stdio.h> + FILE *freopen(const char *<[file]>, const char *<[mode]>, + FILE *<[fp]>); + +TRAD_SYNOPSIS + #include <stdio.h> + FILE *freopen(<[file]>, <[mode]>, <[fp]>) + char *<[file]>; + char *<[mode]>; + FILE *<[fp]>; + +DESCRIPTION +Use this variant of <<fopen>> if you wish to specify a particular file +descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for +the file. + +If <[fp]> was associated with another file or stream, <<freopen>> +closes that other file or stream (but ignores any errors while closing +it). + +<[file]> and <[mode]> are used just as in <<fopen>>. + +RETURNS +If successful, the result is the same as the argument <[fp]>. If the +file cannot be opened as specified, the result is <<NULL>>. + +PORTABILITY +ANSI C requires <<freopen>>. + +Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, +<<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>. +*/ + +#include <time.h> +#include <stdio.h> +#include <fcntl.h> +#include <stdlib.h> +#include "local.h" + +/* + * Re-direct an existing, open (probably) file to some other file. + */ + +FILE * +_DEFUN (freopen, (file, mode, fp), + _CONST char *file _AND + _CONST char *mode _AND + register FILE *fp) +{ + register int f; + int flags, oflags, e; + struct _reent *ptr; + + CHECK_INIT (fp); + ptr = fp->_data; + + if ((flags = __sflags (ptr, mode, &oflags)) == 0) + { + (void) fclose (fp); + return NULL; + } + + /* + * Remember whether the stream was open to begin with, and + * which file descriptor (if any) was associated with it. + * If it was attached to a descriptor, defer closing it, + * so that, e.g., freopen("/dev/stdin", "r", stdin) works. + * This is unnecessary if it was not a Unix file. + */ + + if (fp->_flags == 0) + fp->_flags = __SEOF; /* hold on to it */ + else + { + if (fp->_flags & __SWR) + (void) fflush (fp); + /* if close is NULL, closing is a no-op, hence pointless */ + if (fp->_close != NULL) + (void) (*fp->_close) (fp->_cookie); + } + + /* + * Now get a new descriptor to refer to the new file. + */ + + f = _open_r (ptr, (char *) file, oflags, 0666); + e = ptr->_errno; + + /* + * Finish closing fp. Even if the open succeeded above, + * we cannot keep fp->_base: it may be the wrong size. + * This loses the effect of any setbuffer calls, + * but stdio has always done this before. + */ + + if (fp->_flags & __SMBF) + _free_r (ptr, (char *) fp->_bf._base); + fp->_w = 0; + fp->_r = 0; + fp->_p = NULL; + fp->_bf._base = NULL; + fp->_bf._size = 0; + fp->_lbfsize = 0; + if (HASUB (fp)) + FREEUB (fp); + fp->_ub._size = 0; + if (HASLB (fp)) + FREELB (fp); + fp->_lb._size = 0; + + if (f < 0) + { /* did not get it after all */ + fp->_flags = 0; /* set it free */ + ptr->_errno = e; /* restore in case _close clobbered */ + return NULL; + } + + fp->_flags = flags; + fp->_file = f; + fp->_cookie = (_PTR) fp; + fp->_read = __sread; + fp->_write = __swrite; + fp->_seek = __sseek; + fp->_close = __sclose; + return fp; +} |