1 /* Copyright (C) 2004       Manuel Novoa III    <mjn3@codepoet.org>
2  *
3  * GNU Library General Public License (LGPL) version 2 or later.
4  *
5  * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
6  */
7 
8 #include "_stdio.h"
9 
10 
11 #ifndef __DO_LARGEFILE
12 # define FILEDES_ARG    (-1)
13 #endif
14 
freopen(const char * __restrict filename,const char * __restrict mode,register FILE * __restrict stream)15 FILE *freopen(const char * __restrict filename, const char * __restrict mode,
16 			  register FILE * __restrict stream)
17 {
18 	/*
19 	 * ANSI/ISO allow (implementation-defined) change of mode for an
20 	 * existing file if filename is NULL.  It doesn't look like Linux
21 	 * supports this, so we don't here.
22 	 *
23 	 * NOTE: Whether or not the stream is free'd on failure is unclear
24 	 *       w.r.t. ANSI/ISO.  This implementation chooses to NOT free
25 	 *       the stream and associated buffer if they were dynamically
26 	 *       allocated.
27 	 * NOTE: Previous versions of uClibc did free dynamic storage.
28 	 *
29 	 * TODO: Apparently linux allows setting append mode.  Implement?
30 	 */
31 	unsigned short dynmode;
32 	register FILE *fp;
33 	__STDIO_AUTO_THREADLOCK_VAR;
34 
35 	__STDIO_AUTO_THREADLOCK(stream);
36 
37 	__STDIO_STREAM_VALIDATE(stream);
38 
39 	__STDIO_OPENLIST_INC_USE;	/* Do not remove the file from the list. */
40 
41 	/* First, flush and close, but don't deallocate, the stream. */
42 	/* This also removes the stream for the open file list. */
43 	dynmode = (stream->__modeflags & (__FLAG_FREEBUF|__FLAG_FREEFILE));
44 
45 	stream->__modeflags &= ~(__FLAG_FREEBUF|__FLAG_FREEFILE);
46 
47 	/* Only call fclose on the stream if it is not already closed. */
48 	if ((stream->__modeflags & (__FLAG_READONLY|__FLAG_WRITEONLY))
49 		!= (__FLAG_READONLY|__FLAG_WRITEONLY)
50 		) {
51 		fclose(stream);			/* Failures are ignored. */
52 		/* NOTE: fclose always does __STDIO_OPENLIST_INC_DEL_CNT.  But we don't
53 		 * want to remove this FILE from the open list, even if the freopen fails.
54 		 * Consider the case of a failed freopen() on stdin.  You probably still
55 		 * want to be able to call freopen() again.  Similarly for other "malloc'd"
56 		 * streams. */
57 		__STDIO_OPENLIST_DEC_DEL_CNT;
58 	}
59 
60 	fp = _stdio_fopen(((intptr_t) filename), mode, stream, FILEDES_ARG);
61 	if (!fp) {
62 		/* Don't remove stream from the open file list and (potentially) free it.
63 		 * See _stdio_openlist_dec_use() in fflush.c. */
64 		stream->__modeflags = __FLAG_READONLY|__FLAG_WRITEONLY|__FLAG_FAILED_FREOPEN;
65 	}
66 
67 	/* Reset the allocation flags. */
68 	stream->__modeflags |= dynmode;
69 
70 	__STDIO_OPENLIST_DEC_USE;
71 
72 	__STDIO_AUTO_THREADUNLOCK(stream);
73 
74 	return fp;
75 }
76