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 /* Function to handle transition to reading.
11  *   Initialize or verify the stream's orientation (even if writeonly).
12  *   Check that the stream is readable.
13  *   If currently reading, check that we can transition to writing.
14  *      C99 requires that we not be reading, but attempting to
15  *      auto-transition by commiting the write buffer is a configurable
16  *      option.
17  *   Returns 0 on success and EOF otherwise.
18  *
19  * Notes:
20  *   There are two function signatures, depending on wchar support,
21  *   since with no wchar support the orientation is narrow by default.
22  */
23 
24 #ifdef __UCLIBC_HAS_WCHAR__
__stdio_trans2r_o(FILE * __restrict stream,int oflag)25 int attribute_hidden __stdio_trans2r_o(FILE * __restrict stream, int oflag)
26 #else
27 int attribute_hidden __stdio_trans2r(FILE * __restrict stream)
28 #endif
29 {
30 	__STDIO_STREAM_VALIDATE(stream);
31 	assert(!__STDIO_STREAM_IS_READING(stream));
32 
33 #ifdef __UCLIBC_HAS_WCHAR__
34 	if (!(stream->__modeflags & oflag)) {
35 		if (stream->__modeflags & (__FLAG_NARROW|__FLAG_WIDE)) {
36 			__UNDEFINED_OR_NONPORTABLE;
37 			goto DO_EBADF;
38 		}
39 		stream->__modeflags |= oflag;
40 	}
41 #endif
42 
43 	if (stream->__modeflags & __FLAG_WRITEONLY) {
44 #if defined(__UCLIBC_HAS_WCHAR__) || !defined(__UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__)
45 	DO_EBADF:
46 #endif
47 		__set_errno(EBADF);
48 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
49 	ERROR:
50 #endif
51 		__STDIO_STREAM_SET_ERROR(stream);
52 		__STDIO_STREAM_VALIDATE(stream);
53 		return EOF;
54 	}
55 
56 	if (__STDIO_STREAM_IS_WRITING(stream)) {
57 #ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
58 		if (__STDIO_COMMIT_WRITE_BUFFER(stream)) { /* commit failed! */
59 			goto ERROR;
60 		}
61 		assert(!__STDIO_STREAM_BUFFER_WUSED(stream));
62 
63 		__STDIO_STREAM_DISABLE_PUTC(stream);
64 		__STDIO_STREAM_CLEAR_WRITING(stream);
65 #else
66 		/* C99: Output shall not be directly followed by input without an
67 		   intervening call to the fflush function or to a file positioning
68 		   function (fseek, fsetpos, or rewind). */
69 		__UNDEFINED_OR_NONPORTABLE;
70 		goto DO_EBADF;
71 #endif
72 	}
73 
74 	__STDIO_STREAM_SET_READING(stream);
75 	/* getc macro is enabled when data is read into buffer. */
76 
77 	__STDIO_STREAM_VALIDATE(stream);
78 	return 0;
79 }
80