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-rw-r--r--libc/stdio/_trans2w.c89
1 files changed, 89 insertions, 0 deletions
diff --git a/libc/stdio/_trans2w.c b/libc/stdio/_trans2w.c
new file mode 100644
index 000000000..fdde2bebf
--- /dev/null
+++ b/libc/stdio/_trans2w.c
@@ -0,0 +1,89 @@
+/* Copyright (C) 2004 Manuel Novoa III <mjn3@codepoet.org>
+ *
+ * GNU Library General Public License (LGPL) version 2 or later.
+ *
+ * Dedicated to Toni. See uClibc/DEDICATION.mjn3 for details.
+ */
+
+#include "_stdio.h"
+
+/* Function to handle transition to writing.
+ * Initialize or verify the stream's orientation (even if readonly).
+ * Check that the stream is writable.
+ * If currently reading, check that we can transition to writing.
+ * C99 requires that the stream is at EOF, but attempting to
+ * auto-transition via fseek() is a configurable option.
+ * Returns 0 on success and EOF otherwise.
+ *
+ * Notes:
+ * There are two function signatures, depending on wchar support,
+ * since with no wchar support the orientation is narrow by default.
+ */
+
+#ifdef __UCLIBC_HAS_WCHAR__
+int __stdio_trans2w_o(FILE * __restrict stream, int oflag)
+#else
+int __stdio_trans2w(FILE * __restrict stream)
+#endif
+{
+ __STDIO_STREAM_VALIDATE(stream);
+ assert(!__STDIO_STREAM_IS_WRITING(stream));
+
+#ifdef __UCLIBC_HAS_WCHAR__
+ if (!(stream->__modeflags & oflag)) {
+ if (stream->__modeflags & (__FLAG_NARROW|__FLAG_WIDE)) {
+ __UNDEFINED_OR_NONPORTABLE;
+ goto DO_EBADF;
+ }
+ stream->__modeflags |= oflag;
+ }
+#endif
+
+ if (stream->__modeflags & __FLAG_READONLY) {
+ DO_EBADF:
+ __set_errno(EBADF);
+ ERROR:
+ __STDIO_STREAM_SET_ERROR(stream);
+ __STDIO_STREAM_VALIDATE(stream);
+ return EOF;
+ }
+
+ if (__STDIO_STREAM_IS_READING(stream)) {
+ if (!__FEOF_UNLOCKED(stream)) {
+#ifdef __UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION__
+ /* Need to seek to correct position if we have buffered
+ * read data or ungots. If appending, we might as well
+ * seek to the end.
+ *
+ * NOTE: If the OS does not handle append files correctly,
+ * this is insufficient since we would need to seek to
+ * the end even if not reading.*/
+ if (((__STDIO_STREAM_BUFFER_RAVAIL(stream))
+ || (stream->__modeflags & __FLAG_UNGOT))
+ && fseek(stream, 0L,
+ ((stream->__modeflags & __FLAG_APPEND)
+ ? SEEK_END : SEEK_CUR))
+ ) {
+ /* fseek() only sets error indicator on read/write error. */
+ goto ERROR;
+ }
+#else
+ /* C99 requires either at EOF or currently not reading. */
+ __UNDEFINED_OR_NONPORTABLE;
+ goto DO_EBADF;
+#endif
+ }
+ __STDIO_STREAM_CLEAR_READING_AND_UNGOTS(stream);
+ __STDIO_STREAM_DISABLE_GETC(stream);
+ /* Reaching EOF does not reset buffer pointers... */
+ __STDIO_STREAM_INIT_BUFREAD_BUFPOS(stream);
+ }
+
+ __STDIO_STREAM_SET_WRITING(stream);
+ if (__STDIO_STREAM_IS_NARROW_FBF(stream)) {
+ __STDIO_STREAM_ENABLE_PUTC(stream);
+ }
+
+ __STDIO_STREAM_VALIDATE(stream);
+ return 0;
+}