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/* Multibyte printf buffers writing data to a FILE * stream.
Copyright (C) 2022-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <printf_buffer_to_file.h>
#include <assert.h>
#include <array_length.h>
#include <libio/libioP.h>
/* Switch to the file buffer if possible. If the file has write_ptr
== write_end, use the stage buffer instead. */
void
__printf_buffer_to_file_switch (struct __printf_buffer_to_file *buf)
{
if (buf->fp->_IO_write_ptr < buf->fp->_IO_write_end)
{
/* buf->fp has a buffer associated with it, so write directly to
it from now on. */
buf->base.write_ptr = buf->fp->_IO_write_ptr;
buf->base.write_end = buf->fp->_IO_write_end;
}
else
{
/* Use the staging area if no buffer is available in buf->fp. */
buf->base.write_ptr = buf->stage;
buf->base.write_end = array_end (buf->stage);
}
buf->base.write_base = buf->base.write_ptr;
}
void
__printf_buffer_flush_to_file (struct __printf_buffer_to_file *buf)
{
/* The bytes in the buffer are always consumed. */
buf->base.written += buf->base.write_ptr - buf->base.write_base;
if (buf->base.write_end == array_end (buf->stage))
{
/* If the stage buffer is used, make a copy into the file. The
stage buffer is always consumed fully, even if just partially
written, to ensure that the file stream has all the data. */
size_t count = buf->base.write_ptr - buf->stage;
if ((size_t) _IO_sputn (buf->fp, buf->stage, count) != count)
{
__printf_buffer_mark_failed (&buf->base);
return;
}
/* buf->fp may have a buffer now. */
__printf_buffer_to_file_switch (buf);
return;
}
else if (buf->base.write_end == buf->stage + 1)
{
/* Special one-character buffer case. This is used to avoid
flush-only overflow below. */
if (buf->base.write_ptr == buf->base.write_end)
{
if (__overflow (buf->fp, (unsigned char) *buf->stage) == EOF)
{
__printf_buffer_mark_failed (&buf->base);
return;
}
__printf_buffer_to_file_switch (buf);
}
/* Else there is nothing to write. */
return;
}
/* We have written directly into the buf->fp buffer. */
assert (buf->base.write_end == buf->fp->_IO_write_end);
/* Mark the bytes as written. */
buf->fp->_IO_write_ptr = buf->base.write_ptr;
if (buf->base.write_ptr == buf->base.write_end)
{
/* The buffer in buf->fp has been filled. This should just call
__overflow (buf->fp, EOF), but flush-only overflow is obscure
and not always correctly implemented. See bug 28949. Be
conservative and switch to a one-character buffer instead, to
obtain one more character for a regular __overflow call. */
buf->base.write_ptr = buf->stage;
buf->base.write_end = buf->stage + 1;
}
/* The bytes in the file stream were already marked as written above. */
buf->base.write_base = buf->base.write_ptr;
}
void
__printf_buffer_to_file_init (struct __printf_buffer_to_file *buf, FILE *fp)
{
__printf_buffer_init (&buf->base, buf->stage, array_length (buf->stage),
__printf_buffer_mode_to_file);
buf->fp = fp;
__printf_buffer_to_file_switch (buf);
}
int
__printf_buffer_to_file_done (struct __printf_buffer_to_file *buf)
{
if (__printf_buffer_has_failed (&buf->base))
return -1;
__printf_buffer_flush_to_file (buf);
return __printf_buffer_done (&buf->base);
}
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