php fwrite implementation

gistfile1.c

// from php 5.3.6

PHPAPI size_t _php_stream_write(php_stream *stream, const char *buf, size_t count TSRMLS_DC);
#define php_stream_write_string(stream, str)	_php_stream_write(stream, str, strlen(str) TSRMLS_CC)
#define php_stream_write(stream, buf, count)	_php_stream_write(stream, (buf), (count) TSRMLS_CC)


PHPAPI size_t _php_stream_write(php_stream *stream, const char *buf, size_t count TSRMLS_DC)
{
	if (buf == NULL || count == 0 || stream->ops->write == NULL) {
		return 0;
	}

	if (stream->writefilters.head) {
		return _php_stream_write_filtered(stream, buf, count, PSFS_FLAG_NORMAL TSRMLS_CC);
	} else {
		return _php_stream_write_buffer(stream, buf, count TSRMLS_CC);
	}
}

/* Writes a buffer directly to a stream, using multiple of the chunk size */
static size_t _php_stream_write_buffer(php_stream *stream, const char *buf, size_t count TSRMLS_DC)
{
	size_t didwrite = 0, towrite, justwrote;

 	/* if we have a seekable stream we need to ensure that data is written at the
 	 * current stream->position. This means invalidating the read buffer and then
	 * performing a low-level seek */
	if (stream->ops->seek && (stream->flags & PHP_STREAM_FLAG_NO_SEEK) == 0 && stream->readpos != stream->writepos) {
		stream->readpos = stream->writepos = 0;

		stream->ops->seek(stream, stream->position, SEEK_SET, &stream->position TSRMLS_CC);
	}


	while (count > 0) {
		towrite = count;
		if (towrite > stream->chunk_size)
			towrite = stream->chunk_size;

		justwrote = stream->ops->write(stream, buf, towrite TSRMLS_CC);

		/* convert justwrote to an integer, since normally it is unsigned */
		if ((int)justwrote > 0) {
			buf += justwrote;
			count -= justwrote;
			didwrite += justwrote;

			/* Only screw with the buffer if we can seek, otherwise we lose data
			 * buffered from fifos and sockets */
			if (stream->ops->seek && (stream->flags & PHP_STREAM_FLAG_NO_SEEK) == 0) {
				stream->position += justwrote;
			}
		} else {
			break;
		}
	}
	return didwrite;

}


/* {{{ proto int fwrite(resource fp, string str [, int length])
   Binary-safe file write */
PHPAPI PHP_FUNCTION(fwrite)
{
	zval *arg1;
	char *arg2;
	int arg2len;
	int ret;
	int num_bytes;
	long arg3 = 0;
	char *buffer = NULL;
	php_stream *stream;

	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "rs|l", &arg1, &arg2, &arg2len, &arg3) == FAILURE) {
		RETURN_FALSE;
	}

	if (ZEND_NUM_ARGS() == 2) {
		num_bytes = arg2len;
	} else {
		num_bytes = MAX(0, MIN((int)arg3, arg2len));
	}

	if (!num_bytes) {
		RETURN_LONG(0);
	}

	PHP_STREAM_TO_ZVAL(stream, &arg1);

	if (PG(magic_quotes_runtime)) {
		buffer = estrndup(arg2, num_bytes);
		php_stripslashes(buffer, &num_bytes TSRMLS_CC);
	}

	ret = php_stream_write(stream, buffer ? buffer : arg2, num_bytes);
	if (buffer) {
		efree(buffer);
	}

	RETURN_LONG(ret);
}
/* }}} */


/*
so...

fwrite returns `false` when passed invalid parameters only.

*/