Revisted Wez patch: chunk_size 0 means cahce the whole output. So

we must apply the default before calling php_enable_output_compression().
I have left the default setting in the rinit function even though i do think
it is not necessary.

ext/zlib/zlib.c

@@ -230,8 +230,10 @@ PHP_RINIT_FUNCTION(zlib)
 	ZLIBG(ob_gzhandler_status) = 0;
 	ZLIBG(ob_gzip_coding) = 0;
 	if (chunk_size) {
-		if (chunk_size == 1)
-			chunk_size = 0; /* use the default size */
+		if (chunk_size == 1) {
+			chunk_size = 4096; /* use the default size */
+			ZLIBG(output_compression) = chunk_size;
+		}
 		php_enable_output_compression(chunk_size TSRMLS_CC);
 	}
 	return SUCCESS;

main/output.c

@@ -130,10 +130,10 @@ PHPAPI int php_start_ob_buffer(zval *output_handler, uint chunk_size, zend_bool
 		return FAILURE;
 	}
 	if (chunk_size) {
+		if (chunk_size==1)
+			chunk_size = 4096;
 		initial_size = (chunk_size*3/2);
 		block_size = chunk_size/2;
-		if (block_size == 0)
-			block_size = 1;
 	} else {
 		initial_size = 40*1024;
 		block_size = 10*1024;