Don't pre-allocate strings larger than the buffered size

byroot · byroot · commit 8ba8702cbf86 · 2026-04-11T18:40:10.000+02:00
diff --git a/ext/msgpack/unpacker.c b/ext/msgpack/unpacker.c
@@ -336,7 +336,8 @@ static int read_raw_body_cont(msgpack_unpacker_t* uk)
     size_t length = uk->reading_raw_remaining;
 
     if(uk->reading_raw == Qnil) {
-        uk->reading_raw = rb_str_buf_new(length);
+        size_t buffered_size = msgpack_buffer_all_readable_size(UNPACKER_BUFFER_(uk));
+        uk->reading_raw = rb_str_buf_new(length > buffered_size ? buffered_size : length);
     }
 
     do {

Original file line number	Diff line number	Diff line change
`@@ -336,7 +336,8 @@ static int read_raw_body_cont(msgpack_unpacker_t* uk)`
`336`	`336`	`size_t length = uk->reading_raw_remaining;`
`337`	`337`
`338`	`338`	`if(uk->reading_raw == Qnil) {`
`339`		`- uk->reading_raw = rb_str_buf_new(length);`
	`339`	`+ size_t buffered_size = msgpack_buffer_all_readable_size(UNPACKER_BUFFER_(uk));`
	`340`	`+ uk->reading_raw = rb_str_buf_new(length > buffered_size ? buffered_size : length);`
`340`	`341`	`}`
`341`	`342`
`342`	`343`	`do {`