IO::Buffer#resize: Free internal buffer if new size is zero (#7569)

`#resize(0)` on an IO::Buffer with internal buffer allocated will result in calling `realloc(data->base, 0)`. The behavior of `realloc` with size = 0 is implementation-defined (glibc frees the object and returns NULL, while BSDs return an inaccessible object). And thus such usage is deprecated in standard C (upcoming C23 will make it UB). To avoid this problem, just `free`s the memory when the new size is zero.

1 files changed, 5 insertions, 0 deletions

diff --git a/io_buffer.c b/io_buffer.c
index 91083cd7e4..1ff3935094 100644
--- a/io_buffer.c
+++ b/io_buffer.c
@@ -1422,6 +1422,11 @@ rb_io_buffer_resize(VALUE self, size_t size)
 #endif

 if (data->flags & RB_IO_BUFFER_INTERNAL) {
+ if (size == 0) {
+ io_buffer_free(data);
+ return;
+ }
+
 void *base = realloc(data->base, size);

 if (!base) {