IO::Buffer#resize: Free internal buffer if new size is zero #7569
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hanazuki
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`#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.
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ioquatix
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Mar 24, 2023
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@kou thanks for mentioning me so I can review.
I am okay with this change.
There are several options for resize(0):
- Raise error.
- Free buffer.
- Ignore.
I think that option 2 is proposed in this change, is acceptable. However, after resizing a buffer to size=0, can we resize it back to size=1? I want to add extra tests.
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@ioquatix Thanks for your review. Your addition to the test makes sense. |
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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. --- io_buffer.c | 5 +++++ test/ruby/test_io_buffer.rb | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+)
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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. --- io_buffer.c | 5 +++++ test/ruby/test_io_buffer.rb | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+)
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Fixes: https://bugs.ruby-lang.org/issues/19543
#resize(0)on an IO::Buffer with internal buffer allocated will result in callingrealloc(data->base, 0). The behavior ofreallocwith 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
frees the memory when the new size is zero.