mirror of https://github.com/odrling/Aegisub
c2267bedcc
libass: Fix cache lookup problem causing memory bloat The cache code did hash lookups by storing key values in struct fields and then hashing and comparing the struct as a single memory block. In at least one case such a struct contained uninitialized padding bytes which prevented the complete memory area of the struct from matching even though the fields did. As a result the code failed to find existing objects in the cache and stored new versions of them, causing gigabytes of memory use in some circumstances. Initializing the struct memory to zero before writing the fields avoided such memory use in tests but is not guaranteed to work if I interpret the C standard correctly (the compiler is allowed to write garbage over padding bytes when changing struct member values). Change the code to use struct-specific hashing and comparison functions that work field by field to guarantee correct behavior. Create these by replacing the struct definition with a template that lists the fields and can be used the generate each of struct definition, hash function and compare function with some preprocessor magic (otherwise every field would need to be listed separately in all three). Originally committed to SVN as r2895. |
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