RFR: 8368522: (fs) BasicFileAttributes Linux musl 1.2.5 incompatibility with statx [v4]

[Severin Gehwolf]

On Thu, 9 Oct 2025 08:53:16 GMT, Aleksei Voitylov <avoitylov at openjdk.org> wrote:

>> This cleanup replaces #ifdefs with a standard #include <stdint.h>. Using standard types is less prone to errors.
>> 
>> JDK-8368522 was reported on ARM32 with musl libc, which is not a supported configuration, but I still believe this code cleanup is worth it.
>> 
>> After the introduction of statx with musl 1.2.5, a buffer overflow issue with statx() call handling started happening on ARM32. The root cause is incorrect size of __uint64_t type definition in the JDK for musl libc, where it was defined as 4 bytes (unsigned long int) for 32-bit systems instead of 8 bytes (unsigned long long).
>> 
>> The mismatch between JDK's my_statx structure and kernel's statx structure causes stack corruption when statx() writes beyond the statx_buf boundaries, overwriting adjacent variables, including the 'attrs' argument that was later passed to copy_statx_attributes() function and caused a segfault there.
>> 
>> Built and ran jtreg on standard OpenJDK platforms with no regressions, including the altered test.
>
> Aleksei Voitylov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove extra _

Marked as reviewed by sgehwolf (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/27674#pullrequestreview-3317948862