On Wed, 16 Mar 2022 21:10:14 GMT, Tyler Steele <d...@openjdk.java.net> wrote:
>> As described in the linked issue, NullClassBytesTest fails due an >> OutOfMemoryError produced on AIX when the test calls defineClass with a byte >> array of size of 0. The native implementation of defineClass then calls >> malloc with a size of 0. On AIX malloc(0) returns NULL, while on other >> platforms it return a valid address. When NULL is produced by malloc for >> this reason, ClassLoader.c incorrectly interprets this as a failure due to a >> lack of memory. >> >> ~~This PR modifies ClassLoader.c to produce an OutOfMemoryError only when >> `errno == ENOMEM` and to produce a ClassFormatError with the message >> "ClassLoader internal allocation failure" in all other cases (in which >> malloc returns NULL).~~ [edit: The above no longer describes the PR's >> proposed fix. See discussion below] >> >> In addition, I performed some minor tidy-up work in ClassLoader.c by >> changing instances of `return 0` to `return NULL`, and `if (some_ptr == 0)` >> to `if (some_ptr == NULL)`. This was done to improve the clarity of the code >> in ClassLoader.c, but didn't feel worthy of opening a separate issue. >> >> ### Alternatives >> >> It would be possible to address this failure by modifying the test to accept >> the OutOfMemoryError on AIX. I thought it was a better solution to modify >> ClassLoader.c to produce an OutOfMemoryError only when the system is >> actually out of memory. >> >> ### Testing >> >> This change has been tested on AIX and Linux/x86. > > Tyler Steele has refreshed the contents of this pull request, and previous > commits have been removed. The incremental views will show differences > compared to the previous content of the PR. The pull request contains one new > commit since the last revision: > > Addresses failure in NullClassTest on AIX. > > - Changes malloc(0) call to malloc(1) on AIX. src/java.base/share/native/libjava/ClassLoader.c line 102: > 100: } > 101: > 102: // On malloc(0), implementators of malloc(3) have the choice to > return either It is confusing to mix `malloc(0)`, where you are passing an argument zero to malloc, with `malloc(3)` which actually means the definition of malloc as per the man page in section 3. Given this is only an issue on AIX the comment can simply say: `// On AIX malloc(0) returns NULL which looks like an out-of-memory condition; so adjust it to malloc(1)`. src/java.base/share/native/libjava/ClassLoader.c line 106: > 104: // we chose the latter. (see 8283225) > 105: #ifdef _AIX > 106: body = (jbyte *)malloc(length == 0 ? 1 : length); Using AIX_ONLY this can be simplified: `body = (jbyte *)malloc(length AIX_ONLY( == 0 ? 1 : length));` ------------- PR: https://git.openjdk.java.net/jdk/pull/7829
