From: Jeff King Date: Thu, 30 Aug 2018 07:07:52 +0000 (-0400) Subject: test-delta: read input into a heap buffer X-Git-Tag: v2.20.0-rc0~233^2~5 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/d65930c5a9fe73ebc4d157ebe1fb9fd9907f2f70?ds=inline;hp=d65930c5a9fe73ebc4d157ebe1fb9fd9907f2f70 test-delta: read input into a heap buffer We currently read the input to test-delta by mmap()-ing it. However, memory-checking tools like valgrind and ASan are less able to detect reads/writes past the end of an mmap'd buffer, because the OS is likely to give us extra bytes to pad out the final page size. So instead, let's read into a heap buffer. As a bonus, this also makes it possible to write tests with empty bases, as mmap() will complain about a zero-length map. This is based on a patch by Jann Horn which actually aligned the data at the end of a page, and followed it with another page marked with mprotect(). That would detect problems even without a tool like ASan, but it was significantly more complex and may have introduced portability problems. By comparison, this approach pushes the complexity onto existing memory-checking tools. Note that this could be done even more simply by using strbuf_read_file(), but that would defeat the purpose: strbufs generally overallocate (and at the very least include a trailing NUL which we do not care about), which would defeat most memory checkers. Signed-off-by: Jeff King Reviewed-by: Nicolas Pitre Signed-off-by: Junio C Hamano ---