`logmath_read` ignores `-mmap` flag and crashes if `mmio_file_read` returns `NULL`

[dlyongemallo]

logmath_read() in src/util/logmath.c unconditionally attempts to memory-map model files, ignoring the -mmap configuration flag. All other callers of mmio_file_read (bin_mdef.c, s2_semi_mgau.c, ptm_mgau.c) check ps_config_bool(config, "mmap") before calling mmio_file_read, but logmath_read does not: it always sets do_mmap = 1 (line 231) and only disables it for alignment or endianness reasons.

Additionally, when mmio_file_read returns NULL (e.g., because mmap(MAP_SHARED) failed), the code on line 246 unconditionally dereferences the result, which crashes on any platform where mmap fails at runtime, regardless of whether -mmap no was set in the config. (In particular, this happens in Emscripten/WASM.)

Suggested fix: Check for NULL return from mmio_file_read (on line 245) and fall back to the fread path (lines 248-258), similar to bin_mdef.c:410-412. Additionally, logmath_read should check the -mmap config flag.

[dhdaines]

logmath_read does not: it always sets do_mmap = 1 (line 231) and only disables it for alignment or endianness reasons.

Hmm! That's quite silly, I'm no longer sure why it does that. To be honest, logmath files are not a very commonly used feature, and it appears (from the commit message) that I imported this code from SphinxTrain with the intent of refactoring it later on.

There isn't an actual unit test for this feature which may explain why it is broken. So any fix will obviously need a test!

Out of curiosity what are you using logmath files for?