JVM SIGBUS crash with nested includes

When compiling a table with includes that are more than 6 levels deep the JVM crashes with SIGBUS

According to the internets SIGBUS is generally related to memory problems, so the first thought is of course to blame liblouis and to assume that it is writing over some JVM stack frames.

Options

1. liblouis is somehow corrupting the memory
2. The Java bindings have a problem
3. some other problem

Analysis

liblouis is corrupting memory

• Port the test to C so we can analyze the memory.
• Run Valgrind on the C test case
• Analyze C test case with Electric Fence

So @bertfrees ported the test case to C, see https://github.com/liblouis/liblouis/blob/test_deep_include/tests/deep_include.c. When running Valgrind there is a memory leak around the usage of the DefaultTableResolver. Electric Fence does not indicate any problems whatsoever.

The problem persists on the JVM when using a liblouis where the memory leak is fixed

Java bindings have a problem

It is not clear where there could be a problem here. The test case simply invokes get_Table through a very simple API straight down to C.

• Run gdb on the Java test case: doesn't give much info except that the SIGBUS happens in compileUplow on the line int haveLowerDots = 0 (may not mean anything).
• Run valgrind on the Java test case. Maybe this will give us a hint if JVM or JNA are doing something fishy.

Other problem

Some findings from a google search indicate that the problem could be within the JVM and the use of mmaped files

• Try to reproduce the problem on an other machine

On a Linux machine the problem doesn't occur

Start with tests/deep_include.c and the Java binding entry point in src/main/java/org/liblouis/Louis.java#L57, then reproduce the deep-include case on Linux. Run Valgrind on the Java test case and compare its results with the C analysis, focusing on the crash in compileUplow. Done means the cause is identified and the JVM no longer crashes for includes deeper than six levels.