WIP: quick hack demo of gotcha (do not merge) #701
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- getting segv on printf calls after gotcha registration in this iteration
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Just opening this PR to track the example. DO NOT MERGE.
This commit is a quick and dirty hack to illustrate how gotcha might be used for Darshan instrumentation. It disables the existing H5Fcreate() wrapper and replaces it with a hardcoded wrapper in darshan-core.c loaded using gotcha from within the darshan initialization function. The hardcoded wrapper just prints a "hello world" message. The purpose is to illustrate the potential for wrapping symbols that appear after the darshan library in the runtime link order.
A quick and dirty example of running it with the ph5example test program is included in the darshan-runtime/gotcha-demo-test-case directory.
This example does not work. The gotcha wrapper loading appears to work ok, but then subsequent calls with the existing wrappers (specifically wrappers for printf() ) produce a segfault with the pc set to the zero page.
Possibly a bug, or possibly a bad interaction between gotcha and the dlsym calls made by existing Darshan wrappers.