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Show HN: Heap Explorer (github.com)

73 points by bkallus ↗ HN
I wrote a little LD_PRELOAD library that makes it easy to inspect and interact with a running program's glibc heap.

It's fun to pause processes, free a bunch of their allocations, then resume them. Most of the time, the processes continue as though nothing happened, but sometimes they do interesting things :)

5 comments

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heinrichhartman
Can you modify this to listen to a signal (e.g. SIGUSR) instead, for triggering the REPL?
bkallus
I went with SIGINT because it's more fun to press ctrl-c than to pgrep and kill. If you'd rather use SIGUSR1, just change SIGINT to SIGUSR1 line 654.
dzaima
Would be nice to mention how to determine those *_OFFSET constants. For reference, on my linux mint (glibc 2.39) system this gives them:

    gdb /lib/x86_64-linux-gnu/libc.so.6 -ex 'p &main_arena' -ex 'p malloc'
Also, can attach to an existing process via:

    sudo gdb -p <PID_OF_PROCESS> -ex 'call (void*) dlopen("/path/to/libheap_explorer.so", 2)' -ex 'p explore_heap()'