Can't see symbols from Erlang NIF library in core file
Attila Rajmund Nohl
attila.r.nohl@REDACTED
Tue Jul 20 19:37:58 CEST 2021
Hello!
I'm working on an Erlang wrapper over a 3rd party C library on Ubuntu
Linux on x86, so I'm creating a NIF. Sometimes my code (I think)
crashes, resulting in a core file. Unfortunately the stacktrace is not
really helpful:
(gdb) bt
#0 0x00007fc22229968a in ?? ()
#1 0x0000000060e816d8 in ?? ()
#2 0x0000000007cd48b0 in ?? ()
#3 0x00007fc228031410 in ?? ()
#4 0x00007fc228040b80 in ?? ()
#5 0x00007fc228040c50 in ?? ()
#6 0x00007fc22223de0b in ?? ()
#7 0x0000000000000000 in ?? ()
even though I built my NIF .so file with debug info:
ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically
linked, BuildID[sha1]=b70dd1f2450f5c0e9980c8396aaad2e1cd29024c, with
debug_info, not stripped
The beam binary also has debug info:
ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically
linked, interpreter /lib64/ld-linux-x86-64.so.2,
BuildID[sha1]=e0a5dba6507b8c2b333faebc89fbc6ea2f7263b9, for GNU/Linux
3.2.0, with debug_info, not stripped
However, info sharedlibrary doesn't show neither the NIF nor the 3rd party lib:
(gdb) info sharedlibrary
>From To Syms Read Shared Object Library
0x00007fc28942ed50 0x00007fc289432004 Yes
/lib/x86_64-linux-gnu/libgtk3-nocsd.so.0
0x00007fc289429220 0x00007fc28942a179 Yes
/lib/x86_64-linux-gnu/libdl.so.2
0x00007fc2892e83c0 0x00007fc28938ef18 Yes
/lib/x86_64-linux-gnu/libm.so.6
0x00007fc2892b76a0 0x00007fc2892c517c Yes
/lib/x86_64-linux-gnu/libtinfo.so.6
0x00007fc28928dae0 0x00007fc28929d4d5 Yes
/lib/x86_64-linux-gnu/libpthread.so.0
0x00007fc2890b9630 0x00007fc28922e20d Yes
/lib/x86_64-linux-gnu/libc.so.6
0x00007fc289657100 0x00007fc289679674 Yes (*) /lib64/ld-linux-x86-64.so.2
0x00007fc24459c040 0x00007fc2445ab8ad Yes
/home/nar/otp/23.3.4.2/lib/crypto-4.9.0.2/priv/lib/crypto.so
0x00007fc2239e3000 0x00007fc223b7c800 Yes (*)
/lib/x86_64-linux-gnu/libcrypto.so.1.1
0x00007fc2896500e0 0x00007fc28965028c Yes
/home/nar/otp/23.3.4.2/lib/crypto-4.9.0.2/priv/lib/crypto_callback.so
0x00007fc289649380 0x00007fc28964bc1c Yes
/home/nar/otp/23.3.4.2/lib/asn1-5.0.15/priv/lib/asn1rt_nif.so
0x00007fc289638720 0x00007fc28963bd70 Yes
/lib/x86_64-linux-gnu/librt.so.1
I found an answer at stackoverflow
(https://stackoverflow.com/a/32727752/2414208) mentioning that "The
Erlang VM doesn't load NIF libraries with global symbols exposed".
Could this be the reason why I don't see the symbols? Is there a way
to tell gdb to look up symbols from my .so file?
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