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conan package does not print pretty stack. #299

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jbongseo opened this issue Jun 22, 2023 · 4 comments
Open

conan package does not print pretty stack. #299

jbongseo opened this issue Jun 22, 2023 · 4 comments

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@jbongseo
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Following is my sample project setup.

# conan file
$ cat <<EOF > conanfile.txt
[requires]
backward-cpp/1.6

[generators]
CMakeDeps
CMakeToolchain
EOF

# CMakeLists.txt file
$ cat <<EOF > CMakeLists.txt
cmake_minimum_required(VERSION 3.14...3.22)

project(
  backward_sample
  LANGUAGES CXX
  VERSION 0.1
  DESCRIPTION "backward_sample"
)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

include(./conan_deps/conan_toolchain.cmake)

find_package(Backward REQUIRED)

add_executable(backward_sample backward_sample.cpp)
set_target_properties(backward_sample
  PROPERTIES
  CXX_STANDARD 17
  OUTPUT_NAME backward_sample
)
target_link_libraries(backward_sample PRIVATE Backward::Backward)
EOF

# test source file
$ cat <<EOF > backward_sample.cpp
#include "backward.hpp"

namespace backward {

backward::SignalHandling sh;

} // namespace backward

void crash() {
  volatile int* a = (int*)(NULL);
  *a = 1;
}

int main(int argc, char* argv[]) {
  crash();
  return 0;
}
EOF

I compiled this project by following step:

$ mkdir conan_deps && cd conan_deps

$ conan install .. -pr Debug

$ cmake -B build -DCMAKE_BUILD_TYPE=Debug

$ cmake --build build --verbose

I can see that it is compiled with -g option and DBACKWARD_HAS_DWARF=1 flag.
It also seems be linked with libdwarf and libelf.

[ 50%] Building CXX object CMakeFiles/backward_sample.dir/backward_sample.cpp.o
/usr/bin/c++ -DBACKWARD_HAS_BACKTRACE=0 -DBACKWARD_HAS_BACKTRACE_SYMBOL=0 -DBACKWARD_HAS_BFD=0 -DBACKWARD_HAS_DW=0 -DBACKWARD_HAS_DWARF=1 -DBACKWARD_HAS_LIBUNWIND=0 -DBACKWARD_HAS_PDB_SYMBOL=0 -DBACKWARD_HAS_UNWIND=1 -isystem /home/jbseo/.conan/data/backward-cpp/1.6/_/_/package/2e02edff0a8a2b4d15d2baca54e2cbc7ecca7eae/include -isystem /home/jbseo/.conan/data/libdwarf/20191104/_/_/package/29a01e41514e57b26ac6cb3d59a534cdaa425a4d/include -isystem /home/jbseo/.conan/data/libelf/0.8.13/_/_/package/be27726f9885116da1158027505be62e913cd585/include -isystem /home/jbseo/.conan/data/libelf/0.8.13/_/_/package/be27726f9885116da1158027505be62e913cd585/include/libelf -isystem /home/jbseo/.conan/data/zlib/1.2.13/_/_/package/be27726f9885116da1158027505be62e913cd585/include -g -std=gnu++17 -MD -MT CMakeFiles/backward_sample.dir/backward_sample.cpp.o -MF CMakeFiles/backward_sample.dir/backward_sample.cpp.o.d -o CMakeFiles/backward_sample.dir/backward_sample.cpp.o -c /home/jbseo/playground/backward_cpp/backward_sample.cpp
[100%] Linking CXX executable backward_sample
/usr/bin/cmake -E cmake_link_script CMakeFiles/backward_sample.dir/link.txt --verbose=1
/usr/bin/c++ -g CMakeFiles/backward_sample.dir/backward_sample.cpp.o -o backward_sample  /home/jbseo/.conan/data/backward-cpp/1.6/_/_/package/2e02edff0a8a2b4d15d2baca54e2cbc7ecca7eae/lib/libbackward.a -ldl -lm /home/jbseo/.conan/data/libdwarf/20191104/_/_/package/29a01e41514e57b26ac6cb3d59a534cdaa425a4d/lib/libdwarf.a /home/jbseo/.conan/data/zlib/1.2.13/_/_/package/be27726f9885116da1158027505be62e913cd585/lib/libz.a /home/jbseo/.conan/data/libelf/0.8.13/_/_/package/be27726f9885116da1158027505be62e913cd585/lib/libelf.a

However, the generated binary only print simple stack without debug info.

$ ./build/backward_sample
Stack trace (most recent call last):
#5    Object "", at 0xffffffffffffffff, in
#4    Object "/home/jbseo/playground/backward_cpp/build/backward_sample", at 0x55d51ff8e924, in
#3    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f6ebd166e3f, in __libc_start_main
#2    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f6ebd166d8f, in
#1    Object "/home/jbseo/playground/backward_cpp/build/backward_sample", at 0x55d51ff8ea1d, in
#0    Object "/home/jbseo/playground/backward_cpp/build/backward_sample", at 0x55d51ff8e9fd, in
Segmentation fault (Address not mapped to object [(nil)])
Segmentation fault

I cannot figure out what I have missed.

Thanks for your advice in advance.
@bombela
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bombela commented Jun 22, 2023 via email

@jbongseo
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jbongseo commented Jun 23, 2023 •
edited
Loading

without the necessary libraries it won't be able to read the debug symbols.

That may be the source of the problem.

libdwarf and libelf is compiled and linked statically as specified by conan receipt and we can see that in the build log.

/usr/bin/c++ -g CMakeFiles/backward_sample.dir/backward_sample.cpp.o -o backward_sample  
[BLAH_PATH]/libbackward.a
 -ldl -lm
[BLAH_PATH]/libdwarf.a    <--- linked statically
[BLAH_PATH]/libz.a
[BLAH_PATH]/libelf.a      <--- linked statically

And we can check that using ldd command.

$ ldd build/backward_sample
        linux-vdso.so.1 (0x00007ffe2c943000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f46f6dd0000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f46f6db0000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f46f6b88000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f46f6aa1000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f46f70a3000)

By the way, I tried installing those library globally and linked them forcefully.
Then it worked as expected.

sudo apt-get install libdwarf-dev libelf-dev

# CMakeLists.txt
# add  -ldwarf -lelf flag to forcefully link global library
target_link_libraries(backward_sample PRIVATE Backward::Backward -ldwarf -lelf)

$ cmake --build build --clean-first --verbose
...
[100%] Linking CXX executable backward_sample
/usr/bin/cmake -E cmake_link_script CMakeFiles/backward_sample.dir/link.txt --verbose=1
/usr/bin/c++ -g CMakeFiles/backward_sample.dir/backward_sample.cpp.o -o backward_sample

-ldwarf -lelf     <-- forcefully injected link

[BLAH_PATH]/libbackward.a
 -ldl -lm

[BLAH_PATH]/libdwarf.a  <-- provided by cmake. maybe ignored?
[BLAH_PATH]/libz.a 
[BLAH_PATH]/libelf.a  <-- provided by cmake. maybe ignored?

Now, libdwarf, libelf, libz are linked dynamically.

$ ldd ./build/backward_sample
        linux-vdso.so.1 (0x00007ffde4d86000)
        libdwarf.so.1 => /lib/x86_64-linux-gnu/libdwarf.so.1 (0x00007f7ffa159000)
        libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007f7ffa13b000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f7ff9f11000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f7ff9ef1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7ff9cc9000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f7ff9cab000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f7ffa23a000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f7ff9bc4000)

and it works well now.

$ ./build/backward_sample
Stack trace (most recent call last):
#5    Object "", at 0xffffffffffffffff, in
#4    Object "/home/jbseo/playground/backward_cpp/build/backward_sample", at 0x55a592030a84, in _start
#3    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f76f1442e3f, in __libc_start_main
#2    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f76f1442d8f, in __libc_init_first
#1    Source "/home/jbseo/playground/backward_cpp/backward_sample.cpp", line 15, in int main(int argc, char **argv) [0x55a592030b7d]
         12: }
         13:
         14: int main(int argc, char* argv[]) {
      >  15:   crash();
         16:   return 0;
         17: }
#0    Source "/home/jbseo/playground/backward_cpp/backward_sample.cpp", line 11, in crash() [0x55a592030b5d]
          9: void crash() {
         10:   volatile int* a = (int*)(NULL);
      >  11:   *a = 1;
         12: }
         13:
         14: int main(int argc, char* argv[]) {
Segmentation fault (Address not mapped to object [(nil)])
Segmentation fault

I do not know the reason.
Maybe libdwarf should not be linked statically or libdwarf conan package has some problem in it.
Anyway, conan package should not be encouraged currently.

Thanks for the great library!

@bombela
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bombela commented Jun 23, 2023 via email

@yz1019117968
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without the necessary libraries it won't be able to read the debug symbols.

That may be the source of the problem.

libdwarf and libelf is compiled and linked statically as specified by conan receipt and we can see that in the build log.

/usr/bin/c++ -g CMakeFiles/backward_sample.dir/backward_sample.cpp.o -o backward_sample  
[BLAH_PATH]/libbackward.a
 -ldl -lm
[BLAH_PATH]/libdwarf.a    <--- linked statically
[BLAH_PATH]/libz.a
[BLAH_PATH]/libelf.a      <--- linked statically

And we can check that using ldd command.

$ ldd build/backward_sample
        linux-vdso.so.1 (0x00007ffe2c943000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f46f6dd0000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f46f6db0000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f46f6b88000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f46f6aa1000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f46f70a3000)

By the way, I tried installing those library globally and linked them forcefully. Then it worked as expected.

sudo apt-get install libdwarf-dev libelf-dev

# CMakeLists.txt
# add  -ldwarf -lelf flag to forcefully link global library
target_link_libraries(backward_sample PRIVATE Backward::Backward -ldwarf -lelf)

$ cmake --build build --clean-first --verbose
...
[100%] Linking CXX executable backward_sample
/usr/bin/cmake -E cmake_link_script CMakeFiles/backward_sample.dir/link.txt --verbose=1
/usr/bin/c++ -g CMakeFiles/backward_sample.dir/backward_sample.cpp.o -o backward_sample

-ldwarf -lelf     <-- forcefully injected link

[BLAH_PATH]/libbackward.a
 -ldl -lm

[BLAH_PATH]/libdwarf.a  <-- provided by cmake. maybe ignored?
[BLAH_PATH]/libz.a 
[BLAH_PATH]/libelf.a  <-- provided by cmake. maybe ignored?

Now, libdwarf, libelf, libz are linked dynamically.

$ ldd ./build/backward_sample
        linux-vdso.so.1 (0x00007ffde4d86000)
        libdwarf.so.1 => /lib/x86_64-linux-gnu/libdwarf.so.1 (0x00007f7ffa159000)
        libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007f7ffa13b000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f7ff9f11000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f7ff9ef1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7ff9cc9000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f7ff9cab000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f7ffa23a000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f7ff9bc4000)

and it works well now.

$ ./build/backward_sample
Stack trace (most recent call last):
#5    Object "", at 0xffffffffffffffff, in
#4    Object "/home/jbseo/playground/backward_cpp/build/backward_sample", at 0x55a592030a84, in _start
#3    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f76f1442e3f, in __libc_start_main
#2    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f76f1442d8f, in __libc_init_first
#1    Source "/home/jbseo/playground/backward_cpp/backward_sample.cpp", line 15, in int main(int argc, char **argv) [0x55a592030b7d]
         12: }
         13:
         14: int main(int argc, char* argv[]) {
      >  15:   crash();
         16:   return 0;
         17: }
#0    Source "/home/jbseo/playground/backward_cpp/backward_sample.cpp", line 11, in crash() [0x55a592030b5d]
          9: void crash() {
         10:   volatile int* a = (int*)(NULL);
      >  11:   *a = 1;
         12: }
         13:
         14: int main(int argc, char* argv[]) {
Segmentation fault (Address not mapped to object [(nil)])
Segmentation fault

I do not know the reason. Maybe libdwarf should not be linked statically or libdwarf conan package has some problem in it. Anyway, conan package should not be encouraged currently.

Thanks for the great library!

Hi, can you elaborate more about the steps?? I'm not familiar with cpp....

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@bombela @yz1019117968 @jbongseo