Support separate debug symbol files (as in GDB) #253
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| @@ -261,6 +261,7 @@ | |||
| #else | |||
| #include <dlfcn.h> | |||
| #endif | |||
| #include <libgen.h> | |||
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I expect libgen.h header to exist when libdwarf is available, but that can be not true.
| @@ -2431,17 +2432,25 @@ class TraceResolverLinuxImpl<trace_resolver_tag::libdwarf> | |||
| ELF_GET_DATA(32) | |||
| } else if (e_ident[EI_CLASS] == ELFCLASS64) { | |||
| // libelf might have been built without 64 bit support | |||
| #if __LIBELF64 | |||
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This is a bit unrelated, but libelf installed on my PC (it's Arch Linux, but it's true also for Ubuntu 20.04 at least) does not have this definition, so the entire branch is omitted, so no 64-bit data, so no debuglink info. Probably we can work it around in a better way, but this line really stops me from having nice source locations.
| { | ||
| char* object_filename_copy = strdup(object_filename.c_str()); | ||
| const std::string directory_path = std::string(dirname(object_filename_copy)); | ||
| free(object_filename_copy); | ||
| debuglink_file.reset( | ||
| open((directory_path + '/' + debuglink).c_str(), O_RDONLY)); | ||
| if (debuglink_file.get() < 0) { | ||
| debuglink_file.reset(open( | ||
| (directory_path + "/.debug/" + debuglink).c_str(), O_RDONLY)); | ||
| } | ||
| } |
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There are only 2 locations covered since I don't know what global debug directories contain.
| const std::string directory_path = std::string(dirname(object_filename_copy)); | ||
| free(object_filename_copy); | ||
| debuglink_file.reset( | ||
| open((directory_path + '/' + debuglink).c_str(), O_RDONLY)); |
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I expect debuglink to have only filename since, according to docs:
The executable contains a debug link that specifies the name of the separate debug info file.
Also, objcopy tool writes only the filename component in the .gnu_debuglink section even if an absolute path is provided:
https://github.com/bminor/binutils-gdb/blob/b4edb38e827974ecdbc4a6712d8b21bf876018a2/bfd/opncls.c#L1707-L1708
backward-cpp already supports loading debug symbols from a separate file. But currently, a separate file with debug symbols has to be located in the current working directory while the GDB documentation says:
This way, we have to look for a separate debug symbols file differently to replicate GDB behavior.
There are also a few points that I explained inline.