LLDB debugger doesn't identifying executable symbols that compiled on remote machine

Question

I'm building my project on one computer on Xcode/clang environment, and i'd like to run it under lldb debugger on another station without copying the source code, only the executables, and the symbol files.

I've copied all dSYM directories, so that lldb debugger could identify the symbols I need and present the real function (currently I get function names like ___lldb_unnamed_function532 upon backtrace command)

I tried using the command

settings set target.source_map /source_dir /target_dir

Where target_dir represents the path where i placed all dSYM dirs, and source_dir represents the path of the original parent directory of all the dSYM dirs.

Unfortunately, it doesn't work unless the source code reside on /target_dir.

Where did i go wrong?

Ok, so I've found out that when i copy the dSYM dir to the same location of the executables, so lldb manage to decipher the symbols. is there any way to "tell" lldb for another location?

Answer 1

To specify a different path for dSYM you can do the following steps:

First generate the UUID for the executable using the following command:

xcrun dwarfdump --uuid path-to-executable

Then make the directory by splitting the first 20 hex digits into 4 character chunks and creating a tree of directories: each subsequent directory is created inside the previous one. Then create a symlink whose name is the last 12 hex digits in the deepest directory. For example if the UUID generated is: 23516BE4-29BE-350C-91C9-F36E7999F0F1

then make the Folders: 2351/6BE4/29BE/350C/91C9/

and the Symlink: F36E7999F0F1

The symlinks value is a full path to the mach-o files inside the dSYM bundle which contains the DWARF. If the dSYM is in source/foo.dSYM/Contents/Resources/DWARF/foo, then the link must be the full path to source/foo.dSYM/Contents/Resources/DWARF/foo (see the example below).

The last part is to tell DebugSymbols to check this UUID file map cache using:

% defaults write com.apple.DebugSymbols DBGFileMappedPaths path-to-your uuids tree

For example you can put the directories you have created under ~/Library/SymbolCache/dsyms/uuids/ (or wherever you want) so that the complete path to your final link will be: ~/Library/SymbolCache/dsyms/uuids/2351/6BE4/29BE/350C/91C9/F36E7999F0F1

And the command:

% defaults write com.apple.DebugSymbols DBGFileMappedPaths ~/Library/SymbolCache/dsyms/uuids/

Then check it with:

defaults read com.apple.DebugSymbols DBGFileMappedPaths

source: http://lldb.llvm.org/symbols.html, LLDB: add symbols file?

I tried it on my MAC OS X:

xcrun dwarfdump --uuid ./a.out

UUID: 7C9D0D55-3882-3F1B-99CA-446AFF4B5D0E (x86_64) ./a.out

mkdir PAPERINO
mv a.out.dSYM/ PAPERINO/

mkdir -p ~/Library/SymbolCache/dsyms/uuids/
mkdir -p ~/Library/SymbolCache/dsyms/uuids/7C9D0/0D55/3882/3F1B/99CA
cd ~/Library/SymbolCache/dsyms/uuids/7C9D0/0D55/3882/3F1B/99CA/

ln -s ../../../<my path>/PAPERINO/a.out.dSYM/Contents/Resources/DWARF/a.out 446AFF4B5D0E

And finally I was able to list the source in lldb:

lldb ./a.out 
(lldb) target create "./a.out"
Current executable set to './a.out' (x86_64).
(lldb) source list
   6    {
   7        char input[40] = {'\0'};
   8        int count = 0;