The cc65 source package comes with a C module that allows easy access to the debug information files generated by the ld65 linker. It is available in src/dbginfo and currently available as just one C file and a matching header. If your program is written in C or C++, just include both files in your project, add the header as necessary and start working with cc65 debug info files.
The module is pure C code and mostly C89 compatible. However, it uses vsnprintf in one place and may therefore not work with “real” C89 compilers. The code assumes 8 bit characters and integers to be at least 32 bit wide. Since the data - when parsed and cross-indexed - requires a lot more memory than is available on 16 bit platforms, I haven't even tried to make the code 16 bit compatible. Apart from these restrictions, the code should be pretty portable.