On Mon, 2018-06-25 at 15:12 +0200, Mark Wielaard wrote:
> It is sometimes useful to read .debug_line tables on their own without
> having an associated CU DIE. DWARF5 line tables are self-contained.
>
> Adjust dwarf_begin_elf to accept ELF files with just a .debug_line.
>
> Add a new function dwarf_next_lines that returns the Dwarf_Files and
> Dwarf_Lines while iterating over just the .debug_lines section. Since
> we parse and cache the information it also will try to match the CU
> a table is associated with. This is only necessary for DWARF4 line
> tables (we will need at least the compilation dir from the CU) and
> won't be done for DWARF5 line tables. It also isn't an error if there
> is no associated CU (but will mean for DWARF4 line tables the dir list
> and the file paths might not be complete).
>
> A typical way to call this new function is:
>
> Dwarf_Off off, next_off = 0;
> Dwarf_CU *cu = NULL;
> Dwarf_Files *files;
> size_t nfiles;
> Dwarf_Lines *lines;
> size_t nlines;
> int res;
> while ((res = dwarf_next_lines (dbg, off = next_off, &next_off, &cu,
> &files, &nfiles, &lines, &nlines)) == 0)
> {
> /* ... handle files and lines ... */
> }
>
> if (res < 0)
> printf ("BAD dwarf_next_lines: %s\n", dwarf_errmsg (-1));
>
> See libdw.h for the full documentation. For more examples on how to use
> the function see the new testcases next-files and next-lines.
>
> Also adjust the file paths for line tables missing a comp_dir.
> They are no longer made "absolute" by prepending a slash '/' in front
> of them. This really was not useful and didn't happen in any of the
> testcases. They are now just kept relative.
>
> Make eu-readelf --debug-dump=decodedline use dwarf_next_lines instead
> of iterating over the CUs to show the (decoded) line tables. This allows
> it to show decoded line tables even if there is no .debug_info section.
>
> New tests have been added that mimic the get-files and get-lines tests
> but use dwarf_next_lines instead of iterating over all CUs. They produce
> identical output (modulo the CU information). Also add a new test file
> that contains only a .debug_line section.
Initial testing seems to indicate that it works as expected.
Pushed to git master.
Cheers,
Mark
