[Debugger] Fails to load whole debug info of an executable if its CIE's length is zero

[KENZ_gelsoft]

Environment:

• Haiku: R1/beta4(Revision hrev56578+86) x86_64
• on Real hardware with 8core Core i7-3770 w/ 16GB RAM

The problem (w/ STR):

• The Debugger GUI can't locate source when I debug some libraries of the in-development Firefox. I can't specify source file location manually.
• Rebuilt with DWARF3(by -gdwarf-3) helped a bit (main executable can be debugged with symbol), but didn't help some (most part of) libraries.
• I launched the Debugger from command line like Debugger firefox (with some additional args to firefox).

Problem details I investigated:

• The Debugger (kit) failed to load when the library has 0-length CIE(Common Information Entry).
• 0-length CIE is not forbidden in spec, and llvm-dwarfdump handles correctly this.
• I didn't identify what and why the build tool produces such a binary (contains 0-length CIE). But there are more than one shared objects(.so) in the firefox build output.

[KENZ_gelsoft]

Screenshot with "Source file unavailable" message without button locating source file

[KENZ_gelsoft]

Some links from the related forum topic.

My initial comment about this problem:

• ​https://discuss.haiku-os.org/t/progress-on-porting-firefox/13493/28

My sharing investigated result:

• ​https://discuss.haiku-os.org/t/progress-on-porting-firefox/13493/63

leavengood found 0-length CIE is valid:

• ​https://discuss.haiku-os.org/t/progress-on-porting-firefox/13493/64

[KENZ_gelsoft]

My current change to the Debugger kit (revision is R1/beta4).

diff --git a/src/kits/debugger/dwarf/DwarfFile.cpp b/src/kits/debugger/dwarf/DwarfFile.cpp
index e382d6200e..d6bd0a0b38 100644
--- a/src/kits/debugger/dwarf/DwarfFile.cpp
+++ b/src/kits/debugger/dwarf/DwarfFile.cpp
@@ -1155,6 +1155,11 @@ DwarfFile::_ParseFrameSection(ElfSection* section, uint8 addressSize,
                if (length > (uint64)dataReader.BytesRemaining())
                        return B_BAD_DATA;
                off_t lengthOffset = dataReader.Offset();
+               
+               if (length == 0 && !ehFrame) {
+                       // Just skipping .debug_frame with 0-length CIE
+                       return B_OK;
+               }
 
                // CIE ID/CIE pointer
                uint64 cieID = dwarf64

I think this patch should work with latest Haiku, but will test, and will try submitting to the review.

[KENZ_gelsoft]

I submitted above patch (with change to comply coding style rule):

​https://review.haiku-os.org/c/haiku/+/6538

[waddlesplash]

Merged in hrev57084.