Thanks, it worked. On Mon, 25 Sept 2023, 12:42 Kyle Huey, <kh...@pernos.co> wrote:
> Most likely the .debug_info section is SHF_COMPRESSED. Try compiling with > -gz=none. > > - Kyle > > On Mon, Sep 25, 2023, 1:36 PM Rishi Raj via Dwarf-discuss < > dwarf-discuss@lists.dwarfstd.org> wrote: > >> <https://stackoverflow.com/posts/77169835/timeline> >> >> I am trying to implement a dwarf parser in C++ without using any external >> dependencies. As mentioned in dwarf5 standard, debug info first 4 bytes or >> 12 bytes denotes the unit length Basically this: >> >> unit_length (initial length) >> A 4-byte or 12-byte unsigned integer representing the length of the3 >> .debug_info contribution for that compilation unit, not including the length >> field itself. In the 32-bit DWARF format, this is a 4-byte unsigned integer >> (which must be less than 0xfffffff0); in the 64-bit DWARF format, this >> consists of the 4-byte value 0xffffffff followed by an 8-byte unsigned >> integer that gives the actual length (see Section 7.4 on page 196). >> >> When I am dumping the .debug_info section hexadecimally using objdump I >> am getting this(see readelf output below). >> >> objdump -s -j .debug_info hello.o >> >> hello.o: file format elf64-x86-64 >> >> Contents of section .debug_info: >> >> 0000 01000000 00000000 9a000000 00000000 ................ >> 0010 01000000 00000000 789c9bc6 c0c0c0ca ........x....... >> 0020 c0c801a4 18984084 2c031a10 42623372 ......@.,...Bb3r >> 0030 b0832916 0805d1c6 c804e5b1 4178ac20 ..).........Ax. >> 0040 8a998535 33af04a8 8115498e 05aa2002 ...53.....I... . >> 0050 8bf18c73 58131918 99394172 4c137318 ...sX....9ArL.s. >> 0060 180011e5 0560 >> >> So according to this, the length should be 0x01000000, but the actual >> length is 0x96.(see readelf output below) >> readelf -wi hello.o >> Contents of the .debug_info section: >> >> Compilation Unit @ offset 0: >> Length: 0x96 (32-bit) >> Version: 5 Unit Type: DW_UT_compile (1) Abbrev Offset: 0 >> Pointer Size: 8 >> >> I know I am missing something basic, but even after reading the standards >> for many times. I am unable to find my mistake. One more thing, I searched >> for some basic dwarf parsers so that I could understand what they are doing >> but could not find any. All of the parsers were big libraries, which was >> difficult to understand. If any of you can at least provide some readable >> and understandable parser code, It will be helpful too. >> >> ELF header dump: >> >> ELF Header: >> Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 >> Class: ELF64 >> Data: 2's complement, little endian >> Version: 1 (current) >> OS/ABI: UNIX - System V >> ABI Version: 0 >> Type: REL (Relocatable file) >> Machine: Advanced Micro Devices X86-64 >> Version: 0x1 >> Entry point address: 0x0 >> Start of program headers: 0 (bytes into file) >> Start of section headers: 3048 (bytes into file) >> Flags: 0x0 >> Size of this header: 64 (bytes) >> Size of program headers: 0 (bytes) >> Number of program headers: 0 >> Size of section headers: 64 (bytes) >> -- >> Dwarf-discuss mailing list >> Dwarf-discuss@lists.dwarfstd.org >> https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss >> >
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