loadDwarfFromSections

fn loadDwarfFromSections(
    gpa: Allocator,
    mapped_macho: []const u8,
    section_headers: []align(1) const macho.section_64,
) !Dwarf {
    var sections: Dwarf.SectionArray = @splat(null);
    for (section_headers) |sect_raw| {
        var sect = sect_raw;
        if (builtin.cpu.arch.endian() != .little) std.mem.byteSwapAllFields(macho.section_64, &sect);

        if (!std.mem.eql(u8, "__DWARF", sect.segName())) continue;

        const section_index: usize = inline for (@typeInfo(Dwarf.Section.Id).@"enum".field_names, 0..) |field_name, i| {
            const section_name_long = "__" ++ field_name;
            // Some dwarf section names don't fit in the `sectname` buffer, so they are truncated.
            const section_name_trunc = section_name_long[0..@min(section_name_long.len, sect.sectname.len)];
            if (mem.eql(u8, section_name_trunc, sect.sectName())) break i;
        } else continue;

        if (mapped_macho.len < sect.offset + sect.size) return error.InvalidMachO;
        const section_bytes = mapped_macho[sect.offset..][0..sect.size];
        sections[section_index] = .{
            .data = section_bytes,
            .owned = false,
        };
    }

    if (sections[@backingInt(Dwarf.Section.Id.debug_info)] == null or
        sections[@backingInt(Dwarf.Section.Id.debug_abbrev)] == null or
        sections[@backingInt(Dwarf.Section.Id.debug_str)] == null or
        sections[@backingInt(Dwarf.Section.Id.debug_line)] == null)
    {
        return error.MissingDebugInfo;
    }

    var dwarf: Dwarf = .{ .sections = sections };
    errdefer dwarf.deinit(gpa);
    dwarf.open(gpa, .little) catch |err| switch (err) {
        error.InvalidDebugInfo,
        error.EndOfStream,
        error.Overflow,
        error.StreamTooLong,
        => return error.InvalidDwarf,

        error.MissingDebugInfo,
        error.ReadFailed,
        error.OutOfMemory,
        => |e| return e,
    };

    return dwarf;
}