parseInfoStream

pub fn parseInfoStream(self: *Pdb) !void {
    var stream = self.getStream(pdb.StreamType.pdb) orelse return error.InvalidDebugInfo;
    const reader = &stream.interface;

    // Parse the InfoStreamHeader.
    const version = try reader.takeInt(u32, .little);
    const signature = try reader.takeInt(u32, .little);
    _ = signature;
    const age = try reader.takeInt(u32, .little);
    const guid = try reader.takeArray(16);

    if (version != 20000404) // VC70, only value observed by LLVM team
        return error.UnknownPDBVersion;

    self.guid = guid.*;
    self.age = age;

    const gpa = self.allocator;

    // Find the string table.
    const string_table_index = str_tab_index: {
        const name_bytes_len = try reader.takeInt(u32, .little);
        const name_bytes = try reader.readAlloc(gpa, name_bytes_len);
        defer gpa.free(name_bytes);

        const HashTableHeader = extern struct {
            size: u32,
            capacity: u32,

            fn maxLoad(cap: u32) u32 {
                return cap * 2 / 3 + 1;
            }
        };
        const hash_tbl_hdr = try reader.takeStruct(HashTableHeader, .little);
        if (hash_tbl_hdr.capacity == 0)
            return error.InvalidDebugInfo;

        if (hash_tbl_hdr.size > HashTableHeader.maxLoad(hash_tbl_hdr.capacity))
            return error.InvalidDebugInfo;

        const present = try readSparseBitVector(reader, gpa);
        defer gpa.free(present);
        if (present.len != hash_tbl_hdr.size)
            return error.InvalidDebugInfo;
        const deleted = try readSparseBitVector(reader, gpa);
        defer gpa.free(deleted);

        for (present) |_| {
            const name_offset = try reader.takeInt(u32, .little);
            const name_index = try reader.takeInt(u32, .little);
            if (name_offset > name_bytes.len)
                return error.InvalidDebugInfo;
            const name = std.mem.sliceTo(name_bytes[name_offset..], 0);
            if (std.mem.eql(u8, name, "/names")) {
                break :str_tab_index name_index;
            }
        }
        return error.MissingDebugInfo;
    };

    self.string_table = self.getStreamById(string_table_index) orelse
        return error.MissingDebugInfo;
}