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macho: dynamically calculate code signature padding

master
Jakub Konka 2020-12-01 18:02:12 +01:00
parent abb697e751
commit ed18046518
2 changed files with 11 additions and 3 deletions
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6
src/link/MachO.zig
View File

@ -733,7 +733,8 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
// Pad out space for code signature
const text_cmd = parser.load_commands.items[parser.text_cmd_index.?].Segment.inner;
const dataoff = @intCast(u32, mem.alignForward(parser.end_pos.?, @sizeOf(u64)));
const datasize = 0x400000;
const emit = self.base.options.emit.?;
const datasize = CodeSignature.calcCodeSignaturePadding(emit.sub_path, dataoff);
const code_sig = macho.linkedit_data_command{
.cmd = macho.LC_CODE_SIGNATURE,
.cmdsize = @sizeOf(macho.linkedit_data_command),
@ -772,7 +773,6 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
// Generate adhoc code signature
var signature = CodeSignature.init(self.base.allocator);
defer signature.deinit();
const emit = self.base.options.emit.?;
try signature.calcAdhocSignature(
out_file,
emit.sub_path,
@ -1723,7 +1723,7 @@ fn writeSymbolTable(self: *MachO) !void {
fn writeCodeSignaturePadding(self: *MachO) !void {
const code_sig_cmd = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
const fileoff = self.linkedit_segment_next_offset.?;
const datasize: u32 = 0x1000; // TODO Calculate the expected size of the signature.
const datasize = CodeSignature.calcCodeSignaturePadding(self.base.options.emit.?.sub_path, fileoff);
code_sig_cmd.dataoff = fileoff;
code_sig_cmd.datasize = datasize;

8
src/link/MachO/CodeSignature.zig
View File

@ -179,3 +179,11 @@ test "CodeSignature header" {
const expected = &[_]u8{ 0xfa, 0xde, 0x0c, 0xc0, 0x0, 0x0, 0x0, 0xc, 0x0, 0x0, 0x0, 0x0 };
testing.expect(mem.eql(u8, expected[0..], buffer[0..]));
}
pub fn calcCodeSignaturePadding(id: []const u8, file_size: u64) u32 {
const ident_size = id.len + 1;
const total_pages = mem.alignForwardGeneric(u64, file_size, page_size) / page_size;
const hashed_size = total_pages * hash_size;
const codesig_header = @sizeOf(macho.SuperBlob) + @sizeOf(macho.BlobIndex) + @sizeOf(macho.CodeDirectory);
return @intCast(u32, mem.alignForwardGeneric(u64, codesig_header + ident_size + hashed_size, @sizeOf(u64)));
}