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macho: remove now obsolete LLD fixups
This commit is contained in:
Jakub Konka
Jakub Konka
parent
7516dfff83
commit
861ea64009
@ -947,119 +947,6 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
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log.warn("unexpected LLD stderr:\n{s}", .{stderr});
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}
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}
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// At this stage, LLD has done its job. It is time to patch the resultant
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// binaries up!
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const out_file = try directory.handle.openFile(self.base.options.emit.?.sub_path, .{ .write = true });
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try self.parseFromFile(out_file);
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if (self.libsystem_cmd_index == null and self.header.?.filetype == macho.MH_EXECUTE) {
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const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
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const text_section = text_segment.sections.items[self.text_section_index.?];
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const after_last_cmd_offset = self.header.?.sizeofcmds + @sizeOf(macho.mach_header_64);
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const needed_size = padToIdeal(@sizeOf(macho.linkedit_data_command));
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if (needed_size + after_last_cmd_offset > text_section.offset) {
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log.err("Unable to extend padding between the end of load commands and start of __text section.", .{});
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log.err("Re-run the linker with '-headerpad 0x{x}' option if available, or", .{needed_size});
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log.err("fall back to the system linker by exporting 'ZIG_SYSTEM_LINKER_HACK=1'.", .{});
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return error.NotEnoughPadding;
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}
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// Calculate next available dylib ordinal.
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const next_ordinal = blk: {
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var ordinal: u32 = 1;
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for (self.load_commands.items) |cmd| {
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switch (cmd) {
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.Dylib => ordinal += 1,
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else => {},
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}
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}
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break :blk ordinal;
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};
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// Add load dylib load command
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self.libsystem_cmd_index = @intCast(u16, self.load_commands.items.len);
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const cmdsize = @intCast(u32, mem.alignForwardGeneric(
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u64,
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@sizeOf(macho.dylib_command) + mem.lenZ(LIB_SYSTEM_PATH),
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@sizeOf(u64),
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));
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// TODO Find a way to work out runtime version from the OS version triple stored in std.Target.
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// In the meantime, we're gonna hardcode to the minimum compatibility version of 0.0.0.
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const min_version = 0x0;
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var dylib_cmd = emptyGenericCommandWithData(macho.dylib_command{
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.cmd = macho.LC_LOAD_DYLIB,
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.cmdsize = cmdsize,
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.dylib = .{
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.name = @sizeOf(macho.dylib_command),
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.timestamp = 2, // not sure why not simply 0; this is reverse engineered from Mach-O files
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.current_version = min_version,
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.compatibility_version = min_version,
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},
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});
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dylib_cmd.data = try self.base.allocator.alloc(u8, cmdsize - dylib_cmd.inner.dylib.name);
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mem.set(u8, dylib_cmd.data, 0);
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mem.copy(u8, dylib_cmd.data, mem.spanZ(LIB_SYSTEM_PATH));
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try self.load_commands.append(self.base.allocator, .{ .Dylib = dylib_cmd });
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self.header_dirty = true;
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self.load_commands_dirty = true;
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if (self.symtab_cmd_index == null or self.dysymtab_cmd_index == null) {
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log.err("Incomplete Mach-O binary: no LC_SYMTAB or LC_DYSYMTAB load command found!", .{});
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log.err("Without the symbol table, it is not possible to patch up the binary for cross-compilation.", .{});
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return error.NoSymbolTableFound;
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}
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// Patch dyld info
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try self.fixupBindInfo(next_ordinal);
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try self.fixupLazyBindInfo(next_ordinal);
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// Write updated load commands and the header
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try self.writeLoadCommands();
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try self.writeHeader();
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assert(!self.header_dirty);
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assert(!self.load_commands_dirty);
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}
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if (self.code_signature_cmd_index == null) outer: {
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if (target.cpu.arch != .aarch64) break :outer; // This is currently needed only for aarch64 targets.
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const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
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const text_section = text_segment.sections.items[self.text_section_index.?];
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const after_last_cmd_offset = self.header.?.sizeofcmds + @sizeOf(macho.mach_header_64);
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const needed_size = padToIdeal(@sizeOf(macho.linkedit_data_command));
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if (needed_size + after_last_cmd_offset > text_section.offset) {
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log.err("Unable to extend padding between the end of load commands and start of __text section.", .{});
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log.err("Re-run the linker with '-headerpad 0x{x}' option if available, or", .{needed_size});
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log.err("fall back to the system linker by exporting 'ZIG_SYSTEM_LINKER_HACK=1'.", .{});
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return error.NotEnoughPadding;
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}
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// Add code signature load command
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self.code_signature_cmd_index = @intCast(u16, self.load_commands.items.len);
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try self.load_commands.append(self.base.allocator, .{
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.LinkeditData = .{
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.cmd = macho.LC_CODE_SIGNATURE,
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.cmdsize = @sizeOf(macho.linkedit_data_command),
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.dataoff = 0,
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.datasize = 0,
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},
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});
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self.header_dirty = true;
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self.load_commands_dirty = true;
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// Pad out space for code signature
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try self.writeCodeSignaturePadding();
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// Write updated load commands and the header
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try self.writeLoadCommands();
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try self.writeHeader();
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// Generate adhoc code signature
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try self.writeCodeSignature();
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assert(!self.header_dirty);
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assert(!self.load_commands_dirty);
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}
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}
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}
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@ -3375,177 +3262,6 @@ fn writeHeader(self: *MachO) !void {
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self.header_dirty = false;
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}
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/// Parse MachO contents from existing binary file.
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fn parseFromFile(self: *MachO, file: fs.File) !void {
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self.base.file = file;
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var reader = file.reader();
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const header = try reader.readStruct(macho.mach_header_64);
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try self.load_commands.ensureCapacity(self.base.allocator, header.ncmds);
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var i: u16 = 0;
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while (i < header.ncmds) : (i += 1) {
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const cmd = try LoadCommand.read(self.base.allocator, reader);
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switch (cmd.cmd()) {
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macho.LC_SEGMENT_64 => {
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const x = cmd.Segment;
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if (parseAndCmpName(&x.inner.segname, "__PAGEZERO")) {
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self.pagezero_segment_cmd_index = i;
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} else if (parseAndCmpName(&x.inner.segname, "__LINKEDIT")) {
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self.linkedit_segment_cmd_index = i;
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} else if (parseAndCmpName(&x.inner.segname, "__TEXT")) {
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self.text_segment_cmd_index = i;
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for (x.sections.items) |sect, j| {
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if (parseAndCmpName(§.sectname, "__text")) {
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self.text_section_index = @intCast(u16, j);
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}
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}
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} else if (parseAndCmpName(&x.inner.segname, "__DATA")) {
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self.data_segment_cmd_index = i;
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} else if (parseAndCmpName(&x.inner.segname, "__DATA_CONST")) {
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self.data_const_segment_cmd_index = i;
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}
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},
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macho.LC_DYLD_INFO_ONLY => {
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self.dyld_info_cmd_index = i;
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},
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macho.LC_SYMTAB => {
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self.symtab_cmd_index = i;
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},
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macho.LC_DYSYMTAB => {
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self.dysymtab_cmd_index = i;
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},
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macho.LC_LOAD_DYLINKER => {
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self.dylinker_cmd_index = i;
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},
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macho.LC_VERSION_MIN_MACOSX, macho.LC_VERSION_MIN_IPHONEOS, macho.LC_VERSION_MIN_WATCHOS, macho.LC_VERSION_MIN_TVOS => {
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self.version_min_cmd_index = i;
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},
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macho.LC_SOURCE_VERSION => {
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self.source_version_cmd_index = i;
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},
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macho.LC_UUID => {
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self.uuid_cmd_index = i;
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},
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macho.LC_MAIN => {
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self.main_cmd_index = i;
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},
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macho.LC_LOAD_DYLIB => {
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const x = cmd.Dylib;
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if (parseAndCmpName(x.data, mem.spanZ(LIB_SYSTEM_PATH))) {
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self.libsystem_cmd_index = i;
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}
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},
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macho.LC_FUNCTION_STARTS => {
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self.function_starts_cmd_index = i;
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},
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macho.LC_DATA_IN_CODE => {
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self.data_in_code_cmd_index = i;
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},
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macho.LC_CODE_SIGNATURE => {
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self.code_signature_cmd_index = i;
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},
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else => {
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log.warn("Unknown load command detected: 0x{x}.", .{cmd.cmd()});
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},
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}
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self.load_commands.appendAssumeCapacity(cmd);
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}
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self.header = header;
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}
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fn parseAndCmpName(name: []const u8, needle: []const u8) bool {
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const len = mem.indexOfScalar(u8, name, @as(u8, 0)) orelse name.len;
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return mem.eql(u8, name[0..len], needle);
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}
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fn parseSymbolTable(self: *MachO) !void {
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const symtab = self.load_commands.items[self.symtab_cmd_index.?].Symtab;
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const dysymtab = self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
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var buffer = try self.base.allocator.alloc(macho.nlist_64, symtab.nsyms);
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defer self.base.allocator.free(buffer);
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const nread = try self.base.file.?.preadAll(@ptrCast([*]u8, buffer)[0 .. symtab.nsyms * @sizeOf(macho.nlist_64)], symtab.symoff);
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assert(@divExact(nread, @sizeOf(macho.nlist_64)) == buffer.len);
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try self.locals.ensureCapacity(self.base.allocator, dysymtab.nlocalsym);
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try self.globals.ensureCapacity(self.base.allocator, dysymtab.nextdefsym);
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try self.undef_symbols.ensureCapacity(self.base.allocator, dysymtab.nundefsym);
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self.locals.appendSliceAssumeCapacity(buffer[dysymtab.ilocalsym .. dysymtab.ilocalsym + dysymtab.nlocalsym]);
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self.globals.appendSliceAssumeCapacity(buffer[dysymtab.iextdefsym .. dysymtab.iextdefsym + dysymtab.nextdefsym]);
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self.undef_symbols.appendSliceAssumeCapacity(buffer[dysymtab.iundefsym .. dysymtab.iundefsym + dysymtab.nundefsym]);
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}
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fn parseStringTable(self: *MachO) !void {
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const symtab = self.load_commands.items[self.symtab_cmd_index.?].Symtab;
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var buffer = try self.base.allocator.alloc(u8, symtab.strsize);
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defer self.base.allocator.free(buffer);
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const nread = try self.base.file.?.preadAll(buffer, symtab.stroff);
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assert(nread == buffer.len);
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try self.string_table.ensureCapacity(self.base.allocator, symtab.strsize);
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self.string_table.appendSliceAssumeCapacity(buffer);
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}
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fn fixupBindInfo(self: *MachO, dylib_ordinal: u32) !void {
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const dyld_info = self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfoOnly;
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var buffer = try self.base.allocator.alloc(u8, dyld_info.bind_size);
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defer self.base.allocator.free(buffer);
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const nread = try self.base.file.?.preadAll(buffer, dyld_info.bind_off);
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assert(nread == buffer.len);
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try self.fixupInfoCommon(buffer, dylib_ordinal);
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try self.base.file.?.pwriteAll(buffer, dyld_info.bind_off);
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}
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fn fixupLazyBindInfo(self: *MachO, dylib_ordinal: u32) !void {
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const dyld_info = self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfoOnly;
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var buffer = try self.base.allocator.alloc(u8, dyld_info.lazy_bind_size);
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defer self.base.allocator.free(buffer);
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const nread = try self.base.file.?.preadAll(buffer, dyld_info.lazy_bind_off);
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assert(nread == buffer.len);
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try self.fixupInfoCommon(buffer, dylib_ordinal);
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try self.base.file.?.pwriteAll(buffer, dyld_info.lazy_bind_off);
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}
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fn fixupInfoCommon(self: *MachO, buffer: []u8, dylib_ordinal: u32) !void {
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var stream = std.io.fixedBufferStream(buffer);
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var reader = stream.reader();
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while (true) {
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const inst = reader.readByte() catch |err| switch (err) {
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error.EndOfStream => break,
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else => return err,
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};
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const imm: u8 = inst & macho.BIND_IMMEDIATE_MASK;
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const opcode: u8 = inst & macho.BIND_OPCODE_MASK;
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switch (opcode) {
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macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM => {
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var next = try reader.readByte();
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while (next != @as(u8, 0)) {
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next = try reader.readByte();
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}
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},
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macho.BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB => {
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_ = try std.leb.readULEB128(u64, reader);
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},
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macho.BIND_OPCODE_SET_DYLIB_SPECIAL_IMM, macho.BIND_OPCODE_SET_DYLIB_ORDINAL_IMM => {
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// Perform the fixup.
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try stream.seekBy(-1);
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var writer = stream.writer();
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try writer.writeByte(macho.BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | @truncate(u4, dylib_ordinal));
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},
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macho.BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB => {
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_ = try std.leb.readULEB128(u64, reader);
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},
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macho.BIND_OPCODE_SET_ADDEND_SLEB => {
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_ = try std.leb.readILEB128(i64, reader);
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},
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else => {},
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}
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}
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}
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pub fn padToIdeal(actual_size: anytype) @TypeOf(actual_size) {
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// TODO https://github.com/ziglang/zig/issues/1284
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return std.math.add(@TypeOf(actual_size), actual_size, actual_size / ideal_factor) catch
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