Commit 43b6d0e4b1
lib/std/macho.zig
@@ -797,3 +797,16 @@ pub const CPU_SUBTYPE_X86_64_ALL: cpu_subtype_t = 0x3;
/// All ARM-based Macs
pub const CPU_SUBTYPE_ARM_ALL: cpu_subtype_t = 0x0;
+
+// Protection values defined as bits within the vm_prot_t type
+/// No VM protection
+pub const VM_PROT_NONE: vm_prot_t = 0x0;
+
+/// VM read permission
+pub const VM_PROT_READ: vm_prot_t = 0x1;
+
+/// VM write permission
+pub const VM_PROT_WRITE: vm_prot_t = 0x2;
+
+/// VM execute permission
+pub const VM_PROT_EXECUTE: vm_prot_t = 0x4;
src-self-hosted/link/MachO.zig
@@ -30,24 +30,26 @@ command_file_offset: ?u64 = null,
/// Stored in native-endian format, depending on target endianness needs to be bswapped on read/write.
/// Same order as in the file.
segments: std.ArrayListUnmanaged(macho.segment_command_64) = std.ArrayListUnmanaged(macho.segment_command_64){},
+/// Section (headers) *always* follow segment (load commands) directly!
sections: std.ArrayListUnmanaged(macho.section_64) = std.ArrayListUnmanaged(macho.section_64){},
-segment_table_offset: ?u64 = null,
+
+/// Offset (index) into __TEXT segment load command.
+text_segment_offset: ?u64 = null,
+/// Offset (index) into __LINKEDIT segment load command.
+linkedit_segment_offset: ?u664 = null,
/// Entry point load command
entry_point_cmd: ?macho.entry_point_command = null,
entry_addr: ?u64 = null,
-/// Default VM start address set at 4GB
+/// The first 4GB of process' memory is reserved for the null (__PAGEZERO) segment.
+/// This is also the start address for our binary.
vm_start_address: u64 = 0x100000000,
seg_table_dirty: bool = false,
error_flags: File.ErrorFlags = File.ErrorFlags{},
-/// TODO ultimately this will be propagated down from main() and set (in this form or another)
-/// when user links against system lib.
-link_against_system: bool = false,
-
/// `alloc_num / alloc_den` is the factor of padding when allocating.
const alloc_num = 4;
const alloc_den = 3;
@@ -138,8 +140,8 @@ fn createFile(allocator: *Allocator, file: fs.File, options: link.Options) !Mach
.vmsize = self.vm_start_address,
.fileoff = 0,
.filesize = 0,
- .maxprot = 0,
- .initprot = 0,
+ .maxprot = macho.VM_PROT_NONE,
+ .initprot = macho.VM_PROT_NONE,
.nsects = 0,
.flags = 0,
};
@@ -225,66 +227,62 @@ pub fn flush(self: *MachO, module: *Module) !void {
switch (self.base.options.output_mode) {
.Exe => {
- if (self.link_against_system) {
- if (is_darwin) {
- {
- // Specify path to dynamic linker dyld
- const cmdsize = commandSize(@intCast(u32, @sizeOf(macho.dylinker_command) + mem.lenZ(DEFAULT_DYLD_PATH)));
- const load_dylinker = [1]macho.dylinker_command{
- .{
- .cmd = macho.LC_LOAD_DYLINKER,
- .cmdsize = cmdsize,
- .name = @sizeOf(macho.dylinker_command),
- },
- };
- try self.commands.append(self.base.allocator, .{
+ if (is_darwin) {
+ {
+ // Specify path to dynamic linker dyld
+ const cmdsize = commandSize(@sizeOf(macho.dylinker_command) + mem.lenZ(DEFAULT_DYLD_PATH));
+ const load_dylinker = [1]macho.dylinker_command{
+ .{
.cmd = macho.LC_LOAD_DYLINKER,
.cmdsize = cmdsize,
- });
-
- try self.base.file.?.pwriteAll(mem.sliceAsBytes(load_dylinker[0..1]), self.command_file_offset.?);
-
- const file_offset = self.command_file_offset.? + @sizeOf(macho.dylinker_command);
- try self.addPadding(cmdsize - @sizeOf(macho.dylinker_command), file_offset);
-
- try self.base.file.?.pwriteAll(mem.spanZ(DEFAULT_DYLD_PATH), file_offset);
- self.command_file_offset.? += cmdsize;
- }
-
- {
- // Link against libSystem
- const cmdsize = commandSize(@intCast(u32, @sizeOf(macho.dylib_command) + mem.lenZ(LIB_SYSTEM_PATH)));
- // According to Apple's manual, we should obtain current libSystem version using libc call
- // NSVersionOfRunTimeLibrary.
- const version = std.c.NSVersionOfRunTimeLibrary(LIB_SYSTEM_NAME);
- const dylib = .{
- .name = @sizeOf(macho.dylib_command),
- .timestamp = 2, // not sure why not simply 0; this is reverse engineered from Mach-O files
- .current_version = version,
- .compatibility_version = 0x10000, // not sure why this either; value from reverse engineering
- };
- const load_dylib = [1]macho.dylib_command{
- .{
- .cmd = macho.LC_LOAD_DYLIB,
- .cmdsize = cmdsize,
- .dylib = dylib,
- },
- };
- try self.commands.append(self.base.allocator, .{
+ .name = @sizeOf(macho.dylinker_command),
+ },
+ };
+ try self.commands.append(self.base.allocator, .{
+ .cmd = macho.LC_LOAD_DYLINKER,
+ .cmdsize = cmdsize,
+ });
+
+ try self.base.file.?.pwriteAll(mem.sliceAsBytes(load_dylinker[0..1]), self.command_file_offset.?);
+
+ const file_offset = self.command_file_offset.? + @sizeOf(macho.dylinker_command);
+ try self.addPadding(cmdsize - @sizeOf(macho.dylinker_command), file_offset);
+
+ try self.base.file.?.pwriteAll(mem.spanZ(DEFAULT_DYLD_PATH), file_offset);
+ self.command_file_offset.? += cmdsize;
+ }
+
+ {
+ // Link against libSystem
+ const cmdsize = commandSize(@sizeOf(macho.dylib_command) + mem.lenZ(LIB_SYSTEM_PATH));
+ // According to Apple's manual, we should obtain current libSystem version using libc call
+ // NSVersionOfRunTimeLibrary.
+ const version = std.c.NSVersionOfRunTimeLibrary(LIB_SYSTEM_NAME);
+ const dylib = .{
+ .name = @sizeOf(macho.dylib_command),
+ .timestamp = 2, // not sure why not simply 0; this is reverse engineered from Mach-O files
+ .current_version = version,
+ .compatibility_version = 0x10000, // not sure why this either; value from reverse engineering
+ };
+ const load_dylib = [1]macho.dylib_command{
+ .{
.cmd = macho.LC_LOAD_DYLIB,
.cmdsize = cmdsize,
- });
+ .dylib = dylib,
+ },
+ };
+ try self.commands.append(self.base.allocator, .{
+ .cmd = macho.LC_LOAD_DYLIB,
+ .cmdsize = cmdsize,
+ });
- try self.base.file.?.pwriteAll(mem.sliceAsBytes(load_dylib[0..1]), self.command_file_offset.?);
+ try self.base.file.?.pwriteAll(mem.sliceAsBytes(load_dylib[0..1]), self.command_file_offset.?);
- const file_offset = self.command_file_offset.? + @sizeOf(macho.dylib_command);
- try self.addPadding(cmdsize - @sizeOf(macho.dylib_command), file_offset);
+ const file_offset = self.command_file_offset.? + @sizeOf(macho.dylib_command);
+ try self.addPadding(cmdsize - @sizeOf(macho.dylib_command), file_offset);
- try self.base.file.?.pwriteAll(mem.spanZ(LIB_SYSTEM_PATH), file_offset);
- self.command_file_offset.? += cmdsize;
- }
- } else {
- @panic("linking against libSystem on non-native target is unsupported");
+ try self.base.file.?.pwriteAll(mem.spanZ(LIB_SYSTEM_PATH), file_offset);
+ self.command_file_offset.? += cmdsize;
}
}
},
@@ -327,20 +325,53 @@ pub fn getDeclVAddr(self: *MachO, decl: *const Module.Decl) u64 {
@panic("TODO implement getDeclVAddr for MachO");
}
-pub fn populateMissingMetadata(self: *MachO) !void {}
+pub fn populateMissingMetadata(self: *MachO) !void {
+ if (self.text_segment_offset == null) {
+ self.text_segment_offset = @intCast(u64, self.segments.items.len);
+ const file_size = alignSize(u64, self.base.options.program_code_size_hint, 0x1000);
+ log.debug("vmsize/filesize = {}", .{file_size});
+ const file_offset = 0;
+ const vm_address = self.vm_start_address; // the end of __PAGEZERO segment in VM
+ const protection = macho.VM_PROT_READ | macho.VM_PROT_EXECUTE;
+ const cmdsize = commandSize(@sizeOf(macho.segment_command_64));
+ const text_segment = .{
+ .cmd = macho.LC_SEGMENT_64,
+ .cmdsize = cmdsize,
+ .segname = makeString("__TEXT"),
+ .vmaddr = vm_address,
+ .vmsize = file_size,
+ .fileoff = 0, // __TEXT segment *always* starts at 0 file offset
+ .filesize = 0, //file_size,
+ .maxprot = protection,
+ .initprot = protection,
+ .nsects = 0,
+ .flags = 0,
+ };
+ try self.commands.append(self.base.allocator, .{
+ .cmd = macho.LC_SEGMENT_64,
+ .cmdsize = cmdsize,
+ });
+ try self.segments.append(self.base.allocator, text_segment);
+ }
+}
fn makeString(comptime bytes: []const u8) [16]u8 {
- var buf: [16]u8 = undefined;
+ var buf = [_]u8{0} ** 16;
if (bytes.len > buf.len) @compileError("MachO segment/section name too long");
mem.copy(u8, buf[0..], bytes);
return buf;
}
-fn commandSize(min_size: u32) u32 {
- if (min_size % @sizeOf(u64) == 0) return min_size;
+fn alignSize(comptime Int: type, min_size: anytype, alignment: Int) Int {
+ const size = @intCast(Int, min_size);
+ if (size % alignment == 0) return size;
+
+ const div = size / alignment;
+ return (div + 1) * alignment;
+}
- const div = min_size / @sizeOf(u64);
- return (div + 1) * @sizeOf(u64);
+fn commandSize(min_size: anytype) u32 {
+ return alignSize(u32, min_size, @sizeOf(u64));
}
fn addPadding(self: *MachO, size: u32, file_offset: u64) !void {