Added macho package

docs/macho.md

@@ -0,0 +1,12 @@
+# Mach-O
+
+## Notes
+
+MacOS requires including the headers in the __TEXT segment.
+
+## Links
+
+- https://github.com/apple-oss-distributions/xnu/blob/main/EXTERNAL_HEADERS/mach-o/loader.h
+- https://en.wikipedia.org/wiki/Mach-O
+- https://github.com/aidansteele/osx-abi-macho-file-format-reference
+- https://stackoverflow.com/questions/39863112/what-is-required-for-a-mach-o-executable-to-load

src/linker/WriteFile.go

@@ -8,6 +8,7 @@ import (
 	"git.urbach.dev/cli/q/src/core"
 	"git.urbach.dev/cli/q/src/data"
 	"git.urbach.dev/cli/q/src/elf"
+	"git.urbach.dev/cli/q/src/macho"
 )
 
 // WriteFile writes an executable file to disk.
@@ -37,6 +38,8 @@ func WriteFile(executable string, b *build.Build, env *core.Environment) error {
 	switch b.OS {
 	case build.Linux:
 		elf.Write(file, b, code, data)
+	case build.Mac:
+		macho.Write(file, b, code, data)
 	}
 
 	err = file.Close()

src/macho/Arch.go

@@ -0,0 +1,15 @@
+package macho
+
+import "git.urbach.dev/cli/q/src/build"
+
+// Arch returns the CPU architecture used in the Mach-O header.
+func Arch(arch build.Arch) (CPU, uint32) {
+	switch arch {
+	case build.ARM:
+		return CPU_ARM_64, CPU_SUBTYPE_ARM64_ALL | 0x80000000
+	case build.X86:
+		return CPU_X86_64, CPU_SUBTYPE_X86_64_ALL | 0x80000000
+	default:
+		return 0, 0
+	}
+}

src/macho/CPU.go

@@ -0,0 +1,15 @@
+package macho
+
+type CPU uint32
+
+const (
+	CPU_X86    CPU = 7
+	CPU_X86_64 CPU = CPU_X86 | 0x01000000
+	CPU_ARM    CPU = 12
+	CPU_ARM_64 CPU = CPU_ARM | 0x01000000
+)
+
+const (
+	CPU_SUBTYPE_ARM64_ALL  = 0
+	CPU_SUBTYPE_X86_64_ALL = 3
+)

src/macho/Constants.go

@@ -0,0 +1,7 @@
+package macho
+
+const (
+	BaseAddress  = 0x1000000
+	SizeCommands = Segment64Size*3 + ThreadSize
+	HeaderEnd    = HeaderSize + SizeCommands
+)

src/macho/Header.go

@@ -0,0 +1,15 @@
+package macho
+
+const HeaderSize = 32
+
+// Header contains general information.
+type Header struct {
+	Magic             uint32
+	Architecture      CPU
+	MicroArchitecture uint32
+	Type              HeaderType
+	NumCommands       uint32
+	SizeCommands      uint32
+	Flags             HeaderFlags
+	Reserved          uint32
+}

src/macho/HeaderFlags.go

@@ -0,0 +1,32 @@
+package macho
+
+type HeaderFlags uint32
+
+const (
+	FlagNoUndefs              HeaderFlags = 0x1
+	FlagIncrLink              HeaderFlags = 0x2
+	FlagDyldLink              HeaderFlags = 0x4
+	FlagBindAtLoad            HeaderFlags = 0x8
+	FlagPrebound              HeaderFlags = 0x10
+	FlagSplitSegs             HeaderFlags = 0x20
+	FlagLazyInit              HeaderFlags = 0x40
+	FlagTwoLevel              HeaderFlags = 0x80
+	FlagForceFlat             HeaderFlags = 0x100
+	FlagNoMultiDefs           HeaderFlags = 0x200
+	FlagNoFixPrebinding       HeaderFlags = 0x400
+	FlagPrebindable           HeaderFlags = 0x800
+	FlagAllModsBound          HeaderFlags = 0x1000
+	FlagSubsectionsViaSymbols HeaderFlags = 0x2000
+	FlagCanonical             HeaderFlags = 0x4000
+	FlagWeakDefines           HeaderFlags = 0x8000
+	FlagBindsToWeak           HeaderFlags = 0x10000
+	FlagAllowStackExecution   HeaderFlags = 0x20000
+	FlagRootSafe              HeaderFlags = 0x40000
+	FlagSetuidSafe            HeaderFlags = 0x80000
+	FlagNoReexportedDylibs    HeaderFlags = 0x100000
+	FlagPIE                   HeaderFlags = 0x200000
+	FlagDeadStrippableDylib   HeaderFlags = 0x400000
+	FlagHasTLVDescriptors     HeaderFlags = 0x800000
+	FlagNoHeapExecution       HeaderFlags = 0x1000000
+	FlagAppExtensionSafe      HeaderFlags = 0x2000000
+)

src/macho/HeaderType.go

@@ -0,0 +1,12 @@
+package macho
+
+type HeaderType uint32
+
+const (
+	TypeObject  HeaderType = 0x1
+	TypeExecute HeaderType = 0x2
+	TypeCore    HeaderType = 0x4
+	TypeDylib   HeaderType = 0x6
+	TypeBundle  HeaderType = 0x8
+	TypeDsym    HeaderType = 0xA
+)

src/macho/LoadCommand.go

@@ -0,0 +1,34 @@
+package macho
+
+type LoadCommand uint32
+
+const (
+	LcSegment            LoadCommand = 0x1
+	LcSymtab             LoadCommand = 0x2
+	LcThread             LoadCommand = 0x4
+	LcUnixthread         LoadCommand = 0x5
+	LcDysymtab           LoadCommand = 0xB
+	LcDylib              LoadCommand = 0xC
+	LcIdDylib            LoadCommand = 0xD
+	LcLoadDylinker       LoadCommand = 0xE
+	LcIdDylinker         LoadCommand = 0xF
+	LcSegment64          LoadCommand = 0x19
+	LcUuid               LoadCommand = 0x1B
+	LcCodeSignature      LoadCommand = 0x1D
+	LcSegmentSplitInfo   LoadCommand = 0x1E
+	LcRpath              LoadCommand = 0x8000001C
+	LcEncryptionInfo     LoadCommand = 0x21
+	LcDyldInfo           LoadCommand = 0x22
+	LcDyldInfoOnly       LoadCommand = 0x80000022
+	LcVersionMinMacosx   LoadCommand = 0x24
+	LcVersionMinIphoneos LoadCommand = 0x25
+	LcFunctionStarts     LoadCommand = 0x26
+	LcDyldEnvironment    LoadCommand = 0x27
+	LcMain               LoadCommand = 0x80000028
+	LcDataInCode         LoadCommand = 0x29
+	LcSourceVersion      LoadCommand = 0x2A
+	LcDylibCodeSignDrs   LoadCommand = 0x2B
+	LcEncryptionInfo64   LoadCommand = 0x2C
+	LcVersionMinTvos     LoadCommand = 0x2F
+	LcVersionMinWatchos  LoadCommand = 0x30
+)

src/macho/MachO.go

@@ -0,0 +1,119 @@
+package macho
+
+import (
+	"encoding/binary"
+	"io"
+
+	"git.urbach.dev/cli/q/src/build"
+	"git.urbach.dev/cli/q/src/exe"
+)
+
+// MachO is the executable format used on MacOS.
+type MachO struct {
+	Header
+	PageZero   Segment64
+	CodeHeader Segment64
+	DataHeader Segment64
+	UnixThread Thread
+}
+
+// Write writes the Mach-O format to the given writer.
+func Write(writer io.WriteSeeker, b *build.Build, codeBytes []byte, dataBytes []byte) {
+	x := exe.New(HeaderEnd, b.FileAlign, b.MemoryAlign)
+	x.InitSections(codeBytes, dataBytes)
+	code := x.Sections[0]
+	data := x.Sections[1]
+	arch, microArch := Arch(b.Arch)
+	entryPoint := BaseAddress + code.MemoryOffset
+
+	m := &MachO{
+		Header: Header{
+			Magic:             0xFEEDFACF,
+			Architecture:      arch,
+			MicroArchitecture: microArch,
+			Type:              TypeExecute,
+			NumCommands:       4,
+			SizeCommands:      SizeCommands,
+			Flags:             FlagNoUndefs | FlagPIE | FlagNoHeapExecution,
+			Reserved:          0,
+		},
+		PageZero: Segment64{
+			LoadCommand:  LcSegment64,
+			Length:       72,
+			Name:         [16]byte{'_', '_', 'P', 'A', 'G', 'E', 'Z', 'E', 'R', 'O'},
+			Address:      0,
+			SizeInMemory: uint64(BaseAddress),
+			Offset:       0,
+			SizeInFile:   0,
+			NumSections:  0,
+			Flag:         0,
+			MaxProt:      0,
+			InitProt:     0,
+		},
+		CodeHeader: Segment64{
+			LoadCommand:  LcSegment64,
+			Length:       Segment64Size,
+			Name:         [16]byte{'_', '_', 'T', 'E', 'X', 'T'},
+			Address:      uint64(BaseAddress),
+			SizeInMemory: uint64(code.MemoryOffset + len(code.Bytes)),
+			Offset:       0,
+			SizeInFile:   uint64(code.FileOffset + len(code.Bytes)),
+			NumSections:  0,
+			Flag:         0,
+			MaxProt:      ProtReadable | ProtExecutable,
+			InitProt:     ProtReadable | ProtExecutable,
+		},
+		DataHeader: Segment64{
+			LoadCommand:  LcSegment64,
+			Length:       Segment64Size,
+			Name:         [16]byte{'_', '_', 'D', 'A', 'T', 'A'},
+			Address:      uint64(BaseAddress + data.MemoryOffset),
+			SizeInMemory: uint64(len(data.Bytes)),
+			Offset:       uint64(data.FileOffset),
+			SizeInFile:   uint64(len(data.Bytes)),
+			NumSections:  0,
+			Flag:         0,
+			MaxProt:      ProtReadable,
+			InitProt:     ProtReadable,
+		},
+		UnixThread: Thread{
+			LoadCommand: LcUnixthread,
+			Len:         ThreadSize,
+			Type:        0x4,
+			Data: [43]uint32{
+				42,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				uint32(entryPoint), 0,
+				0, 0,
+				0, 0,
+				0, 0,
+				0, 0,
+			},
+		},
+	}
+
+	binary.Write(writer, binary.LittleEndian, &m.Header)
+	binary.Write(writer, binary.LittleEndian, &m.PageZero)
+	binary.Write(writer, binary.LittleEndian, &m.CodeHeader)
+	binary.Write(writer, binary.LittleEndian, &m.DataHeader)
+	binary.Write(writer, binary.LittleEndian, &m.UnixThread)
+	writer.Seek(int64(code.Padding), io.SeekCurrent)
+	writer.Write(code.Bytes)
+	writer.Seek(int64(data.Padding), io.SeekCurrent)
+	writer.Write(data.Bytes)
+}

src/macho/MachO_test.go

@@ -0,0 +1,15 @@
+package macho_test
+
+import (
+	"testing"
+
+	"git.urbach.dev/cli/q/src/build"
+	"git.urbach.dev/cli/q/src/exe"
+	"git.urbach.dev/cli/q/src/macho"
+)
+
+func TestWrite(t *testing.T) {
+	macho.Write(&exe.Discard{}, &build.Build{Arch: build.ARM, FileAlign: 0x4000, MemoryAlign: 0x4000}, nil, nil)
+	macho.Write(&exe.Discard{}, &build.Build{Arch: build.X86, FileAlign: 0x1000, MemoryAlign: 0x1000}, nil, nil)
+	macho.Write(&exe.Discard{}, &build.Build{Arch: build.UnknownArch, FileAlign: 0x1000, MemoryAlign: 0x1000}, nil, nil)
+}

src/macho/Prot.go

@@ -0,0 +1,9 @@
+package macho
+
+type Prot uint32
+
+const (
+	ProtReadable   Prot = 0x1
+	ProtWritable   Prot = 0x2
+	ProtExecutable Prot = 0x4
+)

src/macho/Segment64.go

@@ -0,0 +1,18 @@
+package macho
+
+const Segment64Size = 72
+
+// Segment64 is a segment load command.
+type Segment64 struct {
+	LoadCommand
+	Length       uint32
+	Name         [16]byte
+	Address      uint64
+	SizeInMemory uint64
+	Offset       uint64
+	SizeInFile   uint64
+	MaxProt      Prot
+	InitProt     Prot
+	NumSections  uint32
+	Flag         uint32
+}

src/macho/Thread.go

@@ -0,0 +1,11 @@
+package macho
+
+const ThreadSize = 184
+
+// Thread is a thread state load command.
+type Thread struct {
+	LoadCommand
+	Len  uint32
+	Type uint32
+	Data [43]uint32
+}