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🌱 A minimal programming language and compiler. git.urbach.dev/cli/q
high-performance programming-language compiler
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import ( "bytes" "encoding/binary" "io"
"git.urbach.dev/cli/q/src/config" "git.urbach.dev/cli/q/src/dll" "git.urbach.dev/cli/q/src/exe")
// MachO is the executable format used on MacOS.type MachO struct { *exe.Executable Header PageZero Segment64 CodeSegment Segment64 CodeSection Section64 DataSegment Segment64 LinkedSegment Segment64 Uuid Uuid Main Main BuildVersion BuildVersion Linker DylinkerCommand Libs []Dylib ChainedFixups LinkEditDataCommand CodeSignature LinkEditDataCommand}
// Write writes the Mach-O format to the given writer.func Write(writer io.WriteSeeker, build *config.Build, codeBytes []byte, dataBytes []byte, libs dll.List) { x := exe.New(HeaderEnd(libs), build.FileAlign(), build.MemoryAlign(), build.Congruent(), true) x.AddSections(codeBytes, dataBytes) code := x.Sections[0] data := x.Sections[1] linkEditBytes := createLinkEditSegment(libs, data, build.MemoryAlign()) x.AddSections(linkEditBytes) linked := x.Sections[2] rawFileSize := linked.FileOffset + len(linked.Bytes) identifier := []byte("\000") codeSignature := NewCodeSignature(rawFileSize, identifier, code) arch, microArch := Arch(build.Arch)
m := &MachO{ Executable: x, Header: Header{ Magic: 0xFEEDFACF, Architecture: arch, MicroArchitecture: microArch, Type: TypeExecute, NumCommands: uint32(NumCommands(libs)), SizeCommands: uint32(SizeCommands(libs)), Flags: FlagNoUndefs | FlagDyldLink | FlagTwoLevel | FlagPIE | FlagNoHeapExecution, }, 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, }, CodeSegment: Segment64{ LoadCommand: LcSegment64, Length: Segment64Size + Section64Size, 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: 1, Flag: 0, MaxProt: ProtReadable | ProtExecutable, InitProt: ProtReadable | ProtExecutable, }, CodeSection: Section64{ SectionName: [16]byte{'_', '_', 't', 'e', 'x', 't'}, SegmentName: [16]byte{'_', '_', 'T', 'E', 'X', 'T'}, Address: uint64(BaseAddress + code.MemoryOffset), Size: uint64(len(code.Bytes)), Offset: uint32(code.FileOffset), Align: 6, Flags: SectionPureInstructions, }, DataSegment: 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 | ProtWritable, InitProt: ProtReadable | ProtWritable, }, LinkedSegment: Segment64{ LoadCommand: LcSegment64, Length: Segment64Size, Name: [16]byte{'_', '_', 'L', 'I', 'N', 'K', 'E', 'D', 'I', 'T'}, Address: uint64(BaseAddress + linked.MemoryOffset), SizeInMemory: uint64(len(linked.Bytes) + int(codeSignature.size())), Offset: uint64(linked.FileOffset), SizeInFile: uint64(len(linked.Bytes) + int(codeSignature.size())), NumSections: 0, Flag: SegmentReadOnly, MaxProt: ProtReadable, InitProt: ProtReadable, }, Uuid: Uuid{ LoadCommand: LcUuid, Length: UuidSize, Bytes: [16]byte{}, }, Main: Main{ LoadCommand: LcMain, Length: MainSize, EntryFileOffset: uint64(code.MemoryOffset), StackSize: 0, }, BuildVersion: BuildVersion{ LoadCommand: LcBuildVersion, Length: BuildVersionSize, Platform: PlatformMacOS, MinOS: Version(12, 0, 0), Sdk: Version(12, 0, 0), NumTools: 0, }, Linker: DylinkerCommand{ LoadCommand: LcLoadDylinker, Length: uint32(DylinkerCommandSize + len(LinkerString)), Name: DylinkerCommandSize, }, ChainedFixups: LinkEditDataCommand{ LoadCommand: LcDyldChainedFixups, Length: LinkEditDataCommandSize, DataOffset: uint32(linked.FileOffset), DataSize: uint32(len(linked.Bytes)), }, CodeSignature: LinkEditDataCommand{ LoadCommand: LcCodeSignature, Length: LinkEditDataCommandSize, DataOffset: uint32(linked.FileOffset + len(linked.Bytes)), DataSize: codeSignature.size(), }, }
for lib := range libs.All() { libName := resolveLibName(lib.Name) paddedName := exe.PadSlice([]byte(libName), 8)
m.Libs = append(m.Libs, Dylib{ DylibCommand: DylibCommand{ LoadCommand: LcLoadDylib, Length: uint32(DylibCommandSize + len(paddedName)), Name: DylibCommandSize, }, Name: paddedName, }) }
buffer := bytes.Buffer{} m.WriteRaw(&buffer, false) contents := buffer.Bytes() m.WriteRaw(writer, true) codeSignature.write(writer, contents, identifier)}
// WriteRaw writes the raw file contents without the code signature.func (m *MachO) WriteRaw(writer io.Writer, seek bool) { binary.Write(writer, binary.LittleEndian, &m.Header) binary.Write(writer, binary.LittleEndian, &m.PageZero) binary.Write(writer, binary.LittleEndian, &m.CodeSegment) binary.Write(writer, binary.LittleEndian, &m.CodeSection) binary.Write(writer, binary.LittleEndian, &m.DataSegment) binary.Write(writer, binary.LittleEndian, &m.LinkedSegment) binary.Write(writer, binary.LittleEndian, &m.Uuid) binary.Write(writer, binary.LittleEndian, &m.Main) binary.Write(writer, binary.LittleEndian, &m.BuildVersion) binary.Write(writer, binary.LittleEndian, &m.Linker) writer.Write([]byte(LinkerString))
for _, lib := range m.Libs { binary.Write(writer, binary.LittleEndian, &lib.DylibCommand) writer.Write(lib.Name) }
binary.Write(writer, binary.LittleEndian, &m.ChainedFixups) binary.Write(writer, binary.LittleEndian, &m.CodeSignature)
for _, section := range m.Executable.Sections { if seek { writer.(io.WriteSeeker).Seek(int64(section.Padding), io.SeekCurrent) } else { writer.Write(bytes.Repeat([]byte{0}, section.Padding)) }
writer.Write(section.Bytes) }}