debug/macho: rearrange code

* group load command structs.
* use hex literal for LoadCommand.
  Decimal number is not a proper representation for some commands.
  (e.g. LC_RPATH = 0x8000001c)
* move Symbol struct from macho.go to file.go.
  Symbol is a high level representation, not in Mach-O.

Change-Id: I3c69923cb464fb1211f2e766c02e1b537e0b5de2
Reviewed-on: https://go-review.googlesource.com/56130
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: hirochachacha

src/debug/macho/file.go

@@ -143,6 +143,15 @@ type Dysymtab struct {
 	IndirectSyms []uint32 // indices into Symtab.Syms
 }
 
+// A Symbol is a Mach-O 32-bit or 64-bit symbol table entry.
+type Symbol struct {
+	Name  string
+	Type  uint8
+	Sect  uint8
+	Desc  uint16
+	Value uint64
+}
+
 /*
  * Mach-O reader
  */

src/debug/macho/macho.go

@@ -79,14 +79,14 @@ func (i Cpu) GoString() string { return stringName(uint32(i), cpuStrings, true)
 type LoadCmd uint32
 
 const (
-	LoadCmdSegment    LoadCmd = 1
-	LoadCmdSymtab     LoadCmd = 2
-	LoadCmdThread     LoadCmd = 4
-	LoadCmdUnixThread LoadCmd = 5 // thread+stack
-	LoadCmdDysymtab   LoadCmd = 11
-	LoadCmdDylib      LoadCmd = 12
-	LoadCmdDylinker   LoadCmd = 15
-	LoadCmdSegment64  LoadCmd = 25
+	LoadCmdSegment    LoadCmd = 0x1
+	LoadCmdSymtab     LoadCmd = 0x2
+	LoadCmdThread     LoadCmd = 0x4
+	LoadCmdUnixThread LoadCmd = 0x5 // thread+stack
+	LoadCmdDysymtab   LoadCmd = 0xb
+	LoadCmdDylib      LoadCmd = 0xc
+	LoadCmdDylinker   LoadCmd = 0xf
+	LoadCmdSegment64  LoadCmd = 0x19
 )
 
 var cmdStrings = []intName{
@@ -100,53 +100,97 @@ var cmdStrings = []intName{
 func (i LoadCmd) String() string   { return stringName(uint32(i), cmdStrings, false) }
 func (i LoadCmd) GoString() string { return stringName(uint32(i), cmdStrings, true) }
 
+type (
+	// A Segment32 is a 32-bit Mach-O segment load command.
+	Segment32 struct {
+		Cmd     LoadCmd
+		Len     uint32
+		Name    [16]byte
+		Addr    uint32
+		Memsz   uint32
+		Offset  uint32
+		Filesz  uint32
+		Maxprot uint32
+		Prot    uint32
+		Nsect   uint32
+		Flag    uint32
+	}
+
+	// A Segment64 is a 64-bit Mach-O segment load command.
+	Segment64 struct {
+		Cmd     LoadCmd
+		Len     uint32
+		Name    [16]byte
+		Addr    uint64
+		Memsz   uint64
+		Offset  uint64
+		Filesz  uint64
+		Maxprot uint32
+		Prot    uint32
+		Nsect   uint32
+		Flag    uint32
+	}
+
+	// A SymtabCmd is a Mach-O symbol table command.
+	SymtabCmd struct {
+		Cmd     LoadCmd
+		Len     uint32
+		Symoff  uint32
+		Nsyms   uint32
+		Stroff  uint32
+		Strsize uint32
+	}
+
+	// A DysymtabCmd is a Mach-O dynamic symbol table command.
+	DysymtabCmd struct {
+		Cmd            LoadCmd
+		Len            uint32
+		Ilocalsym      uint32
+		Nlocalsym      uint32
+		Iextdefsym     uint32
+		Nextdefsym     uint32
+		Iundefsym      uint32
+		Nundefsym      uint32
+		Tocoffset      uint32
+		Ntoc           uint32
+		Modtaboff      uint32
+		Nmodtab        uint32
+		Extrefsymoff   uint32
+		Nextrefsyms    uint32
+		Indirectsymoff uint32
+		Nindirectsyms  uint32
+		Extreloff      uint32
+		Nextrel        uint32
+		Locreloff      uint32
+		Nlocrel        uint32
+	}
+
+	// A DylibCmd is a Mach-O load dynamic library command.
+	DylibCmd struct {
+		Cmd            LoadCmd
+		Len            uint32
+		Name           uint32
+		Time           uint32
+		CurrentVersion uint32
+		CompatVersion  uint32
+	}
+
+	// A Thread is a Mach-O thread state command.
+	Thread struct {
+		Cmd  LoadCmd
+		Len  uint32
+		Type uint32
+		Data []uint32
+	}
+)
+
 const (
 	FlagNoUndefs uint32 = 0x1
 	FlagDyldLink uint32 = 0x4
 	FlagTwoLevel uint32 = 0x80
 	FlagPIE      uint32 = 0x200000
 )
 
-// A Segment64 is a 64-bit Mach-O segment load command.
-type Segment64 struct {
-	Cmd     LoadCmd
-	Len     uint32
-	Name    [16]byte
-	Addr    uint64
-	Memsz   uint64
-	Offset  uint64
-	Filesz  uint64
-	Maxprot uint32
-	Prot    uint32
-	Nsect   uint32
-	Flag    uint32
-}
-
-// A Segment32 is a 32-bit Mach-O segment load command.
-type Segment32 struct {
-	Cmd     LoadCmd
-	Len     uint32
-	Name    [16]byte
-	Addr    uint32
-	Memsz   uint32
-	Offset  uint32
-	Filesz  uint32
-	Maxprot uint32
-	Prot    uint32
-	Nsect   uint32
-	Flag    uint32
-}
-
-// A DylibCmd is a Mach-O load dynamic library command.
-type DylibCmd struct {
-	Cmd            LoadCmd
-	Len            uint32
-	Name           uint32
-	Time           uint32
-	CurrentVersion uint32
-	CompatVersion  uint32
-}
-
 // A Section32 is a 32-bit Mach-O section header.
 type Section32 struct {
 	Name     [16]byte
@@ -178,40 +222,6 @@ type Section64 struct {
 	Reserve3 uint32
 }
 
-// A SymtabCmd is a Mach-O symbol table command.
-type SymtabCmd struct {
-	Cmd     LoadCmd
-	Len     uint32
-	Symoff  uint32
-	Nsyms   uint32
-	Stroff  uint32
-	Strsize uint32
-}
-
-// A DysymtabCmd is a Mach-O dynamic symbol table command.
-type DysymtabCmd struct {
-	Cmd            LoadCmd
-	Len            uint32
-	Ilocalsym      uint32
-	Nlocalsym      uint32
-	Iextdefsym     uint32
-	Nextdefsym     uint32
-	Iundefsym      uint32
-	Nundefsym      uint32
-	Tocoffset      uint32
-	Ntoc           uint32
-	Modtaboff      uint32
-	Nmodtab        uint32
-	Extrefsymoff   uint32
-	Nextrefsyms    uint32
-	Indirectsymoff uint32
-	Nindirectsyms  uint32
-	Extreloff      uint32
-	Nextrel        uint32
-	Locreloff      uint32
-	Nlocrel        uint32
-}
-
 // An Nlist32 is a Mach-O 32-bit symbol table entry.
 type Nlist32 struct {
 	Name  uint32
@@ -230,23 +240,6 @@ type Nlist64 struct {
 	Value uint64
 }
 
-// A Symbol is a Mach-O 32-bit or 64-bit symbol table entry.
-type Symbol struct {
-	Name  string
-	Type  uint8
-	Sect  uint8
-	Desc  uint16
-	Value uint64
-}
-
-// A Thread is a Mach-O thread state command.
-type Thread struct {
-	Cmd  LoadCmd
-	Len  uint32
-	Type uint32
-	Data []uint32
-}
-
 // Regs386 is the Mach-O 386 register structure.
 type Regs386 struct {
 	AX    uint32