src/ObjectFile.h

/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
 *
 * Copyright (c) 2005-2007 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */


#ifndef __OBJECTFILE__
#define __OBJECTFILE__

#include <stdint.h>
#include <vector>
#include <map>


//
// These classes represent the abstract Atoms and References that are the basis of the linker.
// An Atom and a Reference correspond to a Node and Edge in graph theory.
//
// A Reader is a class which parses an object file and presents it as Atoms and References.
// All linking operations are done on Atoms and References.  This makes the linker file
// format independent.
//
// A Writer takes a vector of Atoms with all References resolved and produces an executable file.
//
//


namespace ObjectFile {


struct LineInfo
{
	uint32_t	atomOffset;
	const char* fileName;
	uint32_t	lineNumber;
};


class ReaderOptions
{
public:
						ReaderOptions() : fFullyLoadArchives(false), fLoadAllObjcObjectsFromArchives(false), fFlatNamespace(false), fLinkingMainExecutable(false),
										fForFinalLinkedImage(false), fForStatic(false), fForDyld(false), fMakeTentativeDefinitionsReal(false),
										fWhyLoad(false), fRootSafe(false), fSetuidSafe(false),fDebugInfoStripping(kDebugInfoFull),
										fLogObjectFiles(false), fLogAllFiles(false),
										fTraceDylibs(false), fTraceIndirectDylibs(false), fTraceArchives(false),
										fTraceOutputFile(NULL), fVersionMin(kMinUnset) {}
	enum DebugInfoStripping { kDebugInfoNone, kDebugInfoMinimal, kDebugInfoFull };
	enum VersionMin { kMinUnset, k10_1, k10_2, k10_3, k10_4, k10_5 };

	struct AliasPair {
		const char*			realName;
		const char*			alias;
	};

	bool					fFullyLoadArchives;
	bool					fLoadAllObjcObjectsFromArchives;
	bool					fFlatNamespace;
	bool					fLinkingMainExecutable;
	bool					fForFinalLinkedImage;
	bool					fForStatic;
	bool					fForDyld;
	bool					fMakeTentativeDefinitionsReal;
	bool					fWhyLoad;
	bool					fRootSafe;
	bool					fSetuidSafe;
	DebugInfoStripping		fDebugInfoStripping;
	bool					fLogObjectFiles;
	bool					fLogAllFiles;
	bool					fTraceDylibs;
	bool					fTraceIndirectDylibs;
	bool					fTraceArchives;
	const char*				fTraceOutputFile;
	VersionMin				fVersionMin;
	std::vector<AliasPair>	fAliases;
};


class Reader
{
public:
	enum DebugInfoKind { kDebugInfoNone=0, kDebugInfoStabs=1, kDebugInfoDwarf=2, kDebugInfoStabsUUID=3 };
	struct Stab
	{
		class Atom*	atom;
		uint8_t		type;
		uint8_t		other;
		uint16_t	desc;
		uint32_t	value;
		const char* string;
	};
	enum ObjcConstraint { kObjcNone,  kObjcRetainRelease,  kObjcRetainReleaseOrGC,  kObjcGC };
	enum CpuConstraint  { kCpuAny,  kCpuG3,  kCpuG4,  kCpuG5  };

	class DylibHander
	{
	public:
		virtual				~DylibHander()	{}
		virtual Reader*		findDylib(const char* installPath, const char* fromPath) = 0;
	};


	static Reader* createReader(const char* path, const ReaderOptions& options);

	virtual const char*					getPath() = 0;
	virtual time_t						getModificationTime() = 0;
	virtual DebugInfoKind				getDebugInfoKind() = 0;
	virtual std::vector<class Atom*>&	getAtoms() = 0;
	virtual std::vector<class Atom*>*	getJustInTimeAtomsFor(const char* name) = 0;
	virtual std::vector<Stab>*			getStabs() = 0;
	virtual ObjcConstraint				getObjCConstraint()			{ return kObjcNone; }
	virtual CpuConstraint				getCpuConstraint()			{ return kCpuAny; }
	virtual bool						objcReplacementClasses()	{ return false; }

	// For relocatable object files only
	virtual bool						canScatterAtoms()			{ return true; }
	virtual void						optimize(std::vector<ObjectFile::Atom*>&, std::vector<ObjectFile::Atom*>&, uint32_t)		{ }

	// For Dynamic Libraries only
	virtual const char*					getInstallPath()			{ return NULL; }
	virtual uint32_t					getTimestamp()				{ return 0; }
	virtual uint32_t					getCurrentVersion()			{ return 0; }
	virtual uint32_t					getCompatibilityVersion()	{ return 0; }
	virtual void						processIndirectLibraries(DylibHander* handler)	{ }
	virtual void						setExplicitlyLinked()		{ }
	virtual bool						explicitlyLinked()			{ return false; }
	virtual bool						implicitlyLinked()			{ return false; }
	virtual bool						providedExportAtom()		{ return false; }
	virtual const char*					parentUmbrella()			{ return NULL; }
	virtual std::vector<const char*>*	getAllowableClients()  		{ return NULL; }


protected:
										Reader() {}
	virtual								~Reader() {}
};

class Segment
{
public:
	virtual const char*			getName() const  = 0;
	virtual bool				isContentReadable() const = 0;
	virtual bool				isContentWritable() const = 0;
	virtual bool				isContentExecutable() const = 0;

	uint64_t					getBaseAddress() const { return fBaseAddress; }
	void						setBaseAddress(uint64_t addr) { fBaseAddress = addr; }
	virtual bool				hasFixedAddress() const { return false; }

protected:
								Segment() : fBaseAddress(0) {}
	virtual						~Segment() {}
	uint64_t					fBaseAddress;
};

class Reference;

class Section
{
public:
	unsigned int	getIndex() { return fIndex; }
	uint64_t		getBaseAddress() { return fBaseAddress; }
	void			setBaseAddress(uint64_t addr) { fBaseAddress = addr; }
	void*			fOther;

protected:
					Section() : fOther(NULL), fBaseAddress(0), fIndex(0)  {}
	uint64_t		fBaseAddress;
	unsigned int	fIndex;
};


struct Alignment
{
				Alignment(int p2, int m=0) : powerOf2(p2), modulus(m) {}
	uint8_t		trailingZeros() const { return (modulus==0) ? powerOf2 : __builtin_ctz(modulus); }
	uint16_t	powerOf2;
	uint16_t	modulus;
};

//
// An atom is the fundamental unit of linking.  A C function or global variable is an atom.
// An atom has content and some attributes. The content of a function atom is the instructions
// that implement the function.  The content of a global variable atom is its initial bits.
//
// Name:
// The name of an atom is the label name generated by the compiler.  A C compiler names foo()
// as _foo.  A C++ compiler names foo() as __Z3foov.
// The name refers to the first byte of the content.  An atom cannot have multiple entry points.
// Such code is modeled as multiple atoms, each having a "follow on" reference to the next.
// A "follow on" reference is a contraint to the linker to the atoms must be laid out contiguously.
//
// Scope:
// An atom is in one of three scopes: translation-unit, linkage-unit, or global.  These correspond
// to the C visibility of static, hidden, default.
//
// DefinitionKind:
// An atom is one of five defintion kinds:
//	regular			Most atoms.
//	weak			C++ compiler makes some functions weak if there might be multiple copies
//					that the linker needs to coalesce.
//	tentative		A straggler from ancient C when the extern did not exist. "int foo;" is ambiguous.
//					It could be a prototype or it could be a definition.
//	external		This is a "proxy" atom produced by a dylib reader.  It has no content.  It exists
//					so that all References can be resolved.
//	external-weak	Same as external, but the definition in the dylib is weak.
//
// SymbolTableInclusion:
// An atom may or may not be in the symbol table in an object file.
//  in				Most atoms for functions or global data
//	not-in			Anonymous atoms such literal c-strings, or other compiler generated data
//	in-never-strip	Atom whose name the strip tool should never remove (e.g. REFERENCED_DYNAMICALLY in mach-o)
//
// Ordinal:
// When a reader is created it is given a base ordinal number.  All atoms created by the reader
// should return a contiguous range of ordinal values that start at the base ordinal.  The ordinal
// values are used by the linker to sort the atom graph when producing the output file.
//
class Atom
{
public:
	enum Scope { scopeTranslationUnit, scopeLinkageUnit, scopeGlobal };
	enum DefinitionKind { kRegularDefinition, kWeakDefinition, kTentativeDefinition, kExternalDefinition, kExternalWeakDefinition, kAbsoluteSymbol };
	enum SymbolTableInclusion { kSymbolTableNotIn, kSymbolTableIn, kSymbolTableInAndNeverStrip, kSymbolTableInAsAbsolute };

	virtual Reader*							getFile() const = 0;
	virtual bool							getTranslationUnitSource(const char** dir, const char** name) const = 0;
	virtual const char*						getName() const = 0;
	virtual const char*						getDisplayName() const = 0;
	virtual Scope							getScope() const = 0;
	virtual DefinitionKind					getDefinitionKind() const = 0;
	virtual SymbolTableInclusion			getSymbolTableInclusion() const = 0;
	virtual	bool							dontDeadStrip() const = 0;
	virtual bool							isZeroFill() const = 0;
	virtual uint64_t						getSize() const = 0;
	virtual std::vector<ObjectFile::Reference*>&  getReferences() const = 0;
	virtual bool							mustRemainInSection() const = 0;
	virtual const char*						getSectionName() const = 0;
	virtual Segment&						getSegment() const = 0;
	virtual Atom&							getFollowOnAtom() const = 0;
	virtual uint32_t						getOrdinal() const = 0;
	virtual std::vector<LineInfo>*			getLineInfo() const = 0;
	virtual Alignment						getAlignment() const = 0;
	virtual void							copyRawContent(uint8_t buffer[]) const = 0;
	virtual void							setScope(Scope) = 0;


			uint64_t						getSectionOffset() const	{ return fSectionOffset; }
			uint64_t						getAddress() const	{ return fSection->getBaseAddress() + fSectionOffset; }
			class Section*					getSection() const { return fSection; }

	virtual void							setSectionOffset(uint64_t offset) { fSectionOffset = offset; }
	virtual void							setSection(class Section* sect) { fSection = sect; }

protected:
											Atom() :  fSectionOffset(0), fSection(NULL) {}
		virtual								~Atom() {}

		uint64_t							fSectionOffset;
		class Section*						fSection;
};


//
// A Reference is a directed edge to another Atom.  When an instruction in
// the content of an Atom refers to another Atom, that is represented by a
// Reference.
//
// There are two kinds of references: direct and by-name.  With a direct Reference,
// the target is bound by the Reader that created it.  For instance a reference to a
// static would produce a direct reference.  A by-name reference requires the linker
// to find the target Atom with the required name in order to be bound.
//
// For a link to succeed all References must be bound.
//
// A Reference has an optional "from" target.  This is used when the content to fix-up
// is the difference of two Atom address.  For instance, if a pointer sized data Atom
// is to contain A - B, then the Atom would have on Reference with a target of "A" and
// a from-target of "B".
//
// A Reference also has a fix-up-offset.  This is the offset into the content of the
// Atom holding the reference where the fix-up (relocation) will be applied.
//
//
//
class Reference
{
public:
	enum TargetBinding { kUnboundByName, kBoundDirectly, kBoundByName, kDontBind };

	virtual TargetBinding	getTargetBinding() const = 0;
	virtual TargetBinding	getFromTargetBinding() const = 0;
	virtual uint8_t			getKind() const = 0;
	virtual uint64_t		getFixUpOffset() const = 0;
	virtual const char*		getTargetName() const = 0;
	virtual Atom&			getTarget() const = 0;
	virtual uint64_t		getTargetOffset() const = 0;
	virtual Atom&			getFromTarget() const = 0;
	virtual const char*		getFromTargetName() const = 0;
	virtual uint64_t		getFromTargetOffset() const = 0;

	virtual void			setTarget(Atom&, uint64_t offset) = 0;
	virtual void			setFromTarget(Atom&) = 0;
	virtual const char*		getDescription() const = 0;

protected:
							Reference() {}
	virtual					~Reference() {}
};


};	// namespace ObjectFile


#endif // __OBJECTFILE__
Commit	Line	Data
	1	/* -- mode: C++; c-basic-offset: 4; tab-width: 4 --
	2	*
	3	* Copyright (c) 2005-2007 Apple Inc. All rights reserved.
	4	*
	5	* @APPLE_LICENSE_HEADER_START@
	6	*
	7	* This file contains Original Code and/or Modifications of Original Code
	8	* as defined in and that are subject to the Apple Public Source License
	9	* Version 2.0 (the 'License'). You may not use this file except in
	10	* compliance with the License. Please obtain a copy of the License at
	11	* http://www.opensource.apple.com/apsl/ and read it before using this
	12	* file.
	13	*
	14	* The Original Code and all software distributed under the License are
	15	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	16	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	17	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	19	* Please see the License for the specific language governing rights and
	20	* limitations under the License.
	21	*
	22	* @APPLE_LICENSE_HEADER_END@
	23	*/
	24
	25
	26	#ifndef __OBJECTFILE__
	27	#define __OBJECTFILE__
	28
	29	#include <stdint.h>
	30	#include <vector>
	31	#include <map>
	32
	33
	34
	35	//
	36	// These classes represent the abstract Atoms and References that are the basis of the linker.
	37	// An Atom and a Reference correspond to a Node and Edge in graph theory.
	38	//
	39	// A Reader is a class which parses an object file and presents it as Atoms and References.
	40	// All linking operations are done on Atoms and References. This makes the linker file
	41	// format independent.
	42	//
	43	// A Writer takes a vector of Atoms with all References resolved and produces an executable file.
	44	//
	45	//
	46
	47
	48	namespace ObjectFile {
	49
	50
	51	struct LineInfo
	52	{
	53	uint32_t atomOffset;
	54	const char* fileName;
	55	uint32_t lineNumber;
	56	};
	57
	58
	59	class ReaderOptions
	60	{
	61	public:
	62	ReaderOptions() : fFullyLoadArchives(false), fLoadAllObjcObjectsFromArchives(false), fFlatNamespace(false), fLinkingMainExecutable(false),
	63	fForFinalLinkedImage(false), fForStatic(false), fForDyld(false), fMakeTentativeDefinitionsReal(false),
	64	fWhyLoad(false), fRootSafe(false), fSetuidSafe(false),fDebugInfoStripping(kDebugInfoFull),
	65	fLogObjectFiles(false), fLogAllFiles(false),
	66	fTraceDylibs(false), fTraceIndirectDylibs(false), fTraceArchives(false),
	67	fTraceOutputFile(NULL), fVersionMin(kMinUnset) {}
	68	enum DebugInfoStripping { kDebugInfoNone, kDebugInfoMinimal, kDebugInfoFull };
	69	enum VersionMin { kMinUnset, k10_1, k10_2, k10_3, k10_4, k10_5 };
	70
	71	struct AliasPair {
	72	const char* realName;
	73	const char* alias;
	74	};
	75
	76	bool fFullyLoadArchives;
	77	bool fLoadAllObjcObjectsFromArchives;
	78	bool fFlatNamespace;
	79	bool fLinkingMainExecutable;
	80	bool fForFinalLinkedImage;
	81	bool fForStatic;
	82	bool fForDyld;
	83	bool fMakeTentativeDefinitionsReal;
	84	bool fWhyLoad;
	85	bool fRootSafe;
	86	bool fSetuidSafe;
	87	DebugInfoStripping fDebugInfoStripping;
	88	bool fLogObjectFiles;
	89	bool fLogAllFiles;
	90	bool fTraceDylibs;
	91	bool fTraceIndirectDylibs;
	92	bool fTraceArchives;
	93	const char* fTraceOutputFile;
	94	VersionMin fVersionMin;
	95	std::vector<AliasPair> fAliases;
	96	};
	97
	98
	99	class Reader
	100	{
	101	public:
	102	enum DebugInfoKind { kDebugInfoNone=0, kDebugInfoStabs=1, kDebugInfoDwarf=2, kDebugInfoStabsUUID=3 };
	103	struct Stab
	104	{
	105	class Atom* atom;
	106	uint8_t type;
	107	uint8_t other;
	108	uint16_t desc;
	109	uint32_t value;
	110	const char* string;
	111	};
	112	enum ObjcConstraint { kObjcNone, kObjcRetainRelease, kObjcRetainReleaseOrGC, kObjcGC };
	113	enum CpuConstraint { kCpuAny, kCpuG3, kCpuG4, kCpuG5 };
	114
	115	class DylibHander
	116	{
	117	public:
	118	virtual ~DylibHander() {}
	119	virtual Reader* findDylib(const char* installPath, const char* fromPath) = 0;
	120	};
	121
	122
	123	static Reader* createReader(const char* path, const ReaderOptions& options);
	124
	125	virtual const char* getPath() = 0;
	126	virtual time_t getModificationTime() = 0;
	127	virtual DebugInfoKind getDebugInfoKind() = 0;
	128	virtual std::vector<class Atom*>& getAtoms() = 0;
	129	virtual std::vector<class Atom> getJustInTimeAtomsFor(const char* name) = 0;
	130	virtual std::vector<Stab>* getStabs() = 0;
	131	virtual ObjcConstraint getObjCConstraint() { return kObjcNone; }
	132	virtual CpuConstraint getCpuConstraint() { return kCpuAny; }
	133	virtual bool objcReplacementClasses() { return false; }
	134
	135	// For relocatable object files only
	136	virtual bool canScatterAtoms() { return true; }
	137	virtual void optimize(std::vector<ObjectFile::Atom>&, std::vector<ObjectFile::Atom>&, uint32_t) { }
	138
	139	// For Dynamic Libraries only
	140	virtual const char* getInstallPath() { return NULL; }
	141	virtual uint32_t getTimestamp() { return 0; }
	142	virtual uint32_t getCurrentVersion() { return 0; }
	143	virtual uint32_t getCompatibilityVersion() { return 0; }
	144	virtual void processIndirectLibraries(DylibHander* handler) { }
	145	virtual void setExplicitlyLinked() { }
	146	virtual bool explicitlyLinked() { return false; }
	147	virtual bool implicitlyLinked() { return false; }
	148	virtual bool providedExportAtom() { return false; }
	149	virtual const char* parentUmbrella() { return NULL; }
	150	virtual std::vector<const char> getAllowableClients() { return NULL; }
	151
	152
	153	protected:
	154	Reader() {}
	155	virtual ~Reader() {}
	156	};
	157
	158	class Segment
	159	{
	160	public:
	161	virtual const char* getName() const = 0;
	162	virtual bool isContentReadable() const = 0;
	163	virtual bool isContentWritable() const = 0;
	164	virtual bool isContentExecutable() const = 0;
	165
	166	uint64_t getBaseAddress() const { return fBaseAddress; }
	167	void setBaseAddress(uint64_t addr) { fBaseAddress = addr; }
	168	virtual bool hasFixedAddress() const { return false; }
	169
	170	protected:
	171	Segment() : fBaseAddress(0) {}
	172	virtual ~Segment() {}
	173	uint64_t fBaseAddress;
	174	};
	175
	176	class Reference;
	177
	178	class Section
	179	{
	180	public:
	181	unsigned int getIndex() { return fIndex; }
	182	uint64_t getBaseAddress() { return fBaseAddress; }
	183	void setBaseAddress(uint64_t addr) { fBaseAddress = addr; }
	184	void* fOther;
	185
	186	protected:
	187	Section() : fOther(NULL), fBaseAddress(0), fIndex(0) {}
	188	uint64_t fBaseAddress;
	189	unsigned int fIndex;
	190	};
	191
	192
	193	struct Alignment
	194	{
	195	Alignment(int p2, int m=0) : powerOf2(p2), modulus(m) {}
	196	uint8_t trailingZeros() const { return (modulus==0) ? powerOf2 : __builtin_ctz(modulus); }
	197	uint16_t powerOf2;
	198	uint16_t modulus;
	199	};
	200
	201	//
	202	// An atom is the fundamental unit of linking. A C function or global variable is an atom.
	203	// An atom has content and some attributes. The content of a function atom is the instructions
	204	// that implement the function. The content of a global variable atom is its initial bits.
	205	//
	206	// Name:
	207	// The name of an atom is the label name generated by the compiler. A C compiler names foo()
	208	// as _foo. A C++ compiler names foo() as __Z3foov.
	209	// The name refers to the first byte of the content. An atom cannot have multiple entry points.
	210	// Such code is modeled as multiple atoms, each having a "follow on" reference to the next.
	211	// A "follow on" reference is a contraint to the linker to the atoms must be laid out contiguously.
	212	//
	213	// Scope:
	214	// An atom is in one of three scopes: translation-unit, linkage-unit, or global. These correspond
	215	// to the C visibility of static, hidden, default.
	216	//
	217	// DefinitionKind:
	218	// An atom is one of five defintion kinds:
	219	// regular Most atoms.
	220	// weak C++ compiler makes some functions weak if there might be multiple copies
	221	// that the linker needs to coalesce.
	222	// tentative A straggler from ancient C when the extern did not exist. "int foo;" is ambiguous.
	223	// It could be a prototype or it could be a definition.
	224	// external This is a "proxy" atom produced by a dylib reader. It has no content. It exists
	225	// so that all References can be resolved.
	226	// external-weak Same as external, but the definition in the dylib is weak.
	227	//
	228	// SymbolTableInclusion:
	229	// An atom may or may not be in the symbol table in an object file.
	230	// in Most atoms for functions or global data
	231	// not-in Anonymous atoms such literal c-strings, or other compiler generated data
	232	// in-never-strip Atom whose name the strip tool should never remove (e.g. REFERENCED_DYNAMICALLY in mach-o)
	233	//
	234	// Ordinal:
	235	// When a reader is created it is given a base ordinal number. All atoms created by the reader
	236	// should return a contiguous range of ordinal values that start at the base ordinal. The ordinal
	237	// values are used by the linker to sort the atom graph when producing the output file.
	238	//
	239	class Atom
	240	{
	241	public:
	242	enum Scope { scopeTranslationUnit, scopeLinkageUnit, scopeGlobal };
	243	enum DefinitionKind { kRegularDefinition, kWeakDefinition, kTentativeDefinition, kExternalDefinition, kExternalWeakDefinition, kAbsoluteSymbol };
	244	enum SymbolTableInclusion { kSymbolTableNotIn, kSymbolTableIn, kSymbolTableInAndNeverStrip, kSymbolTableInAsAbsolute };
	245
	246	virtual Reader* getFile() const = 0;
	247	virtual bool getTranslationUnitSource(const char dir, const char name) const = 0;
	248	virtual const char* getName() const = 0;
	249	virtual const char* getDisplayName() const = 0;
	250	virtual Scope getScope() const = 0;
	251	virtual DefinitionKind getDefinitionKind() const = 0;
	252	virtual SymbolTableInclusion getSymbolTableInclusion() const = 0;
	253	virtual bool dontDeadStrip() const = 0;
	254	virtual bool isZeroFill() const = 0;
	255	virtual uint64_t getSize() const = 0;
	256	virtual std::vector<ObjectFile::Reference*>& getReferences() const = 0;
	257	virtual bool mustRemainInSection() const = 0;
	258	virtual const char* getSectionName() const = 0;
	259	virtual Segment& getSegment() const = 0;
	260	virtual Atom& getFollowOnAtom() const = 0;
	261	virtual uint32_t getOrdinal() const = 0;
	262	virtual std::vector<LineInfo>* getLineInfo() const = 0;
	263	virtual Alignment getAlignment() const = 0;
	264	virtual void copyRawContent(uint8_t buffer[]) const = 0;
	265	virtual void setScope(Scope) = 0;
	266
	267
	268	uint64_t getSectionOffset() const { return fSectionOffset; }
	269	uint64_t getAddress() const { return fSection->getBaseAddress() + fSectionOffset; }
	270	class Section* getSection() const { return fSection; }
	271
	272	virtual void setSectionOffset(uint64_t offset) { fSectionOffset = offset; }
	273	virtual void setSection(class Section* sect) { fSection = sect; }
	274
	275	protected:
	276	Atom() : fSectionOffset(0), fSection(NULL) {}
	277	virtual ~Atom() {}
	278
	279	uint64_t fSectionOffset;
	280	class Section* fSection;
	281	};
	282
	283
	284	//
	285	// A Reference is a directed edge to another Atom. When an instruction in
	286	// the content of an Atom refers to another Atom, that is represented by a
	287	// Reference.
	288	//
	289	// There are two kinds of references: direct and by-name. With a direct Reference,
	290	// the target is bound by the Reader that created it. For instance a reference to a
	291	// static would produce a direct reference. A by-name reference requires the linker
	292	// to find the target Atom with the required name in order to be bound.
	293	//
	294	// For a link to succeed all References must be bound.
	295	//
	296	// A Reference has an optional "from" target. This is used when the content to fix-up
	297	// is the difference of two Atom address. For instance, if a pointer sized data Atom
	298	// is to contain A - B, then the Atom would have on Reference with a target of "A" and
	299	// a from-target of "B".
	300	//
	301	// A Reference also has a fix-up-offset. This is the offset into the content of the
	302	// Atom holding the reference where the fix-up (relocation) will be applied.
	303	//
	304	//
	305	//
	306	class Reference
	307	{
	308	public:
	309	enum TargetBinding { kUnboundByName, kBoundDirectly, kBoundByName, kDontBind };
	310
	311	virtual TargetBinding getTargetBinding() const = 0;
	312	virtual TargetBinding getFromTargetBinding() const = 0;
	313	virtual uint8_t getKind() const = 0;
	314	virtual uint64_t getFixUpOffset() const = 0;
	315	virtual const char* getTargetName() const = 0;
	316	virtual Atom& getTarget() const = 0;
	317	virtual uint64_t getTargetOffset() const = 0;
	318	virtual Atom& getFromTarget() const = 0;
	319	virtual const char* getFromTargetName() const = 0;
	320	virtual uint64_t getFromTargetOffset() const = 0;
	321
	322	virtual void setTarget(Atom&, uint64_t offset) = 0;
	323	virtual void setFromTarget(Atom&) = 0;
	324	virtual const char* getDescription() const = 0;
	325
	326	protected:
	327	Reference() {}
	328	virtual ~Reference() {}
	329	};
	330
	331
	332	}; // namespace ObjectFile
	333
	334
	335	#endif // __OBJECTFILE__