com.oracle.objectfile

Class StringSectionImpl

java.lang.Object

com.oracle.objectfile.BasicElementImpl

com.oracle.objectfile.StringSectionImpl

All Implemented Interfaces:

ElementImpl, ObjectFile.ProgbitsSectionImpl, ObjectFile.RelocatableSectionImpl, Iterable<String>

public abstract class StringSectionImpl
extends BasicElementImpl
implements ObjectFile.ProgbitsSectionImpl, Iterable<String>

This class represents a string section, as may be contained in any kind of object file format. The name is something of a misnomer, because it need not be a section -- e.g. in the case of Mach-O string tables, it is not a 'section', but merely an element. The default representation of the string section is as a concatenated collection of null-terminated bytes. A separate contentProvider object enumerates the strings, e.g. by enumerating symbols, DWARF entries, or whatever is required. Subclasses could redefine the representation by overriding getOrDecideContent. We implement ObjectFile.ProgbitsSectionImpl so that we can be used as the core of progbits/regular sections, even though we can be used in other contexts too.

Constructor Summary

Constructors

Constructor and Description
StringSectionImpl()
StringSectionImpl(ObjectFile.Element e)

Method Summary

Modifier and Type	Method and Description
void	addContentProvider(Iterable<String> contentProvider)
Iterator<Iterable<String>>	contentProvidersIterator()
byte[]	getContent()
Iterable<BuildDependency>	getDependencies(Map<ObjectFile.Element,LayoutDecisionMap> decisions) Implementing this method allows to declare dependencies to other Sections (i.e.
ObjectFile.Element	getOrCreateRelocationElement(long addend) Force the creation of a relocation section/element for this section, and return it.
byte[]	getOrDecideContent(Map<ObjectFile.Element,LayoutDecisionMap> alreadyDecided, byte[] contentHint) Implement this method to deliver the content of the section.
Iterator<String>	iterator()
void	markRelocationSite(int offset, ByteBuffer bb, ObjectFile.RelocationKind k, String symbolName, long addend) Record (in a format-specific way) that data at the given offset in the file, for the given number of bytes, should be fixed up according to the value of the given symbol and the given kind of relocation.
void	markRelocationSite(int offset, ObjectFile.RelocationKind k, String symbolName, long addend) This is like ObjectFile.RelocatableSectionImpl.markRelocationSite(int, java.nio.ByteBuffer, com.oracle.objectfile.ObjectFile.RelocationKind, java.lang.String, long), but doesn't need to be passed a buffer.
void	setContent(byte[] c)

Methods inherited from class com.oracle.objectfile.BasicElementImpl

getAlignment, getDecisions, getElement, getMemSize, getOrDecideOffset, getOrDecideSize, getOrDecideVaddr, getOwner, isReferenceable, setElement

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.oracle.objectfile.ElementImpl

getAlignment, getDecisions, getElement, getMemSize, getOrDecideOffset, getOrDecideSize, getOrDecideVaddr, isLoadable, isReferenceable, setElement

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

StringSectionImpl

public StringSectionImpl(ObjectFile.Element e)

StringSectionImpl

public StringSectionImpl()

Method Detail

iterator

public Iterator<String> iterator()

Specified by:

iterator in interface Iterable<String>

getOrDecideContent

public byte[] getOrDecideContent(Map<ObjectFile.Element,LayoutDecisionMap> alreadyDecided,
                                 byte[] contentHint)

Description copied from interface: ElementImpl

Implement this method to deliver the content of the section.

Specified by:

getOrDecideContent in interface ElementImpl

getDependencies

public Iterable<BuildDependency> getDependencies(Map<ObjectFile.Element,LayoutDecisionMap> decisions)

Description copied from interface: ElementImpl

Implementing this method allows to declare dependencies to other Sections (i.e. information about other sections needed to construct this section). The information will be used to construct the buildOrder in ObjectFile.writeInternal(). A good example can be found at: ELFObjectFile.ProgramHeaderTable.getDependencies

Specified by:

getDependencies in interface ElementImpl

Overrides:

getDependencies in class BasicElementImpl

contentProvidersIterator

public Iterator<Iterable<String>> contentProvidersIterator()

addContentProvider

public void addContentProvider(Iterable<String> contentProvider)

getOrCreateRelocationElement

public ObjectFile.Element getOrCreateRelocationElement(long addend)

Description copied from interface: ObjectFile.RelocatableSectionImpl

Force the creation of a relocation section/element for this section, and return it. This is necessary to avoid the on-demand instantiation of relocation sections at write()-time, which leads to unpredictable results (e.g. not appearing in the ELF SHT, if the SHT was written before the section was created).

Specified by:

getOrCreateRelocationElement in interface ObjectFile.RelocatableSectionImpl

Parameters:

addend - whether a full-width addend, or 0 if unneeded

Returns:

the element which will hold relocation records (of the argument-specified kind) for this section

markRelocationSite

public void markRelocationSite(int offset,
                               ObjectFile.RelocationKind k,
                               String symbolName,
                               long addend)

Description copied from interface: ObjectFile.ProgbitsSectionImpl

This is like ObjectFile.RelocatableSectionImpl.markRelocationSite(int, java.nio.ByteBuffer, com.oracle.objectfile.ObjectFile.RelocationKind, java.lang.String, long), but doesn't need to be passed a buffer. It uses the byte array accessed by ObjectFile.ProgbitsSectionImpl.getContent() and ObjectFile.ProgbitsSectionImpl.setContent(byte[]).

Specified by:

markRelocationSite in interface ObjectFile.ProgbitsSectionImpl

markRelocationSite

public void markRelocationSite(int offset,
                               ByteBuffer bb,
                               ObjectFile.RelocationKind k,
                               String symbolName,
                               long addend)

Description copied from interface: ObjectFile.RelocatableSectionImpl

Record (in a format-specific way) that data at the given offset in the file, for the given number of bytes, should be fixed up according to the value of the given symbol and the given kind of relocation. Depending on the object file format, kind of file, and target architecture, the available kinds of relocation and addend modes all vary considerably. Supporting a uniform interface is therefore complicated. In particular, the implementation of these methods somehow has to tell the caller how to fix up the section content, or fix it up itself. For example, ELF uses explicit addends for dynamic linking on x86-64, but Mach-O in the same case always uses implicit (inline) addends and cannot encode explicit addends. I can see two solutions. Firstly, the Mach-O implementation could come back to the caller saying "here is what you need to add to the current section contents". Or secondly, the section implementation could take care of it somehow, but that assumes it has access to the actual contents s.t. any changes will not later be clobbered. TODO: CHECK whether this is true of our native native image code.

Specified by:

markRelocationSite in interface ObjectFile.RelocatableSectionImpl

Parameters:

offset - the offset into the section contents of the beginning of the fixed-up bytes

bb - the byte buffer representing the encoded section contents, at least as far as offset + length bytes

k - the kind of fixup to be applied

symbolName - the name of the symbol whose value is used to compute the fixed-up bytes

addend - a full-width addend, or 0 if unneeded

getContent

public byte[] getContent()

Specified by:

getContent in interface ObjectFile.ProgbitsSectionImpl

setContent

public void setContent(byte[] c)

Specified by:

setContent in interface ObjectFile.ProgbitsSectionImpl