com.facebook.buck.cxx.toolchain.objectfile

Class DylibStubContentsScrubber

java.lang.Object

com.facebook.buck.cxx.toolchain.objectfile.DylibStubContentsScrubber

All Implemented Interfaces:

FileContentsScrubber, FileScrubber

public class DylibStubContentsScrubber
extends Object
implements FileContentsScrubber

Scrubs the contents of dylib stubs, so that they're independent of the contents of the source dylib. That means that if the source dylib's ABI does not change, it will produce the exact same dylib stub.

The linker itself does not actually care about the symbol addresses, it just wants to ensure any referenced symbols exist. That means we can reset the addresses to any value we would like. Note that the symbol addresses themselves are already invalid in the dylib stub, as the contents (i.e., binary instructions) have been stripped by "strip".

Dylib stubs produced by "strip" are still dependent on symbol addresses and the UUID. To make them independent, we do the following:

• Set the UUID to the same value each time
• Update the _LINKEDIT segment and remove any addresses for symbols
  • Update the exports info
  • Update the symbol table

Nested Class Summary

Nested classes/interfaces inherited from interface com.facebook.buck.io.file.FileScrubber

FileScrubber.ScrubException

Constructor Summary

Constructors

Constructor and Description
DylibStubContentsScrubber()

Method Summary

Modifier and Type	Method and Description
void	scrubFile(FileChannel file) Override this method to perform the content modification.

Methods inherited from class java.lang.Object

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

Constructor Detail

DylibStubContentsScrubber

public DylibStubContentsScrubber()

Method Detail

scrubFile

public void scrubFile(FileChannel file)
               throws IOException,
                      FileScrubber.ScrubException

Description copied from interface: FileContentsScrubber

Override this method to perform the content modification.

Specified by:

scrubFile in interface FileContentsScrubber

Throws:

IOException

FileScrubber.ScrubException