Package io.github.classgraph.utils

Class NestedJarHandler

java.lang.Object

io.github.classgraph.utils.NestedJarHandler

public class NestedJarHandler
extends Object

Unzip a jarfile within a jarfile to a temporary file on disk. Also handles the download of jars from http(s) URLs to temp files.

Somewhat paradoxically, the fastest way to support scanning zipfiles-within-zipfiles is to unzip the inner zipfile to a temporary file on disk, because the inner zipfile can only be read using ZipInputStream, not ZipFile (the ZipFile constructors only take a File argument). ZipInputStream doesn't have methods for reading the zip directory at the beginning of the stream, so using ZipInputStream rather than ZipFile, you have to decompress the entire zipfile to read all the directory entries. However, there may be many non-whitelisted entries in the zipfile, so this could be a lot of wasted work.

ClassGraph makes two passes, one to read the zipfile directory, which whitelist and blacklist criteria are applied to (this is a fast operation when using ZipFile), and then an additional pass to read only whitelisted (non-blacklisted) entries. Therefore, in the general case, the ZipFile API is always going to be faster than ZipInputStream. Therefore, decompressing the inner zipfile to disk is the only efficient option.

Field Summary

Fields

Modifier and Type	Field	Description
static String	TEMP_FILENAME_LEAF_SEPARATOR	The separator between random temp filename part and leafname.

Constructor Summary

Constructors

Constructor	Description
NestedJarHandler(ScanSpec scanSpec, LogNode log)	A handler for nested jars.

Method Summary

Modifier and Type	Method	Description
void	close(LogNode log)	Close zipfiles and modules, and delete temporary files.
void	closeRecyclers()	Close zipfiles and modules.
Map.Entry<File,Set<String>>	getInnermostNestedJar(String nestedJarPath, LogNode log)	Get a File for a given (possibly nested) jarfile path, unzipping the first N-1 segments of an N-segment '!'-delimited path to temporary files, then returning the File reference for the N-th temporary file.
JarfileMetadataReader	getJarfileMetadataReader(File zipFile, String jarfilePackageRoot, LogNode log)	Get a JarfileMetadataReader singleton for a given jarfile (so that the manifest and ZipEntries will only be read once).
Recycler<ModuleReaderProxy,IOException>	getModuleReaderProxyRecycler(ModuleRef moduleRef, LogNode log)	Get a ModuleReaderProxy recycler given a ModuleRef.
File	getOutermostJar(File jarFile)	Given a File reference for an inner nested jarfile, find the outermost jarfile it was extracted from.
Recycler<ZipFile,IOException>	getZipFileRecycler(File zipFile, LogNode log)	Get a ZipFile recycler given the (non-nested) canonical path of a jarfile.

Methods inherited from class java.lang.Object

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

Field Detail

TEMP_FILENAME_LEAF_SEPARATOR

public static final String TEMP_FILENAME_LEAF_SEPARATOR

The separator between random temp filename part and leafname.

See Also:

Constant Field Values

Constructor Detail

NestedJarHandler

public NestedJarHandler(ScanSpec scanSpec,
                        LogNode log)

A handler for nested jars.

Parameters:

scanSpec - The ScanSpec.

log - The log.

Method Detail

getZipFileRecycler

public Recycler<ZipFile,IOException> getZipFileRecycler(File zipFile,
                                                        LogNode log)
                                                 throws Exception

Get a ZipFile recycler given the (non-nested) canonical path of a jarfile.

Parameters:

zipFile - The zipfile.

log - The log.

Returns:

The ZipFile recycler.

Throws:

Exception - If the zipfile could not be opened.

getJarfileMetadataReader

public JarfileMetadataReader getJarfileMetadataReader(File zipFile,
                                                      String jarfilePackageRoot,
                                                      LogNode log)
                                               throws Exception

Get a JarfileMetadataReader singleton for a given jarfile (so that the manifest and ZipEntries will only be read once).

Parameters:

zipFile - The zipfile.

jarfilePackageRoot - The package root within the zipfile.

log - The log.

Returns:

The JarfileMetadataReader.

Throws:

Exception - If the zipfile could not be opened.

getModuleReaderProxyRecycler

public Recycler<ModuleReaderProxy,IOException> getModuleReaderProxyRecycler(ModuleRef moduleRef,
                                                                            LogNode log)
                                                                     throws Exception

Get a ModuleReaderProxy recycler given a ModuleRef.

Parameters:

moduleRef - The ModuleRef.

log - The log.

Returns:

The ModuleReaderProxy recycler.

Throws:

Exception - If the module could not be opened.

getInnermostNestedJar

public Map.Entry<File,Set<String>> getInnermostNestedJar(String nestedJarPath,
                                                         LogNode log)
                                                  throws Exception

Get a File for a given (possibly nested) jarfile path, unzipping the first N-1 segments of an N-segment '!'-delimited path to temporary files, then returning the File reference for the N-th temporary file.

If the path does not contain '!', returns the File represented by the path.

All path segments should end in a jarfile extension, e.g. ".jar" or ".zip".

Parameters:

nestedJarPath - The nested jar path.

log - The log.

Returns:

An Entry<File, Set<String>>, where the File is the innermost jar, and the Set<String> is the set of all relative paths of scanning roots within the innermost jar (may be empty, or may contain strings like "target/classes" or similar). If there was an issue with the path, returns null.

Throws:

Exception - If the innermost jarfile could not be extracted.

getOutermostJar

public File getOutermostJar(File jarFile)

Given a File reference for an inner nested jarfile, find the outermost jarfile it was extracted from.

Parameters:

jarFile - The jarfile.

Returns:

The outermost jar that the jarfile was contained within.

closeRecyclers

public void closeRecyclers()

Close zipfiles and modules.

close

public void close(LogNode log)

Close zipfiles and modules, and delete temporary files.

Parameters:

log - The log.