[COMPRESS-298] Cleaner way to catch/detect Seven7 files which are password protected

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.8.1
• Fix Version/s: 1.10
• Component/s: Archivers
• Assignee: Unassigned
• Reporter: Nick Burch
• Created: 18/Jan/15 23:00
• Updated: 20/Jan/15 14:27
• Resolved: 20/Jan/15 14:27

Description

Currently, if we open a password protected 7z file and call getNextEntry() on it, it will blow up with an IOException with a specific string:

java.io.IOException: Cannot read encrypted files without a password
	at org.apache.commons.compress.archivers.sevenz.AES256SHA256Decoder$1.init(AES256SHA256Decoder.java:56)
	at org.apache.commons.compress.archivers.sevenz.AES256SHA256Decoder$1.read(AES256SHA256Decoder.java:112)
	at java.io.DataInputStream.readUnsignedByte(DataInputStream.java:288)
	at org.tukaani.xz.rangecoder.RangeDecoderFromStream.<init>(Unknown Source)
	at org.tukaani.xz.LZMAInputStream.initialize(Unknown Source)
	at org.tukaani.xz.LZMAInputStream.initialize(Unknown Source)
	at org.tukaani.xz.LZMAInputStream.<init>(Unknown Source)
	at org.apache.commons.compress.archivers.sevenz.Coders$LZMADecoder.decode(Coders.java:113)
	at org.apache.commons.compress.archivers.sevenz.Coders.addDecoder(Coders.java:77)
	at org.apache.commons.compress.archivers.sevenz.SevenZFile.buildDecoderStack(SevenZFile.java:853)
	at org.apache.commons.compress.archivers.sevenz.SevenZFile.buildDecodingStream(SevenZFile.java:820)
	at org.apache.commons.compress.archivers.sevenz.SevenZFile.getNextEntry(SevenZFile.java:151)

It would be good if either a specific subtype of IOException could be thrown (which could then be caught to differentiate this from other kinds of IO problems), or if a method could be added to SevenZFile which could be called to see if a password is needed / given password is correct

(If implemented, this would help make the code in Tika dealing with 7z files cleaner)