ZZDeflateOutputStream write:maxLength erroneously returning zero

[levigroker]

When supplying a streamBlock to ZZArchiveEntry archiveEntryWithFileName:compress:streamBlock: the given output stream is of type ZZDeflateOutputStream which sometimes returns a zero when it doesn't mean it, causing problems.

The docs for NSOutputStream write:maxLength: say:

Return Value
A number indicating the outcome of the operation:

• A positive number indicates the number of bytes written.
• 0 indicates that a fixed-length stream and has reached its capacity.
• -1 means that the operation failed; more information about the error can be obtained with streamError.

so when ZZDeflateOutputStream write:maxLength: returns zero the calling code believes the stream has reached capacity and attempts no more writes. This causes a crash in ZZArchive loadCanMiss:error: due to the contained ZZChannel attempting to init an NSData object with a nil URL (from the _URL ivar).

- (BOOL)loadCanMiss:(BOOL)canMiss error:(out NSError**)error
{
	// memory-map the contents from the zip file
	NSError* __autoreleasing readError;
	NSData* contents = [_channel newInput:&readError];

In practice, if one ignores a return of zero from ZZDeflateOutputStream write:maxLength: and continues to attempt writes the process completes without issue. This, however, is non-standard.

The return value from NSOutputStream write:maxLength: is a contract with the caller and the value returned should accurately reflect those bytes which were consumed from the given buffer, not how many bytes the stream wrote out somewhere else.

[pfandrade]

+1