Decoder regression: mandrill.tiff from upstream

[Ingvar Stepanyan]

I've tried to upgrade upstream image crate to tiff 0.7.0, and it uncovered a regression bug: upstream image mandrill.tiff used to decode with 0.6.0, but fails with 0.7.0 with:

Cannot create decoder: FormatError(Format("Neither strips nor tiles were found or both were used in the same file"))

I verified that this problem is reproducible with just image-tiff too, so it's not an issue with integration in the image crate itself. It's also an uncompressed TIFF, so doesn't seem related to my deflate PR (#132) either.

Beyond that, I'm not that familiar with changes between releases, so leaving it up to others to debug this further.

[Tomáš Král]

Sorry, this is the result of some code I added.

image-tiff/src/decoder/mod.rs

Lines 704 to 719 in bd1e37d

 self.chunk_type = 
     match ( 
         self.get_tag_u32(Tag::RowsPerStrip), 
         self.get_tag_u32(Tag::TileWidth), 
         self.get_tag_u32(Tag::TileLength), 
     ) { 
         (Ok(_), Err(_), Err(_)) => ChunkType::Strip, 
         (Err(_), Ok(_), Ok(_)) => ChunkType::Tile, 
         // TODO: The spec says not to use both strip-oriented fields and tile-oriented fields. 
         // We can relax this later if it becomes a problem 
         _ => return Err(TiffError::FormatError(TiffFormatError::Format( 
             String::from( 
                 "Neither strips nor tiles were found or both were used in the same file", 
             ), 
         ))), 
     }; 

This file has StripOffsets and StripByteCounts, but doesn't have RowsPerStrip, which I didn't expect.
Maybe I should just check for (StripOffsets && StripByteCounts) || (TileOffsets && TileByteCounts), otherwise reject the file ?