A. Molzer
43d7f66c9e
The previous strategy could not keep track of all cycles such as reflexive ones at the very start. Additionally, it would fail to be able to iterate after seeking since it was overly cautious and verified the next IFD position before allowing the read of a current IFD. The new implementation is furthermore proof against having multiple independent chains of IFD which may occur when iterating SubIFDs for thumbnails. (Note that we do not verify the tree-structure, only a freedom from cycles).
41 lines
1.4 KiB
Rust
41 lines
1.4 KiB
Rust
use tiff::decoder::Decoder;
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// This file has the following IFD structure:
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//
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// ```
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// IFD -> IFD -> IFD
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// |-> IFD
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// |-> IFD -> IFD
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// | \-> IFD -> IFD
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// \-> IFD
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// ```
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//
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// where the main chain of IFD has 3 images, the second of which has several sub-IFDs and some have
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// more nested IFDs.
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const TEST_IMAGE_SUBIFD: &str = "./tests/subsubifds.tif";
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use std::fs::File;
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#[test]
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fn decode_seek_chain() {
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let file = File::open(TEST_IMAGE_SUBIFD).expect("Cannot open test image");
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let mut decoder = Decoder::new(file).expect("Invalid format to create decoder");
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// Remember the offsets in the first iteration.
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let offset0 = decoder.ifd_pointer().expect("First IFD pointer not found");
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decoder.next_image().unwrap();
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let offset1 = decoder.ifd_pointer().expect("Second IFD pointer not found");
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decoder.next_image().unwrap();
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let offset2 = decoder.ifd_pointer().expect("Third IFD pointer not found");
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assert!(!decoder.more_images());
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// Ensure we can seek, to do this again.
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decoder.seek_to_image(0)
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.expect("Failed to seek to first image");
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assert_eq!(Some(offset0), decoder.ifd_pointer());
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decoder.next_image().unwrap();
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assert_eq!(Some(offset1), decoder.ifd_pointer());
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decoder.next_image().unwrap();
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assert_eq!(Some(offset2), decoder.ifd_pointer());
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assert!(!decoder.more_images());
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}
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