A. Molzer
c073841a9d
This serves two purposes: reliably resetting the state of the decoder after kinds of failure; and moving the decoder to a SubIFD chain.
68 lines
2.4 KiB
Rust
68 lines
2.4 KiB
Rust
use tiff::{decoder::Decoder, tags::IfdPointer};
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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
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.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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#[test]
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fn decode_seek_recover() {
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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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// oops!
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let fails = decoder.restart_ifds(IfdPointer(0xdead_beef));
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assert!(fails.is_err());
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// However we can recover by restarting our seek.
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decoder.restart_ifds(offset0)
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.expect("Failed to restart IFDs from 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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}
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