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kamadak / exif-rs

Exif parsing library written in pure Rust
BSD 2-Clause "Simplified" License
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order in which read_from_container() is called can fail read. #21

Open Jeremiah-Griffin opened 2 years ago

Jeremiah-Griffin commented 2 years ago

if read_from_container(&mut bufreader) is called sometime after the read_to_end() has been called on the same File, read_from_container() will always fail with error InvalidFormat("Unknown image format")

The mitigation is to place the read_from_container() before the read_to_end() and to try_clone() the File when passing its reader to the read_from_container().

I have only tested this on Windows 10. All versions 0.5.x and 0.4 seem to be affected. I have not tested on earlier versions of the library.

I am unsure if this behavior is known, but it should be documented as the operation fails otherwise silently aside from the aforementioned error which is incorrect; the data on disk is not corrupt, just the handle.

kamadak commented 2 years ago

I may be able to help you if your high-level goal is described. Anyway, I will comment on the behavior.

If you have called read_to_end(), it is no surprise that read_from_container() will fail, because there is no data left.

Your "mitigation" does not make sense to me. Even if try_clone() is used, read_from_container() advances the underlying file pointer, so read_to_end() will not read what you expect, I guess.