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cdgriffith / puremagic

Pure python implementation of identifying files based off their magic numbers
MIT License
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Add a `imghdr_strict` option to `.what()` to deliver the same false positives #81

Closed cclauss closed 3 months ago

cclauss commented 3 months ago 
- def what(file: os.PathLike | str | None, h: bytes | None) -> str | None:
+ def what(file: os.PathLike | str | None, h: bytes | None, imghdr_strict: bool = True) -> str | None:

imghdr_strict enables bug-for-bug compatibility between imghdr.what() and puremagic.what() when the imghdr returns a match but puremagic returns None. We believe that imghdr is delivering a "false positive" in each of these scenarios but we want puremagic.what()'s default behavior to match imghdr.what()'s false positives so we do not break existing applications.

If imghdr_strict is True (the default) then a lookup will be done to deliver a matching result on all known false positives. If imghdr_strict is False then puremagic's algorithms will determine the image type. True is more compatible while False is more correct.

NOTE: This compatibility effort only deals with imghdr's false positives and we are not interested in tracking the opposite situation where puremagic's delivers a match while imghdr would have returned None. Also, puremagic.what() can recognize many more file types than the twelve image file types that imghdr focused on.

@NebularNerd Your review, please.

NebularNerd commented 3 months ago

Sounds good, at least folks using imghdr will continue to get the results they expect. 🙂

cclauss commented 3 months ago

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