Fix UB caused by casting a Rust fn ptr to a *c_void (BMO bug #1351497) #81
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I don't want to go back to maintaining |
This addresses https://bugzilla.mozilla.org/show_bug.cgi?id=1351497, which was filed as a rustc bug in rust-lang/rust#40913, but revealed to be undefined behaviour that happened to work with earlier compiler versions. As the comment removed in this patch describes, the only reason this code existed was to work around a limitation of rusty-cheddar.
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Okay, so I've forked rusty-cheddar and fixed it: kinetiknz/moz-cheddar@bb819e5 And repushed this fix with the rusty-cheddar dep switched to my repo. |
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Most awesome, thanks! |
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Use Option<extern fn()> to represent potentially-null function pointer.
This addresses https://bugzilla.mozilla.org/show_bug.cgi?id=1351497, which was filed as a rustc bug in rust-lang/rust#40913, but revealed to be undefined behaviour that happened to work with earlier compiler versions.
As the comment removed in this patch describes, the only reason this code existed was to work around a limitation of rusty-cheddar.
Not sure what to do about the rusty-cheddar issue. We can patch the generated header manually (by replacing the bogus mp4parse_io member
Option readwithintptr_t (*read)(uint8_t* buffer, uintptr_t size, void* userdata)for now, but that's not an ideal solution.