embed.fnc: Add ability to assert string ptr is in-bounds #23774
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Where s is a pointer into a string, and e is the end of it.
I went through the declarations in embed.fnc and added PTR hints for all the ones that looked to have pointers to the beginning and end of a string. I then ran the test suite, and reverted any that had problems. This is the result. Testing in the field may reveal others that the test suite missed; we can fix those as they occur.
This is the first use of the new MPTR hint that is used to generate an assertion that a pointer is somewhere in the middle of a string.
Generally, a pointer to a string upper bound actually to one beyond the actual final byte in the string. This is sanctioned by the C Standard, and allows you to just subtract the lower bound from it to get its length, without having to add 1. But some function we have tolerate the upper bound pointer being set to the actual final byte. The EPTRQ hint in embed.fnc is used for those; the assertion becomes 'l <= u' instead of strictly less-than. This commit is the first to use this type of hint, and it applies it only to those functions whose documentation and behavior clearly indicate this is expected. There's a dozen-ish ones where that isn't true. And they need to be investigated further before deciding their disposition.
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There are a bunch of functions that are passed both a string pointer and a pointer to the string end. This commit allows you to declare the latter in embed.fnc, and have an
assert(s < e)generated that goes in thePERL_ARGS_ASSERTfor the function.This is extended for functions where it should instead be
assert(s <= e)andassert(s <= cur)