Messages in this thread | | | Subject | Re: [PATCH] RISC-V: cpu: refactor deprecated strncpy | From | Jessica Clarke <> | Date | Wed, 2 Aug 2023 00:02:11 +0100 |
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On 1 Aug 2023, at 22:14, Justin Stitt <justinstitt@google.com> wrote: > > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > A suitable replacement is `strscpy` [2] due to the fact that it > guarantees NUL-termination on its destination buffer argument which is > _not_ the case for `strncpy`! > > The `sv_type` buffer is declared with a size of 16 which is then > followed by some `strncpy` calls to populate the buffer with one of: > "sv32", "sv57", "sv48", "sv39" or "none". Hard-coding the max length as 5 is > error-prone and involves counting the number of characters (and > hopefully not forgetting to count the NUL-byte) in the raw string. > > Using a pre-determined max length in combination with `strscpy` provides > a cleaner, less error-prone as well as a less ambiguous implementation. > `strscpy` guarantees that it's destination buffer is NUL-terminated even > if it's source argument exceeds the max length as defined by the third > argument.
I would imagine you’d want a BUG_ON() rather than silent truncation if that ever happened (well, silent if you ignore it then printing the truncated string).
Though really you just want a static_strcpy that looks at sizeof* for source and destination and fails to build if it doesn’t fit; there’s no reason this needs to be found at run time.
(* and __builtin_types_compatible_p(char[], ...))
Jess
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