Messages in this thread | | | From | Nick Desaulniers <> | Date | Wed, 26 Jan 2022 09:49:38 -0800 | Subject | Re: [PATCH v3 1/3] string: Make stpcpy() possible to use |
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On Wed, Jan 26, 2022 at 6:19 AM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > It is a good rule to avoid submitting code without users. > Currently the stpcpy() is unusable due to missed declaration. > Any attempts to use it will bring something like: > > error: implicit declaration of function ‘stpcpy’ [-Werror=implicit-function-declaration] > > Move declaration to the header and guard it as other string functions. > > Fixes: 1e1b6d63d634 ("lib/string.c: implement stpcpy") > Reported-by: kernel test robot <lkp@intel.com> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Cc: Nathan Chancellor <natechancellor@gmail.com> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Recall the discussion from Kees: https://lore.kernel.org/lkml/CAK7LNAQXo5-5W6hvNMEVPBPf3tRWaf-pQdSR-0OHyi4RCGhjsQ@mail.gmail.com/ and https://lore.kernel.org/lkml/202008150921.B70721A359@keescook/
I'm guessing that the 0day bot report was on the third patch in this series, which looks to use stpcpy: https://lore.kernel.org/lkml/20220126141917.75399-3-andriy.shevchenko@linux.intel.com/
for patch 3, I'd s/"compress"/de-duplicate/ or s/"compress"/merge/.
Kees, I'm curious if we can do something like require the string length to be known at compile time otherwise BUILD_BUG_ON?
> --- > v3: new patch to fix reported issue > include/linux/string.h | 3 +++ > lib/string.c | 3 ++- > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/string.h b/include/linux/string.h > index b6572aeca2f5..b1aeb3475396 100644 > --- a/include/linux/string.h > +++ b/include/linux/string.h > @@ -31,6 +31,9 @@ size_t strlcpy(char *, const char *, size_t); > #ifndef __HAVE_ARCH_STRSCPY > ssize_t strscpy(char *, const char *, size_t); > #endif > +#ifndef __HAVE_ARCH_STPCPY > +char *stpcpy(char *__restrict__ dest, const char *__restrict__ src); > +#endif > > /* Wraps calls to strscpy()/memset(), no arch specific code required */ > ssize_t strscpy_pad(char *dest, const char *src, size_t count); > diff --git a/lib/string.c b/lib/string.c > index 485777c9da83..4ecb8ec1fdd1 100644 > --- a/lib/string.c > +++ b/lib/string.c > @@ -233,6 +233,7 @@ ssize_t strscpy(char *dest, const char *src, size_t count) > EXPORT_SYMBOL(strscpy); > #endif > > +#ifndef __HAVE_ARCH_STPCPY > /** > * stpcpy - copy a string from src to dest returning a pointer to the new end > * of dest, including src's %NUL-terminator. May overrun dest. > @@ -248,7 +249,6 @@ EXPORT_SYMBOL(strscpy); > * not recommended for usage. Instead, its definition is provided in case > * the compiler lowers other libcalls to stpcpy. > */ > -char *stpcpy(char *__restrict__ dest, const char *__restrict__ src); > char *stpcpy(char *__restrict__ dest, const char *__restrict__ src) > { > while ((*dest++ = *src++) != '\0') > @@ -256,6 +256,7 @@ char *stpcpy(char *__restrict__ dest, const char *__restrict__ src) > return --dest; > } > EXPORT_SYMBOL(stpcpy); > +#endif > > #ifndef __HAVE_ARCH_STRCAT > /** > -- > 2.34.1 >
-- Thanks, ~Nick Desaulniers
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