On Wed, Jul 24, 2024 at 10:54:52PM GMT, Alejandro Colomar wrote: > Hi Paul, > > On Wed, Jul 24, 2024 at 01:11:33PM GMT, Paul Eggert wrote: > > On 2024-07-24 12:27, Alejandro Colomar wrote: > > > POSIX leaves the value of *endptr unspecified if the base is invalid; > > > it is not unmodified. > > > > Fine, we can let xstrtol do the same. > > > > > That, combined with the fact that POSIX allows implementations of > > > strtol(3) to set EINVAL when no digits are found, makes it impossible to > > > portably check if the base was valid after the call. > > > > I don't see why not. Current gnulib xstrtol.c does something reasonable if > > the base is invalid. Why isn't that good enough? > > The following is a POSIX-compliant implementation of strtol(3): > > On an invalid base: > > - *endptr = nptr // POSIX leaves it unspecified so this is valid > - errno = EINVAL // POSIX mandates this > - return 0 // POSIX mandates this > > On no digits: > > - *endptr = nptr // POSIX mandates this > - errno = EINVAL // POSIX explicitly allows this > - return 0 // POSIX mandates this > > Find the 7^W 0 differences. :)
I forgot to reply to the last part: "Why isn't that [current gnulib] good enough? With an implementation of strtol(3) that does what I wrote above, the test `if (!t_ptr)` isn't true, so we go to `if (*p == nptr && (errno == 0 || errno == EINVAL))`, which is true. Assuming that the string matches a valid suffix, it'd succeed, but the call should have failed early. (And the worst part might be suggesting readers that an invalid base can be successfully tested after a call to strtol(3), so that they do something similar.) > > > > - char *t_ptr = nullptr; > > > + char *t_ptr; > > > char **p = endptr ? endptr : &t_ptr; > > > + *p = (char *) nptr; > > > + > > > + if (base < 0 || base == 1 || 36 < base) > > > + return LONGINT_INVALID; > > > + > > > > This would cause xstrtol to fail even if the underlying strtol supports base > > 1, base 64, etc. Why would we want to do that? > > We don't want to do that. But we have no choice. :-) > > > > I'm tired of strtol(3). :) > > > > Likewise. This issue about an invalid base is unimportant in practice, as > > the base is almost invariably a valid constant. > > Have a lovely night! > Alex > > -- > <https://www.alejandro-colomar.es/> -- <https://www.alejandro-colomar.es/>
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