On Fri, Jul 19, 2024 at 03:09:52PM GMT, Alejandro Colomar wrote:
> Hi Paul,
>
> On Fri, Jul 19, 2024 at 02:53:38PM GMT, Alejandro Colomar wrote:
> > strtol(3) doesn't set the end pointer if the base is invalid. This
> > allows a caller to differentiate between "invalid base" (what
> > strtoi(3bsd) calls EINVAL) and an "no digits seen" (what strtoi(3bsd)
> > calls ECANCELED) in systems that report EINVAL on no digits seen (POSIX
> > allows this).
> >
> > strtol("foo", &e, 0);
> > strtol("0", &e, -1);
> >
> > The former call will set e = nptr.
> > The latter will leave e untouched.
> >
> > The caller has no other way to portably differentiate the calls.
> >
> > The way to differentiate those, thus, is to initialize e = NULL, to
> > allow reading it after the call.
> >
> > While doing this, change the behavior of this function to only set
> > *endptr if strtol(3) has set it, leaving it untouched otherwise.
> >
> > Fixes: 034a18049cbc (2014-12-20, "assure: new module")
>
> Self-correction: I had a typo while running git-blame(1), which led me
> to not find that the assure() call already existed --as assert()--
> before your commit, Paul.
>
> It was actually introduced in 3af47ca3f67 (1994-12-20, ".").
>
> Please amend the Fixes tags to:
>
> Fixes: 3af47ca3f67 (1994-12-20, ".")
Oops; For consistency, use 12 chars:
3af47ca3f672
> Fixes: 64ddc975e72c (2024-07-18, "xstrtol: document and stray less from
> strtol")
>
> Sorry for the confusion!
>
> Cheers,
> Alex
>
> > Fixes: 64ddc975e72c (2024-07-18, "xstrtol: document and stray less from
> > strtol")
> > Cc: Paul Eggert <egg...@cs.ucla.edu>
> > Cc: Bruno Haible <br...@clisp.org>
> > Cc: Đoàn Trần Công Danh <congdan...@gmail.com>
> > Cc: Eli Schwartz <eschwart...@gmail.com>
> > Cc: Sam James <s...@gentoo.org>
> > Cc: Serge Hallyn <se...@hallyn.com>
> > Cc: Iker Pedrosa <ipedr...@redhat.com>
> > Cc: Michael Vetter <jub...@iodoru.org>
> > Cc: <lib...@lists.linux.dev>
> > Signed-off-by: Alejandro Colomar <a...@kernel.org>
> > ---
> > lib/xstrtol.c | 35 +++++++++++++++++++++--------------
> > 1 file changed, 21 insertions(+), 14 deletions(-)
> >
> > diff --git a/lib/xstrtol.c b/lib/xstrtol.c
> > index c3145171f3..592673557f 100644
> > --- a/lib/xstrtol.c
> > +++ b/lib/xstrtol.c
> > @@ -71,9 +71,7 @@ strtol_error
> > __xstrtol (char const *nptr, char **endptr, int base,
> > __strtol_t *val, char const *valid_suffixes)
> > {
> > - char *t_ptr;
> > - char **p = endptr ? endptr : &t_ptr;
> > - *p = (char *) nptr;
> > + char *e = NULL;
> >
> > if (! TYPE_SIGNED (__strtol_t))
> > {
> > @@ -82,14 +80,21 @@ __xstrtol (char const *nptr, char **endptr, int base,
> > while (isspace (ch))
> > ch = *++q;
> > if (ch == '-')
> > - return LONGINT_INVALID;
> > + {
> > + if (endptr)
> > + *endptr = (char *) nptr;
> > + return LONGINT_INVALID;
> > + }
> > }
> >
> > errno = 0;
> > - __strtol_t tmp = __strtol (nptr, p, base);
> > + __strtol_t tmp = __strtol (nptr, &e, base);
> > strtol_error err = LONGINT_OK;
> >
> > - if (*p == nptr)
> > + if (endptr && e)
> > + *endptr = e;
> > +
> > + if (e == nptr)
> > {
> > /* If there is no number but there is a valid suffix, assume the
> > number is 1. The string is invalid otherwise. */
> > @@ -113,19 +118,19 @@ __xstrtol (char const *nptr, char **endptr, int base,
> > return err;
> > }
> >
> > - if (**p != '\0')
> > + if (*e != '\0')
> > {
> > int xbase = 1024;
> > int suffixes = 1;
> > strtol_error overflow;
> >
> > - if (!strchr (valid_suffixes, **p))
> > + if (!strchr (valid_suffixes, *e))
> > {
> > *val = tmp;
> > return err | LONGINT_INVALID_SUFFIX_CHAR;
> > }
> >
> > - switch (**p)
> > + switch (*e)
> > {
> > case 'E': case 'G': case 'g': case 'k': case 'K': case 'M': case
> > 'm':
> > case 'P': case 'Q': case 'R': case 'T': case 't': case 'Y': case
> > 'Z':
> > @@ -138,10 +143,10 @@ __xstrtol (char const *nptr, char **endptr, int base,
> > power-of-1024. */
> >
> > if (strchr (valid_suffixes, '0'))
> > - switch (p[0][1])
> > + switch (e[1])
> > {
> > case 'i':
> > - if (p[0][2] == 'B')
> > + if (e[2] == 'B')
> > suffixes += 2;
> > break;
> >
> > @@ -153,7 +158,7 @@ __xstrtol (char const *nptr, char **endptr, int base,
> > }
> > }
> >
> > - switch (**p)
> > + switch (*e)
> > {
> > case 'b':
> > overflow = bkm_scale (&tmp, 512);
> > @@ -224,8 +229,10 @@ __xstrtol (char const *nptr, char **endptr, int base,
> > }
> >
> > err |= overflow;
> > - *p += suffixes;
> > - if (**p)
> > + e += suffixes;
> > + if (endptr)
> > + *endptr = e;
> > + if (*e)
> > err |= LONGINT_INVALID_SUFFIX_CHAR;
> > }
> >
> > --
> > 2.45.2
> >
>
>
>
> --
> <https://www.alejandro-colomar.es/>
--
<https://www.alejandro-colomar.es/>
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