[dpdk-dev] [PATCH] eal: fix API to get error string
Thomas Monjalon
thomas at monjalon.net
Wed Oct 31 19:43:24 CET 2018
31/10/2018 19:26, Ferruh Yigit:
> On 10/31/2018 6:26 PM, Ferruh Yigit wrote:
> > On 10/31/2018 5:16 PM, Thomas Monjalon wrote:
> >> 31/10/2018 18:19, Ferruh Yigit:
> >>> rte_strerror uses strerror_r(), and strerror_r() has two version of it.
> >>> - XSI-compliant version, (_POSIX_C_SOURCE >= 200112L) && ! _GNU_SOURCE
> >>> - GNU-specific version
> >>>
> >>> Those two has different return types, so the exiting return type check
> >>> is not correct for GNU-specific version.
> >>>
> >>> And this is causing failure in errno_autotest unit test.
> >>>
> >>> Adding different implementation for FreeBSD and Linux.
> >>>
> >>> Fixes: 016c32bd3e3d ("eal: cleanup strerror function")
> >>> Cc: stable at dpdk.org
> >>>
> >>> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
> >>> ---
> >>> --- a/lib/librte_eal/common/eal_common_errno.c
> >>> +++ b/lib/librte_eal/common/eal_common_errno.c
> >>> default:
> >>> +#ifdef RTE_EXEC_ENV_BSDAPP
> >>> if (strerror_r(errnum, ret, RETVAL_SZ) != 0)
> >>> snprintf(ret, RETVAL_SZ, "Unknown error%s %d",
> >>> sep, errnum);
> >>> +#else
> >>> + /*
> >>> + * _GNU_SOURCE version, error string is not always
> >>> + * strored in "ret" buffer, need to use return value
> >>> + */
> >>> + ret = strerror_r(errnum, ret, RETVAL_SZ);
> >>> +#endif
> >>
> >> Why not use the return value in both cases?
> >>
> >> Why not writing an error message in Linux case?
> >
> > "man strerror_r" has more details, but briefly,
> >
> > The XSI-compliant strerror_r() function returns 0 on success. GNU one returns
> > the pointer to string.
> >
> > The XSI-compliant can return an empty buffer, GNU one always return a string,
> > either proper error string or "Unknown .." one.
You say "GNU one always return a string"
The comment says:
_GNU_SOURCE version, error string is not always strored in "ret" buffer
> strerror_r() not portable. An alternative can be not using it at all...
It's fine to use it.
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