On Wed, Dec 16, 2020 at 07:30:11PM -0300, Érico Nogueira via Elfutils-devel
wrote:
> From: Érico Rolim <erico....@gmail.com>
>
> The Linux man pages recommend this version of the function for portable
> applications.
>
> Signed-off-by: Érico Rolim <erico....@gmail.com>
I'd rather not do it this way because __xpg_strerror_r in glibc is a
wrapper around GNU strerror_r which does this almost always unneeded
string copying. Instead of penalizing GNU systems, I'd suggest checking
at configure time what kind of strerror_r do we have, and choosing the
code appropriately.
> ---
>
> Only difference from the initial patch is that this includes the
> Signed-off-by line.
>
> libdwfl/ChangeLog | 4 ++++
> libdwfl/dwfl_error.c | 11 ++++++++++-
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
> index f9f6f01f..d22f9892 100644
> --- a/libdwfl/ChangeLog
> +++ b/libdwfl/ChangeLog
> @@ -1,3 +1,7 @@
> +2020-12-16 Érico Nogueira <eric...@disroot.org>
> +
> + * dwfl_error.c (strerror_r): Always use the XSI-compliant version.
> +
> 2020-12-16 Dmitry V. Levin <l...@altlinux.org>
>
> * argp-std.c (_): Remove.
> diff --git a/libdwfl/dwfl_error.c b/libdwfl/dwfl_error.c
> index 7bcf61cc..e5db1217 100644
> --- a/libdwfl/dwfl_error.c
> +++ b/libdwfl/dwfl_error.c
> @@ -30,6 +30,11 @@
> # include <config.h>
> #endif
>
> +/* Guarantee that we get the XSI compliant strerror_r */
> +#ifdef _GNU_SOURCE
> +#undef _GNU_SOURCE
> +#endif
> +
> #include <assert.h>
> #include <libintl.h>
> #include <stdbool.h>
> @@ -136,6 +141,8 @@ __libdwfl_seterrno (Dwfl_Error error)
> global_error = canonicalize (error);
> }
>
> +/* To store the error message from strerror_r */
> +static __thread char errormsg[128];
>
> const char *
> dwfl_errmsg (int error)
> @@ -154,7 +161,9 @@ dwfl_errmsg (int error)
> switch (error &~ 0xffff)
> {
> case OTHER_ERROR (ERRNO):
> - return strerror_r (error & 0xffff, "bad", 0);
> + if (strerror_r (error & 0xffff, errormsg, sizeof errormsg))
> + return "strerror_r() failed()";
> + return errormsg;
> case OTHER_ERROR (LIBELF):
> return elf_errmsg (error & 0xffff);
> case OTHER_ERROR (LIBDW):
What if we had something like this:
static const char *
errnomsg(int error)
{
static const char unknown[] = "unknown error";
#ifdef HAVE_STRERROR_R_POSIX_SIGNATURE
static __thread char msg[128];
return strerror_r (error, msg, sizeof (msg)) ? unknown : msg;
#else
return strerror_r (error, unknown, 0);
#endif
}
and use it in dwfl_errmsg instead of strerror_r?
--
ldv
