string: Add sigabbrev_np and sigdescr_np

The sigabbrev_np returns the abbreviated signal name (e.g. "HUP" for
SIGHUP) while sigdescr_np returns the string describing the error
number (e.g "Hangup" for SIGHUP).  Different than strsignal,
sigdescr_np does not attempt to translate the return description and
both functions return NULL for an invalid signal number.

They should be used instead of sys_siglist or sys_sigabbrev and they
are both thread and async-signal safe.  They are added as GNU
extensions on string.h header (same as strsignal).

Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
and s390x-linux-gnu.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/manual/signal.texi b/manual/signal.texi
index 34def1c06c..4009ff48a4 100644
--- a/manual/signal.texi
+++ b/manual/signal.texi
@@ -880,6 +880,30 @@ to @var{signum}.
 This function is a BSD feature, declared in the header file @file{signal.h}.
 @end deftypefun
 
+@deftypefun void sigdescr_np (int @var{signum})
+@standards{GNU, string.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+This function returns the message describing the signal @var{signum} or
+@code{NULL} for invalid signal number (e.g "Hangup" for @code{SIGHUP}).
+Different than @code{strsignal} the returned description is not translated.
+The message points to a static storage whose lifetime is the whole lifetime
+of the program.
+
+@pindex string.h
+This function is a GNU extension, declared in the header file @file{string.h}.
+@end deftypefun
+
+@deftypefun void sigabbrev_np (int @var{signum})
+@standards{GNU, string.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+This function returns the abbreviation describing the signal @var{signum} or
+@code{NULL} for invalid signal number.  The message points to a static
+storage whose lifetime is the whole lifetime of the program.
+
+@pindex string.h
+This function is a GNU extension, declared in the header file @file{string.h}.
+@end deftypefun
+
 @node Signal Actions
 @section Specifying Signal Actions
 @cindex signal actions