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>

7 files changed, 134 insertions, 9 deletions

diff --git a/string/Makefile b/string/Makefile
index 2725c86c34..8fe7e17fe2 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -44,7 +44,8 @@ routines	:= strcat strchr strcmp strcoll strcpy strcspn		\
 				     addsep replace)			\
 		   envz basename					\
 		   strcoll_l strxfrm_l string-inlines memrchr		\
-		   xpg-strerror strerror_l explicit_bzero
+		   xpg-strerror strerror_l explicit_bzero		\
+		   sigdescr_np sigabbrev_np
 
 strop-tests	:= memchr memcmp memcpy memmove mempcpy memset memccpy	\
 		   stpcpy stpncpy strcat strchr strcmp strcpy strcspn	\
@@ -61,7 +62,7 @@ tests		:= tester inl-tester noinl-tester testcopy test-ffs	\
 		   tst-strtok_r bug-strcoll2 tst-cmp tst-xbzero-opt	\
 		   test-endian-types test-endian-file-scope		\
 		   test-endian-sign-conversion tst-memmove-overflow	\
-		   tst-strsignal tst-strerror
+		   tst-strsignal tst-strerror test-sig_np
 
 # This test allocates a lot of memory and can run for a long time.
 xtests = tst-strcoll-overflow
diff --git a/string/Versions b/string/Versions
index 9b709d12a9..6f8dd2d372 100644
--- a/string/Versions
+++ b/string/Versions
@@ -85,4 +85,7 @@ libc {
   GLIBC_2.25 {
     explicit_bzero;
   }
+  GLIBC_2.32 {
+    sigdescr_np; sigabbrev_np;
+  }
 }
diff --git a/string/sigabbrev_np.c b/string/sigabbrev_np.c
new file mode 100644
index 0000000000..3cbe14e769
--- /dev/null
+++ b/string/sigabbrev_np.c
@@ -0,0 +1,33 @@
+/* Return string describing signal abbreviation.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <signal.h>
+#include <array_length.h>
+
+const char *const
+sigabbrev_np (int signum)
+{
+  const char *abbrev = NULL;
+
+  if (signum >= 0 && signum <= NSIG
+      && signum < array_length (__sys_sigabbrev))
+    abbrev = __sys_sigabbrev[signum];
+
+  return abbrev;
+}
diff --git a/string/sigdescr_np.c b/string/sigdescr_np.c
new file mode 100644
index 0000000000..5bcf814c1d
--- /dev/null
+++ b/string/sigdescr_np.c
@@ -0,0 +1,34 @@
+/* Return string describing signal.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <signal.h>
+#include <array_length.h>
+
+const char *const
+__sigdescr_np (int signum)
+{
+  const char *descr = NULL;
+
+  if (signum >= 0 && signum <= NSIG && signum < array_length (__sys_siglist))
+    descr = __sys_siglist[signum];
+
+  return descr;
+}
+libc_hidden_def (__sigdescr_np)
+weak_alias (__sigdescr_np, sigdescr_np)
diff --git a/string/string.h b/string/string.h
index d7ce0f4a1b..0119d7f45d 100644
--- a/string/string.h
+++ b/string/string.h
@@ -454,6 +454,14 @@ extern char *strsep (char **__restrict __stringp,
 /* Return a string describing the meaning of the signal number in SIG.  */
 extern char *strsignal (int __sig) __THROW;
 
+# ifdef __USE_GNU
+/* Return an abbreviation string for the signal number SIG.  */
+extern const char *sigabbrev_np (int __sig) __THROW;
+/* Return a string describing the meaning of the signal number in SIG,
+   the result is not translated.  */
+extern const char *sigdescr_np (int __sig) __THROW;
+# endif
+
 /* Copy SRC to DEST, returning the address of the terminating '\0' in DEST.  */
 extern char *__stpcpy (char *__restrict __dest, const char *__restrict __src)
      __THROW __nonnull ((1, 2));
diff --git a/string/strsignal.c b/string/strsignal.c
index 701ce20e6e..a9b911ce6e 100644
--- a/string/strsignal.c
+++ b/string/strsignal.c
@@ -21,19 +21,14 @@
 #include <string.h>
 #include <libintl.h>
 #include <tls-internal.h>
-#include <array_length.h>
 
 /* Return a string describing the meaning of the signal number SIGNUM.  */
 char *
 strsignal (int signum)
 {
-  const char *desc = NULL;
-
-  if (signum >= 0 && signum <= NSIG && signum < array_length (__sys_siglist))
-    desc = __sys_siglist[signum];
-
+  const char *desc = __sigdescr_np (signum);
   if (desc != NULL)
-    return (char *) _(desc);
+    return _(desc);
 
   struct tls_internal_t *tls_internal = __glibc_tls_internal ();
   free (tls_internal->strsignal_buf);
diff --git a/string/test-sig_np.c b/string/test-sig_np.c
new file mode 100644
index 0000000000..8b5117050c
--- /dev/null
+++ b/string/test-sig_np.c
@@ -0,0 +1,51 @@
+/* Test and sigabbrev_np and sigdescr_np.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <signal.h>
+#include <array_length.h>
+
+#include <support/support.h>
+#include <support/check.h>
+
+static const struct test_t
+{
+  int errno;
+  const char *abbrev;
+  const char *descr;
+} tests[] =
+{
+#define N_(name)                      name
+#define init_sig(sig, abbrev, desc)   { sig, abbrev, desc },
+#include <siglist.h>
+#undef init_sig
+};
+
+static int
+do_test (void)
+{
+  for (size_t i = 0; i < array_length (tests); i++)
+    {
+      TEST_COMPARE_STRING (sigabbrev_np (tests[i].errno), tests[i].abbrev);
+      TEST_COMPARE_STRING (sigdescr_np (tests[i].errno), tests[i].descr);
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>