Use sigabbrev_np(3) to access signal abbreviations if supported.

glibc-2.32 has removed sys_sigabbrev[], we can use sigabbrev_np(3) instead.

config.h.in

@@ -740,6 +740,9 @@
 /* Define to 1 if you have the `sig2str' function. */
 #undef HAVE_SIG2STR
 
+/* Define to 1 if you have the `sigabbrev_np' function. */
+#undef HAVE_SIGABBREV_NP
+
 /* Define to 1 if you use S/Key. */
 #undef HAVE_SKEY
 

configure

@@ -23687,6 +23687,18 @@ done
 
 
 if test x"${ac_cv_func_sig2str}${ac_cv_func_str2sig}" != x"yesyes"; then
+    for ac_func in sigabbrev_np
+do :
+  ac_fn_c_check_func "$LINENO" "sigabbrev_np" "ac_cv_func_sigabbrev_np"
+if test "x$ac_cv_func_sigabbrev_np" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_SIGABBREV_NP 1
+_ACEOF
+
+fi
+done
+
+    if test x"${ac_cv_func_sigabbrev_np}" != x"yes"; then
 	COMPAT_TEST_PROGS="${COMPAT_TEST_PROGS}${COMPAT_TEST_PROGS+ }strsig_test"
 	HAVE_SIGNAME="false"
 	ac_fn_c_check_decl "$LINENO" "sys_signame" "ac_cv_have_decl_sys_signame" "
@@ -23791,6 +23803,7 @@ esac
 	    fi
 	fi
     fi
+fi
 
 OLIBS="$LIBS"
 LIBS="$LIBS $lt_cv_dlopen_libs"

configure.ac

@@ -3498,6 +3498,8 @@ dnl Check for sys_signame or sys_sigabbrev if missing sig2str() or str2sig().
 dnl Also enable unit tests for sig2str() and str2sig().
 dnl
 if test x"${ac_cv_func_sig2str}${ac_cv_func_str2sig}" != x"yesyes"; then
+    AC_CHECK_FUNCS([sigabbrev_np])
+    if test x"${ac_cv_func_sigabbrev_np}" != x"yes"; then
 	COMPAT_TEST_PROGS="${COMPAT_TEST_PROGS}${COMPAT_TEST_PROGS+ }strsig_test"
 	HAVE_SIGNAME="false"
 	AC_CHECK_DECLS([sys_signame, _sys_signame, sys_sigabbrev], [
@@ -3524,6 +3526,7 @@ AC_INCLUDES_DEFAULT
 	    fi
 	fi
     fi
+fi
 
 dnl
 dnl Check for dl_iterate_phdr, may require -ldl

lib/util/sig2str.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2012-2015, 2017-2019 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2012-2015, 2017-2020 Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -32,20 +32,24 @@
 #include <unistd.h>
 
 #include "sudo_compat.h"
+#include "sudo_util.h"
 
+#if !defined(HAVE_SIGABBREV_NP)
 # if defined(HAVE_DECL_SYS_SIGNAME) && HAVE_DECL_SYS_SIGNAME == 1
-#  define sudo_sys_signame	sys_signame
+#   define sigabbrev_np(_x)	sys_signame[(_x)]
 # elif defined(HAVE_DECL__SYS_SIGNAME) && HAVE_DECL__SYS_SIGNAME == 1
-#  define sudo_sys_signame	_sys_signame
+#   define sigabbrev_np(_x)	_sys_signame[(_x)]
-#elif defined(HAVE_DECL_SYS_SIGABBREV) && HAVE_DECL_SYS_SIGABBREV == 1
+# elif defined(HAVE_SYS_SIGABBREV)
-#  define sudo_sys_signame	sys_sigabbrev
+#   define sigabbrev_np(_x)	sys_sigabbrev[(_x)]
-#else
+#  if defined(HAVE_DECL_SYS_SIGABBREV) && HAVE_DECL_SYS_SIGABBREV == 0
-# ifdef HAVE_SYS_SIGABBREV
     /* sys_sigabbrev is not declared by glibc */
-#  define sudo_sys_signame	sys_sigabbrev
+    extern const char *const sys_sigabbrev[NSIG];
 #  endif
+# else
+#   define sigabbrev_np(_x)	sudo_sys_signame[(_x)]
     extern const char *const sudo_sys_signame[NSIG];
 # endif
+#endif /* !HAVE_SIGABBREV_NP */
 
 /*
  * Translate signal number to name.
@@ -77,8 +81,10 @@ sudo_sig2str(int signo, char *signame)
 	return 0;
     }
 #endif
-    if (signo > 0 && signo < NSIG && sudo_sys_signame[signo] != NULL) {
+    if (signo > 0 && signo < NSIG) {
-	strlcpy(signame, sudo_sys_signame[signo], SIG2STR_MAX);
+	const char *cp = sigabbrev_np(signo);
+	if (cp != NULL) {
+	    strlcpy(signame, cp, SIG2STR_MAX);
 	    /* Make sure we always return an upper case signame. */
 	    if (islower((unsigned char)signame[0])) {
 		int i;
@@ -87,6 +93,7 @@ sudo_sig2str(int signo, char *signame)
 	    }
 	    return 0;
 	}
+    }
     errno = EINVAL;
     return -1;
 }

lib/util/str2sig.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2019 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2019-2020 Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -37,19 +37,22 @@
 #include "sudo_compat.h"
 #include "sudo_util.h"
 
+#if !defined(HAVE_SIGABBREV_NP)
 # if defined(HAVE_DECL_SYS_SIGNAME) && HAVE_DECL_SYS_SIGNAME == 1
-#  define sudo_sys_signame	sys_signame
+#   define sigabbrev_np(_x)	sys_signame[(_x)]
 # elif defined(HAVE_DECL__SYS_SIGNAME) && HAVE_DECL__SYS_SIGNAME == 1
-#  define sudo_sys_signame	_sys_signame
+#   define sigabbrev_np(_x)	_sys_signame[(_x)]
-#elif defined(HAVE_DECL_SYS_SIGABBREV) && HAVE_DECL_SYS_SIGABBREV == 1
+# elif defined(HAVE_SYS_SIGABBREV)
-#  define sudo_sys_signame	sys_sigabbrev
+#   define sigabbrev_np(_x)	sys_sigabbrev[(_x)]
-#else
+#  if defined(HAVE_DECL_SYS_SIGABBREV) && HAVE_DECL_SYS_SIGABBREV == 0
-# ifdef HAVE_SYS_SIGABBREV
     /* sys_sigabbrev is not declared by glibc */
-#  define sudo_sys_signame	sys_sigabbrev
+    extern const char *const sys_sigabbrev[NSIG];
 #  endif
+# else
+#   define sigabbrev_np(_x)	sudo_sys_signame[(_x)]
     extern const char *const sudo_sys_signame[NSIG];
 # endif
+#endif /* !HAVE_SIGABBREV_NP */
 
 /*
  * Many systems use aliases for source backward compatibility.
@@ -154,11 +157,11 @@ sudo_str2sig(const char *signame, int *result)
 	}
     }
 
-    /* Check sys_signame[]. */
     for (signo = 1; signo < NSIG; signo++) {
-	if (sudo_sys_signame[signo] != NULL) {
+	const char *cp = sigabbrev_np(signo);
+	if (cp != NULL) {
 	    /* On macOS sys_signame[] may contain lower-case names. */
-	    if (strcasecmp(signame, sudo_sys_signame[signo]) == 0) {
+	    if (strcasecmp(signame, cp) == 0) {
 		*result = signo;
 		return 0;
 	    }