systemctl,loginctl,machinectl: use a shared helper for arg_signal

I seems frivolous to yet another two -util.[ch] files, but the helper
should be in shared/ and it doesn't seem to fit anywhere else.

9 files changed, 60 insertions, 51 deletions

diff --git a/man/machinectl.xml b/man/machinectl.xml
index 9026849559..556fe309dc 100644
--- a/man/machinectl.xml
+++ b/man/machinectl.xml
@@ -699,17 +699,7 @@
         <option>all</option>.</para></listitem>
       </varlistentry>
 
-      <varlistentry>
-        <term><option>-s</option></term>
-        <term><option>--signal=</option></term>
-
-        <listitem><para>When used with <command>kill</command>, choose
-        which signal to send to selected processes. Must be one of the
-        well-known signal specifiers, such as
-        <constant>SIGTERM</constant>, <constant>SIGINT</constant> or
-        <constant>SIGSTOP</constant>. If omitted, defaults to
-        <constant>SIGTERM</constant>.</para></listitem>
-      </varlistentry>
+      <xi:include href="standard-options.xml" xpointer="signal" />
 
       <varlistentry>
          <term><option>--uid=</option></term>
diff --git a/man/standard-options.xml b/man/standard-options.xml
index 8ba5b09df8..848439119e 100644
--- a/man/standard-options.xml
+++ b/man/standard-options.xml
@@ -61,4 +61,19 @@
     (for a pretty version of the same, with indentation and line breaks) or <literal>off</literal> (to turn
     off JSON output, the default).</para></listitem>
   </varlistentry>
+
+  <varlistentry id='signal'>
+    <term><option>-s</option></term>
+    <term><option>--signal=</option></term>
+
+    <listitem>
+      <para>When used with <command>kill</command>, choose which signal to send to selected processes. Must
+      be one of the well-known signal specifiers such as <constant>SIGTERM</constant>,
+      <constant>SIGINT</constant> or <constant>SIGSTOP</constant>. If omitted, defaults to
+      <option>SIGTERM</option>.</para>
+
+      <para>The special value <literal>help</literal> will list the known values and the program will exit
+      immediately.</para>
+    </listitem>
+  </varlistentry>
 </variablelist>
diff --git a/man/systemctl.xml b/man/systemctl.xml
index db4e2b2c65..2ed58eb33b 100644
--- a/man/systemctl.xml
+++ b/man/systemctl.xml
@@ -2067,21 +2067,9 @@ Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output err
           is defined. If omitted, defaults to
           <option>all</option>.</para>
         </listitem>
-
       </varlistentry>
 
-      <varlistentry>
-        <term><option>-s</option></term>
-        <term><option>--signal=</option></term>
-
-        <listitem>
-          <para>When used with <command>kill</command>, choose which
-          signal to send to selected processes. Must be one of the
-          well-known signal specifiers such as <constant>SIGTERM</constant>, <constant>SIGINT</constant> or
-          <constant>SIGSTOP</constant>. If omitted, defaults to
-          <option>SIGTERM</option>.</para>
-        </listitem>
-      </varlistentry>
+      <xi:include href="standard-options.xml" xpointer="signal" />
 
       <varlistentry>
         <term><option>--what=</option></term>
diff --git a/src/login/loginctl.c b/src/login/loginctl.c
index 918e05e1cd..3e135858a8 100644
--- a/src/login/loginctl.c
+++ b/src/login/loginctl.c
@@ -22,6 +22,7 @@
 #include "main-func.h"
 #include "memory-util.h"
 #include "pager.h"
+#include "parse-argument.h"
 #include "parse-util.h"
 #include "pretty-print.h"
 #include "process-util.h"
@@ -1395,14 +1396,9 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case 's':
-                        if (streq(optarg, "help")) {
-                                DUMP_STRING_TABLE(signal, int, _NSIG);
-                                return 0;
-                        }
-
-                        arg_signal = signal_from_string(optarg);
-                        if (arg_signal < 0)
-                                return log_error_errno(arg_signal, "Failed to parse signal string %s.", optarg);
+                        r = parse_signal_argument(optarg, &arg_signal);
+                        if (r <= 0)
+                                return r;
                         break;
 
                 case 'H':
diff --git a/src/machine/machinectl.c b/src/machine/machinectl.c
index 3d6048eaff..1ae10e5880 100644
--- a/src/machine/machinectl.c
+++ b/src/machine/machinectl.c
@@ -39,6 +39,7 @@
 #include "mkdir.h"
 #include "nulstr-util.h"
 #include "pager.h"
+#include "parse-argument.h"
 #include "parse-util.h"
 #include "path-util.h"
 #include "pretty-print.h"
@@ -2715,15 +2716,9 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case 's':
-                        if (streq(optarg, "help")) {
-                                DUMP_STRING_TABLE(signal, int, _NSIG);
-                                return 0;
-                        }
-
-                        r = signal_from_string(optarg);
-                        if (r < 0)
-                                return log_error_errno(r, "Failed to parse signal string %s.", optarg);
-                        arg_signal = r;
+                        r = parse_signal_argument(optarg, &arg_signal);
+                        if (r <= 0)
+                                return r;
                         break;
 
                 case ARG_NO_ASK_PASSWORD:
diff --git a/src/shared/meson.build b/src/shared/meson.build
index 4e47e15c09..6d9a5c5b65 100644
--- a/src/shared/meson.build
+++ b/src/shared/meson.build
@@ -202,6 +202,8 @@ shared_sources = files('''
         output-mode.h
         pager.c
         pager.h
+        parse-argument.c
+        parse-argument.h
         pe-header.h
         pkcs11-util.c
         pkcs11-util.h
diff --git a/src/shared/parse-argument.c b/src/shared/parse-argument.c
new file mode 100644
index 0000000000..a30d3adc13
--- /dev/null
+++ b/src/shared/parse-argument.c
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "parse-argument.h"
+#include "signal-util.h"
+#include "string-table.h"
+#include "string-util.h"
+
+int parse_signal_argument(const char *s, int *ret) {
+        int r;
+
+        assert(s);
+        assert(ret);
+
+        if (streq(s, "help")) {
+                DUMP_STRING_TABLE(signal, int, _NSIG);
+                return 0;
+        }
+
+        r = signal_from_string(s);
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse signal string \"%s\".", s);
+
+        *ret = r;
+        return 1; /* work to do */
+}
diff --git a/src/shared/parse-argument.h b/src/shared/parse-argument.h
new file mode 100644
index 0000000000..7a5419174d
--- /dev/null
+++ b/src/shared/parse-argument.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+int parse_signal_argument(const char *s, int *ret);
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 97a02ff035..0371ff355e 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -11,6 +11,7 @@
 #include "main-func.h"
 #include "output-mode.h"
 #include "pager.h"
+#include "parse-argument.h"
 #include "path-util.h"
 #include "pretty-print.h"
 #include "rlimit-util.h"
@@ -673,16 +674,9 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                         break;
 
                 case 's':
-                        if (streq(optarg, "help")) {
-                                DUMP_STRING_TABLE(signal, int, _NSIG);
-                                return 0;
-                        }
-
-                        arg_signal = signal_from_string(optarg);
-                        if (arg_signal < 0)
-                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
-                                                       "Failed to parse signal string %s.",
-                                                       optarg);
+                        r = parse_signal_argument(optarg, &arg_signal);
+                        if (r <= 0)
+                                return r;
                         break;
 
                 case ARG_NO_ASK_PASSWORD: