Add $SYSTEMD_INVOKED_AS (#42286)

src/basic/argv-util.c

@@ -29,13 +29,15 @@ void save_argc_argv(int argc, char **argv) {
 }
 
 bool invoked_as(char *argv[], const char *token) {
-        if (!argv || isempty(argv[0]))
+        const char *progname = secure_getenv("SYSTEMD_INVOKED_AS");
+
+        if (!progname && argv)
+                progname = argv[0];
+
+        if (isempty(progname) || isempty(token))
                 return false;
 
-        if (isempty(token))
-                return false;
-
-        return strstr(last_path_component(argv[0]), token);
+        return strstr(last_path_component(progname), token);
 }
 
 bool invoked_by_systemd(void) {

src/shared/help-util.c

@@ -1,8 +1,11 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <stdlib.h>
+
 #include "alloc-util.h"
 #include "ansi-color.h"
 #include "help-util.h"
+#include "path-util.h"
 #include "pretty-print.h"
 
 /* These are helpers for putting together --help texts in a uniform way with a common output style. Each
@@ -25,12 +28,16 @@
  *   options.[ch] APIs. */
 
 void help_cmdline(const char *arguments) {
+        const char *progname =
+                last_path_component(secure_getenv("SYSTEMD_INVOKED_AS"))
+                ?: program_invocation_short_name;
+
         assert(arguments);
 
         printf("%s>%s %s %s\n",
                ansi_grey(),
                ansi_normal(),
-               program_invocation_short_name,
+               progname,
                arguments);
 }
 

src/test/test-process-util.c

@@ -1125,6 +1125,21 @@ TEST(getenv_for_pid) {
         }
 }
 
+TEST(invoked_as) {
+        ASSERT_FALSE(invoked_as(NULL, "foobar"));
+        ASSERT_FALSE(invoked_as(NULL, "barbar"));
+
+        ASSERT_EQ(setenv("SYSTEMD_INVOKED_AS", "/usr/bin/foobar", 1), 0);
+
+        ASSERT_TRUE(invoked_as(NULL, "foobar"));
+        ASSERT_FALSE(invoked_as(NULL, "barbar"));
+        ASSERT_TRUE(invoked_as(NULL, "foo"));
+        ASSERT_TRUE(invoked_as(STRV_MAKE("barbar", "barbar", "y"), "foobar"));
+        ASSERT_FALSE(invoked_as(STRV_MAKE("barbar", "barbar", "y"), "barbar"));
+
+        ASSERT_EQ(unsetenv("SYSTEMD_INVOKED_AS"), 0);
+}
+
 static int intro(void) {
         log_show_color(true);
         return EXIT_SUCCESS;