Add $SYSTEMD_INVOKED_AS (#42286)

docs/ENVIRONMENT.md

@@ -35,11 +35,15 @@ All tools:
   no-ops. If that's what's explicitly desired, you might consider setting
   `$SYSTEMD_OFFLINE=1`.
 
+* `$SYSTEMD_IN_INITRD` — takes a boolean. If set, overrides initrd detection.
+  This is useful for debugging and testing initrd-only programs in the main
+  system.
+
 * `$SYSTEMD_FIRST_BOOT=0|1` — if set, assume "first boot" condition to be false
   or true, instead of checking the flag file created by PID 1.
 
-* `$SD_EVENT_PROFILE_DELAYS=1` — if set, the sd-event event loop implementation
-  will print latency information at runtime.
+* `$SYSTEMD_INVOKED_AS=name` — override argv[0] for detection of a multicall
+  binary. E.g. `SYSTEMD_INVOKED_AS=systemd-udevd build/udevadm`.
 
 * `$SYSTEMD_PROC_CMDLINE` — if set, the contents are used as the kernel command
   line instead of the actual one in `/proc/cmdline`. This is useful for
@@ -76,9 +80,8 @@ All tools:
   (relevant in particular for the system manager and `systemd-hostnamed`).
   Must be a valid hostname (either a single label or a FQDN).
 
-* `$SYSTEMD_IN_INITRD` — takes a boolean. If set, overrides initrd detection.
-  This is useful for debugging and testing initrd-only programs in the main
-  system.
+* `$SD_EVENT_PROFILE_DELAYS=1` — if set, the sd-event event loop implementation
+  will print latency information at runtime.
 
 * `$SYSTEMD_BUS_TIMEOUT=SECS` — specifies the maximum time to wait for method call
   completion. If no time unit is specified, assumes seconds. The usual other units

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;

test/units/TEST-75-RESOLVED.sh

@@ -248,19 +248,14 @@ manual_testcase_01_resolvectl() {
     resolvectl dns hoge.foo 10.0.1.3 10.0.1.4
     assert_in '10.0.1.1 10.0.1.2' "$(resolvectl dns hoge)"
     assert_in '10.0.1.3 10.0.1.4' "$(resolvectl dns hoge.foo)"
-    if ! RESOLVCONF=$(command -v resolvconf 2>/dev/null); then
-        TMPDIR=$(mktemp -d -p /tmp resolvconf-tests.XXXXXX)
-        RESOLVCONF="$TMPDIR"/resolvconf
-        ln -s "$(command -v resolvectl 2>/dev/null)" "$RESOLVCONF"
-    fi
 
     # DNS servers
-    echo nameserver 10.0.2.1 10.0.2.2 | "$RESOLVCONF" -a hoge
-    echo nameserver 10.0.2.3 10.0.2.4 | "$RESOLVCONF" -a hoge.foo
+    echo nameserver 10.0.2.1 10.0.2.2 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge
+    echo nameserver 10.0.2.3 10.0.2.4 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge.foo
     assert_in '10.0.2.1 10.0.2.2' "$(resolvectl dns hoge)"
     assert_in '10.0.2.3 10.0.2.4' "$(resolvectl dns hoge.foo)"
-    echo nameserver 10.0.3.1 10.0.3.2 | "$RESOLVCONF" -a hoge.inet.ipsec.192.168.35
-    echo nameserver 10.0.3.3 10.0.3.4 | "$RESOLVCONF" -a hoge.foo.dhcp
+    echo nameserver 10.0.3.1 10.0.3.2 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge.inet.ipsec.192.168.35
+    echo nameserver 10.0.3.3 10.0.3.4 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge.foo.dhcp
     assert_in '10.0.3.1 10.0.3.2' "$(resolvectl dns hoge)"
     assert_in '10.0.3.3 10.0.3.4' "$(resolvectl dns hoge.foo)"
 
@@ -268,36 +263,37 @@ manual_testcase_01_resolvectl() {
     # without domain/search clears existing domain
     resolvectl domain hoge test-domain.example.com
     assert_in 'test-domain.example.com' "$(resolvectl domain hoge)"
-    echo nameserver 10.0.2.1 10.0.2.2 | "$RESOLVCONF" -a hoge
+    echo nameserver 10.0.2.1 10.0.2.2 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge
     assert_not_in 'test-domain.example.com' "$(resolvectl domain hoge)"
     # cannot set domain without DNS servers
-    (! echo domain test-domain.example.com | "$RESOLVCONF" -a hoge)
+    (! echo domain test-domain.example.com | SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge)
     # can set domain with DNS server(s)
-    echo -e "nameserver 10.0.2.1 10.0.2.2\ndomain test-domain1.example.com test-domain2.example.com\nsearch test-search-domain.example.com" | "$RESOLVCONF" -a hoge
+    echo -e "nameserver 10.0.2.1 10.0.2.2\ndomain test-domain1.example.com test-domain2.example.com\nsearch test-search-domain.example.com" | \
+        SYSTEMD_INVOKED_AS=resolvconf resolvectl -a hoge
     assert_in 'test-domain1.example.com' "$(resolvectl domain hoge)"
     assert_in 'test-domain2.example.com' "$(resolvectl domain hoge)"
     assert_in 'test-search-domain.example.com' "$(resolvectl domain hoge)"
 
     # Tests for 'resolvconf -x'
-    echo nameserver 10.0.2.1 | "$RESOLVCONF" -x -a hoge
+    echo nameserver 10.0.2.1 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -x -a hoge
     assert_in '~.' "$(resolvectl domain hoge)"
     resolvectl domain hoge "hoge.example.com"
     assert_in 'hoge.example.com' "$(resolvectl domain hoge)"
     assert_not_in '~.' "$(resolvectl domain hoge)"
-    echo -e "nameserver 10.0.2.1\ndomain test-domain.example.com" | "$RESOLVCONF" -x -a hoge
+    echo -e "nameserver 10.0.2.1\ndomain test-domain.example.com" | SYSTEMD_INVOKED_AS=resolvconf resolvectl -x -a hoge
     assert_in 'test-domain.example.com' "$(resolvectl domain hoge)"
     assert_in '~.' "$(resolvectl domain hoge)"
 
     # Tests for 'resolvconf -p'
     resolvectl default-route hoge yes
     assert_in 'yes' "$(resolvectl default-route hoge)"
-    echo nameserver 10.0.3.3 10.0.3.4 | "$RESOLVCONF" -p -a hoge
+    echo nameserver 10.0.3.3 10.0.3.4 | SYSTEMD_INVOKED_AS=resolvconf resolvectl -p -a hoge
     assert_in 'no' "$(resolvectl default-route hoge)"
 
     # Tests for 'resolvconf -d'
     resolvectl dns hoge 10.0.3.1 10.0.3.2
     resolvectl domain hoge test-domain.example.com
-    "$RESOLVCONF" -d hoge
+    SYSTEMD_INVOKED_AS=resolvconf resolvectl -d hoge
     assert_not_in '10.0.3.1' "$(resolvectl dns hoge)"
     assert_not_in '10.0.3.2' "$(resolvectl dns hoge)"
     assert_not_in 'test-domain.example.com' "$(resolvectl domain hoge)"