nspawn: optionally tint the background color of a container

systemd · Jan 23, 2024 · 3d8ba7b · 3d8ba7b
1 parent 9ebd115
commit 3d8ba7b
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Showing 3 changed files with 35 additions and 4 deletions.
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
@@ -1711,6 +1711,21 @@ After=sys-subsystem-net-devices-ens1.device</programlisting>
 
         <xi:include href="version-info.xml" xpointer="v242"/></listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><option>--background=<replaceable>COLOR</replaceable></option></term>
+
+        <listitem><para>Change the terminal background color to the specified ANSI color as long as the
+        container runs. The color specified should be an ANSI X3.64 SGR background color, i.e. strings such
+        as <literal>40</literal>, <literal>41</literal>, …, <literal>47</literal>, <literal>48;2;…</literal>,
+        <literal>48;5;…</literal>. See <ulink
+        url="https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters">ANSI
+        Escape Code (Wikipedia)</ulink> for details. Assign an empty string to disable any coloring.</para>
+
+        <xi:include href="version-info.xml" xpointer="v256"/>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
 
     </refsect2>

diff --git a/shell-completion/bash/systemd-nspawn b/shell-completion/bash/systemd-nspawn
@@ -73,7 +73,7 @@ _systemd_nspawn() {
                       --pivot-root --property --private-users --private-users-ownership --network-namespace-path
                       --network-ipvlan --network-veth-extra --network-zone -p --port --system-call-filter --overlay
                       --overlay-ro --settings --rlimit --hostname --no-new-privileges --oom-score-adjust --cpu-affinity
-                      --resolv-conf --timezone --root-hash-sig'
+                      --resolv-conf --timezone --root-hash-sig --background'
     )
 
     _init_completion || return

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
@@ -236,6 +236,7 @@ static bool arg_suppress_sync = false;
 static char *arg_settings_filename = NULL;
 static Architecture arg_architecture = _ARCHITECTURE_INVALID;
 static ImagePolicy *arg_image_policy = NULL;
+static char *arg_background = NULL;
 
 STATIC_DESTRUCTOR_REGISTER(arg_directory, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_template, freep);
@@ -272,6 +273,7 @@ STATIC_DESTRUCTOR_REGISTER(arg_sysctl, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_bind_user, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_settings_filename, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_image_policy, image_policy_freep);
+STATIC_DESTRUCTOR_REGISTER(arg_background, freep);
 
 static int handle_arg_console(const char *arg) {
         if (streq(arg, "help")) {
@@ -450,6 +452,7 @@ static int help(void) {
                "     --console=MODE         Select how stdin/stdout/stderr and /dev/console are\n"
                "                            set up for the container.\n"
                "  -P --pipe                 Equivalent to --console=pipe\n\n"
+               "     --background=COLOR     Set ANSI color for background\n"
                "%3$sCredentials:%4$s\n"
                "     --set-credential=ID:VALUE\n"
                "                            Pass a credential with literal value to container.\n"
@@ -745,6 +748,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_BIND_USER,
                 ARG_SUPPRESS_SYNC,
                 ARG_IMAGE_POLICY,
+                ARG_BACKGROUND,
         };
 
         static const struct option options[] = {
@@ -819,6 +823,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "bind-user",              required_argument, NULL, ARG_BIND_USER              },
                 { "suppress-sync",          required_argument, NULL, ARG_SUPPRESS_SYNC          },
                 { "image-policy",           required_argument, NULL, ARG_IMAGE_POLICY           },
+                { "background",             required_argument, NULL, ARG_BACKGROUND             },
                 {}
         };
 
@@ -1608,6 +1613,12 @@ static int parse_argv(int argc, char *argv[]) {
                                 return r;
                         break;
 
+                case ARG_BACKGROUND:
+                        r = free_and_strdup_warn(&arg_background, optarg);
+                        if (r < 0)
+                                return r;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -5339,9 +5350,14 @@ static int run_container(
                                 return log_error_errno(r, "Failed to create PTY forwarder: %m");
 
                         if (arg_console_width != UINT_MAX || arg_console_height != UINT_MAX)
-                                (void) pty_forward_set_width_height(forward,
-                                                                    arg_console_width,
-                                                                    arg_console_height);
+                                (void) pty_forward_set_width_height(
+                                                forward,
+                                                arg_console_width,
+                                                arg_console_height);
+
+                        if (!isempty(arg_background))
+                                (void) pty_forward_set_background_color(forward, arg_background);
+
                         break;
 
                 default: