sd-boot: introduce a one-time override for the boot menu timeout

This is useful to allow userspace to request a "boot into boot menu"
feature.

diff --git a/man/systemd-boot.xml b/man/systemd-boot.xml
index 3b726e63a4fa7646488840a2cc08d682aeaaa3c0..e1d1910c910d3e2ed92afdb3b5e94073fa2e763f 100644 (file)
--- a/man/systemd-boot.xml
+++ b/man/systemd-boot.xml
@@ -256,8 +256,12 @@
 
       <varlistentry>
         <term><varname>LoaderConfigTimeout</varname></term>
-        <listitem><para>The menu time-out. Read by the boot loader. (Also, modified by it when the
-        <keycap>t</keycap>/<keycap>T</keycap> keys are used, see above.)</para></listitem>
+        <term><varname>LoaderConfigTimeoutOneShot</varname></term>
+        <listitem><para>The menu time-out in seconds. Read by the boot loader. <varname>LoaderConfigTimeout</varname>
+        is maintained persistently, while <varname>LoaderConfigTimeoutOneShot</varname> is a one-time override which is
+        read once (in which case it takes precedence over <varname>LoaderConfigTimeout</varname>) and then
+        removed. <varname>LoaderConfigTimeout</varname> may be manipulated with the
+        <keycap>t</keycap>/<keycap>T</keycap> keys, see above.)</para></listitem>
       </varlistentry>
 
       <varlistentry>

diff --git a/src/boot/efi/boot.c b/src/boot/efi/boot.c
index 3190849b7e43326ceca3bd7e965cc280d9d8e67c..b2fa8f1e2a55224b29ef8da0f5259322a07dcdcf 100644 (file)
--- a/src/boot/efi/boot.c
+++ b/src/boot/efi/boot.c
@@ -62,6 +62,7 @@ typedef struct {
         BOOLEAN editor;
         BOOLEAN auto_entries;
         BOOLEAN auto_firmware;
+        BOOLEAN force_menu;
         UINTN console_mode;
         enum console_mode_change_type console_mode_change;
 } Config;
@@ -1417,6 +1418,15 @@ static VOID config_load_defaults(Config *config, EFI_FILE *root_dir) {
                 config->timeout_sec = sec;
         } else
                 config->timeout_sec_efivar = -1;
+
+        err = efivar_get_int(L"LoaderConfigTimeoutOneShot", &sec);
+        if (!EFI_ERROR(err)) {
+                /* Unset variable now, after all it's "one shot". */
+                (void) efivar_set(L"LoaderConfigTimeoutOneShot", NULL, TRUE);
+
+                config->timeout_sec = sec;
+                config->force_menu = TRUE; /* force the menu when this is set */
+        }
 }
 
 static VOID config_load_entries(
@@ -2167,7 +2177,9 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
         }
 
         /* select entry or show menu when key is pressed or timeout is set */
-        if (config.timeout_sec == 0) {
+        if (config.force_menu || config.timeout_sec > 0)
+                menu = TRUE;
+        else {
                 UINT64 key;
 
                 err = console_key_read(&key, FALSE);
@@ -2181,8 +2193,7 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
                         else
                                 menu = TRUE;
                 }
-        } else
-                menu = TRUE;
+        }
 
         for (;;) {
                 ConfigEntry *entry;