sd-boot: write the IDs of all discovered entries to an EFI variable

This is primarily useful for debugging, but can be useful for other
purposes too. For example userspace could check whether "auto-windows"
is included in the list, before triggering a boot-into-windows
operation.

3 files changed, 28 insertions, 1 deletions

diff --git a/src/boot/efi/boot.c b/src/boot/efi/boot.c
index 02c46c44c2..7fff880414 100644
--- a/src/boot/efi/boot.c
+++ b/src/boot/efi/boot.c
@@ -2028,6 +2028,29 @@ static VOID config_free(Config *config) {
         FreePool(config->entry_oneshot);
 }
 
+static VOID config_write_entries_to_variable(Config *config) {
+        _cleanup_freepool_ CHAR16 *buffer = NULL;
+        UINTN i, sz = 0;
+        CHAR16 *p;
+
+        for (i = 0; i < config->entry_count; i++)
+                sz += StrLen(config->entries[i]->id) + 1;
+
+        p = buffer = AllocatePool(sz * sizeof(CHAR16));
+
+        for (i = 0; i < config->entry_count; i++) {
+                UINTN l;
+
+                l = StrLen(config->entries[i]->id) + 1;
+                CopyMem(p, config->entries[i]->id, l * sizeof(CHAR16));
+
+                p += l;
+        }
+
+        /* Store the full list of discovered entries. */
+        (void) efivar_set_raw(&loader_guid, L"LoaderEntries", buffer, (UINT8*) p - (UINT8*) buffer, FALSE);
+}
+
 EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
         _cleanup_freepool_ CHAR16 *infostr = NULL, *typestr = NULL;
         CHAR8 *b;
@@ -2119,6 +2142,8 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
                 goto out;
         }
 
+        config_write_entries_to_variable(&config);
+
         config_title_generate(&config);
 
         /* select entry by configured pattern or EFI LoaderDefaultEntry= variable */
diff --git a/src/boot/efi/util.c b/src/boot/efi/util.c
index e286b14bcc..fd4be681a5 100644
--- a/src/boot/efi/util.c
+++ b/src/boot/efi/util.c
@@ -10,7 +10,7 @@
  * the (ESP)\loader\entries\<vendor>-<revision>.conf convention and the
  * associated EFI variables.
  */
-static const EFI_GUID loader_guid = { 0x4a67b082, 0x0a4c, 0x41cf, {0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f} };
+const EFI_GUID loader_guid = { 0x4a67b082, 0x0a4c, 0x41cf, {0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f} };
 
 #ifdef __x86_64__
 UINT64 ticks_read(VOID) {
diff --git a/src/boot/efi/util.h b/src/boot/efi/util.h
index ae06444014..40ede66d4a 100644
--- a/src/boot/efi/util.h
+++ b/src/boot/efi/util.h
@@ -50,3 +50,5 @@ static inline void FileHandleClosep(EFI_FILE_HANDLE *handle) {
 
         uefi_call_wrapper((*handle)->Close, 1, *handle);
 }
+
+const EFI_GUID loader_guid;