blsuki: Add blscfg command to parse Boot Loader Specification snippets

The BootLoaderSpec (BLS) defines a scheme where different bootloaders can
share a format for boot items and a configuration directory that accepts
these common configurations as drop-in files.

The BLS Specification: https://uapi-group.org/specifications/specs/boot_loader_specification/

Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Will Thompson <wjt@endlessm.com>
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

bootstrap.conf

@@ -24,6 +24,7 @@ gnulib_modules="
   argp
   base64
   error
+  filevercmp
   fnmatch
   getdelim
   getline

docs/grub.texi

@@ -3282,6 +3282,7 @@ These variables have special meaning to GRUB.
 
 @menu
 * biosnum::
+* blsuki_save_default::
 * check_signatures::
 * chosen::
 * cmdpath::
@@ -3345,6 +3346,13 @@ For an alternative approach which also changes BIOS drive mappings for the
 chain-loaded system, @pxref{drivemap}.
 
 
+@node blsuki_save_default
+@subsection blsuki_save_default
+
+If this variable is set, menu entries generated from BLS config files
+(@pxref{blscfg}) will be set as the default boot entry when selected.
+
+
 @node check_signatures
 @subsection check_signatures
 
@@ -6471,6 +6479,7 @@ you forget a command, you can run the command @command{help}
 * background_image::            Load background image for active terminal
 * badram::                      Filter out bad regions of RAM
 * blocklist::                   Print a block list
+* blscfg::                      Load Boot Loader Specification menu entries
 * boot::                        Start up your operating system
 * cat::                         Show the contents of a file
 * clear::                       Clear the screen
@@ -6659,6 +6668,72 @@ Print a block list (@pxref{Block list syntax}) for @var{file}.
 @end deffn
 
 
+@node blscfg
+@subsection blscfg
+
+@deffn Command blscfg [@option{-p|--path} dir] [@option{-f|--enable-fallback}] [@option{-d|--show-default}] [@option{-n|--show-non-default}] [@option{-e|--entry} file]
+Load Boot Loader Specification (BLS) entries into the GRUB menu. Boot entries
+generated from @command{blscfg} won't interfere with entries from @file{grub.cfg} appearing in
+the GRUB menu. Also, entries generated from @command{blscfg} exists only in memory and
+don't update @file{grub.cfg}.
+
+By default, the BLS entries are stored in the @file{/loader/entries} directory in the
+boot partition. If BLS entries are stored elsewhere, the @option{--path} option can be
+used to check a different directory instead of the default location. If no BLS
+entries are found while using the @option{--path} option, the @option{--enable-fallback} option
+can be used to check for entries in the default location.
+
+The @option{--show-default} option allows the default boot entry to be added to the
+GRUB menu from the BLS entries.
+
+The @option{--show-non-default} option allows non-default boot entries to be added to
+the GRUB menu from the BLS entries.
+
+The @option{--entry} option allows specific boot entries to be added to the GRUB menu
+from the BLS entries.
+
+The @option{--entry}, @option{--show-default}, and @option{--show-non-default} options
+are used to filter which BLS entries are added to the GRUB menu. If none are
+used, all entries in the default location or the location specified by @option{--path}
+will be added to the GRUB menu.
+
+A BLS config file example:
+@example
+# /boot/loader/entries/6a9857a393724b7a981ebb5b8495b9ea-3.8.0-2.fc19.x86_64.conf
+title        Fedora 19 (Rawhide)
+sort-key     fedora
+machine-id   6a9857a393724b7a981ebb5b8495b9ea
+version      3.8.0-2.fc19.x86_64
+options      root=UUID=6d3376e4-fc93-4509-95ec-a21d68011da2 quiet
+architecture x64
+linux        /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/linux
+initrd       /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/initrd
+@end example
+
+For more information on BLS entry keys as well as other information on BLS,
+see: @uref{https://uapi-group.org/specifications/specs/boot_loader_specification/, The Boot Loader Specification}. For the GRUB, there are a few additional
+BLS entry keys based on the @command{menuentry} command (@pxref{menuentry}).
+
+The @code{grub_class} key may be used any number of times to group menu entries into
+classes. Menu themes may display different classes using different styles.
+
+The @code{grub_users} key grants specific users access to specific menu
+entries.  @xref{Security}.
+
+The @code{grub_hotkey} key associates a hotkey with a menu entry.
+@var{key} may be a single letter, or one of the aliases @samp{backspace},
+@samp{tab}, or @samp{delete}.
+
+The @code{grub_args} key can be used for any other argument to be passed as positonal
+parameters when the list of commands generated from the BLS config file are
+executed.
+
+Variable expansion using the @samp{$} character (@xref{Shell-like scripting}) may be
+used with BLS config files for the GRUB but might not be compatible with other
+bootloaders.
+@end deffn
+
+
 @node boot
 @subsection boot
 

grub-core/Makefile.core.def

@@ -847,6 +847,18 @@ module = {
   common = commands/blocklist.c;
 };
 
+module = {
+  name = blsuki;
+  common = commands/blsuki.c;
+  common = lib/gnulib/filevercmp.c;
+  enable = powerpc_ieee1275;
+  enable = efi;
+  enable = i386_pc;
+  enable = emu;
+  cflags = '$(CFLAGS_POSIX) $(CFLAGS_GNULIB)';
+  cppflags = '$(CPPFLAGS_POSIX) $(CPPFLAGS_GNULIB)';
+};
+
 module = {
   name = boot;
   common = commands/boot.c;

grub-core/commands/legacycfg.c

@@ -143,7 +143,7 @@ legacy_file (const char *filename)
 	    args[0] = oldname;
 	    grub_normal_add_menu_entry (1, args, NULL, NULL, "legacy",
 					NULL, NULL,
-					entrysrc, 0);
+					entrysrc, 0, NULL);
 	    grub_free (args);
 	    entrysrc[0] = 0;
 	    grub_free (oldname);
@@ -204,7 +204,7 @@ legacy_file (const char *filename)
 	}
       args[0] = entryname;
       grub_normal_add_menu_entry (1, args, NULL, NULL, NULL,
-				  NULL, NULL, entrysrc, 0);
+				  NULL, NULL, entrysrc, 0, NULL);
       grub_free (args);
     }
 

grub-core/commands/menuentry.c

@@ -78,7 +78,7 @@ grub_normal_add_menu_entry (int argc, const char **args,
 			    char **classes, const char *id,
 			    const char *users, const char *hotkey,
 			    const char *prefix, const char *sourcecode,
-			    int submenu)
+			    int submenu, grub_blsuki_entry_t *blsuki)
 {
   int menu_hotkey = 0;
   char **menu_args = NULL;
@@ -188,6 +188,7 @@ grub_normal_add_menu_entry (int argc, const char **args,
   (*last)->args = menu_args;
   (*last)->sourcecode = menu_sourcecode;
   (*last)->submenu = submenu;
+  (*last)->blsuki = blsuki;
 
   menu->size++;
   return GRUB_ERR_NONE;
@@ -286,7 +287,8 @@ grub_cmd_menuentry (grub_extcmd_context_t ctxt, int argc, char **args)
 				       users,
 				       ctxt->state[2].arg, 0,
 				       ctxt->state[3].arg,
-				       ctxt->extcmd->cmd->name[0] == 's');
+				       ctxt->extcmd->cmd->name[0] == 's',
+				       NULL);
 
   src = args[argc - 1];
   args[argc - 1] = NULL;
@@ -303,7 +305,7 @@ grub_cmd_menuentry (grub_extcmd_context_t ctxt, int argc, char **args)
 				  ctxt->state[0].args, ctxt->state[4].arg,
 				  users,
 				  ctxt->state[2].arg, prefix, src + 1,
-				  ctxt->extcmd->cmd->name[0] == 's');
+				  ctxt->extcmd->cmd->name[0] == 's', NULL);
 
   src[len - 1] = ch;
   args[argc - 1] = src;

grub-core/normal/main.c

@@ -21,6 +21,7 @@
 #include <grub/net.h>
 #include <grub/normal.h>
 #include <grub/dl.h>
+#include <grub/menu.h>
 #include <grub/misc.h>
 #include <grub/file.h>
 #include <grub/mm.h>
@@ -67,6 +68,11 @@ grub_normal_free_menu (grub_menu_t menu)
 	  grub_free (entry->args);
 	}
 
+      if (entry->blsuki)
+	{
+	  entry->blsuki->visible = 0;
+	}
+
       grub_free ((void *) entry->id);
       grub_free ((void *) entry->users);
       grub_free ((void *) entry->title);

include/grub/menu.h

@@ -20,6 +20,18 @@
 #ifndef GRUB_MENU_HEADER
 #define GRUB_MENU_HEADER 1
 
+struct grub_blsuki_entry
+{
+  struct grub_blsuki_entry *next;
+  struct grub_blsuki_entry **prev;
+  struct keyval **keyvals;
+  grub_size_t keyvals_size;
+  int nkeyvals;
+  char *filename;
+  bool visible;
+};
+typedef struct grub_blsuki_entry grub_blsuki_entry_t;
+
 struct grub_menu_entry_class
 {
   char *name;
@@ -60,6 +72,9 @@ struct grub_menu_entry
 
   /* The next element.  */
   struct grub_menu_entry *next;
+
+  /* BLS used to populate the entry */
+  grub_blsuki_entry_t *blsuki;
 };
 typedef struct grub_menu_entry *grub_menu_entry_t;
 

include/grub/normal.h

@@ -145,7 +145,7 @@ grub_normal_add_menu_entry (int argc, const char **args, char **classes,
 			    const char *id,
 			    const char *users, const char *hotkey,
 			    const char *prefix, const char *sourcecode,
-			    int submenu);
+			    int submenu, grub_blsuki_entry_t *blsuki);
 
 grub_err_t
 grub_normal_set_password (const char *user, const char *password);