From 496b6b20cbce3fc27228d1d8290089fb7107b8de Mon Sep 17 00:00:00 2001
From: Michael Chang <[email protected]>
Date: Fri, 18 Feb 2022 21:51:16 +0800
Subject: [PATCH 5/5] export environment at start up

If the prep_loadenv module is built into the core image, it will read
the environment block automatically during start up and export all
variables. The will ease integration with those without early scripts to
running the command.

Signed-off-by: Michael Chang <[email protected]>
---
 grub-core/Makefile.core.def       |  2 +
 grub-core/commands/prep_loadenv.c | 77 +++++++++++++++++++++++++++++++
 grub-core/kern/env.c              |  2 +
 grub-core/kern/main.c             |  3 ++
 include/grub/env.h                |  1 +
 5 files changed, 85 insertions(+)

--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -2678,4 +2678,6 @@
   name = prep_loadenv;
   common = commands/prep_loadenv.c;
   enable = powerpc_ieee1275;
+  cflags = '$(CFLAGS_POSIX) $(CFLAGS_GNULIB)';
+  cppflags = '$(CPPFLAGS_POSIX) $(CPPFLAGS_GNULIB)';
 };
--- a/grub-core/commands/prep_loadenv.c
+++ b/grub-core/commands/prep_loadenv.c
@@ -10,6 +10,7 @@
 #include <grub/extcmd.h>
 #include <grub/i18n.h>
 #include <grub/gpt_partition.h>
+#include <regex.h>
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
@@ -185,6 +186,65 @@
 }
 
 static grub_err_t
+boot_disk_prep_partname (char **name)
+{
+  regex_t regex;
+  int ret;
+  grub_size_t s;
+  char *comperr;
+  const char *cmdpath;
+  regmatch_t *matches = NULL;
+  grub_err_t err = GRUB_ERR_NONE;
+
+  *name = NULL;
+
+  cmdpath = grub_env_get ("cmdpath");
+  if (!cmdpath)
+    return GRUB_ERR_NONE;
+
+  ret = regcomp (&regex, "\\(([^,]+)(,?.*)?\\)(.*)", REG_EXTENDED);
+  if (ret)
+    goto fail;
+
+  matches = grub_calloc (regex.re_nsub + 1, sizeof (*matches));
+  if (! matches)
+    goto fail;
+
+  ret = regexec (&regex, cmdpath, regex.re_nsub + 1, matches, 0);
+  if (!ret)
+    {
+      char *devname = devname = match_substr (matches + 1, cmdpath);
+      if (!devname)
+	{
+	  err = grub_error (GRUB_ERR_FILE_NOT_FOUND, "%s contains no disk name", cmdpath);
+	  goto out;
+	}
+
+      err = prep_partname (devname, name);
+ out:
+      grub_free (devname);
+      regfree (&regex);
+      grub_free (matches);
+      return err;
+    }
+
+ fail:
+  grub_free (matches);
+  s = regerror (ret, &regex, 0, 0);
+  comperr = grub_malloc (s);
+  if (!comperr)
+    {
+      regfree (&regex);
+      return grub_errno;
+    }
+  regerror (ret, &regex, comperr, s);
+  err = grub_error (GRUB_ERR_TEST_FAILURE, "%s", comperr);
+  regfree (&regex);
+  grub_free (comperr);
+  return err;
+}
+
+static grub_err_t
 grub_cmd_prep_loadenv (grub_command_t cmd __attribute__ ((unused)),
 		       int argc,
 		       char **argv)
@@ -214,10 +274,27 @@
   return GRUB_ERR_NONE;
 }
 
+static void
+early_prep_loadenv (void)
+{
+  grub_err_t err;
+  char *prep;
+
+  err = boot_disk_prep_partname (&prep);
+  if (err == GRUB_ERR_NONE && prep)
+    err = prep_read_envblk (prep);
+  if (err == GRUB_ERR_BAD_FILE_TYPE || err == GRUB_ERR_FILE_NOT_FOUND)
+    grub_error_pop ();
+  if (err != GRUB_ERR_NONE)
+    grub_print_error ();
+  grub_free (prep);
+}
+
 static grub_command_t cmd_prep_load;
 
 GRUB_MOD_INIT(prep_loadenv)
 {
+  early_env_hook = early_prep_loadenv;
   cmd_prep_load =
     grub_register_command("prep_load_env", grub_cmd_prep_loadenv,
 			  "DEVICE",
--- a/grub-core/kern/env.c
+++ b/grub-core/kern/env.c
@@ -28,6 +28,8 @@
 /* The current context.  */
 struct grub_env_context *grub_current_context = &initial_context;
 
+void (*early_env_hook) (void) = NULL;
+
 /* Return the hash representation of the string S.  */
 static unsigned int
 grub_env_hashval (const char *s)
--- a/grub-core/kern/main.c
+++ b/grub-core/kern/main.c
@@ -309,6 +309,9 @@
 
   grub_boot_time ("Before execution of embedded config.");
 
+  if (early_env_hook != NULL)
+    early_env_hook ();
+
   if (load_config)
     grub_parser_execute (load_config);
 
--- a/include/grub/env.h
+++ b/include/grub/env.h
@@ -69,5 +69,6 @@
 grub_err_t
 grub_env_extractor_close (int source);
 
+extern void (*EXPORT_VAR (early_env_hook)) (void);
 
 #endif /* ! GRUB_ENV_HEADER */