Blame SOURCES/0486-normal-main-Discover-the-device-to-read-the-config-f.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Javier Martinez Canillas <javierm@redhat.com>
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Date: Thu, 8 Jul 2021 16:39:39 +0200
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Subject: [PATCH] normal/main: Discover the device to read the config from as a
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 fallback
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The GRUB core.img is generated locally, when this is done the grub2-probe
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tool figures out the device and partition that needs to be read to parse
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the GRUB configuration file.
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But in some cases the core.img can't be generated on the host and instead
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has to be done at package build time. For example, if needs to get signed
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with a key that's only available on the package building infrastructure.
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If that's the case, the prefix variable won't have a device and partition
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but only a directory path. So there's no way for GRUB to know from which
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device has to read the configuration file.
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To allow GRUB to continue working on that scenario, fallback to iterating
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over all the available devices, if reading the config failed when using
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the prefix and fw_path variables.
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Related: rhbz#1899864
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Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
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---
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 grub-core/normal/main.c | 58 +++++++++++++++++++++++++++++++++++++++++++------
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 1 file changed, 51 insertions(+), 7 deletions(-)
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diff --git a/grub-core/normal/main.c b/grub-core/normal/main.c
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index 49141039f8f..93f33c16732 100644
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--- a/grub-core/normal/main.c
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+++ b/grub-core/normal/main.c
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@@ -333,16 +333,11 @@ grub_enter_normal_mode (const char *config)
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 }
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 static grub_err_t
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-grub_try_normal (const char *variable)
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+grub_try_normal_prefix (const char *prefix)
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 {
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     char *config;
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-    const char *prefix;
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     grub_err_t err = GRUB_ERR_FILE_NOT_FOUND;
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-    prefix = grub_env_get (variable);
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-    if (!prefix)
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-      return GRUB_ERR_FILE_NOT_FOUND;
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-
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     if (grub_strncmp (prefix + 1, "tftp", sizeof ("tftp") - 1) == 0)
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       {
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 	grub_size_t config_len;
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@@ -351,7 +346,7 @@ grub_try_normal (const char *variable)
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 	config = grub_malloc (config_len);
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 	if (! config)
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-	  return GRUB_ERR_FILE_NOT_FOUND;
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+	  return err;
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 	grub_snprintf (config, config_len, "%s/grub.cfg", prefix);
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 	err = grub_net_search_configfile (config);
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@@ -380,6 +375,53 @@ grub_try_normal (const char *variable)
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     return err;
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 }
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+static int
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+grub_try_normal_dev (const char *name, void *data)
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+{
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+  grub_err_t err;
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+  const char *prefix = grub_xasprintf ("(%s)%s", name, (char *)data);
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+
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+  if (!prefix)
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+    return 0;
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+
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+  err = grub_try_normal_prefix (prefix);
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+  if (err == GRUB_ERR_NONE)
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+    return 1;
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+
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+  return 0;
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+}
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+
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+static grub_err_t
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+grub_try_normal_discover (void)
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+{
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+  char *prefix = grub_env_get ("prefix");
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+  grub_err_t err = GRUB_ERR_FILE_NOT_FOUND;
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+
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+  if (!prefix)
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+    return err;
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+
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+  if (grub_device_iterate (grub_try_normal_dev, (void *)prefix))
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+    return GRUB_ERR_NONE;
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+
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+  return err;
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+}
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+
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+static grub_err_t
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+grub_try_normal (const char *variable)
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+{
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+  grub_err_t err = GRUB_ERR_FILE_NOT_FOUND;
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+  const char *prefix;
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+
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+  if (!variable)
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+    return err;
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+
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+  prefix = grub_env_get (variable);
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+  if (!prefix)
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+    return err;
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+
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+  return grub_try_normal_prefix (prefix);
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+}
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+
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 /* Enter normal mode from rescue mode.  */
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 static grub_err_t
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 grub_cmd_normal (struct grub_command *cmd __attribute__ ((unused)),
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@@ -394,6 +436,8 @@ grub_cmd_normal (struct grub_command *cmd __attribute__ ((unused)),
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       err = grub_try_normal ("fw_path");
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       if (err == GRUB_ERR_FILE_NOT_FOUND)
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         err = grub_try_normal ("prefix");
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+      if (err == GRUB_ERR_FILE_NOT_FOUND)
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+        err = grub_try_normal_discover ();
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       if (err == GRUB_ERR_FILE_NOT_FOUND)
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         grub_enter_normal_mode (0);
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     }