bootman: only do partitionless boot when the bootloader supports it

src/bootloaders/bootloader.h

@@ -35,12 +35,13 @@ typedef int (*boot_loader_caps)(const BootManager *);
 
 typedef enum {
         BOOTLOADER_CAP_MIN = 1 << 0,
-        BOOTLOADER_CAP_UEFI = 1 << 1,   /**<Bootloader supports UEFI */
-        BOOTLOADER_CAP_GPT = 1 << 2,    /**<Bootloader supports GPT boot partition */
-        BOOTLOADER_CAP_LEGACY = 1 << 3, /**<Bootloader supports legacy boot */
-        BOOTLOADER_CAP_EXTFS = 1 << 4,  /**<Bootloader supports ext2/3/4 */
-        BOOTLOADER_CAP_FATFS = 1 << 5,  /**<Bootloader supports vfat */
-        BOOTLOADER_CAP_MAX = 1 << 6
+        BOOTLOADER_CAP_UEFI = 1 << 1,    /**<Bootloader supports UEFI */
+        BOOTLOADER_CAP_GPT = 1 << 2,     /**<Bootloader supports GPT boot partition */
+        BOOTLOADER_CAP_LEGACY = 1 << 3,  /**<Bootloader supports legacy boot */
+        BOOTLOADER_CAP_EXTFS = 1 << 4,   /**<Bootloader supports ext2/3/4 */
+        BOOTLOADER_CAP_FATFS = 1 << 5,   /**<Bootloader supports vfat */
+        BOOTLOADER_CAP_PARTLESS = 1<< 6, /**<Bootloader supports partitionless boot */
+        BOOTLOADER_CAP_MAX = 1 << 7
 } BootLoaderCapability;
 
 /**

src/bootloaders/extlinux.c

@@ -86,7 +86,8 @@ static int extlinux_get_capabilities(const BootManager *manager)
                 return 0;
         }
 
-        return BOOTLOADER_CAP_GPT | BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_EXTFS;
+        return BOOTLOADER_CAP_GPT | BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_EXTFS |
+               BOOTLOADER_CAP_PARTLESS;
 }
 
 __cbm_export__ const BootLoader extlinux_bootloader = {.name = "extlinux",

src/bootloaders/grub2.c

@@ -564,7 +564,7 @@ int grub2_get_capabilities(const BootManager *manager)
                 return 0;
         }
         /* Or in other words, we're the last bootloader candidate. */
-        return BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_EXTFS;
+        return BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_EXTFS | BOOTLOADER_CAP_PARTLESS;
 }
 
 __cbm_export__ const BootLoader grub2_bootloader = {.name = "grub2",

src/bootloaders/syslinux.c

@@ -88,7 +88,8 @@ static int syslinux_get_capabilities(const BootManager *manager)
                 return 0;
         }
 
-        return BOOTLOADER_CAP_GPT | BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_FATFS;
+        return BOOTLOADER_CAP_GPT | BOOTLOADER_CAP_LEGACY | BOOTLOADER_CAP_FATFS |
+               BOOTLOADER_CAP_PARTLESS;
 }
 
 __cbm_export__ const BootLoader syslinux_bootloader = {.name = "syslinux",

src/bootman/bootman.c

@@ -460,10 +460,9 @@ int mount_boot(BootManager *self, char **boot_directory)
 
         /*
          * Already mounted at the default boot dir or boot doesn't have its own partition,
-         * we check if /boot is empty, if it's not then we assume it's a "partitionless" /boot
-         * (the system has no /boot partition), in both cases there's nothing for us to do
+         * in both cases there's nothing for us to do.
          */
-        if (cbm_system_is_mounted(boot_dir) || !cbm_is_dir_empty(boot_dir)) {
+        if (cbm_system_is_mounted(boot_dir) || check_partitionless_boot(self, boot_dir)) {
                 LOG_INFO("boot_dir is already mounted: %s", boot_dir);
                 *boot_directory = strdup(boot_dir);
                 if (*boot_directory) {
@@ -1011,6 +1010,14 @@ bool boot_manager_is_update_efi_vars(BootManager *self)
         return self->update_efi_vars;
 }
 
+bool check_partitionless_boot(const BootManager *self, const char *boot_dir)
+{
+        assert(self != NULL);
+        return ((self->bootloader->get_capabilities(self) & BOOTLOADER_CAP_PARTLESS)
+                && !(self->sysconfig->wanted_boot_mask & BOOTLOADER_CAP_UEFI)
+                && !cbm_is_dir_empty(boot_dir));
+}
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *

src/bootman/bootman_private.h

@@ -82,6 +82,15 @@ int kernel_compare_reverse(const void *a, const void *b);
  */
 const char *cbm_get_fstype_name(const char *boot_device);
 
+/**
+ * Check if the system supports a "partitionless" (the system has no /boot partition) boot.
+ * Conditions are:
+ * - The bootloader supports this.
+ * - The system is not UEFI.
+ * - The /boot folder is not empty.
+ */
+bool check_partitionless_boot(const BootManager *self, const char *boot_dir);
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *