[bootloader] Fix systemd-boot installation

When choosing `systemd-boot` as the bootloader, numerous problems
occurred:

- the kernel and initrd were not copied to the EFI System Partition,
and therefore could not be reached by the bootloader
- the fallback entry used the default initramfs image instead of the
fallback image

`systemd-boot` provides the `kernel-install` utility, which
automatically copies the kernel + initramfs to the EFI partition, and
creates the corresponding bootloader entry.

Unfortunately, `kernel-install` cannot be used here as the module is not
executed in a chroot. As setting up one only for running a single
command would be overkill, this patch re-creates what `kernel-install`
usually does:

- copy the kernel and initramfs to their own subdirectory at the root of
the EFI partition
- create the corresponding entry configuration file

To this end, the `systemd-boot` installation code in the `bootloader`
module has been largely refactored, including removing a few duplicate
LOCs.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>

src/modules/bootloader/main.py

@@ -87,17 +87,18 @@ def get_kernel_line(kernel_type):
             return ""
 
 
-def create_systemd_boot_conf(uuid, conf_path, kernel_line):
+def create_systemd_boot_conf(install_path, efi_dir, uuid, entry, entry_name, kernel_type):
     """
     Creates systemd-boot configuration files based on given parameters.
 
+    :param install_path:
+    :param efi_dir:
     :param uuid:
-    :param conf_path:
-    :param kernel_line:
+    :param entry:
+    :param entry_name:
+    :param kernel_type:
     """
-    distribution = get_bootloader_entry_name()
     kernel = libcalamares.job.configuration["kernel"]
-    img = libcalamares.job.configuration["img"]
     kernel_params = ["quiet"]
 
     partitions = libcalamares.globalstorage.value("partitions")
@@ -131,14 +132,40 @@ def create_systemd_boot_conf(uuid, conf_path, kernel_line):
     if swap_uuid:
         kernel_params.append("resume=UUID={!s}".format(swap_uuid))
 
+    kernel_line = get_kernel_line(kernel_type)
+    libcalamares.utils.debug("Configure: \"{!s}\"".format(kernel_line))
+
+    if kernel_type == "fallback":
+        img = libcalamares.job.configuration["fallback"]
+        entry_name = entry_name + "-fallback"
+    else:
+        img = libcalamares.job.configuration["img"]
+
+    conf_path = os.path.join(install_path + efi_dir,
+                             "loader",
+                             "entries",
+                             entry_name + ".conf")
+
+    # Copy kernel and initramfs to a subdirectory of /efi partition
+    files_dir = os.path.join(install_path + efi_dir, entry_name)
+    os.mkdir(files_dir)
+
+    kernel_path = install_path + kernel
+    kernel_name = os.path.basename(kernel_path)
+    shutil.copyfile(kernel_path, os.path.join(files_dir, kernel_name))
+
+    img_path = install_path + img
+    img_name = os.path.basename(img_path)
+    shutil.copyfile(img_path, os.path.join(files_dir, img_name))
+
     lines = [
         '## This is just an example config file.\n',
         '## Please edit the paths and kernel parameters according\n',
         '## to your system.\n',
         '\n',
-        "title   {!s}{!s}\n".format(distribution, kernel_line),
-        "linux   {!s}\n".format(kernel),
-        "initrd  {!s}\n".format(img),
+        "title   {!s}{!s}\n".format(entry, kernel_line),
+        "linux   {!s}\n".format(os.path.join("/", entry_name, kernel_name)),
+        "initrd  {!s}\n".format(os.path.join("/", entry_name, img_name)),
         "options {!s} rw\n".format(" ".join(kernel_params)),
     ]
 
@@ -147,19 +174,17 @@ def create_systemd_boot_conf(uuid, conf_path, kernel_line):
             conf_file.write(line)
 
 
-def create_loader(loader_path):
+def create_loader(loader_path, entry):
     """
     Writes configuration for loader.
 
     :param loader_path:
+    :param entry:
     """
-    distribution = get_bootloader_entry_name()
     timeout = libcalamares.job.configuration["timeout"]
-    file_name_sanitizer = str.maketrans(" /", "_-")
-    distribution_translated = distribution.translate(file_name_sanitizer)
     lines = [
         "timeout {!s}\n".format(timeout),
-        "default {!s}\n".format(distribution_translated),
+        "default {!s}\n".format(entry),
     ]
 
     with open(loader_path, 'w') as loader_file:
@@ -204,27 +229,26 @@ def install_systemd_boot(efi_directory):
     distribution = get_bootloader_entry_name()
     file_name_sanitizer = str.maketrans(" /", "_-")
     distribution_translated = distribution.translate(file_name_sanitizer)
-    conf_path = os.path.join(install_efi_directory,
-                             "loader",
-                             "entries",
-                             distribution_translated + ".conf")
-    fallback_path = os.path.join(install_efi_directory,
-                                 "loader",
-                                 "entries",
-                                 distribution_translated + "-fallback.conf")
     loader_path = os.path.join(install_efi_directory,
                                "loader",
                                "loader.conf")
     subprocess.call(["bootctl",
                      "--path={!s}".format(install_efi_directory),
                      "install"])
-    kernel_line = get_kernel_line("default")
-    libcalamares.utils.debug("Configure: \"{!s}\"".format(kernel_line))
-    create_systemd_boot_conf(uuid, conf_path, kernel_line)
-    kernel_line = get_kernel_line("fallback")
-    libcalamares.utils.debug("Configure: \"{!s}\"".format(kernel_line))
-    create_systemd_boot_conf(uuid, fallback_path, kernel_line)
-    create_loader(loader_path)
+    create_systemd_boot_conf(install_path,
+                             efi_directory,
+                             uuid,
+                             distribution,
+                             distribution_translated,
+                             "default")
+    if "fallback" in libcalamares.job.configuration:
+        create_systemd_boot_conf(install_path,
+                                 efi_directory,
+                                 uuid,
+                                 distribution,
+                                 distribution_translated,
+                                 "fallback")
+    create_loader(loader_path, distribution_translated)
 
 
 def install_grub(efi_directory, fw_type):