utils: replace the legacy function ogConfigureFstab

Implement configure_fstab() as a replacement of ogConfigureFstab.

Create src/utils/fstab.py to implement the main fstab
configuration functions. Define two fstab helper classes,
FstabBuilder and FstabEntry.

FstabEntry
Represents each line in the fstab file.
Has the values: device, mountpoint, fstype, options, dump_code
and pass_code.

FstabBuilder
Contains a list of FstabEntry. Handles loading of a
preexisting fstab file and the serialization of multiple
FstabEntry into a file.

The fstab configuration has 3 main steps:

Root partition:
- Update the device field with the device where
the new system is installed.

Swap partition:
- Preserve all the swapfile entries in every case.
- If the filesystem has a swap partition: update the device field
  in the first fstab swap entry and remove the rest swap entries
  pointing to a swap partition. Only one swap partition is supported.
  Create a new fstab entry if no preexisting swap entry exists.
- If the system has no swap partition remove every swap partition
  entry.

EFI partition:
- Update the device field of the EFI fstab entry if it exists.
  Create a new fstab entry if no preexisting EFI entry exists.

Add get_filesystem_id to disk.py to obtain the UUID.
Define every device field as a UUID. That method is more robust
than a plain device path as it works after disks being added or
removed.

1 files changed, 11 insertions, 9 deletions

diff --git a/src/utils/postinstall.py b/src/utils/postinstall.py
index 7e21e67..94a7e4b 100644
--- a/src/utils/postinstall.py
+++ b/src/utils/postinstall.py
@@ -18,6 +18,7 @@ from src.utils.disk import *
 from src.utils.winreg import *
 from src.utils.fs import *
 from src.utils.uefi import *
+from src.utils.fstab import *
 from socket import gethostname
 
 CONFIGUREOS_LEGACY_ENABLED = False
@@ -148,16 +149,17 @@ def configure_grub_in_mbr(disk, partition):
 
 
 def configure_fstab(disk, partition):
-    cmd_configure = f"ogConfigureFstab {disk} {partition}"
+    logging.info(f'Configuring /etc/fstab')
+    device = get_partition_device(disk, partition)
+    mountpoint = device.replace('dev', 'mnt')
 
-    proc = subprocess.run(cmd_configure,
-                          stdout=subprocess.DEVNULL,
-                          stderr=subprocess.DEVNULL,
-                          encoding='utf-8',
-                          shell=True,
-                          check=True)
-    if proc.returncode != 0:
-        logging.warning(f'{cmd_configure} returned non-zero exit status {proc.returncode}')
+    if not mount_mkdir(device, mountpoint):
+        raise OgError(f'Unable to mount {device} into {mountpoint}')
+
+    try:
+        update_fstab(disk, partition, mountpoint)
+    finally:
+        umount(mountpoint)
 
 
 def install_grub(disk, partition):