filesystem: store the actual size in bytes alongside the human readab…

…le size

Currently, the partition form stores the size as a human readable value.
(e.g., 123456K, 1.1G, 1.876G, 100G). When we exit the size field (i.e., upon
losing focus), we convert the value to a number of bytes and then align
it up to the nearest MiB (or whatever the alignment requirement is).

Unfortunately, after computing the aligned value, we turn it back into a
human-readable string and store it as is. It is not okay because the
conversion does not ensure that the alignment requirement is still
honored.

For instance, if the user types in 1.1G, we do the following:

 * convert it to a number of bytes -> 1181116006.4 (surprise, it is not
   even an integer).

 * round it up to the nearest MiB -> 1181745152 (this is the correct
   value)

 * transform it into a human readable string and store it as is -> 1.1G
   - which actually corresponds to the original value.

This leads to an exception later when creating the partition:

    File "subiquity/models/filesystem.py", line 1841, in add_partition
      raise Exception(
   Exception: ('size %s or offset %s not aligned to %s', 1181116006, 1048576, 1048576)

Fixed by storing the actual size as a number of bytes - alongside the
human readable size.

Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>

subiquity/ui/views/filesystem/partition.py

@@ -89,6 +89,7 @@ def _make_widget(self, form):
 class SizeWidget(StringEditor):
     def __init__(self, form):
         self.form = form
+        self.accurate_value: Optional[int] = None
         super().__init__()
 
     def lost_focus(self):
@@ -114,6 +115,9 @@ def lost_focus(self):
                     ),
                 )
             )
+            # This will invoke self.form.clean_size() and it is expected that
+            # size_str (and therefore self.value) are propertly aligned.
+            self.accurate_value = self.form.size
         else:
             aligned_sz = align_up(sz, self.form.alignment)
             aligned_sz_str = humanize_size(aligned_sz)
@@ -125,6 +129,7 @@ def lost_focus(self):
                         _("Rounded size up to {size}").format(size=aligned_sz_str),
                     )
                 )
+            self.accurate_value = aligned_sz
 
 
 class SizeField(FormField):

subiquity/ui/views/filesystem/tests/test_partition.py

@@ -58,6 +58,7 @@ def test_create_partition(self):
         gap = gaps.Gap(device=disk, offset=1 << 20, size=99 << 30)
         view, stretchy = make_partition_view(model, disk, gap=gap)
         view_helpers.enter_data(stretchy.form, valid_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         valid_data["mount"] = "/"
         valid_data["size"] = dehumanize_size(valid_data["size"])
@@ -77,6 +78,7 @@ def test_edit_partition(self):
         view, stretchy = make_partition_view(model, disk, partition=partition)
         self.assertTrue(stretchy.form.done_btn.enabled)
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             "size": dehumanize_size(form_data["size"]),
@@ -111,6 +113,7 @@ def test_edit_existing_partition(self):
         self.assertFalse(stretchy.form.size.enabled)
         self.assertTrue(stretchy.form.done_btn.enabled)
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             "fstype": "xfs",
@@ -177,6 +180,7 @@ def test_edit_boot_partition(self):
         self.assertEqual(stretchy.form.mount.value, "/boot/efi")
 
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             "size": dehumanize_size(form_data["size"]),

subiquitycore/ui/form.py

@@ -531,7 +531,11 @@ def as_data(self):
         data = {}
         for field in self._fields:
             if field.enabled:
-                data[field.field.name] = field.value
+                accurate_value = getattr(field.widget, "accurate_value", None)
+                if accurate_value is not None:
+                    data[field.field.name] = accurate_value
+                else:
+                    data[field.field.name] = field.value
         return data