From ced14746a8bc35550199b8dd30eb5c1c06458bd1 Mon Sep 17 00:00:00 2001
From: Robert Osowiecki <robert.osowiecki@gmail.com>
Date: Tue, 23 Jun 2020 14:02:35 +0200
Subject: [PATCH] parted: Allow passing negative numbers to specify partition
 boundary relative to disk end (#129)

* Allow passing negative numbers to specify partition boundary relative to disk end
Fixes: https://github.com/ansible/ansible/issues/43369

* parted: unit test case, create partition with part_start: -1GiB

* fs_type parameter is not really optional for negative part_start parameter

* Revert "fs_type parameter is not really optional for negative part_start parameter"

This reverts commit 800b1cb00b37c32e95d664df34f3fd76747b41d4.

Instead: added notes and documentation about netagive part_start and fs_type.

* include fs_type in negative part_start example
---
 .../fragments/parted_negative_numbers.yml     |  2 ++
 plugins/modules/system/parted.py              | 25 +++++++++++++++----
 .../plugins/modules/system/test_parted.py     | 11 ++++++++
 3 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 changelogs/fragments/parted_negative_numbers.yml

diff --git a/changelogs/fragments/parted_negative_numbers.yml b/changelogs/fragments/parted_negative_numbers.yml
new file mode 100644
index 0000000000..9a54a2c173
--- /dev/null
+++ b/changelogs/fragments/parted_negative_numbers.yml
@@ -0,0 +1,2 @@
+minor_changes:
+ - "parted - accept negative numbers in ``part_start`` and ``part_end``"
diff --git a/plugins/modules/system/parted.py b/plugins/modules/system/parted.py
index c2f1005d7c..a962ee1963 100644
--- a/plugins/modules/system/parted.py
+++ b/plugins/modules/system/parted.py
@@ -66,15 +66,18 @@ options:
   part_start:
     description:
     - Where the partition will start as offset from the beginning of the disk,
-      that is, the "distance" from the start of the disk.
+      that is, the "distance" from the start of the disk. Negative numbers
+      specify distance from the end of the disk.
     - The distance can be specified with all the units supported by parted
       (except compat) and it is case sensitive, e.g. C(10GiB), C(15%).
+    - Using negative values may require setting of C(fs_type) (see notes).
     type: str
     default: 0%
-  part_end :
+  part_end:
     description:
     - Where the partition will end as offset from the beginning of the disk,
-      that is, the "distance" from the start of the disk.
+      that is, the "distance" from the start of the disk. Negative numbers
+      specify distance from the end of the disk.
     - The distance can be specified with all the units supported by parted
       (except compat) and it is case sensitive, e.g. C(10GiB), C(15%).
     type: str
@@ -96,6 +99,7 @@ options:
   fs_type:
     description:
      - If specified and the partition does not exist, will set filesystem type to given partition.
+     - Parameter optional, but see notes below about negative negative C(part_start) values.
     type: str
     version_added: '0.2.0'
 notes:
@@ -103,6 +107,9 @@ notes:
     installed on the system is before version 3.1, the module queries the kernel
     through C(/sys/) to obtain disk information. In this case the units CHS and
     CYL are not supported.
+  - Negative C(part_start) start values were rejected if C(fs_type) was not given.
+    This bug was fixed in parted 3.2.153. If you want to use negative C(part_start),
+    specify C(fs_type) as well or make sure your system contains newer parted.
 '''
 
 RETURN = r'''
@@ -180,6 +187,14 @@ EXAMPLES = r'''
     state: present
     part_start: 1GiB
 
+- name: Create a new primary partition with a size of 1GiB at disk's end
+  parted:
+    device: /dev/sdb
+    number: 3
+    state: present
+    fs_type: ext3
+    part_start: -1GiB
+
 # Example on how to read info and reuse it in subsequent task
 - name: Read device information (always use unit when probing)
   parted: device=/dev/sdb unit=MiB
@@ -208,9 +223,9 @@ parted_units = units_si + units_iec + ['s', '%', 'cyl', 'chs', 'compact']
 
 def parse_unit(size_str, unit=''):
     """
-    Parses a string containing a size of information
+    Parses a string containing a size or boundary information
     """
-    matches = re.search(r'^([\d.]+)([\w%]+)?$', size_str)
+    matches = re.search(r'^(-?[\d.]+)([\w%]+)?$', size_str)
     if matches is None:
         # "<cylinder>,<head>,<sector>" format
         matches = re.search(r'^(\d+),(\d+),(\d+)$', size_str)
diff --git a/tests/unit/plugins/modules/system/test_parted.py b/tests/unit/plugins/modules/system/test_parted.py
index 2846d70dd7..c709938d6d 100644
--- a/tests/unit/plugins/modules/system/test_parted.py
+++ b/tests/unit/plugins/modules/system/test_parted.py
@@ -198,6 +198,17 @@ class TestParted(ModuleTestCase):
         with patch('ansible_collections.community.general.plugins.modules.system.parted.get_device_info', return_value=parted_dict1):
             self.execute_module(changed=True, script='unit KiB mkpart primary 0% 1GiB')
 
+    def test_create_new_partition_minus_1G(self):
+        set_module_args({
+            'device': '/dev/sdb',
+            'number': 4,
+            'state': 'present',
+            'fs_type': 'ext2',
+            'part_start': '-1GiB',
+        })
+        with patch('ansible_collections.community.general.plugins.modules.system.parted.get_device_info', return_value=parted_dict1):
+            self.execute_module(changed=True, script='unit KiB mkpart primary ext2 -1GiB 100%')
+
     def test_remove_partition_number_1(self):
         set_module_args({
             'device': '/dev/sdb',