ci: improve gitlint (max line length in body with exceptions)

Follow-up of 5aa1540c5d but way more
mature. We now use custom gitlint rules written in Python to better
handle the max line length, with respect to a few valid exceptions.
Recognizing code blocks or compiler output, as discussed, is not
trivial and hard to get right for all corner-cases. Therefore, this
commit is a pragmatic way forward. The CI job should be kept optional.

Allowed exceptions for the 72 line length limit are now:

1. links in the following three common patterns:
https://example.com/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links
[0] https://example.com/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links
[0]: https://example.com/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links/very-long-links

2. code blocks (anything between the three backticks)

```
let x = "very_long_very_long_very_long_very_long_very_long_very_long_very_long_very_long_very_long_very_long_"
```

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

scripts/gitlint/rules/BodyMaxLineLengthEx.py

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: Apache-2.0
+
+from gitlint.rules import LineRule, RuleViolation, CommitMessageBody
+import re
+
+
+class BodyMaxLineLengthEx(LineRule):
+    """A rule to enforce a line limit of 72 characters, except for valid cases."""
+
+    # A rule MUST have a human friendly name
+    name = "body-max-line-length-ex"
+
+    # A rule MUST have a *unique* id.
+    # We recommend starting with UL (for User-defined Line-rule)
+    id = "UL-ll"
+
+    # A line-rule MUST have a target (not required for CommitRules).
+    target = CommitMessageBody
+
+    max_len = 72
+
+    # Updated property as the commit messages is validated line by line.
+    inside_open_codeblock = False
+
+    def validate(self, line, commit):
+        # Pattern allowing:
+        # - [0]: https://foobar
+        # - [0] https://foobar
+        # - https://foobar
+        link_regex = re.compile(r"^((\[[0-9]+\]:?\s?)?https?:\/\/).*$")
+
+        is_codeblock_marker = line.startswith("```")
+
+        inside_open_codeblock_ = self.inside_open_codeblock
+        if is_codeblock_marker:
+            self.inside_open_codeblock = not self.inside_open_codeblock
+
+        if len(line) > self.max_len:
+            is_link = link_regex.match(line)
+
+            if inside_open_codeblock_:
+                return
+
+            if is_link:
+                return
+
+            return [
+                RuleViolation(self.id, f"Line '{line}' exceeds limit of {self.max_len}")
+            ]

scripts/gitlint/rules/TitleStartsWithComponent.py

@@ -0,0 +1,94 @@
+# SPDX-License-Identifier: Apache-2.0
+
+from gitlint.rules import LineRule, RuleViolation, CommitMessageTitle
+import re
+
+
+class TitleStartsWithComponent(LineRule):
+    """A rule to enforce valid commit message title
+
+    Valid title format:
+    component1[, component2, componentN]: submodule: summary
+
+    Title should have at least one component
+    Components are separated by comma+space: ", "
+    Components are validated to be in valid_components
+    Components list is ended by a colon
+    Submodules are not validated
+
+    """
+
+    # A rule MUST have a human friendly name
+    name = "title-has-valid-component"
+
+    # A rule MUST have a *unique* id.
+    # We recommend starting with UL (for User-defined Line-rule)
+    id = "UL1"
+
+    # A line-rule MUST have a target (not required for CommitRules).
+    target = CommitMessageTitle
+
+    def validate(self, line, _commit):
+        valid_components = (
+            'api_client',
+            'arch',
+            'block',
+            'build',
+            'ch-remote',
+            'ci',
+            'devices',
+            'docs',
+            'event_monitor',
+            'fuzz',
+            'github',
+            'gitignore',
+            'gitlint',
+            'hypervisor',
+            'main',
+            'misc',
+            'net_gen',
+            'net_util',
+            'openapi',
+            'option_parser',
+            'pci',
+            'performance-metrics',
+            'rate_limiter',
+            'README',
+            'resources',
+            'scripts',
+            'serial_buffer',
+            'test_data',
+            'test_infra',
+            'tests',
+            'tpm',
+            'tracer',
+            'vhost_user_block',
+            'vhost_user_net',
+            'virtio-devices',
+            'vm-allocator',
+            'vm-device',
+            'vmm',
+            'vm-migration',
+            'vm-virtio')
+
+        ptrn_title = re.compile(r'^(.+?):\s(.+)$')
+        match = ptrn_title.match(line)
+
+        if not match:
+            self.log.debug("Invalid commit title {}", line)
+            return [RuleViolation(self.id, "Commit title does not comply with "
+                                  "rule: 'component: change summary'")]
+        components = match.group(1)
+        summary = match.group(2)
+        self.log.debug(f"\nComponents: {components}\nSummary: {summary}")
+
+        ptrn_components = re.compile(r',\s')
+        components_list = re.split(ptrn_components, components)
+        self.log.debug("components list: %s" % components_list)
+
+        for component in components_list:
+            if component not in valid_components:
+                return [RuleViolation(self.id,
+                                      f"Invalid component: {component}, "
+                                      "\nValid components are: {}".format(
+                                          " ".join(valid_components)))]