[libcamera-devel] [PATCH 2/2] checkstyle: Add support for pre-commit hook

[nicolas at ndufresne.ca]

From: Nicolas Dufresne <nicolas.dufresne at collabora.com>

This adds support for pre-commit hook workflow. In pre-commit hook we
check the style on the changes currently staged. Note that this patch
also includes a bit of sugar to support --amend.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
---
 utils/checkstyle.py    | 55 +++++++++++++++++++++++++++++-------------
 utils/hooks/pre-commit | 16 ++++++++++++
 2 files changed, 54 insertions(+), 17 deletions(-)
 mode change 100644 => 100755 utils/checkstyle.py
 create mode 100755 utils/hooks/pre-commit

diff --git a/utils/checkstyle.py b/utils/checkstyle.py
old mode 100644
new mode 100755
index 7edea25..23eb3f6
--- a/utils/checkstyle.py
+++ b/utils/checkstyle.py
@@ -458,11 +458,16 @@ class StripTrailingSpaceFormatter(Formatter):
 # Style checking
 #
 
-def check_file(top_level, commit, filename):
+def check_file(top_level, commit, filename, staged):
     # Extract the line numbers touched by the commit.
-    diff = subprocess.run(['git', 'diff', '%s~..%s' % (commit, commit), '--',
-                           '%s/%s' % (top_level, filename)],
-                          stdout=subprocess.PIPE).stdout
+    if staged:
+        diff = subprocess.run(['git', 'diff', '--staged', commit, '--',
+                               '%s/%s' % (top_level, filename)],
+                              stdout=subprocess.PIPE).stdout
+    else:
+        diff = subprocess.run(['git', 'diff', '%s~..%s' % (commit, commit), '--',
+                               '%s/%s' % (top_level, filename)],
+                              stdout=subprocess.PIPE).stdout
     diff = diff.decode('utf-8').splitlines(True)
     commit_diff = parse_diff(diff)
 
@@ -476,8 +481,12 @@ def check_file(top_level, commit, filename):
 
     # Format the file after the commit with all formatters and compute the diff
     # between the unformatted and formatted contents.
-    after = subprocess.run(['git', 'show', '%s:%s' % (commit, filename)],
-                           stdout=subprocess.PIPE).stdout
+    if staged:
+        after = subprocess.run(['git', 'show', ':%s' % (filename)],
+                               stdout=subprocess.PIPE).stdout
+    else:
+        after = subprocess.run(['git', 'show', '%s:%s' % (commit, filename)],
+                               stdout=subprocess.PIPE).stdout
     after = after.decode('utf-8')
 
     formatted = after
@@ -521,13 +530,20 @@ def check_file(top_level, commit, filename):
     return len(formatted_diff) + len(issues)
 
 
-def check_style(top_level, commit):
-    # Get the commit title and list of files.
-    ret = subprocess.run(['git', 'show', '--pretty=oneline','--name-only', commit],
-                         stdout=subprocess.PIPE)
-    files = ret.stdout.decode('utf-8').splitlines()
-    title = files[0]
-    files = files[1:]
+def check_style(top_level, commit, staged):
+    if staged:
+        # Get list of staged changed files
+        ret = subprocess.run(['git', 'diff', '--staged', '--name-only', commit],
+                             stdout=subprocess.PIPE)
+        files = ret.stdout.decode('utf-8').splitlines()
+        title = "Pre-commit"
+    else:
+        # Get the commit title and list of files.
+        ret = subprocess.run(['git', 'show', '--pretty=oneline', '--name-only', commit],
+                             stdout=subprocess.PIPE)
+        files = ret.stdout.decode('utf-8').splitlines()
+        title = files[0]
+        files = files[1:]
 
     separator = '-' * len(title)
     print(separator)
@@ -541,11 +557,11 @@ def check_style(top_level, commit):
     files = [f for f in files if len([p for p in patterns if fnmatch.fnmatch(os.path.basename(f), p)])]
     if len(files) == 0:
         print("Commit doesn't touch source files, skipping")
-        return
+        return 0
 
     issues = 0
     for f in files:
-        issues += check_file(top_level, commit, f)
+        issues += check_file(top_level, commit, f, staged)
 
     if issues == 0:
         print("No style issue detected")
@@ -554,6 +570,8 @@ def check_style(top_level, commit):
         print("%u potential style %s detected, please review" % \
                 (issues, 'issue' if issues == 1 else 'issues'))
 
+    return issues
+
 
 def extract_revlist(revs):
     """Extract a list of commits on which to operate from a revision or revision
@@ -595,6 +613,8 @@ def main(argv):
     parser = argparse.ArgumentParser()
     parser.add_argument('--formatter', '-f', type=str, choices=['astyle', 'clang-format'],
                         help='Code formatter. Default to clang-format if not specified.')
+    parser.add_argument('--staged', '-s', action='store_true',
+                        help='Looks at the staged changes, used for pre-commit, defaults to False')
     parser.add_argument('revision_range', type=str, default='HEAD', nargs='?',
                         help='Revision range (as defined by git rev-parse). Defaults to HEAD if not specified.')
     args = parser.parse_args(argv[1:])
@@ -632,11 +652,12 @@ def main(argv):
 
     revlist = extract_revlist(args.revision_range)
 
+    issues = 0
     for commit in revlist:
-        check_style(top_level, commit)
+        issues += check_style(top_level, commit, args.staged)
         print('')
 
-    return 0
+    return issues
 
 
 if __name__ == '__main__':
diff --git a/utils/hooks/pre-commit b/utils/hooks/pre-commit
new file mode 100755
index 0000000..57d23ef
--- /dev/null
+++ b/utils/hooks/pre-commit
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Execute the checkstyle script before committing any code, failing the commit
+# if needed. With this workflow, false positive can be ignored using:
+#   git commit -n
+#
+# To utilise this hook, install this file with:
+#   cp utils/hooks/pre-commit .git/hooks/pre-commit
+
+commit=
+if ps -ocommand= -p $PPID | grep -- "--amend"
+then
+   commit="HEAD~"
+fi
+
+./utils/checkstyle.py --staged $commit
-- 
2.24.1