Merge bitcoin/bitcoin#24853: lint: Convert lint-git-commit-check.sh to Python

f27fcd9bf4d667f78055d4b3ee6f426e4c5ffe16 lint: Convert lint-git-commit-check.sh to Python (Dimitri)

Pull request description:

  A port of `/test/lint/lint-git-commit-check.sh` to a Python-script as part of the request of #24783 . Checked for output-consistency.

ACKs for top commit:
  laanwj:
    re-ACK f27fcd9bf4d667f78055d4b3ee6f426e4c5ffe16

Tree-SHA512: afc4a662f4aec1796c023b98a875c1591940ecdfc709eefe2df29d33e51e807c3c2e2b5c410aa3ad1cd3f6f8207f5c15b638637ff9f5659cafa7543bbe8a0bae

2 files changed, 63 insertions, 48 deletions

diff --git a/test/lint/lint-git-commit-check.py b/test/lint/lint-git-commit-check.py
new file mode 100755
index 0000000000..a1d03370e8
--- /dev/null
+++ b/test/lint/lint-git-commit-check.py
@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2020-2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+# Linter to check that commit messages have a new line before the body
+# or no body at all
+
+import argparse
+import os
+import sys
+
+from subprocess import check_output
+
+
+def parse_args():
+    """Parse command line arguments."""
+    parser = argparse.ArgumentParser(
+        description="""
+            Linter to check that commit messages have a new line before
+            the body or no body at all.
+        """,
+        epilog=f"""
+            You can manually set the commit-range with the COMMIT_RANGE
+            environment variable (e.g. "COMMIT_RANGE='47ba2c3...ee50c9e'
+            {sys.argv[0]}"). Defaults to current merge base when neither
+            prev-commits nor the environment variable is set.
+        """)
+
+    parser.add_argument("--prev-commits", "-p", required=False, help="The previous n commits to check")
+
+    return parser.parse_args()
+
+
+def main():
+    args = parse_args()
+    exit_code = 0
+
+    if not os.getenv("COMMIT_RANGE"):
+        if args.prev_commits:
+            commit_range = "HEAD~" + args.prev_commits + "...HEAD"
+        else:
+            # This assumes that the target branch of the pull request will be master.
+            merge_base = check_output(["git", "merge-base", "HEAD", "master"], universal_newlines=True, encoding="utf8").rstrip("\n")
+            commit_range = merge_base + "..HEAD"
+    else:
+        commit_range = os.getenv("COMMIT_RANGE")
+
+    commit_hashes = check_output(["git", "log", commit_range, "--format=%H"], universal_newlines=True, encoding="utf8").splitlines()
+
+    for hash in commit_hashes:
+        commit_info = check_output(["git", "log", "--format=%B", "-n", "1", hash], universal_newlines=True, encoding="utf8").splitlines()
+        if len(commit_info) >= 2:
+            if commit_info[1]:
+                print(f"The subject line of commit hash {hash} is followed by a non-empty line. Subject lines should always be followed by a blank line.")
+                exit_code = 1
+
+    sys.exit(exit_code)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/test/lint/lint-git-commit-check.sh b/test/lint/lint-git-commit-check.sh
deleted file mode 100755
index f77373ed00..0000000000
--- a/test/lint/lint-git-commit-check.sh
+++ /dev/null
@@ -1,48 +0,0 @@
-#!/usr/bin/env bash
-# Copyright (c) 2020-2021 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-#
-# Linter to check that commit messages have a new line before the body
-# or no body at all
-
-export LC_ALL=C
-
-EXIT_CODE=0
-
-while getopts "?" opt; do
-  case $opt in
-    ?)
-      echo "Usage: $0 [N]"
-      echo "       COMMIT_RANGE='<commit range>' $0"
-      echo "       $0 -?"
-      echo "Checks unmerged commits, the previous N commits, or a commit range."
-      echo "COMMIT_RANGE='47ba2c3...ee50c9e' $0"
-      exit ${EXIT_CODE}
-    ;;
-  esac
-done
-
-if [ -z "${COMMIT_RANGE}" ]; then
-    if [ -n "$1" ]; then
-      COMMIT_RANGE="HEAD~$1...HEAD"
-    else
-      # This assumes that the target branch of the pull request will be master.
-      MERGE_BASE=$(git merge-base HEAD master)
-      COMMIT_RANGE="$MERGE_BASE..HEAD"
-    fi
-fi
-
-while IFS= read -r commit_hash  || [[ -n "$commit_hash" ]]; do
-    n_line=0
-    while IFS= read -r line || [[ -n "$line" ]]; do
-        n_line=$((n_line+1))
-        length=${#line}
-        if [ $n_line -eq 2 ] && [ "$length" -ne 0 ]; then
-            echo "The subject line of commit hash ${commit_hash} is followed by a non-empty line. Subject lines should always be followed by a blank line."
-            EXIT_CODE=1
-        fi
-    done < <(git log --format=%B -n 1 "$commit_hash")
-done < <(git log "${COMMIT_RANGE}" --format=%H)
-
-exit ${EXIT_CODE}