releng: added gitlog_to_whatsnew script

Author: avarga

releng/gitlog_to_whatsnew

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+
+import argparse
+import subprocess
+import sys
+
+
+_RECORD_SEP = "\x1e"  # record separator
+_FIELD_SEP = "\x1f"   # unit separator
+
+
+def _run_git_log(rev_range: str) -> str:
+    fmt = f"%H{_FIELD_SEP}%s{_FIELD_SEP}%b{_RECORD_SEP}"
+    # Note: keep commit message body verbatim (%b); subject is %s
+    cmd = [
+        "git",
+        "log",
+        rev_range,
+        "--reverse",
+        f"--format={fmt}",
+    ]
+    try:
+        return subprocess.check_output(cmd, text=True)
+    except subprocess.CalledProcessError as e:
+        return e.output
+
+
+def _format_commit(subject: str, body: str, include_hash: bool, commit_hash: str) -> str:
+    subject = subject.rstrip("\n")
+    body = body.rstrip("\n")
+
+    header = subject
+    if include_hash:
+        header = f"{header} ({commit_hash[:12]})"
+
+    out_lines = [f"- {header}"]
+
+    if body.strip() != "":
+        # Indent body verbatim under the bullet.
+        # Keep empty lines as a bare indentation line.
+        for line in body.splitlines():
+            if line == "":
+                out_lines.append("  ")
+            else:
+                out_lines.append(f"  {line}")
+
+    return "\n".join(out_lines)
+
+
+def main(argv: list[str]) -> int:
+    parser = argparse.ArgumentParser(
+        description=(
+            "Format git commit messages (subject+body) as WHATSNEW-style markdown bullets. "
+            "Useful as raw material for release notes."
+        )
+    )
+    parser.add_argument(
+        "range",
+        nargs="?",
+        default="v1.4.2..HEAD",
+        help="Git revision range to list, default: v1.4.2..HEAD",
+    )
+    parser.add_argument(
+        "--include-hash",
+        action="store_true",
+        help="Append abbreviated commit hash to the bullet header",
+    )
+    parser.add_argument(
+        "--separator",
+        default="\n\n",
+        help="Text to print between commits (default: blank line)",
+    )
+
+    args = parser.parse_args(argv)
+
+    raw = _run_git_log(args.range)
+    if raw is None:
+        return 2
+
+    records = [r for r in raw.split(_RECORD_SEP) if r.strip() != ""]
+
+    formatted: list[str] = []
+    for rec in records:
+        parts = rec.split(_FIELD_SEP)
+        if len(parts) < 3:
+            continue
+        commit_hash = parts[0]
+        subject = parts[1]
+        body = _FIELD_SEP.join(parts[2:])
+        formatted.append(_format_commit(subject, body, args.include_hash, commit_hash))
+
+    sys.stdout.write(args.separator.join(formatted))
+    if formatted:
+        sys.stdout.write("\n")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv[1:]))