1 files changed, 49 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/action/buildlist.py b/python/mozbuild/mozbuild/action/buildlist.py
new file mode 100644
index 0000000000..ab32ad92cc
--- /dev/null
+++ b/python/mozbuild/mozbuild/action/buildlist.py
@@ -0,0 +1,49 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""A generic script to add entries to a file
+if the entry does not already exist.
+
+Usage: buildlist.py <filename> <entry> [<entry> ...]
+"""
+import io
+import os
+import sys
+
+from mozbuild.action.util import log_build_task
+from mozbuild.util import ensureParentDir, lock_file
+
+
+def addEntriesToListFile(listFile, entries):
+    """Given a file ``listFile`` containing one entry per line,
+    add each entry in ``entries`` to the file, unless it is already
+    present."""
+    ensureParentDir(listFile)
+    lock = lock_file(listFile + ".lck")
+    try:
+        if os.path.exists(listFile):
+            f = io.open(listFile)
+            existing = set(x.strip() for x in f.readlines())
+            f.close()
+        else:
+            existing = set()
+        for e in entries:
+            if e not in existing:
+                existing.add(e)
+        with io.open(listFile, "w", newline="\n") as f:
+            f.write("\n".join(sorted(existing)) + "\n")
+    finally:
+        del lock  # Explicitly release the lock_file to free it
+
+
+def main(args):
+    if len(args) < 2:
+        print("Usage: buildlist.py <list file> <entry> [<entry> ...]", file=sys.stderr)
+        return 1
+
+    return addEntriesToListFile(args[0], args[1:])
+
+
+if __name__ == "__main__":
+    sys.exit(log_build_task(main, sys.argv[1:]))