Add unlicense support to add3prf.py

This adds the ability to detect and generate the correct METADATA file
for unlicense licensed crates.

Bug: 317361040
Test: atest --host add3prf_test; Ran against https://crates.io/crates/aho-corasick
Change-Id: Icbed2fbab7368f5faef2194a4836c369b038979c
diff --git a/scripts/add3prf.py b/scripts/add3prf.py
index 985cfa5..ff25952 100755
--- a/scripts/add3prf.py
+++ b/scripts/add3prf.py
@@ -51,6 +51,8 @@
 BSD_MATCHER = re.compile(BSD_PATTERN)
 MPL_PATTERN = r"^.Mozilla Public License.*$"
 MPL_MATCHER = re.compile(MPL_PATTERN)
+UNLICENSE_PATTERN = r"^.*unlicense\.org.*$"
+UNLICENSE_MATCHER = re.compile(UNLICENSE_PATTERN)
 ZERO_BSD_PATTERN = r"^.*Zero-Clause BSD.*$"
 ZERO_BSD_MATCHER = re.compile(ZERO_BSD_PATTERN)
 MULTI_LICENSE_COMMENT = ("# Dual-licensed, using the least restrictive "
@@ -140,6 +142,8 @@
         return License(LicenseType.BSD_LIKE, LicenseGroup.NOTICE, license_file)
       if MPL_MATCHER.match(line):
         return License(LicenseType.MPL, LicenseGroup.RECIPROCAL, license_file)
+      if UNLICENSE_MATCHER.match(line):
+        return License(LicenseType.UNLICENSE, LicenseGroup.PERMISSIVE, license_file)
       if ZERO_BSD_MATCHER.match(line):
         return License(LicenseType.ZERO_BSD, LicenseGroup.PERMISSIVE, license_file)
   print("ERROR: cannot decide license type in", license_file,
@@ -160,6 +164,7 @@
   ISC = 4
   MPL = 5
   ZERO_BSD = 6
+  UNLICENSE = 7
 
 class LicenseGroup(enum.Enum):
   """A group of license as defined by go/thirdpartylicenses#types
@@ -187,7 +192,7 @@
   # Some crate like time-macros-impl uses lower case names like LICENSE-Apache.
   licenses = []
   license_file = None
-  for license_file in glob.glob("LICENSE*") + glob.glob("COPYING*"):
+  for license_file in glob.glob("LICENSE*") + glob.glob("COPYING*") + glob.glob("UNLICENSE"):
     lowered_name = license_file.lower()
     if lowered_name == "license-apache":
       licenses.append(License(LicenseType.APACHE2, LicenseGroup.NOTICE, license_file))
@@ -195,6 +200,8 @@
       licenses.append(License(LicenseType.MIT, LicenseGroup.NOTICE, license_file))
     elif lowered_name == "license-0bsd":
       licenses.append(License(LicenseType.ZERO_BSD, LicenseGroup.PERMISSIVE, license_file))
+    elif lowered_name == "unlicense":
+      licenses.append(License(LicenseType.UNLICENSE, LicenseGroup.PERMISSIVE, license_file))
   if licenses:
     licenses.sort(key=lambda l: l.type)
     return licenses
@@ -214,6 +221,8 @@
     return [License(LicenseType.ISC, LicenseGroup.NOTICE, license_file)]
   if "MPL" in cargo_license:
     return [License(LicenseType.MPL, LicenseGroup.RECIPROCAL, license_file)]
+  if "Unlicense" in cargo_license:
+    return [License(LicenseType.UNLICENSE, LicenseGroup.PERMISSIVE, license_file)]
   return [grep_license_keyword(license_file)]
 
 
@@ -252,7 +261,7 @@
 def add_module_license(license_type):
   """Touch MODULE_LICENSE_type file."""
   # Do not change existing MODULE_* files.
-  for suffix in ["MIT", "APACHE", "APACHE2", "BSD_LIKE", "MPL", "0BSD"]:
+  for suffix in ["MIT", "APACHE", "APACHE2", "BSD_LIKE", "MPL", "0BSD", "UNLICENSE"]:
     module_file = "MODULE_LICENSE_" + suffix
     if os.path.exists(module_file):
       if license_type.name != suffix:
diff --git a/scripts/add3prf_test.py b/scripts/add3prf_test.py
index 80bcfa4..32d5c7a 100755
--- a/scripts/add3prf_test.py
+++ b/scripts/add3prf_test.py
@@ -82,6 +82,24 @@
     self.assertEqual(preferred_license.group, add3prf.LicenseGroup.PERMISSIVE)
     self.assertEqual(preferred_license.filename, "LICENSE-0BSD")
 
+  def test_unlicense_license(self):
+    self.fs.create_file("LICENSE")
+    licenses = add3prf.decide_license_type("Unlicense")
+    self.assertEqual(len(licenses), 1)
+    preferred_license = licenses[0]
+    self.assertEqual(preferred_license.type, add3prf.LicenseType.UNLICENSE)
+    self.assertEqual(preferred_license.group, add3prf.LicenseGroup.PERMISSIVE)
+    self.assertEqual(preferred_license.filename, "LICENSE")
+
+  def test_unlicense_licensefile(self):
+    self.fs.create_file("UNLICENSE")
+    licenses = add3prf.decide_license_type("")
+    self.assertEqual(len(licenses), 1)
+    preferred_license = licenses[0]
+    self.assertEqual(preferred_license.type, add3prf.LicenseType.UNLICENSE)
+    self.assertEqual(preferred_license.group, add3prf.LicenseGroup.PERMISSIVE)
+    self.assertEqual(preferred_license.filename, "UNLICENSE")
+
 
 class AddModuleLicenseTestCase(fake_filesystem_unittest.TestCase):