parser: recognise git commit consisting only of empty new file

Commits with only an empty new file are liable to be missed.
The parser state machine doesn't recognise the headers "new
file mode" and "index": teach it about them.

Add a test to demonstrate.

It's a little bit academic as you don't usually send patches like
that but sometimes you do, especially if you're a snowpatch dev :)

Closes: #256
Reported-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Stephen Finucane <stephen@that.guru>

3 files changed, 43 insertions, 4 deletions

diff --git a/patchwork/parser.py b/patchwork/parser.py
index 946b668..712780a 100644
--- a/patchwork/parser.py
+++ b/patchwork/parser.py
@@ -742,7 +742,7 @@ def parse_patch(content):
     # 3: patch header line 2 (+++)
     # 4: patch hunk header line (@@ line)
     # 5: patch hunk content
-    # 6: patch meta header (rename from/rename to)
+    # 6: patch meta header (rename from/rename to/new file/index)
     #
     # valid transitions:
     #  0 -> 1 (diff, Index:)
@@ -752,7 +752,7 @@ def parse_patch(content):
     #  3 -> 4 (@@ line)
     #  4 -> 5 (patch content)
     #  5 -> 1 (run out of lines from @@-specifed count)
-    #  1 -> 6 (rename from / rename to)
+    #  1 -> 6 (rename from / rename to / new file / index)
     #  6 -> 2 (---)
     #  6 -> 1 (other text)
     #
@@ -782,7 +782,8 @@ def parse_patch(content):
             if line.startswith('--- '):
                 state = 2
 
-            if line.startswith(('rename from ', 'rename to ')):
+            if line.startswith(('rename from ', 'rename to ',
+                                'new file mode ', 'index ')):
                 state = 6
         elif state == 2:
             if line.startswith('+++ '):
@@ -843,7 +844,8 @@ def parse_patch(content):
             else:
                 state = 5
         elif state == 6:
-            if line.startswith(('rename to ', 'rename from ')):
+            if line.startswith(('rename to ', 'rename from ',
+                                'new file mode ', 'index ')):
                 patchbuf += buf + line
                 buf = ''
             elif line.startswith('--- '):
diff --git a/patchwork/tests/mail/0021-git-empty-new-file.mbox b/patchwork/tests/mail/0021-git-empty-new-file.mbox
new file mode 100644
index 0000000..c3be48e
--- /dev/null
+++ b/patchwork/tests/mail/0021-git-empty-new-file.mbox
@@ -0,0 +1,32 @@
+From andrew.donnellan@au1.ibm.com Thu Feb 28 00:37:42 2019
+Delivered-To: dja@axtens.net
+Received: by 2002:a4a:2812:0:0:0:0:0 with SMTP id h18csp2242ooa;
+        Wed, 27 Feb 2019 16:37:59 -0800 (PST)
+From: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
+Subject: [snowpatch] [PATCH 1/3] Test commit; please ignore
+To: Daniel Axtens <dja@axtens.net>
+Date: Thu, 28 Feb 2019 11:37:42 +1100
+User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
+ Thunderbird/60.5.1
+MIME-Version: 1.0
+Content-Language: en-AU
+
+
+Doing some snowpatching.
+---
+  banana | 0
+  1 file changed, 0 insertions(+), 0 deletions(-)
+  create mode 100644 banana
+
+diff --git a/banana b/banana
+new file mode 100644
+index 000000000000..e69de29bb2d1
+-- 
+2.11.0
+
+_______________________________________________
+snowpatch mailing list
+snowpatch@lists.ozlabs.org
+https://lists.ozlabs.org/listinfo/snowpatch
+
+
diff --git a/patchwork/tests/test_parser.py b/patchwork/tests/test_parser.py
index 664edd5..ddbcf5b 100644
--- a/patchwork/tests/test_parser.py
+++ b/patchwork/tests/test_parser.py
@@ -583,6 +583,11 @@ class PatchParseTest(PatchTest):
         self.assertEqual(diff.count("\nrename to "), 2)
         self.assertEqual(diff.count('\n-a\n+b'), 1)
 
+    def test_git_new_empty_file(self):
+        diff, message = self._find_content('0021-git-empty-new-file.mbox')
+        self.assertTrue(diff is not None)
+        self.assertTrue(message is not None)
+
     def test_cvs_format(self):
         diff, message = self._find_content('0007-cvs-format-diff.mbox')
         self.assertTrue(diff.startswith('Index'))