localrepo: add configurable limits for files count in a commit

Summary: Currently, commit can have unbounded number of files. This can cause problems if users (including bot) create commits with exceptionally large number of files.

Reviewed By: muirdm

Differential Revision: D51647160

fbshipit-source-id: 3fc91a7f09c9588be404a650f1424993b99dd30d

eden/scm/sapling/localrepo.py

@@ -2782,6 +2782,13 @@ def commitctx(self, ctx, error=False):
                     % (extraslen, extraslimit)
                 )
 
+        file_count_limit = self.ui.configint("commit", "file-count-limit")
+        if file_count_limit and file_count_limit < len(ctx.files()):
+            raise errormod.Abort(
+                _("commit file count (%d) exceeds configured limit (%d)")
+                % (len(ctx.files()), file_count_limit)
+            )
+
         isgit = git.isgitformat(self)
         lock = self.lock()
         try:

eden/scm/tests/test-commit-files-count-limits.t

@@ -0,0 +1,17 @@
+#debugruntest-compatible
+  $ eagerepo
+  $ newrepo
+
+  $ echo 1 > foo
+  $ echo 2 > bar
+  $ hg add . -q
+
+Commit should fail if the number of changed files exceeds the limit
+  $ hg commit -m init --config commit.file-count-limit=1
+  abort: commit file count (2) exceeds configured limit (1)
+  [255]
+
+Commit should succeed if the number of changed files <= the limit
+  $ hg commit -m init --config commit.file-count-limit=2
+  $ hg log -G -T '{desc}'
+  @  init