# HG changeset patch
# User Siddharth Agarwal <sid0@fb.com>
# Date 2015-12-29 06:51:37
# Node ID 6a6e78f84cc6a3bcb0c429ce2c19aad170a78c1f
# Parent  ca8ada499529c1182292d21c72b116bd68ffe42d

merge: while checking for unknown files don't follow symlinks (issue5027)

Previously, we were using Python's native 'os.path.isfile' method which follows
symlinks. In this case, since we're operating on repo contents, we don't want
to follow symlinks.

There's a behaviour change here, as shown by the second part of the added test.
Consider a symlink 'f' pointing to a file containing 'abc'. If we try and
replace it with a file with contents 'abc', previously we would have let it
though. Now we don't. Although this breaks naive inspection with tools like
'cat' and 'diff', on balance I believe this is the right change.

diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -404,7 +404,7 @@ class mergestate(object):
 def _checkunknownfile(repo, wctx, mctx, f, f2=None):
     if f2 is None:
         f2 = f
-    return (os.path.isfile(repo.wjoin(f))
+    return (repo.wvfs.isfileorlink(f)
         and repo.wvfs.audit.check(f)
         and repo.dirstate.normalize(f) not in repo.dirstate
         and mctx[f2].cmp(wctx[f]))
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -312,6 +312,17 @@ class abstractvfs(object):
     def islink(self, path=None):
         return os.path.islink(self.join(path))
 
+    def isfileorlink(self, path=None):
+        '''return whether path is a regular file or a symlink
+
+        Unlike isfile, this doesn't follow symlinks.'''
+        try:
+            st = self.lstat(path)
+        except OSError:
+            return False
+        mode = st.st_mode
+        return stat.S_ISREG(mode) or stat.S_ISLNK(mode)
+
     def reljoin(self, *paths):
         """join various elements of a path together (as os.path.join would do)
 
diff --git a/tests/test-merge1.t b/tests/test-merge1.t
--- a/tests/test-merge1.t
+++ b/tests/test-merge1.t
@@ -102,6 +102,28 @@ merge should fail
   b: untracked file differs
   abort: untracked files in working directory differ from files in requested revision
   [255]
+
+#if symlink
+symlinks to directories should be treated as regular files (issue5027)
+  $ rm b
+  $ ln -s 'This is file b2' b
+  $ hg merge 1
+  b: untracked file differs
+  abort: untracked files in working directory differ from files in requested revision
+  [255]
+symlinks shouldn't be followed
+  $ rm b
+  $ echo This is file b1 > .hg/b
+  $ ln -s .hg/b b
+  $ hg merge 1
+  b: untracked file differs
+  abort: untracked files in working directory differ from files in requested revision
+  [255]
+
+  $ rm b
+  $ echo This is file b2 > b
+#endif
+
 merge of b expected
   $ hg merge -f 1
   merging b