[Support, Windows] Handle long paths with unix separators

Summary:
The function widenPath() for Windows also normalizes long path names by
iterating over the path's components and calling append().  The
assumption during the iteration that separators are not returned by the
iterator doesn't hold because the iterators do return a separator when
the path has a drive name.  Handle this case by ignoring separators
during iteration.

Reviewers: rnk

Subscribers: danalbert, srhines

Differential Revision: https://reviews.llvm.org/D36752

llvm-svn: 311382

lib/Support/Windows/Path.inc

@@ -94,13 +94,16 @@ std::error_code widenPath(const Twine &Path8,
         return EC;
       FullPath.append(CurPath);
     }
-    // Traverse the requested path, canonicalizing . and .. as we go (because
-    // the \\?\ prefix is documented to treat them as real components).
-    // The iterators don't report separators and append() always attaches
-    // preferred_separator so we don't need to call native() on the result.
+    // Traverse the requested path, canonicalizing . and .. (because the \\?\
+    // prefix is documented to treat them as real components).  Ignore
+    // separators, which can be returned from the iterator if the path has a
+    // drive name.  We don't need to call native() on the result since append()
+    // always attaches preferred_separator.
     for (llvm::sys::path::const_iterator I = llvm::sys::path::begin(Path8Str),
                                          E = llvm::sys::path::end(Path8Str);
                                          I != E; ++I) {
+      if (I->size() == 1 && is_separator((*I)[0]))
+        continue;
       if (I->size() == 1 && *I == ".")
         continue;
       if (I->size() == 2 && *I == "..")

unittests/Support/Path.cpp

@@ -699,6 +699,21 @@ TEST_F(FileSystemTest, CreateDir) {
     ThisDir = path::parent_path(ThisDir);
   }
 
+  // Also verify that paths with Unix separators are handled correctly.
+  std::string LongPathWithUnixSeparators(TestDirectory.str());
+  // Add at least one subdirectory to TestDirectory, and replace slashes with
+  // backslashes
+  do {
+    LongPathWithUnixSeparators.append("/DirNameWith19Charss");
+  } while (LongPathWithUnixSeparators.size() < 260);
+  std::replace(LongPathWithUnixSeparators.begin(),
+               LongPathWithUnixSeparators.end(),
+               '\\', '/');
+  ASSERT_NO_ERROR(fs::create_directories(Twine(LongPathWithUnixSeparators)));
+  // cleanup
+  ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) +
+                                         "/DirNameWith19Charss"));
+
   // Similarly for a relative pathname.  Need to set the current directory to
   // TestDirectory so that the one we create ends up in the right place.
   char PreviousDir[260];