adb: fix stat on Windows.

stat on Windows fails with ENOENT when passed a path with a trailing
slash or backslash, regardless of whether the target is actually a
directory. Emulate the correct POSIX behavior by stripping trailing
path separators and then checking if the target is a directory if
successful.

Bug: http://b/30481559
Bug: https://code.google.com/p/android/issues/detail?id=214633
Change-Id: I1d398d19a9bce1ecb3fdc4aabc31aa98c82c3f93
Test: Relevant adb_tests pass on Linux and Windows 10.
diff --git a/adb/sysdeps/stat.h b/adb/sysdeps/stat.h
new file mode 100644
index 0000000..5953595
--- /dev/null
+++ b/adb/sysdeps/stat.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if defined(_WIN32)
+// stat is broken on Win32: stat on a path with a trailing slash or backslash will always fail with
+// ENOENT.
+int adb_stat(const char* path, struct adb_stat* buf);
+
+// We later define a macro mapping 'stat' to 'adb_stat'. This causes:
+//   struct stat s;
+//   stat(filename, &s);
+// To turn into the following:
+//   struct adb_stat s;
+//   adb_stat(filename, &s);
+// To get this to work, we need to make 'struct adb_stat' the same as
+// 'struct stat'. Note that this definition of 'struct adb_stat' uses the
+// *current* macro definition of stat, so it may actually be inheriting from
+// struct _stat32i64 (or some other remapping).
+struct adb_stat : public stat {};
+
+#undef stat
+#define stat adb_stat
+
+// Windows doesn't have lstat.
+#define lstat adb_stat
+
+#endif