Bazel client, Windows: implement AsWindowsPath
This method converts MSYS paths to Windows path.
It uses the BAZEL_SH envvar to obtain the MSYS
root directory, to which all Unix paths (except
for mounts) are relative.
We cannot handle mounts because we don't want to
read /etc/mtab every time there's a file operation
so we simply apply a heuristic similar to
https://github.com/bazelbuild/bazel/blob/cd4cc09fa6ef96380a3d0888f825dfd1dbada651/src/main/java/com/google/devtools/build/lib/vfs/WindowsFileSystem.java#L52-L63
Also clean up the #ifdefs surrounding SyncFile.
See https://github.com/bazelbuild/bazel/issues/2107
--
PiperOrigin-RevId: 142531986
MOS_MIGRATED_REVID=142531986
diff --git a/src/main/cpp/util/file_platform.h b/src/main/cpp/util/file_platform.h
index e6df884..15bfd5d 100644
--- a/src/main/cpp/util/file_platform.h
+++ b/src/main/cpp/util/file_platform.h
@@ -120,6 +120,26 @@
void ForEachDirectoryEntry(const std::string &path,
DirectoryEntryConsumer *consume);
+#if defined(COMPILER_MSVC) || defined(__CYGWIN__)
+// Converts a UTF8-encoded `path` to a widechar Windows path.
+//
+// Returns true if conversion succeeded and sets the contents of `result` to it.
+//
+// The `path` may be absolute or relative, and may be a Windows or MSYS path.
+// In every case, this method replaces forward slashes with backslashes if
+// necessary.
+//
+// Recognizes the drive letter in MSYS paths, so e.g. "/c/windows" becomes
+// "c:\windows". Prepends the MSYS root (computed from the BAZEL_SH envvar) to
+// absolute MSYS paths, so e.g. "/usr" becomes "c:\tools\msys64\usr".
+//
+// The result may be longer than MAX_PATH. It's the caller's responsibility to
+// prepend the long path prefix ("\\?\") in case they need to pass it to a
+// Windows API function (some require the prefix, some don't), or to quote the
+// path if necessary.
+bool AsWindowsPath(const std::string &path, std::wstring *result);
+#endif // defined(COMPILER_MSVC) || defined(__CYGWIN__)
+
} // namespace blaze_util
#endif // BAZEL_SRC_MAIN_CPP_UTIL_FILE_PLATFORM_H_
