add path.hpp: CanonicalPath class, etc.

Apparently, relative paths in the Win32 namespace (e.g. \\?\test.txt)
are not a thing.

1 files changed, 47 insertions, 0 deletions

diff --git a/src/path.cpp b/src/path.cpp
new file mode 100644
index 0000000..2c2deda
--- /dev/null
+++ b/src/path.cpp
@@ -0,0 +1,47 @@
+// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+// This file is part of the "winapi-common" project.
+// For details, see https://github.com/egor-tensin/winapi-common.
+// Distributed under the MIT License.
+
+#include <winapi/error.hpp>
+#include <winapi/path.hpp>
+#include <winapi/utf8.hpp>
+
+#include <windows.h>
+
+#include <string>
+#include <vector>
+
+namespace winapi {
+namespace {
+
+std::wstring do_canonicalize(const std::wstring& path) {
+    std::vector<wchar_t> buffer;
+    buffer.resize(MAX_PATH);
+
+    while (true) {
+        const auto nch = ::GetFullPathNameW(path.c_str(), buffer.size(), buffer.data(), NULL);
+
+        if (nch == 0) {
+            throw error::windows(GetLastError(), "GetFullPathNameW");
+        }
+
+        if (nch < buffer.size()) {
+            return {buffer.data(), nch};
+        }
+
+        if (nch > buffer.size()) {
+            buffer.resize(2 * buffer.size());
+        }
+    }
+}
+
+} // namespace
+
+CanonicalPath::CanonicalPath(const std::string& path) : m_path(canonicalize(path)) {}
+
+std::string CanonicalPath::canonicalize(const std::string& path) {
+    return narrow(do_canonicalize(widen(path)));
+}
+
+} // namespace winapi