From 4eed412140b37b3d967ab712f6d4feee36f6eb87 Mon Sep 17 00:00:00 2001
From: Egor Tensin <Egor.Tensin@gmail.com>
Date: Sun, 16 May 2021 00:53:30 +0300
Subject: File: add get_size/query_id

---
 CMakeLists.txt          |  7 +++++++
 include/winapi/file.hpp | 37 +++++++++++++++++++++++++++++++++++++
 src/file.cpp            | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8553200..035ea3a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,6 +17,13 @@ target_link_libraries(winapi_common PUBLIC Boost::disable_autolinking Boost::boo
 install(TARGETS winapi_common ARCHIVE DESTINATION lib)
 install(DIRECTORY include/winapi DESTINATION include)
 
+if(MINGW)
+    # FILE_ID_INFO and friends require at least 0x0602:
+    target_compile_definitions(winapi_common PUBLIC
+        NTDDI_VERSION=NTDDI_WIN8
+        _WIN32_WINNT=_WIN32_WINNT_WIN8)
+endif()
+
 if(WINAPI_COMMON_TESTS)
     add_subdirectory(test)
 endif()
diff --git a/include/winapi/file.hpp b/include/winapi/file.hpp
index b9688e9..78187d9 100644
--- a/include/winapi/file.hpp
+++ b/include/winapi/file.hpp
@@ -8,15 +8,34 @@
 #include "handle.hpp"
 #include "path.hpp"
 
+#include <boost/functional/hash.hpp>
+
+#include <windows.h>
+
+#include <cstddef>
+#include <functional>
 #include <string>
 #include <utility>
 
 namespace winapi {
 
+bool operator==(const FILE_ID_128& a, const FILE_ID_128& b);
+
 class File : private Handle {
 public:
+    struct ID {
+        const FILE_ID_INFO impl;
+
+        bool operator==(const ID& other) const {
+            return impl.VolumeSerialNumber == other.impl.VolumeSerialNumber &&
+                   impl.FileId == other.impl.FileId;
+        }
+    };
+
     static Handle open_r(const std::string&);
     static Handle open_r(const CanonicalPath&);
+    static Handle open_read_attributes(const std::string&);
+    static Handle open_read_attributes(const CanonicalPath&);
     static Handle open_w(const std::string&);
     static Handle open_w(const CanonicalPath&);
 
@@ -29,6 +48,24 @@ public:
 
     using Handle::read;
     using Handle::write;
+
+    std::size_t get_size() const;
+
+    ID query_id() const;
 };
 
 } // namespace winapi
+
+namespace std {
+
+template <>
+struct hash<winapi::File::ID> {
+    std::size_t operator()(const winapi::File::ID& id) const {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, id.impl.VolumeSerialNumber);
+        boost::hash_combine(seed, id.impl.FileId.Identifier);
+        return seed;
+    }
+};
+
+} // namespace std
diff --git a/src/file.cpp b/src/file.cpp
index 165f36e..2b04f80 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -9,7 +9,10 @@
 #include <winapi/path.hpp>
 #include <winapi/utf8.hpp>
 
+#include <cstddef>
+#include <cstdint>
 #include <cstring>
+#include <stdexcept>
 #include <string>
 
 namespace winapi {
@@ -32,6 +35,13 @@ struct CreateFileParams {
         return params;
     }
 
+    static CreateFileParams read_attributes() {
+        auto params = read();
+        params.dwDesiredAccess = FILE_READ_ATTRIBUTES;
+        params.dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
+        return params;
+    }
+
     static CreateFileParams write() {
         CreateFileParams params;
         params.dwDesiredAccess = GENERIC_WRITE;
@@ -87,6 +97,38 @@ Handle File::open_r(const CanonicalPath& path) {
     return open_file(to_system_path(path), CreateFileParams::read());
 }
 
+Handle File::open_read_attributes(const std::string& path) {
+    return open_file(to_system_path(path), CreateFileParams::read_attributes());
+}
+
+Handle File::open_read_attributes(const CanonicalPath& path) {
+    return open_file(to_system_path(path), CreateFileParams::read_attributes());
+}
+
+std::size_t File::get_size() const {
+    LARGE_INTEGER size;
+
+    if (!GetFileSizeEx(get(), &size))
+        throw error::windows(GetLastError(), "GetFileSizeEx");
+
+    if (size.QuadPart < 0 || size.QuadPart > SIZE_MAX)
+        throw std::runtime_error{"invalid file size"};
+    return static_cast<std::size_t>(size.QuadPart);
+}
+
+bool operator==(const FILE_ID_128& a, const FILE_ID_128& b) {
+    return 0 == std::memcmp(a.Identifier, b.Identifier, sizeof(a.Identifier));
+}
+
+File::ID File::query_id() const {
+    FILE_ID_INFO id;
+
+    if (!GetFileInformationByHandleEx(get(), FileIdInfo, &id, sizeof(id)))
+        throw error::windows(GetLastError(), "GetFileInformationByHandleEx");
+
+    return {id};
+}
+
 Handle File::open_w(const std::string& path) {
     return open_file(to_system_path(path), CreateFileParams::write());
 }
-- 
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