Disallow more unsafe string->path conversions allowed by path append operators

Add more fs::path operator/ and operator+ overloads to prevent unsafe
string->path conversions on Windows that would cause strings to be
decoded according to the current Windows locale & code page instead of
the correct string encoding.

Update application code to deal with loss of implicit string->path
conversions by calling fs::u8path or fs::PathFromString explicitly, or
by just changing variable types from std::string to fs::path to avoid
conversions altoghther, or make them happen earlier.

In all cases, there's no change in behavior either (1) because strings
only contained ASCII characters and would be decoded the same regardless
of what encoding was used, or (2) because of the 1:1 mapping between
paths and strings using the PathToString and PathFromString functions.

Co-authored-by: Hennadii Stepanov <[email protected]>

Author: ryanofsky

src/addrdb.cpp

@@ -53,7 +53,7 @@ bool SerializeFileDB(const std::string& prefix, const fs::path& path, const Data
     std::string tmpfn = strprintf("%s.%04x", prefix, randv);
 
     // open temp output file, and associate with CAutoFile
-    fs::path pathTmp = gArgs.GetDataDirNet() / tmpfn;
+    fs::path pathTmp = gArgs.GetDataDirNet() / fs::u8path(tmpfn);
     FILE *file = fsbridge::fopen(pathTmp, "wb");
     CAutoFile fileout(file, SER_DISK, version);
     if (fileout.IsNull()) {

src/flatfile.cpp

@@ -27,7 +27,7 @@ std::string FlatFilePos::ToString() const
 
 fs::path FlatFileSeq::FileName(const FlatFilePos& pos) const
 {
-    return m_dir / strprintf("%s%05u.dat", m_prefix, pos.nFile);
+    return m_dir / fs::u8path(strprintf("%s%05u.dat", m_prefix, pos.nFile));
 }
 
 FILE* FlatFileSeq::Open(const FlatFilePos& pos, bool read_only)

src/fs.h

@@ -92,11 +92,30 @@ static inline auto quoted(const std::string& s)
 }
 
 // Allow safe path append operations.
-static inline path operator+(path p1, path p2)
+static inline path operator/(path p1, path p2)
 {
-    p1 += std::move(p2);
+    p1 /= std::move(p2);
     return p1;
 }
+static inline path operator/(path p1, const char* p2)
+{
+    p1 /= p2;
+    return p1;
+}
+static inline path operator+(path p1, const char* p2)
+{
+    p1 += p2;
+    return p1;
+}
+static inline path operator+(path p1, path::value_type p2)
+{
+    p1 += p2;
+    return p1;
+}
+
+// Disallow unsafe path append operations.
+template<typename T> static inline path operator/(path p1, T p2) = delete;
+template<typename T> static inline path operator+(path p1, T p2) = delete;
 
 // Disallow implicit std::string conversion for copy_file
 // to avoid locale-dependent encoding on Windows.

src/index/blockfilterindex.cpp

@@ -100,7 +100,7 @@ BlockFilterIndex::BlockFilterIndex(BlockFilterType filter_type,
     const std::string& filter_name = BlockFilterTypeName(filter_type);
     if (filter_name.empty()) throw std::invalid_argument("unknown filter_type");
 
-    fs::path path = gArgs.GetDataDirNet() / "indexes" / "blockfilter" / filter_name;
+    fs::path path = gArgs.GetDataDirNet() / "indexes" / "blockfilter" / fs::u8path(filter_name);
     fs::create_directories(path);
 
     m_name = filter_name + " block filter index";

src/net.cpp

@@ -3127,7 +3127,7 @@ void CaptureMessageToFile(const CAddress& addr,
     std::string clean_addr = addr.ToString();
     std::replace(clean_addr.begin(), clean_addr.end(), ':', '_');
 
-    fs::path base_path = gArgs.GetDataDirNet() / "message_capture" / clean_addr;
+    fs::path base_path = gArgs.GetDataDirNet() / "message_capture" / fs::u8path(clean_addr);
     fs::create_directories(base_path);
 
     fs::path path = base_path / (is_incoming ? "msgs_recv.dat" : "msgs_sent.dat");

src/qt/guiutil.cpp

@@ -508,7 +508,7 @@ fs::path static StartupShortcutPath()
         return GetSpecialFolderPath(CSIDL_STARTUP) / "Bitcoin.lnk";
     if (chain == CBaseChainParams::TESTNET) // Remove this special case when CBaseChainParams::TESTNET = "testnet4"
         return GetSpecialFolderPath(CSIDL_STARTUP) / "Bitcoin (testnet).lnk";
-    return GetSpecialFolderPath(CSIDL_STARTUP) / strprintf("Bitcoin (%s).lnk", chain);
+    return GetSpecialFolderPath(CSIDL_STARTUP) / fs::u8path(strprintf("Bitcoin (%s).lnk", chain));
 }
 
 bool GetStartOnSystemStartup()
@@ -589,7 +589,7 @@ fs::path static GetAutostartFilePath()
     std::string chain = gArgs.GetChainName();
     if (chain == CBaseChainParams::MAIN)
         return GetAutostartDir() / "bitcoin.desktop";
-    return GetAutostartDir() / strprintf("bitcoin-%s.desktop", chain);
+    return GetAutostartDir() / fs::u8path(strprintf("bitcoin-%s.desktop", chain));
 }
 
 bool GetStartOnSystemStartup()

src/test/util/chainstate.h

@@ -30,7 +30,7 @@ CreateAndActivateUTXOSnapshot(node::NodeContext& node, const fs::path root, F ma
     //
     int height;
     WITH_LOCK(::cs_main, height = node.chainman->ActiveHeight());
-    fs::path snapshot_path = root / tfm::format("test_snapshot.%d.dat", height);
+    fs::path snapshot_path = root / fs::u8path(tfm::format("test_snapshot.%d.dat", height));
     FILE* outfile{fsbridge::fopen(snapshot_path, "wb")};
     CAutoFile auto_outfile{outfile, SER_DISK, CLIENT_VERSION};
 

src/test/util_tests.cpp

@@ -2049,7 +2049,7 @@ BOOST_AUTO_TEST_CASE(test_ParseFixedPoint)
     BOOST_CHECK(!ParseFixedPoint("31.999999999999999999999", 3, &amount));
 }
 
-static void TestOtherThread(fs::path dirname, std::string lockname, bool *result)
+static void TestOtherThread(fs::path dirname, fs::path lockname, bool *result)
 {
     *result = LockDirectory(dirname, lockname);
 }
@@ -2059,7 +2059,7 @@ static constexpr char LockCommand = 'L';
 static constexpr char UnlockCommand = 'U';
 static constexpr char ExitCommand = 'X';
 
-[[noreturn]] static void TestOtherProcess(fs::path dirname, std::string lockname, int fd)
+[[noreturn]] static void TestOtherProcess(fs::path dirname, fs::path lockname, int fd)
 {
     char ch;
     while (true) {
@@ -2090,7 +2090,7 @@ static constexpr char ExitCommand = 'X';
 BOOST_AUTO_TEST_CASE(test_LockDirectory)
 {
     fs::path dirname = m_args.GetDataDirBase() / "lock_dir";
-    const std::string lockname = ".lock";
+    const fs::path lockname = ".lock";
 #ifndef WIN32
     // Revert SIGCHLD to default, otherwise boost.test will catch and fail on
     // it: there is BOOST_TEST_IGNORE_SIGCHLD but that only works when defined

src/util/getuniquepath.cpp

@@ -9,6 +9,6 @@
 fs::path GetUniquePath(const fs::path& base)
 {
     FastRandomContext rnd;
-    fs::path tmpFile = base / HexStr(rnd.randbytes(8));
+    fs::path tmpFile = base / fs::u8path(HexStr(rnd.randbytes(8)));
     return tmpFile;
 }

src/util/system.cpp

@@ -104,7 +104,7 @@ static Mutex cs_dir_locks;
  */
 static std::map<std::string, std::unique_ptr<fsbridge::FileLock>> dir_locks GUARDED_BY(cs_dir_locks);
 
-bool LockDirectory(const fs::path& directory, const std::string lockfile_name, bool probe_only)
+bool LockDirectory(const fs::path& directory, const fs::path& lockfile_name, bool probe_only)
 {
     LOCK(cs_dir_locks);
     fs::path pathLockFile = directory / lockfile_name;
@@ -128,7 +128,7 @@ bool LockDirectory(const fs::path& directory, const std::string lockfile_name, b
     return true;
 }
 
-void UnlockDirectory(const fs::path& directory, const std::string& lockfile_name)
+void UnlockDirectory(const fs::path& directory, const fs::path& lockfile_name)
 {
     LOCK(cs_dir_locks);
     dir_locks.erase(fs::PathToString(directory / lockfile_name));