diff options
Diffstat (limited to 'src/fs.h')
| -rw-r--r-- | src/fs.h | 137 |
1 files changed, 135 insertions, 2 deletions
@@ -1,4 +1,4 @@ -// Copyright (c) 2017-2019 The Bitcoin Core developers +// Copyright (c) 2017-2021 The Bitcoin Core developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. @@ -13,9 +13,135 @@ #include <boost/filesystem.hpp> #include <boost/filesystem/fstream.hpp> +#include <tinyformat.h> /** Filesystem operations and types */ -namespace fs = boost::filesystem; +namespace fs { + +using namespace boost::filesystem; + +/** + * Path class wrapper to prepare application code for transition from + * boost::filesystem library to std::filesystem implementation. The main + * purpose of the class is to define fs::path::u8string() and fs::u8path() + * functions not present in boost. It also blocks calls to the + * fs::path(std::string) implicit constructor and the fs::path::string() + * method, which worked well in the boost::filesystem implementation, but have + * unsafe and unpredictable behavior on Windows in the std::filesystem + * implementation (see implementation note in \ref PathToString for details). + */ +class path : public boost::filesystem::path +{ +public: + using boost::filesystem::path::path; + + // Allow path objects arguments for compatibility. + path(boost::filesystem::path path) : boost::filesystem::path::path(std::move(path)) {} + path& operator=(boost::filesystem::path path) { boost::filesystem::path::operator=(std::move(path)); return *this; } + path& operator/=(boost::filesystem::path path) { boost::filesystem::path::operator/=(std::move(path)); return *this; } + + // Allow literal string arguments, which are safe as long as the literals are ASCII. + path(const char* c) : boost::filesystem::path(c) {} + path& operator=(const char* c) { boost::filesystem::path::operator=(c); return *this; } + path& operator/=(const char* c) { boost::filesystem::path::operator/=(c); return *this; } + path& append(const char* c) { boost::filesystem::path::append(c); return *this; } + + // Disallow std::string arguments to avoid locale-dependent decoding on windows. + path(std::string) = delete; + path& operator=(std::string) = delete; + path& operator/=(std::string) = delete; + path& append(std::string) = delete; + + // Disallow std::string conversion method to avoid locale-dependent encoding on windows. + std::string string() const = delete; + + // Define UTF-8 string conversion method not present in boost::filesystem but present in std::filesystem. + std::string u8string() const { return boost::filesystem::path::string(); } +}; + +// Define UTF-8 string conversion function not present in boost::filesystem but present in std::filesystem. +static inline path u8path(const std::string& string) +{ + return boost::filesystem::path(string); +} + +// Disallow implicit std::string conversion for system_complete to avoid +// locale-dependent encoding on windows. +static inline path system_complete(const path& p) +{ + return boost::filesystem::system_complete(p); +} + +// Disallow implicit std::string conversion for exists to avoid +// locale-dependent encoding on windows. +static inline bool exists(const path& p) +{ + return boost::filesystem::exists(p); +} + +// Allow explicit quoted stream I/O. +static inline auto quoted(const std::string& s) +{ + return boost::io::quoted(s, '&'); +} + +// Allow safe path append operations. +static inline path operator+(path p1, path p2) +{ + p1 += std::move(p2); + return p1; +} + +/** + * Convert path object to byte string. On POSIX, paths natively are byte + * strings, so this is trivial. On Windows, paths natively are Unicode, so an + * encoding step is necessary. The inverse of \ref PathToString is \ref + * PathFromString. The strings returned and parsed by these functions can be + * used to call POSIX APIs, and for roundtrip conversion, logging, and + * debugging. + * + * Because \ref PathToString and \ref PathFromString functions don't specify an + * encoding, they are meant to be used internally, not externally. They are not + * appropriate to use in applications requiring UTF-8, where + * fs::path::u8string() and fs::u8path() methods should be used instead. Other + * applications could require still different encodings. For example, JSON, XML, + * or URI applications might prefer to use higher level escapes (\uXXXX or + * &XXXX; or %XX) instead of multibyte encoding. Rust, Python, Java applications + * may require encoding paths with their respective UTF-8 derivatives WTF-8, + * PEP-383, and CESU-8 (see https://en.wikipedia.org/wiki/UTF-8#Derivatives). + */ +static inline std::string PathToString(const path& path) +{ + // Implementation note: On Windows, the std::filesystem::path(string) + // constructor and std::filesystem::path::string() method are not safe to + // use here, because these methods encode the path using C++'s narrow + // multibyte encoding, which on Windows corresponds to the current "code + // page", which is unpredictable and typically not able to represent all + // valid paths. So std::filesystem::path::u8string() and + // std::filesystem::u8path() functions are used instead on Windows. On + // POSIX, u8string/u8path functions are not safe to use because paths are + // not always valid UTF-8, so plain string methods which do not transform + // the path there are used. +#ifdef WIN32 + return path.u8string(); +#else + static_assert(std::is_same<path::string_type, std::string>::value, "PathToString not implemented on this platform"); + return path.boost::filesystem::path::string(); +#endif +} + +/** + * Convert byte string to path object. Inverse of \ref PathToString. + */ +static inline path PathFromString(const std::string& string) +{ +#ifdef WIN32 + return u8path(string); +#else + return boost::filesystem::path(string); +#endif +} +} // namespace fs /** Bridge operations to C stdio */ namespace fsbridge { @@ -103,4 +229,11 @@ namespace fsbridge { #endif // WIN32 && __GLIBCXX__ }; +// Disallow path operator<< formatting in tinyformat to avoid locale-dependent +// encoding on windows. +namespace tinyformat { +template<> inline void formatValue(std::ostream&, const char*, const char*, int, const boost::filesystem::path&) = delete; +template<> inline void formatValue(std::ostream&, const char*, const char*, int, const fs::path&) = delete; +} // namespace tinyformat + #endif // BITCOIN_FS_H |