fs.h

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// Copyright (c) 2017 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_UTIL_FS_H
#define BITCOIN_UTIL_FS_H
 
#include <tinyformat.h>
 
#include <cstdio>
#include <filesystem>
#include <functional>
#include <iomanip>
#include <ios>
#include <ostream>
#include <string>
#include <utility>
 
namespace fs {
 
using namespace std::filesystem;
 
class path : public std::filesystem::path {
public:
    using std::filesystem::path::path;
    // Allow path objects arguments for compatibility.
    path(std::filesystem::path path)
        : std::filesystem::path::path(std::move(path)) {}
    path &operator=(std::filesystem::path path) {
        std::filesystem::path::operator=(std::move(path));
        return *this;
    }
    path &operator/=(std::filesystem::path path) {
        std::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) : std::filesystem::path(c) {}
    path &operator=(const char *c) {
        std::filesystem::path::operator=(c);
        return *this;
    }
    path &operator/=(const char *c) {
        std::filesystem::path::operator/=(c);
        return *this;
    }
    path &append(const char *c) {
        std::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;
 
    std::string u8string() const {
        const auto &utf8_str{std::filesystem::path::u8string()};
        // utf8_str might either be std::string (C++17) or std::u8string
        // (C++20). Convert both to std::string. This method can be removed
        // after switching to C++20.
        return std::string{utf8_str.begin(), utf8_str.end()};
    }
 
    // Required for path overloads in <fstream>.
    // See
    // https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=96e0367ead5d8dcac3bec2865582e76e2fbab190
    path &make_preferred() {
        std::filesystem::path::make_preferred();
        return *this;
    }
    path filename() const { return std::filesystem::path::filename(); }
};
 
static inline path u8path(const std::string &utf8_str) {
#if __cplusplus < 202002L
    return std::filesystem::u8path(utf8_str);
#else
    return std::filesystem::path(
        std::u8string{utf8_str.begin(), utf8_str.end()});
#endif
}
 
// Disallow implicit std::string conversion for absolute to avoid
// locale-dependent encoding on windows.
static inline path absolute(const path &p) {
    return std::filesystem::absolute(p);
}
 
// Disallow implicit std::string conversion for exists to avoid
// locale-dependent encoding on windows.
static inline bool exists(const path &p) {
    return std::filesystem::exists(p);
}
 
// Allow explicit quoted stream I/O.
static inline auto quoted(const std::string &s) {
    return std::quoted(s, '"', '&');
}
 
// Allow safe path append operations.
static inline path operator+(path p1, path p2) {
    p1 += std::move(p2);
    return p1;
}
 
// Disallow implicit std::string conversion for copy_file
// to avoid locale-dependent encoding on Windows.
static inline bool copy_file(const path &from, const path &to,
                             copy_options options) {
    return std::filesystem::copy_file(from, to, options);
}
 
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 fs::path::u8string() and
    // fs::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.std::filesystem::path::string();
#endif
}
 
static inline path PathFromString(const std::string &string) {
#ifdef WIN32
    return u8path(string);
#else
    return std::filesystem::path(string);
#endif
}
 
static inline bool create_directories(const std::filesystem::path &p) {
    if (std::filesystem::is_symlink(p) && std::filesystem::is_directory(p)) {
        return false;
    }
    return std::filesystem::create_directories(p);
}
 
bool create_directories(const std::filesystem::path &p,
                        std::error_code &ec) = delete;
 
} // namespace fs
 
namespace fsbridge {
using FopenFn = std::function<FILE *(const fs::path &, const char *)>;
FILE *fopen(const fs::path &p, const char *mode);
FILE *freopen(const fs::path &p, const char *mode, FILE *stream);
 
fs::path AbsPathJoin(const fs::path &base, const fs::path &path);
 
class FileLock {
public:
    FileLock() = delete;
    FileLock(const FileLock &) = delete;
    FileLock(FileLock &&) = delete;
    explicit FileLock(const fs::path &file);
    ~FileLock();
    bool TryLock();
    std::string GetReason() { return reason; }
 
private:
    std::string reason;
#ifndef WIN32
    int fd = -1;
#else
    // INVALID_HANDLE_VALUE
    void *hFile = (void *)-1;
#endif
};
 
std::string get_filesystem_error_message(const fs::filesystem_error &e);
 
fs::path GetTempDirectoryPath();
}; // namespace fsbridge
 
// 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 std::filesystem::path &) = delete;
template <>
inline void formatValue(std::ostream &, const char *, const char *, int,
                        const fs::path &) = delete;
} // namespace tinyformat
 
#endif // BITCOIN_UTIL_FS_H