LCOV - code coverage report
Current view: top level - src/util - fs.h (source / functions) Hit Total Coverage
Test: fuzz_coverage.info Lines: 28 48 58.3 %
Date: 2023-10-05 12:38:51 Functions: 21 29 72.4 %
Branches: 5 16 31.2 %

           Branch data     Line data    Source code
       1                 :            : // Copyright (c) 2017-2022 The Bitcoin Core developers
       2                 :            : // Distributed under the MIT software license, see the accompanying
       3                 :            : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :            : 
       5                 :            : #ifndef BITCOIN_UTIL_FS_H
       6                 :            : #define BITCOIN_UTIL_FS_H
       7                 :            : 
       8                 :            : #include <tinyformat.h>
       9                 :            : 
      10                 :            : #include <cstdio>
      11                 :            : #include <filesystem> // IWYU pragma: export
      12                 :            : #include <functional>
      13                 :            : #include <iomanip>
      14                 :            : #include <ios>
      15                 :            : #include <ostream>
      16                 :            : #include <string>
      17                 :            : #include <utility>
      18                 :            : 
      19                 :            : /** Filesystem operations and types */
      20                 :            : namespace fs {
      21                 :            : 
      22                 :            : using namespace std::filesystem;
      23                 :            : 
      24                 :            : /**
      25                 :            :  * Path class wrapper to block calls to the fs::path(std::string) implicit
      26                 :            :  * constructor and the fs::path::string() method, which have unsafe and
      27                 :            :  * unpredictable behavior on Windows (see implementation note in
      28                 :            :  * \ref PathToString for details)
      29                 :            :  */
      30                 :            : class path : public std::filesystem::path
      31                 :            : {
      32                 :            : public:
      33                 :            :     using std::filesystem::path::path;
      34                 :            : 
      35                 :            :     // Allow path objects arguments for compatibility.
      36                 :       4039 :     path(std::filesystem::path path) : std::filesystem::path::path(std::move(path)) {}
      37                 :       4011 :     path& operator=(std::filesystem::path path) { std::filesystem::path::operator=(std::move(path)); return *this; }
      38                 :          9 :     path& operator/=(std::filesystem::path path) { std::filesystem::path::operator/=(path); return *this; }
      39                 :            : 
      40                 :            :     // Allow literal string arguments, which are safe as long as the literals are ASCII.
      41                 :         12 :     path(const char* c) : std::filesystem::path(c) {}
      42                 :          0 :     path& operator=(const char* c) { std::filesystem::path::operator=(c); return *this; }
      43                 :          8 :     path& operator/=(const char* c) { std::filesystem::path::operator/=(c); return *this; }
      44                 :            :     path& append(const char* c) { std::filesystem::path::append(c); return *this; }
      45                 :            : 
      46                 :            :     // Disallow std::string arguments to avoid locale-dependent decoding on windows.
      47                 :            :     path(std::string) = delete;
      48                 :            :     path& operator=(std::string) = delete;
      49                 :            :     path& operator/=(std::string) = delete;
      50                 :            :     path& append(std::string) = delete;
      51                 :            : 
      52                 :            :     // Disallow std::string conversion method to avoid locale-dependent encoding on windows.
      53                 :            :     std::string string() const = delete;
      54                 :            : 
      55                 :          0 :     std::string u8string() const
      56                 :            :     {
      57                 :          0 :         const auto& utf8_str{std::filesystem::path::u8string()};
      58                 :            :         // utf8_str might either be std::string (C++17) or std::u8string
      59                 :            :         // (C++20). Convert both to std::string. This method can be removed
      60                 :            :         // after switching to C++20.
      61         [ #  # ]:          0 :         return std::string{utf8_str.begin(), utf8_str.end()};
      62                 :          0 :     }
      63                 :            : 
      64                 :            :     // Required for path overloads in <fstream>.
      65                 :            :     // See https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=96e0367ead5d8dcac3bec2865582e76e2fbab190
      66                 :          0 :     path& make_preferred() { std::filesystem::path::make_preferred(); return *this; }
      67         [ #  # ]:          0 :     path filename() const { return std::filesystem::path::filename(); }
      68                 :            : };
      69                 :            : 
      70                 :          4 : static inline path u8path(const std::string& utf8_str)
      71                 :            : {
      72                 :            : #if __cplusplus < 202002L
      73         [ +  - ]:          4 :     return std::filesystem::u8path(utf8_str);
      74                 :            : #else
      75                 :            :     return std::filesystem::path(std::u8string{utf8_str.begin(), utf8_str.end()});
      76                 :            : #endif
      77                 :          0 : }
      78                 :            : 
      79                 :            : // Disallow implicit std::string conversion for absolute to avoid
      80                 :            : // locale-dependent encoding on windows.
      81                 :          4 : static inline path absolute(const path& p)
      82                 :            : {
      83         [ +  - ]:          4 :     return std::filesystem::absolute(p);
      84                 :          0 : }
      85                 :            : 
      86                 :            : // Disallow implicit std::string conversion for exists to avoid
      87                 :            : // locale-dependent encoding on windows.
      88                 :          3 : static inline bool exists(const path& p)
      89                 :            : {
      90                 :          3 :     return std::filesystem::exists(p);
      91                 :            : }
      92                 :            : 
      93                 :            : // Allow explicit quoted stream I/O.
      94                 :          0 : static inline auto quoted(const std::string& s)
      95                 :            : {
      96                 :          0 :     return std::quoted(s, '"', '&');
      97                 :            : }
      98                 :            : 
      99                 :            : // Allow safe path append operations.
     100                 :          5 : static inline path operator/(path p1, path p2)
     101                 :            : {
     102         [ +  - ]:          5 :     p1 /= std::move(p2);
     103                 :          5 :     return p1;
     104                 :          0 : }
     105                 :          6 : static inline path operator/(path p1, const char* p2)
     106                 :            : {
     107                 :          6 :     p1 /= p2;
     108                 :          6 :     return p1;
     109                 :            : }
     110                 :          2 : static inline path operator+(path p1, const char* p2)
     111                 :            : {
     112                 :          2 :     p1 += p2;
     113                 :          2 :     return p1;
     114                 :            : }
     115                 :          0 : static inline path operator+(path p1, path::value_type p2)
     116                 :            : {
     117                 :          0 :     p1 += p2;
     118                 :          0 :     return p1;
     119                 :            : }
     120                 :            : 
     121                 :            : // Disallow unsafe path append operations.
     122                 :            : template<typename T> static inline path operator/(path p1, T p2) = delete;
     123                 :            : template<typename T> static inline path operator+(path p1, T p2) = delete;
     124                 :            : 
     125                 :            : // Disallow implicit std::string conversion for copy_file
     126                 :            : // to avoid locale-dependent encoding on Windows.
     127                 :          0 : static inline bool copy_file(const path& from, const path& to, copy_options options)
     128                 :            : {
     129                 :          0 :     return std::filesystem::copy_file(from, to, options);
     130                 :            : }
     131                 :            : 
     132                 :            : /**
     133                 :            :  * Convert path object to a byte string. On POSIX, paths natively are byte
     134                 :            :  * strings, so this is trivial. On Windows, paths natively are Unicode, so an
     135                 :            :  * encoding step is necessary. The inverse of \ref PathToString is \ref
     136                 :            :  * PathFromString. The strings returned and parsed by these functions can be
     137                 :            :  * used to call POSIX APIs, and for roundtrip conversion, logging, and
     138                 :            :  * debugging.
     139                 :            :  *
     140                 :            :  * Because \ref PathToString and \ref PathFromString functions don't specify an
     141                 :            :  * encoding, they are meant to be used internally, not externally. They are not
     142                 :            :  * appropriate to use in applications requiring UTF-8, where
     143                 :            :  * fs::path::u8string() and fs::u8path() methods should be used instead. Other
     144                 :            :  * applications could require still different encodings. For example, JSON, XML,
     145                 :            :  * or URI applications might prefer to use higher-level escapes (\uXXXX or
     146                 :            :  * &XXXX; or %XX) instead of multibyte encoding. Rust, Python, Java applications
     147                 :            :  * may require encoding paths with their respective UTF-8 derivatives WTF-8,
     148                 :            :  * PEP-383, and CESU-8 (see https://en.wikipedia.org/wiki/UTF-8#Derivatives).
     149                 :            :  */
     150                 :         13 : static inline std::string PathToString(const path& path)
     151                 :            : {
     152                 :            :     // Implementation note: On Windows, the std::filesystem::path(string)
     153                 :            :     // constructor and std::filesystem::path::string() method are not safe to
     154                 :            :     // use here, because these methods encode the path using C++'s narrow
     155                 :            :     // multibyte encoding, which on Windows corresponds to the current "code
     156                 :            :     // page", which is unpredictable and typically not able to represent all
     157                 :            :     // valid paths. So fs::path::u8string() and
     158                 :            :     // fs::u8path() functions are used instead on Windows. On
     159                 :            :     // POSIX, u8string/u8path functions are not safe to use because paths are
     160                 :            :     // not always valid UTF-8, so plain string methods which do not transform
     161                 :            :     // the path there are used.
     162                 :            : #ifdef WIN32
     163                 :            :     return path.u8string();
     164                 :            : #else
     165                 :            :     static_assert(std::is_same<path::string_type, std::string>::value, "PathToString not implemented on this platform");
     166                 :         13 :     return path.std::filesystem::path::string();
     167                 :            : #endif
     168                 :            : }
     169                 :            : 
     170                 :            : /**
     171                 :            :  * Convert byte string to path object. Inverse of \ref PathToString.
     172                 :            :  */
     173                 :          8 : static inline path PathFromString(const std::string& string)
     174                 :            : {
     175                 :            : #ifdef WIN32
     176                 :            :     return u8path(string);
     177                 :            : #else
     178         [ +  - ]:          8 :     return std::filesystem::path(string);
     179                 :            : #endif
     180                 :          0 : }
     181                 :            : 
     182                 :            : /**
     183                 :            :  * Create directory (and if necessary its parents), unless the leaf directory
     184                 :            :  * already exists or is a symlink to an existing directory.
     185                 :            :  * This is a temporary workaround for an issue in libstdc++ that has been fixed
     186                 :            :  * upstream [PR101510].
     187                 :            :  */
     188                 :          6 : static inline bool create_directories(const std::filesystem::path& p)
     189                 :            : {
     190   [ -  +  #  # ]:          6 :     if (std::filesystem::is_symlink(p) && std::filesystem::is_directory(p)) {
     191                 :          0 :         return false;
     192                 :            :     }
     193                 :          6 :     return std::filesystem::create_directories(p);
     194                 :          6 : }
     195                 :            : 
     196                 :            : /**
     197                 :            :  * This variant is not used. Delete it to prevent it from accidentally working
     198                 :            :  * around the workaround. If it is needed, add a workaround in the same pattern
     199                 :            :  * as above.
     200                 :            :  */
     201                 :            : bool create_directories(const std::filesystem::path& p, std::error_code& ec) = delete;
     202                 :            : 
     203                 :            : } // namespace fs
     204                 :            : 
     205                 :            : /** Bridge operations to C stdio */
     206                 :            : namespace fsbridge {
     207                 :            :     using FopenFn = std::function<FILE*(const fs::path&, const char*)>;
     208                 :            :     FILE *fopen(const fs::path& p, const char *mode);
     209                 :            : 
     210                 :            :     /**
     211                 :            :      * Helper function for joining two paths
     212                 :            :      *
     213                 :            :      * @param[in] base  Base path
     214                 :            :      * @param[in] path  Path to combine with base
     215                 :            :      * @returns path unchanged if it is an absolute path, otherwise returns base joined with path. Returns base unchanged if path is empty.
     216                 :            :      * @pre  Base path must be absolute
     217                 :            :      * @post Returned path will always be absolute
     218                 :            :      */
     219                 :            :     fs::path AbsPathJoin(const fs::path& base, const fs::path& path);
     220                 :            : 
     221                 :            :     class FileLock
     222                 :            :     {
     223                 :            :     public:
     224                 :            :         FileLock() = delete;
     225                 :            :         FileLock(const FileLock&) = delete;
     226                 :            :         FileLock(FileLock&&) = delete;
     227                 :            :         explicit FileLock(const fs::path& file);
     228                 :            :         ~FileLock();
     229                 :            :         bool TryLock();
     230                 :          0 :         std::string GetReason() { return reason; }
     231                 :            : 
     232                 :            :     private:
     233                 :            :         std::string reason;
     234                 :            : #ifndef WIN32
     235                 :            :         int fd = -1;
     236                 :            : #else
     237                 :            :         void* hFile = (void*)-1; // INVALID_HANDLE_VALUE
     238                 :            : #endif
     239                 :            :     };
     240                 :            : 
     241                 :            :     std::string get_filesystem_error_message(const fs::filesystem_error& e);
     242                 :            : };
     243                 :            : 
     244                 :            : // Disallow path operator<< formatting in tinyformat to avoid locale-dependent
     245                 :            : // encoding on windows.
     246                 :            : namespace tinyformat {
     247                 :            : template<> inline void formatValue(std::ostream&, const char*, const char*, int, const std::filesystem::path&) = delete;
     248                 :            : template<> inline void formatValue(std::ostream&, const char*, const char*, int, const fs::path&) = delete;
     249                 :            : } // namespace tinyformat
     250                 :            : 
     251                 :            : #endif // BITCOIN_UTIL_FS_H

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