refactor: replace boost::filesystem with std::filesystem

Warning: Replacing fs::system_complete calls with fs::absolute calls
in this commit may cause minor changes in behaviour because fs::absolute
no longer strips trailing slashes; however these changes are believed to
be safe.

Co-authored-by: Russell Yanofsky <russ@yanofsky.org>
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

4 files changed, 25 insertions, 22 deletions

diff --git a/src/util/asmap.cpp b/src/util/asmap.cpp
index ffa2755970..ceb8379c1c 100644
--- a/src/util/asmap.cpp
+++ b/src/util/asmap.cpp
@@ -6,6 +6,7 @@
 
 #include <clientversion.h>
 #include <crypto/common.h>
+#include <fs.h>
 #include <logging.h>
 #include <streams.h>
 
diff --git a/src/util/settings.cpp b/src/util/settings.cpp
index 683b7ae652..26439b010b 100644
--- a/src/util/settings.cpp
+++ b/src/util/settings.cpp
@@ -2,11 +2,17 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include <fs.h>
 #include <util/settings.h>
 
 #include <tinyformat.h>
 #include <univalue.h>
 
+#include <fstream>
+#include <map>
+#include <string>
+#include <vector>
+
 namespace util {
 namespace {
 
@@ -63,7 +69,7 @@ bool ReadSettings(const fs::path& path, std::map<std::string, SettingsValue>& va
     // Ok for file to not exist
     if (!fs::exists(path)) return true;
 
-    fsbridge::ifstream file;
+    std::ifstream file;
     file.open(path);
     if (!file.is_open()) {
       errors.emplace_back(strprintf("%s. Please check permissions.", fs::PathToString(path)));
@@ -106,7 +112,7 @@ bool WriteSettings(const fs::path& path,
     for (const auto& value : values) {
         out.__pushKV(value.first, value.second);
     }
-    fsbridge::ofstream file;
+    std::ofstream file;
     file.open(path);
     if (file.fail()) {
         errors.emplace_back(strprintf("Error: Unable to open settings file %s for writing", fs::PathToString(path)));
diff --git a/src/util/syscall_sandbox.cpp b/src/util/syscall_sandbox.cpp
index 3c250b7704..4157be9d9f 100644
--- a/src/util/syscall_sandbox.cpp
+++ b/src/util/syscall_sandbox.cpp
@@ -595,6 +595,7 @@ public:
         allowed_syscalls.insert(__NR_readlink);        // read value of a symbolic link
         allowed_syscalls.insert(__NR_rename);          // change the name or location of a file
         allowed_syscalls.insert(__NR_rmdir);           // delete a directory
+        allowed_syscalls.insert(__NR_sendfile);        // transfer data between file descriptors
         allowed_syscalls.insert(__NR_stat);            // get file status
         allowed_syscalls.insert(__NR_statfs);          // get filesystem statistics
         allowed_syscalls.insert(__NR_statx);           // get file status (extended)
diff --git a/src/util/system.cpp b/src/util/system.cpp
index 19de08d1ea..0ee63f6381 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -10,6 +10,7 @@
 #endif // ENABLE_EXTERNAL_SIGNER
 
 #include <chainparamsbase.h>
+#include <fs.h>
 #include <sync.h>
 #include <util/check.h>
 #include <util/getuniquepath.h>
@@ -66,10 +67,15 @@
 #endif
 
 #include <boost/algorithm/string/replace.hpp>
+#include <univalue.h>
+
+#include <fstream>
+#include <map>
+#include <memory>
 #include <optional>
+#include <string>
 #include <thread>
 #include <typeinfo>
-#include <univalue.h>
 
 // Application startup time (used for uptime calculation)
 const int64_t nStartupTime = GetTime();
@@ -146,7 +152,7 @@ bool CheckDiskSpace(const fs::path& dir, uint64_t additional_bytes)
 }
 
 std::streampos GetFileSize(const char* path, std::streamsize max) {
-    fsbridge::ifstream file{path, std::ios::binary};
+    std::ifstream file{path, std::ios::binary};
     file.ignore(max);
     return file.gcount();
 }
@@ -243,7 +249,7 @@ namespace {
 fs::path StripRedundantLastElementsOfPath(const fs::path& path)
 {
     auto result = path;
-    while (fs::PathToString(result.filename()) == ".") {
+    while (result.filename().empty() || fs::PathToString(result.filename()) == ".") {
         result = result.parent_path();
     }
 
@@ -403,7 +409,7 @@ const fs::path& ArgsManager::GetBlocksDirPath() const
     if (!path.empty()) return path;
 
     if (IsArgSet("-blocksdir")) {
-        path = fs::system_complete(fs::PathFromString(GetArg("-blocksdir", "")));
+        path = fs::absolute(fs::PathFromString(GetArg("-blocksdir", "")));
         if (!fs::is_directory(path)) {
             path = "";
             return path;
@@ -415,7 +421,6 @@ const fs::path& ArgsManager::GetBlocksDirPath() const
     path /= fs::PathFromString(BaseParams().DataDir());
     path /= "blocks";
     fs::create_directories(path);
-    path = StripRedundantLastElementsOfPath(path);
     return path;
 }
 
@@ -430,7 +435,7 @@ const fs::path& ArgsManager::GetDataDir(bool net_specific) const
 
     std::string datadir = GetArg("-datadir", "");
     if (!datadir.empty()) {
-        path = fs::system_complete(fs::PathFromString(datadir));
+        path = fs::absolute(StripRedundantLastElementsOfPath(fs::PathFromString(datadir)));
         if (!fs::is_directory(path)) {
             path = "";
             return path;
@@ -808,7 +813,7 @@ fs::path GetDefaultDataDir()
 bool CheckDataDirOption()
 {
     std::string datadir = gArgs.GetArg("-datadir", "");
-    return datadir.empty() || fs::is_directory(fs::system_complete(fs::PathFromString(datadir)));
+    return datadir.empty() || fs::is_directory(fs::absolute(fs::PathFromString(datadir)));
 }
 
 fs::path GetConfigFile(const std::string& confPath)
@@ -898,7 +903,7 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
     }
 
     const std::string confPath = GetArg("-conf", BITCOIN_CONF_FILENAME);
-    fsbridge::ifstream stream(GetConfigFile(confPath));
+    std::ifstream stream{GetConfigFile(confPath)};
 
     // not ok to have a config file specified that cannot be opened
     if (IsArgSet("-conf") && !stream.good()) {
@@ -945,7 +950,7 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
             const size_t default_includes = add_includes({});
 
             for (const std::string& conf_file_name : conf_file_names) {
-                fsbridge::ifstream conf_file_stream(GetConfigFile(conf_file_name));
+                std::ifstream conf_file_stream{GetConfigFile(conf_file_name)};
                 if (conf_file_stream.good()) {
                     if (!ReadConfigStream(conf_file_stream, conf_file_name, error, ignore_invalid_keys)) {
                         return false;
@@ -1069,7 +1074,7 @@ bool RenameOver(fs::path src, fs::path dest)
 }
 
 /**
- * Ignores exceptions thrown by Boost's create_directories if the requested directory exists.
+ * Ignores exceptions thrown by create_directories if the requested directory exists.
  * Specifically handles case where path p exists, but it wasn't possible for the user to
  * write to the parent directory.
  */
@@ -1313,16 +1318,6 @@ void SetupEnvironment()
     SetConsoleCP(CP_UTF8);
     SetConsoleOutputCP(CP_UTF8);
 #endif
-    // The path locale is lazy initialized and to avoid deinitialization errors
-    // in multithreading environments, it is set explicitly by the main thread.
-    // A dummy locale is used to extract the internal default locale, used by
-    // fs::path, which is then used to explicitly imbue the path.
-    std::locale loc = fs::path::imbue(std::locale::classic());
-#ifndef WIN32
-    fs::path::imbue(loc);
-#else
-    fs::path::imbue(std::locale(loc, new std::codecvt_utf8_utf16<wchar_t>()));
-#endif
 }
 
 bool SetupNetworking()