fs: consistently use fsbridge for {i,o}fstream

Part of #20744, but this can be done now, and will simplify the diff.

src/bench/bench.cpp

@@ -4,10 +4,10 @@
 
 #include <bench/bench.h>
 
+#include <fs.h>
 #include <test/util/setup_common.h>
 
 #include <chrono>
-#include <fstream>
 #include <functional>
 #include <iostream>
 #include <map>
@@ -29,7 +29,7 @@ void GenerateTemplateResults(const std::vector<ankerl::nanobench::Result>& bench
         // nothing to write, bail out
         return;
     }
-    std::ofstream fout(filename);
+    fsbridge::ofstream fout{fs::PathFromString(filename)};
     if (fout.is_open()) {
         ankerl::nanobench::render(tpl, benchmarkResults, fout);
     } else {

src/qt/psbtoperationsdialog.cpp

@@ -158,7 +158,7 @@ void PSBTOperationsDialog::saveTransaction() {
     if (filename.isEmpty()) {
         return;
     }
-    std::ofstream out(filename.toLocal8Bit().data(), std::ofstream::out | std::ofstream::binary);
+    fsbridge::ofstream out{filename.toLocal8Bit().data(), fsbridge::ofstream::out | fsbridge::ofstream::binary};
     out << ssTx.str();
     out.close();
     showStatus(tr("PSBT saved to disk."), StatusLevel::INFO);

src/qt/sendcoinsdialog.cpp

@@ -509,7 +509,7 @@ void SendCoinsDialog::sendButtonClicked([[maybe_unused]] bool checked)
             if (filename.isEmpty()) {
                 return;
             }
-            std::ofstream out(filename.toLocal8Bit().data(), std::ofstream::out | std::ofstream::binary);
+            fsbridge::ofstream out{filename.toLocal8Bit().data(), fsbridge::ofstream::out | fsbridge::ofstream::binary};
             out << ssTx.str();
             out.close();
             Q_EMIT message(tr("PSBT saved"), "PSBT saved to disk", CClientUIInterface::MSG_INFORMATION);

src/qt/walletframe.cpp

@@ -210,7 +210,7 @@ void WalletFrame::gotoLoadPSBT(bool from_clipboard)
             Q_EMIT message(tr("Error"), tr("PSBT file must be smaller than 100 MiB"), CClientUIInterface::MSG_ERROR);
             return;
         }
-        std::ifstream in(filename.toLocal8Bit().data(), std::ios::binary);
+        fsbridge::ifstream in{filename.toLocal8Bit().data(), std::ios::binary};
         data = std::string(std::istreambuf_iterator<char>{in}, {});
     }
 

src/test/fuzz/fuzz.cpp

@@ -80,7 +80,7 @@ void initialize()
     }
     if (const char* out_path = std::getenv("WRITE_ALL_FUZZ_TARGETS_AND_ABORT")) {
         std::cout << "Writing all fuzz target names to '" << out_path << "'." << std::endl;
-        std::ofstream out_stream(out_path, std::ios::binary);
+        fsbridge::ofstream out_stream{out_path, std::ios::binary};
         for (const auto& t : FuzzTargets()) {
             if (std::get<2>(t.second)) continue;
             out_stream << t.first << std::endl;

src/util/system.cpp

@@ -146,7 +146,7 @@ bool CheckDiskSpace(const fs::path& dir, uint64_t additional_bytes)
 }
 
 std::streampos GetFileSize(const char* path, std::streamsize max) {
-    std::ifstream file(path, std::ios::binary);
+    fsbridge::ifstream file{path, std::ios::binary};
     file.ignore(max);
     return file.gcount();
 }