Merge #20519: Handle rename failure in DumpMempool(...) by using the RenameOver(...) return value. Add [[nodiscard]] to RenameOver(...).

ce9dd45 Add [[nodiscard]] to RenameOver(...) (practicalswift)
9429a39 Handle rename failure in DumpMempool(...) by using RenameOver(...) return value (practicalswift)

Pull request description:

  Handle rename failure in `DumpMempool(...)` by using the `RenameOver(...)` return value.

  Add `[[nodiscard]]` to `RenameOver(...)` to reduce the risk of similar rename issues in the future.

ACKs for top commit:
  vasild:
    ACK ce9dd45
  theStack:
    ACK ce9dd45 🏷️

Tree-SHA512: 1e63d7f3061e1f6ea2df5750dbc1547a39bd50b6c529812a0c8a0c11d3100c241afdf14094e69b69a38bade7e54a12b2a42888545874398eaf5d02421b57e874

Author: MarcoFalke

src/util/system.h

@@ -60,7 +60,7 @@ bool FileCommit(FILE *file);
 bool TruncateFile(FILE *file, unsigned int length);
 int RaiseFileDescriptorLimit(int nMinFD);
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
-bool RenameOver(fs::path src, fs::path dest);
+[[nodiscard]] bool RenameOver(fs::path src, fs::path dest);
 bool LockDirectory(const fs::path& directory, const std::string lockfile_name, bool probe_only=false);
 void UnlockDirectory(const fs::path& directory, const std::string& lockfile_name);
 bool DirIsWritable(const fs::path& directory);

src/validation.cpp

@@ -5110,7 +5110,9 @@ bool DumpMempool(const CTxMemPool& pool)
         if (!FileCommit(file.Get()))
             throw std::runtime_error("FileCommit failed");
         file.fclose();
-        RenameOver(GetDataDir() / "mempool.dat.new", GetDataDir() / "mempool.dat");
+        if (!RenameOver(GetDataDir() / "mempool.dat.new", GetDataDir() / "mempool.dat")) {
+            throw std::runtime_error("Rename failed");
+        }
         int64_t last = GetTimeMicros();
         LogPrintf("Dumped mempool: %gs to copy, %gs to dump\n", (mid-start)*MICRO, (last-mid)*MICRO);
     } catch (const std::exception& e) {