Merge #19259: fuzz: Add fuzzing harness for LoadMempool(...) and DumpMempool(...)

68afd3eeec27a270765ad26cd62d87cd0935e99f tests: Add fuzzing harness for LoadMempool(...) and DumpMempool(...) (practicalswift)
91af6b97c9197f8ac9766a8559dd50bbc443ad38 validation: Make DumpMempool(...) and LoadMempool(...) easier to test/fuzz/mock (practicalswift)
af322c7494d6bc4b94890c85d16623b082c4fe24 tests: Set errno in FuzzedFileProvider. Implement seek(..., ..., SEEK_END). (practicalswift)

Pull request description:

  Add fuzzing harness for `LoadMempool(...)` and `DumpMempool(...)`.

  See [`doc/fuzzing.md`](https://github.com/bitcoin/bitcoin/blob/master/doc/fuzzing.md) for information on how to fuzz Bitcoin Core. Don't forget to contribute any coverage increasing inputs you find to the [Bitcoin Core fuzzing corpus repo](https://github.com/bitcoin-core/qa-assets).

  Happy fuzzing :)

ACKs for top commit:
  jonatack:
    Tested re-ACK 68afd3eeec27a270765ad26cd62d87cd0935e99f

Tree-SHA512: 4b5fcaa87e6eb478611d3b68eb6859645a5e121e7e3b056ad2815699dace0a6123706ff542def371b47f4ab3ce2b8a29782026d84fb505827121e9b4cc7dac31

1 files changed, 5 insertions, 5 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index be0be904e9..a1bd79bdfc 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -5010,11 +5010,11 @@ CBlockFileInfo* GetBlockFileInfo(size_t n)
 
 static const uint64_t MEMPOOL_DUMP_VERSION = 1;
 
-bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate)
+bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate, FopenFn mockable_fopen_function)
 {
     const CChainParams& chainparams = Params();
     int64_t nExpiryTimeout = gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60;
-    FILE* filestr = fsbridge::fopen(GetDataDir() / "mempool.dat", "rb");
+    FILE* filestr{mockable_fopen_function(GetDataDir() / "mempool.dat", "rb")};
     CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
     if (file.IsNull()) {
         LogPrintf("Failed to open mempool file from disk. Continuing anyway.\n");
@@ -5095,7 +5095,7 @@ bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate)
     return true;
 }
 
-bool DumpMempool(const CTxMemPool& pool)
+bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function, bool skip_file_commit)
 {
     int64_t start = GetTimeMicros();
 
@@ -5118,7 +5118,7 @@ bool DumpMempool(const CTxMemPool& pool)
     int64_t mid = GetTimeMicros();
 
     try {
-        FILE* filestr = fsbridge::fopen(GetDataDir() / "mempool.dat.new", "wb");
+        FILE* filestr{mockable_fopen_function(GetDataDir() / "mempool.dat.new", "wb")};
         if (!filestr) {
             return false;
         }
@@ -5141,7 +5141,7 @@ bool DumpMempool(const CTxMemPool& pool)
         LogPrintf("Writing %d unbroadcast transactions to disk.\n", unbroadcast_txids.size());
         file << unbroadcast_txids;
 
-        if (!FileCommit(file.Get()))
+        if (!skip_file_commit && !FileCommit(file.Get()))
             throw std::runtime_error("FileCommit failed");
         file.fclose();
         if (!RenameOver(GetDataDir() / "mempool.dat.new", GetDataDir() / "mempool.dat")) {