Merge #15297: wallet: Releases dangling files on BerkeleyEnvironment::Close

d3bf3b930 qa: Test .walletlock file is closed (João Barbosa)
2f8b8f479 wallet: Close wallet env lock file (João Barbosa)
8602a1e6a wallet: Close dbenv error file db.log (João Barbosa)

Pull request description:

  This PR closes `db.log` and removes `.walletlock` files when `BerkeleyEnvironment` is closed.

  Fixes https://github.com/bitcoin/bitcoin/issues/15291#issuecomment-459131886.

Tree-SHA512: 05d8b027feea914e0ba873e75d117857473d1fd7b400e41bd473d638171fa39d5be048990bf685dc0807f7d92418579b763056dc2a6dcf6b96777d5688ddee04

3 files changed, 14 insertions, 0 deletions

diff --git a/src/util/system.cpp b/src/util/system.cpp
index 789dcfaba9..bb9fcab59e 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -111,6 +111,12 @@ bool LockDirectory(const fs::path& directory, const std::string lockfile_name, b
     return true;
 }
 
+void UnlockDirectory(const fs::path& directory, const std::string& lockfile_name)
+{
+    std::lock_guard<std::mutex> lock(cs_dir_locks);
+    dir_locks.erase((directory / lockfile_name).string());
+}
+
 void ReleaseDirectoryLocks()
 {
     std::lock_guard<std::mutex> ulock(cs_dir_locks);
diff --git a/src/util/system.h b/src/util/system.h
index 5932e55793..17723d427d 100644
--- a/src/util/system.h
+++ b/src/util/system.h
@@ -70,6 +70,7 @@ int RaiseFileDescriptorLimit(int nMinFD);
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
 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);
 
 /** Release all directory locks. This is used for unit testing only, at runtime
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index cfa9bdd20e..c64a85c910 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -126,11 +126,18 @@ void BerkeleyEnvironment::Close()
         }
     }
 
+    FILE* error_file = nullptr;
+    dbenv->get_errfile(&error_file);
+
     int ret = dbenv->close(0);
     if (ret != 0)
         LogPrintf("BerkeleyEnvironment::Close: Error %d closing database environment: %s\n", ret, DbEnv::strerror(ret));
     if (!fMockDb)
         DbEnv((u_int32_t)0).remove(strPath.c_str(), 0);
+
+    if (error_file) fclose(error_file);
+
+    UnlockDirectory(strPath, ".walletlock");
 }
 
 void BerkeleyEnvironment::Reset()