Merge #12220: Error if relative -walletdir is specified

ec527c6 Don't allow relative -walletdir paths (Russell Yanofsky)

Pull request description:

  This makes it an error to explicitly specify a non-absolute -walletdir path, and also adds a debug.log warning if a relative rather than absolute -datadir path is configured.

  Specifying paths relative to the current working directory in a daemon process can be dangerous, because files can fail to be located even if the configuration doesn't change, but the daemon is started up differently.

  Specifying a relative -datadir now adds a warning to the debug log. It would not be backwards-compatible to forbid relative -datadir paths entirely, and it could also be inconvenient for command line testing.

  Specifying a relative -walletdir now results in a startup error. But since the -walletdir option is new in 0.16.0, there should be no compatibility issues. Another reason not to use working directory paths for -walletdir specifically is that the default -walletdir is a "wallets" subdirectory inside the datadir, so it could be surprising that setting -walletdir manually would choose a directory rooted in a completely different location.

Tree-SHA512: 67cbdae677f82487a9031c5ec96b0205a488ab08718a0f4f49365e025119f3d7f6cfc88ba1eba04c1ecd8b9561a5b2c42e2e1a267af7c08c76b83e5e361f5a31

1 files changed, 9 insertions, 0 deletions

diff --git a/src/init.cpp b/src/init.cpp
index b48802637..d1d733af9 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1210,6 +1210,15 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     LogPrintf("Using config file %s\n", GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME)).string());
     LogPrintf("Using at most %i automatic connections (%i file descriptors available)\n", nMaxConnections, nFD);
 
+    // Warn about relative -datadir path.
+    if (gArgs.IsArgSet("-datadir") && !fs::path(gArgs.GetArg("-datadir", "")).is_absolute()) {
+        LogPrintf("Warning: relative datadir option '%s' specified, which will be interpreted relative to the "
+                  "current working directory '%s'. This is fragile, because if bitcoin is started in the future "
+                  "from a different location, it will be unable to locate the current data files. There could "
+                  "also be data loss if bitcoin is started while in a temporary directory.\n",
+            gArgs.GetArg("-datadir", ""), fs::current_path().string());
+    }
+
     InitSignatureCache();
     InitScriptExecutionCache();