util: improve bitcoin-wallet exit codes

Adjust the exit codes / functionality of bitcoin-wallet such that it's
not returning a non-zero exit code if there isn't a problem.

This is a followup from bitcoin#24263, and should allow us to add and
additional check=True to our gen-manpages.py script.

src/bitcoin-wallet.cpp

@@ -24,6 +24,7 @@
 #include <string>
 #include <tuple>
 
+static constexpr int CONTINUE_EXECUTION=-1;
 const std::function<std::string(const char*)> G_TRANSLATION_FUN = nullptr;
 UrlDecodeFn* const URL_DECODE = nullptr;
 
@@ -49,13 +50,13 @@ static void SetupWalletToolArgs(ArgsManager& argsman)
     argsman.AddCommand("createfromdump", "Create new wallet file from dumped records");
 }
 
-static bool WalletAppInit(ArgsManager& args, int argc, char* argv[])
+static int WalletAppInit(ArgsManager& args, int argc, char* argv[])
 {
     SetupWalletToolArgs(args);
     std::string error_message;
     if (!args.ParseParameters(argc, argv, error_message)) {
         tfm::format(std::cerr, "Error parsing command line arguments: %s\n", error_message);
-        return false;
+        return EXIT_FAILURE;
     }
     if (argc < 2 || HelpRequested(args) || args.IsArgSet("-version")) {
         std::string strUsage = strprintf("%s bitcoin-wallet version", PACKAGE_NAME) + " " + FormatFullVersion() + "\n";
@@ -72,20 +73,24 @@ static bool WalletAppInit(ArgsManager& args, int argc, char* argv[])
             strUsage += "\n" + args.GetHelpMessage();
         }
         tfm::format(std::cout, "%s", strUsage);
-        return false;
+        if (argc < 2) {
+            tfm::format(std::cerr, "Error: too few parameters\n");
+            return EXIT_FAILURE;
+        }
+        return EXIT_SUCCESS;
     }
 
     // check for printtoconsole, allow -debug
     LogInstance().m_print_to_console = args.GetBoolArg("-printtoconsole", args.GetBoolArg("-debug", false));
 
     if (!CheckDataDirOption()) {
         tfm::format(std::cerr, "Error: Specified data directory \"%s\" does not exist.\n", args.GetArg("-datadir", ""));
-        return false;
+        return EXIT_FAILURE;
     }
     // Check for chain settings (Params() calls are only valid after this clause)
     SelectParams(args.GetChainName());
 
-    return true;
+    return CONTINUE_EXECUTION;
 }
 
 int main(int argc, char* argv[])
@@ -105,7 +110,10 @@ int main(int argc, char* argv[])
     SetupEnvironment();
     RandomInit();
     try {
-        if (!WalletAppInit(args, argc, argv)) return EXIT_FAILURE;
+        int ret = WalletAppInit(args, argc, argv);
+        if (ret != CONTINUE_EXECUTION) {
+            return ret;
+        }
     } catch (const std::exception& e) {
         PrintExceptionContinue(&e, "WalletAppInit()");
         return EXIT_FAILURE;