kernel: move RunCommandParseJSON to its own file

Because libbitcoinkernel does not include this new object, this has the
side-effect of eliminating the unnecessary boost::process dependency.

src/util/run_command.cpp

@@ -0,0 +1,64 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <util/run_command.h>
+
+#include <tinyformat.h>
+#include <univalue.h>
+
+#ifdef ENABLE_EXTERNAL_SIGNER
+#if defined(__GNUC__)
+// Boost 1.78 requires the following workaround.
+// See: https://github.com/boostorg/process/issues/235
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnarrowing"
+#endif
+#include <boost/process.hpp>
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#endif
+#endif // ENABLE_EXTERNAL_SIGNER
+
+UniValue RunCommandParseJSON(const std::string& str_command, const std::string& str_std_in)
+{
+#ifdef ENABLE_EXTERNAL_SIGNER
+    namespace bp = boost::process;
+
+    UniValue result_json;
+    bp::opstream stdin_stream;
+    bp::ipstream stdout_stream;
+    bp::ipstream stderr_stream;
+
+    if (str_command.empty()) return UniValue::VNULL;
+
+    bp::child c(
+        str_command,
+        bp::std_out > stdout_stream,
+        bp::std_err > stderr_stream,
+        bp::std_in < stdin_stream
+    );
+    if (!str_std_in.empty()) {
+        stdin_stream << str_std_in << std::endl;
+    }
+    stdin_stream.pipe().close();
+
+    std::string result;
+    std::string error;
+    std::getline(stdout_stream, result);
+    std::getline(stderr_stream, error);
+
+    c.wait();
+    const int n_error = c.exit_code();
+    if (n_error) throw std::runtime_error(strprintf("RunCommandParseJSON error: process(%s) returned %d: %s\n", str_command, n_error, error));
+    if (!result_json.read(result)) throw std::runtime_error("Unable to parse JSON: " + result);
+
+    return result_json;
+#else
+    throw std::runtime_error("Compiled without external signing support (required for external signing).");
+#endif // ENABLE_EXTERNAL_SIGNER
+}

src/util/run_command.h

@@ -0,0 +1,21 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_RUN_COMMAND_H
+#define BITCOIN_UTIL_RUN_COMMAND_H
+
+#include <string>
+
+class UniValue;
+
+/**
+ * Execute a command which returns JSON, and parse the result.
+ *
+ * @param str_command The command to execute, including any arguments
+ * @param str_std_in string to pass to stdin
+ * @return parsed JSON
+ */
+UniValue RunCommandParseJSON(const std::string& str_command, const std::string& str_std_in="");
+
+#endif // BITCOIN_UTIL_RUN_COMMAND_H

src/util/system.cpp

@@ -5,19 +5,6 @@
 
 #include <util/system.h>
 
-#ifdef ENABLE_EXTERNAL_SIGNER
-#if defined(__GNUC__)
-// Boost 1.78 requires the following workaround.
-// See: https://github.com/boostorg/process/issues/235
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wnarrowing"
-#endif
-#include <boost/process.hpp>
-#if defined(__GNUC__)
-#pragma GCC diagnostic pop
-#endif
-#endif // ENABLE_EXTERNAL_SIGNER
-
 #include <chainparamsbase.h>
 #include <fs.h>
 #include <sync.h>
@@ -1332,44 +1319,6 @@ void runCommand(const std::string& strCommand)
 }
 #endif
 
-UniValue RunCommandParseJSON(const std::string& str_command, const std::string& str_std_in)
-{
-#ifdef ENABLE_EXTERNAL_SIGNER
-    namespace bp = boost::process;
-
-    UniValue result_json;
-    bp::opstream stdin_stream;
-    bp::ipstream stdout_stream;
-    bp::ipstream stderr_stream;
-
-    if (str_command.empty()) return UniValue::VNULL;
-
-    bp::child c(
-        str_command,
-        bp::std_out > stdout_stream,
-        bp::std_err > stderr_stream,
-        bp::std_in < stdin_stream
-    );
-    if (!str_std_in.empty()) {
-        stdin_stream << str_std_in << std::endl;
-    }
-    stdin_stream.pipe().close();
-
-    std::string result;
-    std::string error;
-    std::getline(stdout_stream, result);
-    std::getline(stderr_stream, error);
-
-    c.wait();
-    const int n_error = c.exit_code();
-    if (n_error) throw std::runtime_error(strprintf("RunCommandParseJSON error: process(%s) returned %d: %s\n", str_command, n_error, error));
-    if (!result_json.read(result)) throw std::runtime_error("Unable to parse JSON: " + result);
-
-    return result_json;
-#else
-    throw std::runtime_error("Compiled without external signing support (required for external signing).");
-#endif // ENABLE_EXTERNAL_SIGNER
-}
 
 void SetupEnvironment()
 {

src/util/system.h

@@ -107,14 +107,6 @@ std::string ShellEscape(const std::string& arg);
 #if HAVE_SYSTEM
 void runCommand(const std::string& strCommand);
 #endif
-/**
- * Execute a command which returns JSON, and parse the result.
- *
- * @param str_command The command to execute, including any arguments
- * @param str_std_in string to pass to stdin
- * @return parsed JSON
- */
-UniValue RunCommandParseJSON(const std::string& str_command, const std::string& str_std_in="");
 
 /**
  * Most paths passed as configuration arguments are treated as relative to