Merge #15382: util: add RunCommandParseJSON

31cf68a3ad [util] add RunCommandParseJSON (Sjors Provoost)
c17f54ee53 [ci] use boost::process (Sjors Provoost)
32128ba682 [doc] include Doxygen comments for HAVE_BOOST_PROCESS (Sjors Provoost)
3c84d85f7d [build] msvc: add boost::process (Sjors Provoost)
c47e4bbf0b [build] make boost-process opt-in (Sjors Provoost)
929cda5470 configure: add ax_boost_process (Sjors Provoost)
8314c23d7b [depends] boost: patch unused variable in boost_process (Sjors Provoost)

Pull request description:

  Prerequisite for external signer support in #16546. Big picture overview in [this gist](https://gist.github.com/Sjors/29d06728c685e6182828c1ce9b74483d).

  This adds a new dependency [boost process](https://github.com/boostorg/process/tree/boost-1.64.0). This is part of Boost since 1.64 which is part of `depends`. Because the minimum Boost version is 1.47, this functionality is skipped for older versions of Boost.

  Use `./configure --with-boost-process` to opt in, which checks for the presence of Boost::Process.

  We add `UniValue runCommandParseJSON(const std::string& strCommand)` to `system.{h,cpp}` which calls an arbitrary command and processes the JSON returned by it. This is currently only called by the test suite.

  ~For testing purposes this adds a new regtest-only RPC method `runcommand`, as well as `test/mocks/command.py` used by functional tests.~ (this is no longer the case)

  TODO:
  - [ ] review boost process in #15440

ACKs for top commit:
  achow101:
    ACK 31cf68a3ad
  hebasto:
    re-ACK 31cf68a3ad, only rebased (verified with `git range-diff`) and removed an unintentional tab character since the [previous](https://github.com/bitcoin/bitcoin/pull/15382#pullrequestreview-458371035) review.
  meshcollider:
    Very light utACK 31cf68a3ad, although I am not very confident with build stuff.
  promag:
    Code review ACK 31cf68a3ad, don't mind the nit.
  ryanofsky:
    Code review ACK 31cf68a3ad. I left some comments below that could be ignored or followed up later. The current change is clean and comprehensive.

Tree-SHA512: c506e747014b263606e1f538ed4624a8ad7bcf4e025cb700c12cc5739964e254dc04a2bbb848996b170e2ccec3fbfa4fe9e2b3976b191222cfb82fc3e6ab182d

src/test/system_tests.cpp

@@ -0,0 +1,95 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+//
+#include <test/util/setup_common.h>
+#include <util/system.h>
+#include <univalue.h>
+
+#ifdef HAVE_BOOST_PROCESS
+#include <boost/process.hpp>
+#endif // HAVE_BOOST_PROCESS
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(system_tests, BasicTestingSetup)
+
+// At least one test is required (in case HAVE_BOOST_PROCESS is not defined).
+// Workaround for https://github.com/bitcoin/bitcoin/issues/19128
+BOOST_AUTO_TEST_CASE(dummy)
+{
+    BOOST_CHECK(true);
+}
+
+#ifdef HAVE_BOOST_PROCESS
+
+bool checkMessage(const std::runtime_error& ex)
+{
+    // On Linux & Mac: "No such file or directory"
+    // On Windows: "The system cannot find the file specified."
+    const std::string what(ex.what());
+    BOOST_CHECK(what.find("file") != std::string::npos);
+    return true;
+}
+
+bool checkMessageFalse(const std::runtime_error& ex)
+{
+    BOOST_CHECK_EQUAL(ex.what(), std::string("RunCommandParseJSON error: process(false) returned 1: \n"));
+    return true;
+}
+
+bool checkMessageStdErr(const std::runtime_error& ex)
+{
+    const std::string what(ex.what());
+    BOOST_CHECK(what.find("RunCommandParseJSON error:") != std::string::npos);
+    return checkMessage(ex);
+}
+
+BOOST_AUTO_TEST_CASE(run_command)
+{
+    {
+        const UniValue result = RunCommandParseJSON("");
+        BOOST_CHECK(result.isNull());
+    }
+    {
+#ifdef WIN32
+        // Windows requires single quotes to prevent escaping double quotes from the JSON...
+        const UniValue result = RunCommandParseJSON("echo '{\"success\": true}'");
+#else
+        // ... but Linux and macOS echo a single quote if it's used
+        const UniValue result = RunCommandParseJSON("echo \"{\"success\": true}\"");
+#endif
+        BOOST_CHECK(result.isObject());
+        const UniValue& success = find_value(result, "success");
+        BOOST_CHECK(!success.isNull());
+        BOOST_CHECK_EQUAL(success.getBool(), true);
+    }
+    {
+        // An invalid command is handled by Boost
+        BOOST_CHECK_EXCEPTION(RunCommandParseJSON("invalid_command"), boost::process::process_error, checkMessage); // Command failed
+    }
+    {
+        // Return non-zero exit code, no output to stderr
+        BOOST_CHECK_EXCEPTION(RunCommandParseJSON("false"), std::runtime_error, checkMessageFalse);
+    }
+    {
+        // Return non-zero exit code, with error message for stderr
+        BOOST_CHECK_EXCEPTION(RunCommandParseJSON("ls nosuchfile"), std::runtime_error, checkMessageStdErr);
+    }
+    {
+        BOOST_REQUIRE_THROW(RunCommandParseJSON("echo \"{\""), std::runtime_error); // Unable to parse JSON
+    }
+    // Test std::in, except for Windows
+#ifndef WIN32
+    {
+        const UniValue result = RunCommandParseJSON("cat", "{\"success\": true}");
+        BOOST_CHECK(result.isObject());
+        const UniValue& success = find_value(result, "success");
+        BOOST_CHECK(!success.isNull());
+        BOOST_CHECK_EQUAL(success.getBool(), true);
+    }
+#endif
+}
+#endif // HAVE_BOOST_PROCESS
+
+BOOST_AUTO_TEST_SUITE_END()