Docker: Improve error reporting

Change-Id: I7ff4d54e1a4a82baa267419930f61206f238ebce
Reviewed-by: hjk <hjk@qt.io>

src/plugins/docker/dockerdevice.cpp

@@ -193,7 +193,8 @@ public:
 
     expected_str<Environment> environment();
 
-    CommandLine withDockerExecCmd(const CommandLine &cmd,
+    expected_str<CommandLine> withDockerExecCmd(
+        const CommandLine &cmd,
         const std::optional<Environment> &env = std::nullopt,
         const std::optional<FilePath> &workDir = std::nullopt,
         bool interactive = false,
@@ -374,15 +375,25 @@ void DockerProcessImpl::start()
     const bool interactive = m_setup.m_processMode == ProcessMode::Writer
                              || !m_setup.m_writeData.isEmpty() || inTerminal;
 
-    const CommandLine fullCommandLine
-        = m_devicePrivate->withDockerExecCmd(m_setup.m_commandLine,
+    const expected_str<CommandLine> fullCommandLine = m_devicePrivate->withDockerExecCmd(
+        m_setup.m_commandLine,
         m_setup.m_environment,
         m_setup.m_workingDirectory,
         interactive,
         inTerminal,
         !m_process.ptyData().has_value());
 
-    m_process.setCommand(fullCommandLine);
+    if (!fullCommandLine) {
+        emit done(ProcessResultData{
+            -1,
+            QProcess::ExitStatus::CrashExit,
+            QProcess::ProcessError::FailedToStart,
+            fullCommandLine.error(),
+        });
+        return;
+    }
+
+    m_process.setCommand(*fullCommandLine);
     m_process.start();
 }
 
@@ -610,7 +621,7 @@ DockerDevice::DockerDevice()
             return fileAccess->get();
         }
 
-        qCWarning(dockerDeviceLog) << "Failed to start CmdBridge:" << fAccess.error()
+        qCWarning(dockerDeviceLog).noquote() << "Failed to start CmdBridge:" << fAccess.error()
                                              << ", falling back to slow direct access";
 
         *fileAccess = std::make_unique<DockerFallbackFileAccess>(rootPath());
@@ -679,15 +690,16 @@ expected_str<void> DockerDevice::updateContainerAccess() const
     return d->updateContainerAccess();
 }
 
-CommandLine DockerDevicePrivate::withDockerExecCmd(const CommandLine &cmd,
+expected_str<CommandLine> DockerDevicePrivate::withDockerExecCmd(
+    const CommandLine &cmd,
     const std::optional<Environment> &env,
     const std::optional<FilePath> &workDir,
     bool interactive,
     bool withPty,
     bool withMarker)
 {
-    if (!updateContainerAccess())
-        return {};
+    if (const auto result = updateContainerAccess(); !result)
+        return make_unexpected(result.error());
 
     CommandLine dockerCmd{settings().dockerBinaryPath(), {"exec"}};
 
@@ -1101,8 +1113,12 @@ expected_str<void> DockerDevicePrivate::fetchSystemEnviroment()
     if (!result)
         return result;
 
+    const expected_str<CommandLine> fullCommandLine = withDockerExecCmd(CommandLine{"env"});
+    if (!fullCommandLine)
+        return make_unexpected(fullCommandLine.error());
+
     Process proc;
-    proc.setCommand(withDockerExecCmd(CommandLine{"env"}));
+    proc.setCommand(*fullCommandLine);
     proc.runBlocking();
     const QString remoteOutput = proc.cleanedStdOut();