[posix-host] add command mode for ot-ctl (#4457)

ot-ctl will now send the command line arguments to ot-daemon and print
the reply.

.travis/check-posix-app-pty

@@ -80,6 +80,10 @@ check() {
         OT_CLI_CMD="$(pwd)/$(ls output/posix/*linux*/bin/ot-cli) ${OT_NCP_PATH} ${CORE_PTY}"
     fi
 
+    if [[ "${DAEMON}" = 1 ]]; then
+        sudo ${OT_CLI_CMD} panid 0xface | grep 'Done' || die 'failed to get panid with ot-ctl'
+    fi
+
     sudo expect <<EOF > "${OT_OUTPUT}" &
 spawn ${OT_CLI_CMD}
 send "panid 0xface\r\n"

src/posix/client.c

@@ -75,6 +75,107 @@ static void InputCallback(char *aLine)
 }
 #endif // OPENTHREAD_USE_READLINE
 
+static bool FindDone(int *aDoneState, char aNowCharacter)
+{
+    switch (aNowCharacter)
+    {
+    case 'D':
+        *aDoneState = *aDoneState == 0 ? 1 : -1;
+        break;
+    case 'o':
+        *aDoneState = *aDoneState == 1 ? 2 : -1;
+        break;
+    case 'n':
+        *aDoneState = *aDoneState == 2 ? 3 : -1;
+        break;
+    case 'e':
+        *aDoneState = *aDoneState == 3 ? 4 : -1;
+        break;
+    case '\r':
+    case '\n':
+        if (*aDoneState == 4)
+        {
+            *aDoneState = 5;
+        }
+        else
+        {
+            *aDoneState = 0;
+        }
+        break;
+    default:
+        *aDoneState = -1;
+        break;
+    }
+
+    return *aDoneState == 5;
+}
+
+static bool FindError(int *aErrorState, char aNowCharacter)
+{
+    switch (aNowCharacter)
+    {
+    case 'E':
+        *aErrorState = *aErrorState == 0 ? 1 : -1;
+        break;
+    case 'r':
+        if (*aErrorState == 1 || *aErrorState == 2 || *aErrorState == 4)
+        {
+            (*aErrorState)++;
+        }
+        else
+        {
+            *aErrorState = -1;
+        }
+        break;
+    case 'o':
+        *aErrorState = *aErrorState == 3 ? 4 : -1;
+        break;
+    case ' ':
+        *aErrorState = *aErrorState == 5 ? 6 : -1;
+        break;
+    case '\r':
+    case '\n':
+        *aErrorState = 0;
+        break;
+    default:
+        *aErrorState = -1;
+        break;
+    }
+
+    return *aErrorState == 6;
+}
+
+static void SendBlockingCommand(int aArgc, char *aArgv[])
+{
+    char buffer[OPENTHREAD_CONFIG_DIAG_CMD_LINE_BUFFER_SIZE];
+    int  doneState  = 0;
+    int  errorState = 0;
+
+    for (int i = 0; i < aArgc; i++)
+    {
+        otEXPECT_ACTION(write(sSessionFd, aArgv[i], strlen(aArgv[i])) >= 0, perror("Failed to send command"));
+        otEXPECT_ACTION(write(sSessionFd, " ", 1) >= 0, perror("Failed to send command"));
+    }
+    otEXPECT_ACTION(write(sSessionFd, "\n", 1) >= 0, perror("Failed to send command"));
+
+    while (true)
+    {
+        ssize_t rval = read(sSessionFd, buffer, sizeof(buffer));
+
+        otEXPECT(rval >= 0);
+        write(STDOUT_FILENO, buffer, rval);
+        for (ssize_t i = 0; i < rval; i++)
+        {
+            if (FindDone(&doneState, buffer[i]) || FindError(&errorState, buffer[i]))
+            {
+                otEXIT_NOW();
+            }
+        }
+    }
+exit:
+    return;
+}
+
 int main(int argc, char *argv[])
 {
     OT_UNUSED_VARIABLE(argc);
@@ -109,6 +210,12 @@ int main(int argc, char *argv[])
 #endif
     }
 
+    if (argc > 1)
+    {
+        SendBlockingCommand(argc - 1, &argv[1]);
+        otEXIT_NOW(ret = 0);
+    }
+
     while (1)
     {
         fd_set  readFdSet;