DM: add command module for command monitor

The command module provides interfaces to find a command
intance, register handler for specified command, dispatch
command and invoke related handler.
find_command: find a command instance by name.
register_command_handler: register the handler for one
command instance.
dispatch_command_handlers: dispatch the command and invoke
registered handler.

v1-->v2:
	Only support single handler for one command instance.
v2-->v3:
	Remove command id.
	Add error check to avoid regiter handler to command
	instance which has handler.
	Update the second parameter type of register_command_handler
	to avoid unnecessary type conversion.

Tracked-On: #5921

Signed-off-by: Xiangyang Wu <xiangyang.wu@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>

devicemodel/core/cmd_monitor/command.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2022 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <pthread.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/un.h>
+#include "command.h"
+#include "vmmapi.h"
+#include "log.h"
+
+#define GEN_CMD_OBJ(cmd_name) \
+	{.name = cmd_name,}
+#define CMD_OBJS \
+	GEN_CMD_OBJ(DESTROY), \
+	GEN_CMD_OBJ(BLKRESCAN), \
+
+struct command dm_command_list[CMDS_NUM] = {CMD_OBJS};
+
+int dispatch_command_handlers(void *arg)
+{
+	struct command *cmd = (struct command *)arg;
+	int ret = 0;
+
+	pr_info("Handle command %s in command monitor.\n", cmd->name);
+	if (cmd->cmd_handler.fn) {
+		ret = cmd->cmd_handler.fn(cmd->cmd_handler.arg, &cmd->para);
+		pr_info("Command handler ret=%d.\n", ret);
+	} else {
+		pr_info("No handler for command: %s.\r\n", cmd->name);
+	}
+
+	return 0;
+}
+struct command *find_command(const char *name)
+{
+	for (int i = 0; (i < CMDS_NUM) && (name != NULL); i++) {
+		if (strcmp(dm_command_list[i].name, name) == 0)
+			return &dm_command_list[i];
+	}
+	return NULL;
+}
+
+int register_command_handler(cmd_handler *fn, struct handler_args *arg, const char *cmd_name)
+{
+	struct command *cmd;
+	struct handler_args *handler_arg;
+
+	if ((!fn) || (!arg) || (!cmd_name)) {
+		pr_err("%s : Failed to register command_handler.\n", __func__);
+		return -EINVAL;
+	}
+
+	cmd = find_command(cmd_name);
+	if (cmd == NULL) {
+		pr_err("%s : invalid command name %s.\r\n", __func__, cmd_name);
+		return -EINVAL;
+	}
+
+	if (cmd->cmd_handler.fn != NULL) {
+		pr_err("Failed to register command handler since the handler have already been registered.\n");
+		return -EINVAL;
+	}
+	cmd->cmd_handler.fn = fn;
+
+	handler_arg = calloc(1, sizeof(*handler_arg));
+	if (!handler_arg) {
+		pr_err("Failed to allocate command handler argument.\r\n");
+		return -ENOMEM;
+	}
+	cmd->cmd_handler.arg = handler_arg;
+	cmd->cmd_handler.arg->channel_arg = arg->channel_arg;
+	cmd->cmd_handler.arg->ctx_arg = arg->ctx_arg;
+
+	return 0;
+}

devicemodel/core/cmd_monitor/command.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2022 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef _COMMAND_H_
+#define _COMMAND_H_
+#include <pthread.h>
+#include <sys/queue.h>
+
+
+#define DESTROY "destroy"
+#define BLKRESCAN "blkrescan"
+
+#define CMDS_NUM 2U
+#define CMD_NAME_MAX 32U
+#define CMD_ARG_MAX 320U
+
+typedef int (cmd_handler)(void *arg, void *command_para);
+struct handler_args {
+	void *channel_arg;
+	void *ctx_arg;
+};
+struct command_handler {
+	struct handler_args *arg;
+	cmd_handler *fn;
+};
+struct command_parameters {
+	int fd;
+	char option[CMD_ARG_MAX];
+};
+struct command {
+	const char name[CMD_NAME_MAX]; /**< command name */
+	struct command_parameters para;
+
+	/* command handler */
+	struct command_handler cmd_handler;
+};
+/**
+ * @brief register command handler, other module can use this interface to
+ * register multiple handler for one command.
+ *
+ * @param fn the command handler which will be registered
+ * @param arg the parameter which will be passed into hanlder
+ * @param cmd_name the command name
+ */
+int register_command_handler(cmd_handler *fn, struct handler_args *arg, const char *cmd_name);
+/**
+ * @brief find a command instance by name
+ *
+ * @param name the command name
+ * @return command instance
+ */
+struct command *find_command(const char *name);
+/**
+ * @brief dispatch the command and invoke registered handler.
+ *
+ * @param arg command instance
+ * @return the flag indicates the state of command handler execution
+ */
+int dispatch_command_handlers(void *arg);
+#endif