Implement netdata command server and cli tool (#7325)

* Checkpoint commit (POC)

* Implemented command server in the daemon

* Add netdatacli implementation

* Added prints in command server setup functions

* Make libuv version 1 a hard dependency for the agent

* Additional documentation

* Improved accuracy of names and documentation

* Fixed documentation

* Fixed buffer overflow

* Added support for exit status in cli. Added prefixes for exit code, stdout and stderr. Fixed parsers.

* Fix compilation errors

* Fix compile errors

* Fix compile errors

* Fix compile error

* Fix linker error for muslc

1 files changed, 76 insertions, 0 deletions

diff --git a/daemon/commands.h b/daemon/commands.h
new file mode 100644
index 0000000000..55cd6455d6
--- /dev/null
+++ b/daemon/commands.h
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_COMMANDS_H
+#define NETDATA_COMMANDS_H 1
+
+#ifdef _WIN32
+# define PIPENAME "\\\\?\\pipe\\netdata-cli"
+#else
+# define PIPENAME "/tmp/netdata-ipc"
+#endif
+
+#define MAX_COMMAND_LENGTH 4096
+#define MAX_EXIT_STATUS_LENGTH 23 /* Can't ever be bigger than "X-18446744073709551616" */
+
+typedef enum cmd {
+    CMD_HELP = 0,
+    CMD_RELOAD_HEALTH,
+    CMD_SAVE_DATABASE,
+    CMD_REOPEN_LOGS,
+    CMD_EXIT,
+    CMD_FATAL,
+    CMD_TOTAL_COMMANDS
+} cmd_t;
+
+typedef enum cmd_status {
+    CMD_STATUS_SUCCESS = 0,
+    CMD_STATUS_FAILURE,
+    CMD_STATUS_BUSY
+} cmd_status_t;
+
+#define CMD_PREFIX_INFO 'O'         /* Following string should go to cli stdout */
+#define CMD_PREFIX_ERROR 'E'        /* Following string should go to cli stderr */
+#define CMD_PREFIX_EXIT_CODE 'X'    /* Following string is cli integer exit code */
+
+typedef enum cmd_type {
+    /*
+     * No other command is allowed to run at the same time (except for CMD_TYPE_HIGH_PRIORITY).
+     */
+    CMD_TYPE_EXCLUSIVE = 0,
+    /*
+     * Other commands are allowed to run concurrently (except for CMD_TYPE_EXCLUSIVE) but calls to this command are
+     * serialized.
+     */
+    CMD_TYPE_ORTHOGONAL,
+    /*
+     * Other commands are allowed to run concurrently (except for CMD_TYPE_EXCLUSIVE) as are calls to this command.
+     */
+    CMD_TYPE_CONCURRENT,
+    /*
+     * Those commands are always allowed to run.
+     */
+    CMD_TYPE_HIGH_PRIORITY
+} cmd_type_t;
+
+/**
+ * Executes a command and returns the status.
+ *
+ * @param args a string that may contain additional parameters to be parsed
+ * @param message allocate and return a message if need be (up to MAX_COMMAND_LENGTH bytes)
+ * @return CMD_FAILURE or CMD_SUCCESS
+ */
+typedef cmd_status_t (command_action_t) (char *args, char **message);
+
+typedef struct command_info {
+    char *cmd_str;              // the command string
+    command_action_t *func;     // the function that executes the command
+    cmd_type_t type;            // Concurrency control information for the command
+} command_info_t;
+
+typedef void (command_lock_t) (unsigned index);
+
+cmd_status_t execute_command(cmd_t idx, char *args, char **message);
+extern void commands_init(void);
+extern void commands_exit(void);
+
+#endif //NETDATA_COMMANDS_H