feat(MP/daemon): create ipc server to handle socketpair

src/06-mini-project/daemon/ipc/ipc_server.c

@@ -0,0 +1,161 @@
+// ipc_socket.c
+#include "ipc_server.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+/* Global variables for the IPC module */
+static int server_fd = -1;
+static pthread_t ipc_thread;
+static struct ipc_callbacks_t current_cbs = {0};
+static int is_running = 0;
+
+/**
+ * process_message() - Route the received IPC message to the correct callback.
+ */
+static void process_message(ipc_msg_t *msg) {
+    switch (msg->command) {
+        case CMD_SET_MODE:
+            if (current_cbs.on_set_mode) {
+                current_cbs.on_set_mode(msg->value);
+            }
+            break;
+
+        case CMD_SET_FREQ:
+            if (current_cbs.on_set_frequency) {
+                current_cbs.on_set_frequency(msg->value);
+            }
+            break;
+
+        case CMD_INC_FREQ:
+            if (current_cbs.on_inc_frequency) {
+                current_cbs.on_inc_frequency();
+            }
+            break;
+
+        case CMD_DEC_FREQ:
+            if (current_cbs.on_dec_frequency) {
+                current_cbs.on_dec_frequency();
+            }
+            break;
+
+        default:
+            printf("[IPC] Received unknown command: %d\n", msg->command);
+            break;
+    }
+}
+
+/**
+ * ipc_thread_func() - The main loop of the background IPC thread.
+ */
+static void *ipc_thread_func(void *arg) {
+    ipc_msg_t msg;
+    ssize_t bytes_read;
+
+    printf("[IPC] Thread started. Listening on %s\n", SOCKET_PATH);
+
+    while (is_running) {
+        /* Block until a message arrives or the socket is closed */
+        bytes_read = recvfrom(server_fd, &msg, sizeof(msg), 0, NULL, NULL);
+
+        if (bytes_read == sizeof(ipc_msg_t)) {
+            process_message(&msg);
+        }
+        else if (bytes_read <= 0 && is_running == 0) {
+            /* Normal exit condition when shutdown() is called */
+            break;
+        }
+        else if (bytes_read > 0) {
+            printf("[IPC] Received malformed message (size %zd)\n", bytes_read);
+        }
+        else {
+            perror("[IPC] Error receiving message");
+        }
+    }
+
+    printf("[IPC] Thread stopped.\n");
+    return NULL;
+}
+
+/* --- Public functions --- */
+
+int start_ipc_server(struct ipc_callbacks_t *cbs) {
+    struct sockaddr_un server_addr;
+
+    if (is_running) {
+        printf("[IPC] Server is already running.\n");
+        return -1;
+    }
+
+    /* Save the provided callbacks */
+    if (cbs) {
+        current_cbs = *cbs;
+    }
+
+    /* Create local socket */
+    server_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+    if (server_fd < 0) {
+        perror("[IPC] Failed to create socket");
+        return -1;
+    }
+
+    /* Bind socket to the file path */
+    memset(&server_addr, 0, sizeof(server_addr));
+    server_addr.sun_family = AF_UNIX;
+    strncpy(server_addr.sun_path, SOCKET_PATH, sizeof(server_addr.sun_path) - 1);
+
+    unlink(SOCKET_PATH); /* Clean up existing orphaned socket file */
+
+    if (bind(server_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
+        perror("[IPC] Failed to bind socket");
+        close(server_fd);
+        server_fd = -1;
+        return -1;
+    }
+
+    /* Start the background thread */
+    is_running = 1;
+    if (pthread_create(&ipc_thread, NULL, ipc_thread_func, NULL) != 0) {
+        perror("[IPC] Failed to create IPC thread");
+        is_running = 0;
+        close(server_fd);
+        unlink(SOCKET_PATH);
+        server_fd = -1;
+        return -1;
+    }
+
+    return 0;
+}
+
+int stop_ipc_server(void) {
+    if (!is_running) {
+        return 0;
+    }
+
+    printf("[IPC] Stopping server...\n");
+
+    /* Signal thread to stop */
+    is_running = 0;
+
+    /* Unblock the recvfrom() by shutting down the socket */
+    if (server_fd != -1) {
+        shutdown(server_fd, SHUT_RDWR);
+        close(server_fd);
+        server_fd = -1;
+    }
+
+    /* Wait for thread to exit */
+    pthread_join(ipc_thread, NULL);
+
+    /* Remove the socket file */
+    unlink(SOCKET_PATH);
+
+    /* Clear callbacks */
+    memset(&current_cbs, 0, sizeof(struct ipc_callbacks_t));
+
+    return 0;
+}

src/06-mini-project/daemon/ipc/ipc_server.h

@@ -0,0 +1,32 @@
+#ifndef IPC_SERVER_H
+#define IPC_SERVER_H
+
+#include "../../common/common_ipc.h"
+
+/*
+ * Structure holding the callbacks for IPC commands.
+ * Each function pointer will be called when the corresponding command is received.
+ */
+struct ipc_callbacks_t {
+    void (*on_set_mode)(int mode);
+    void (*on_set_frequency)(int freq);
+    void (*on_inc_frequency)(void);
+    void (*on_dec_frequency)(void);
+} ;
+
+/**
+ * start_ipc_server() - Start the IPC background thread.
+ * @cbs: Pointer to the structure containing the callback functions.
+ *
+ * Return: 0 on success, or a negative value on error.
+ */
+int start_ipc_server(struct ipc_callbacks_t *cbs);
+
+/**
+ * stop_ipc_server() - Stop the IPC thread and clean up the socket.
+ *
+ * Return: 0 on success.
+ */
+int stop_ipc_server(void);
+
+#endif //IPC_SERVER_H