refactor(MP/daemon): use stack instead of heap for gpio

src/06-mini-project/daemon/gpio/button.c

@@ -29,9 +29,9 @@ void BTN_add_epoll_event(BTN* btn, int tail);
 void epoll_init();
 static void* epoll_thread(void* arg);
 
-BTN* BTN_init(BTN_type type) {
+int BTN_init(BTN* btn, BTN_type type) {
-    BTN* btn = malloc(sizeof(BTN));
+    if (btn == NULL) return -1;
-    if (btn == NULL) return NULL;
+
     pthread_mutex_init(&btn->mutex, NULL);
     btn->callback = NULL;
 
@@ -48,15 +48,18 @@ BTN* BTN_init(BTN_type type) {
             break;
         default:
             printf("Invalid button type\n");
-            return NULL;
+            return -1;
     }
     strcat(gpio_path, btn->pin);
 
     int f = open(GPIO_UNEXPORT, O_WRONLY);
+    if (f != -1) {
         write(f, btn->pin, strlen(btn->pin));
         close(f);
+    }
 
     f = open(GPIO_EXPORT, O_WRONLY);
+    if (f == -1) return -1;
     write(f, btn->pin, strlen(btn->pin));
     close(f);
 
@@ -65,6 +68,7 @@ BTN* BTN_init(BTN_type type) {
     strcat(direction_path, "/direction");
 
     f = open(direction_path, O_WRONLY);
+    if (f == -1) return -1;
     write(f, "in", 2);
     close(f);
 
@@ -73,7 +77,8 @@ BTN* BTN_init(BTN_type type) {
     strcat(edge_path, "/edge");
 
     f = open(edge_path, O_WRONLY);
-    write(f, "both", 4); // "both" means it triggers on press AND release
+    if (f == -1) return -1;
+    write(f, "both", 4);
     close(f);
 
     char value_path[100];
@@ -83,7 +88,7 @@ BTN* BTN_init(BTN_type type) {
     f = open(value_path, O_RDONLY);
     if (f == -1) {
         printf("Failed to setup button on pin %s\n", btn->pin);
-        return NULL;
+        return -1;
     }
     btn->fd = f;
 
@@ -96,7 +101,8 @@ BTN* BTN_init(BTN_type type) {
     if (tail >= MAX_BTN) {
         pthread_mutex_unlock(&btn_list_mutex);
         perror("Failed to add epoll event");
-        exit(EXIT_FAILURE);
+        close(btn->fd);
+        return -1;
     }
 
     btn_list[tail] = btn;
@@ -106,7 +112,18 @@ BTN* BTN_init(BTN_type type) {
     BTN_add_epoll_event(btn, tail);
     pthread_mutex_unlock(&btn_list_mutex);
 
-    return btn;
+    return 0;
+}
+
+void BTN_deinit(BTN* btn) {
+    if (btn == NULL) return;
+    pthread_mutex_lock(&btn->mutex);
+    if (btn->fd != -1) {
+        close(btn->fd);
+        btn->fd = -1;
+    }
+    pthread_mutex_unlock(&btn->mutex);
+    pthread_mutex_destroy(&btn->mutex);
 }
 
 void BTN_set_callback(BTN* btn, BTN_callback callback) {
@@ -121,7 +138,7 @@ void BTN_add_epoll_event(BTN* btn, int tail) {
     // EPOLLERR is used to detect if there is an error
     // EPOLLET is for edge triggered mode (non-blocking)
     ev[tail].events = EPOLLIN | EPOLLERR | EPOLLET;
-    ev[tail].data.fd = btn->fd;
+    ev[tail].data.ptr = btn;
 
     int ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, btn->fd, &ev[tail]);
     if (ret < 0) {
@@ -154,29 +171,20 @@ static void* epoll_thread(void* arg) {
         }
         for (int i = 0; i < n; i++) {
             char buf[2];
-            int fd = events[i].data.fd;
+            BTN* btn = (BTN*)events[i].data.ptr;
-            int tail = -1;
+            if (btn == NULL) continue;
-            BTN* btn = NULL;
+
-            for (int j = 0; j < MAX_BTN; j++) {
+            pthread_mutex_lock(&btn->mutex);
-                if (btn_list[j] == NULL) continue;
+            if (btn->fd != -1) {
-                if (btn_list[j]->fd == fd) {
-                    tail = j;
-                    btn = btn_list[j];
-                    break;
-                }
-            }
-            if (tail == -1) {
-                printf("No button found for fd %d\n", fd);
-                continue;
-            }
                 pread(btn->fd, buf, sizeof(buf), 0);
                 if (buf[0] == '1') {
-                // printf("Button %s pressed\n", btn->pin);
                     if (btn->callback != NULL) {
                         btn->callback();
                     }
                 }
             }
+            pthread_mutex_unlock(&btn->mutex);
+        }
     }
     return NULL;
 }

src/06-mini-project/daemon/gpio/button.h

@@ -22,7 +22,8 @@ typedef struct {
     pthread_mutex_t mutex;
 } BTN;
 
-BTN* BTN_init(BTN_type type);
+int BTN_init(BTN* btn, BTN_type type);
+void BTN_deinit(BTN* btn);
 void BTN_set_callback(BTN* btn, BTN_callback callback);
 
 #endif

src/06-mini-project/daemon/gpio/led.c

@@ -16,9 +16,8 @@
 
 #include <stdlib.h>
 
-LED* LED_init(LED_type type) {
+int LED_init(LED* led, LED_type type) {
-    LED* led = malloc(sizeof(LED));
+    if (led == NULL) return -1;
-    if (led == NULL) return NULL;
 
     // Concatenate GPIO LED path based on type
     char gpio_path[32] = GPIO_LED_BASE;
@@ -32,7 +31,7 @@ LED* LED_init(LED_type type) {
             break;
         default:
             printf("Invalid LED type\n");
-            return NULL;
+            return -1;
     }
     strcat(gpio_path, pin);
 
@@ -63,15 +62,15 @@ LED* LED_init(LED_type type) {
     f = open(value_path, O_RDWR);
     if (f == -1) {
         printf("Failed to setup led on pin %s\n", pin);
-        return NULL;
+        return -1;
     }
 
     led->gpio = f;
     if (pthread_mutex_init(&led->mutex, NULL) != 0) {
         close(f);
-        return NULL;
+        return -1;
     }
-    return led;
+    return 0;
 }
 
 void LED_on(LED* led) {
@@ -100,8 +99,17 @@ void LED_toggle(LED* led) {
     char value[2];
     pread(led->gpio, value, sizeof(value), 0);
     if (value[0] == '0') {
-        LED_on(led);
+        pwrite(led->gpio, "1", sizeof("1"), 0);
     } else {
-        LED_off(led);
+        pwrite(led->gpio, "0", sizeof("0"), 0);
     }
+    pthread_mutex_unlock(&led->mutex);
+}
+
+void LED_deinit(LED* led) {
+    if (led == NULL) {
+        return;
+    }
+    pthread_mutex_destroy(&led->mutex);
+    close(led->gpio);
 }

src/06-mini-project/daemon/gpio/led.h

@@ -16,9 +16,10 @@ typedef struct {
     pthread_mutex_t mutex;
 } LED;
 
-LED* LED_init(LED_type type);
+int LED_init(LED* led, LED_type type);
 void LED_on(LED* led);
 void LED_off(LED* led);
 void LED_toggle(LED* led);
+void LED_deinit(LED* led);
 
 #endif //LED_H

src/06-mini-project/daemon/main.c

@@ -21,17 +21,30 @@
 
 
 int main(void) {
+    BTN btn_inc, btn_dec, btn_mode;
 
+    if (BTN_init(&btn_inc, BTN_INCREASE) != 0) {
+        fprintf(stderr, "Failed to initialize increase button\n");
+        return 1;
+    }
+    if (BTN_init(&btn_dec, BTN_DECREASE) != 0) {
+        fprintf(stderr, "Failed to initialize decrease button\n");
+        return 1;
+    }
+    if (BTN_init(&btn_mode, BTN_MODE) != 0) {
+        fprintf(stderr, "Failed to initialize mode button\n");
+        return 1;
+    }
 
-    BTN* btn_inc = BTN_init(BTN_INCREASE);
+    LED led_power;
-    BTN* btn_dec = BTN_init(BTN_DECREASE);
+    if (LED_init(&led_power, LED_POWER) != 0) {
-    BTN* btn_mode = BTN_init(BTN_MODE);
+        fprintf(stderr, "Failed to initialize power LED\n");
+        return 1;
+    }
 
-    LED* led_power = LED_init(LED_POWER);
+    BTN_set_callback(&btn_inc, btn_increase_period);
-
+    BTN_set_callback(&btn_dec, btn_decrease_period);
-    BTN_set_callback(btn_inc, btn_increase_period);
+    BTN_set_callback(&btn_mode, mode_toggle);
-    BTN_set_callback(btn_dec, btn_decrease_period);
-    BTN_set_callback(btn_mode, mode_toggle);
 
     struct ipc_callbacks_t ipc_cbs = {
         .on_dec_period = decrease_period,
@@ -54,7 +67,7 @@ int main(void) {
 
     init_oled(&oled_cbs);
 
-    btn_set_led(led_power);
+    btn_set_led(&led_power);
     init_animations();
 
     while (1) {
@@ -62,5 +75,9 @@ int main(void) {
     }
 
     stop_ipc_server();
+    LED_deinit(&led_power);
+    BTN_deinit(&btn_inc);
+    BTN_deinit(&btn_dec);
+    BTN_deinit(&btn_mode);
     return 0;
 }