From 0f6502bf9b685d6a56f17387eacbea5c9dc0efdf Mon Sep 17 00:00:00 2001
From: Klagarge <remi@heredero.ch>
Date: Sun, 7 Jun 2026 15:11:13 +0200
Subject: [PATCH] fix(MP/daemon): add mutex on gpio

---
 src/06-mini-project/daemon/gpio/button.c | 10 +++++++++-
 src/06-mini-project/daemon/gpio/button.h |  3 +++
 src/06-mini-project/daemon/gpio/led.c    |  9 +++++++++
 src/06-mini-project/daemon/gpio/led.h    |  3 +++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/06-mini-project/daemon/gpio/button.c b/src/06-mini-project/daemon/gpio/button.c
index 3cb82fa..587adf1 100644
--- a/src/06-mini-project/daemon/gpio/button.c
+++ b/src/06-mini-project/daemon/gpio/button.c
@@ -18,6 +18,8 @@
 #define MAX_BTN 10
 BTN* btn_list[MAX_BTN];
 
+pthread_mutex_t btn_list_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 int epoll_fd;
 struct epoll_event ev[MAX_BTN];
 atomic_int btn_tail = 0;
@@ -30,6 +32,8 @@ static void* epoll_thread(void* arg);
 BTN* BTN_init(BTN_type type) {
     BTN* btn = malloc(sizeof(BTN));
     if (btn == NULL) return NULL;
+    pthread_mutex_init(&btn->mutex, NULL);
+    btn->callback = NULL;
 
     char gpio_path[32] = GPIO_BTN_BASE;
     switch (type) {
@@ -87,8 +91,10 @@ BTN* BTN_init(BTN_type type) {
     char buf[2];
     pread(btn->fd, buf, sizeof(buf), 0);
 
+    pthread_mutex_lock(&btn_list_mutex);
     int tail = atomic_fetch_add(&btn_tail, 1);
     if (tail >= MAX_BTN) {
+        pthread_mutex_unlock(&btn_list_mutex);
         perror("Failed to add epoll event");
         exit(EXIT_FAILURE);
     }
@@ -98,15 +104,17 @@ BTN* BTN_init(BTN_type type) {
         epoll_init();
     }
     BTN_add_epoll_event(btn, tail);
+    pthread_mutex_unlock(&btn_list_mutex);
 
     return btn;
 }
 
 void BTN_set_callback(BTN* btn, BTN_callback callback) {
+    pthread_mutex_lock(&btn->mutex);
     btn->callback = callback;
+    pthread_mutex_unlock(&btn->mutex);
 }
 
-// TODO add mutex to protect this function
 void BTN_add_epoll_event(BTN* btn, int tail) {
 
     // EPOLLIN is working well as EPOLLPRI (which is more used for priority data)
diff --git a/src/06-mini-project/daemon/gpio/button.h b/src/06-mini-project/daemon/gpio/button.h
index 2c281f3..6778b42 100644
--- a/src/06-mini-project/daemon/gpio/button.h
+++ b/src/06-mini-project/daemon/gpio/button.h
@@ -1,6 +1,8 @@
 #ifndef BUTTON_H
 #define BUTTON_H
 
+#include <pthread.h>
+
 #define GPIO_BTN_INCREASE "3"
 #define GPIO_BTN_DECREASE "0"
 #define GPIO_BTN_MODE "2"
@@ -17,6 +19,7 @@ typedef struct {
     int fd;
     char pin[32];
     BTN_callback callback;
+    pthread_mutex_t mutex;
 } BTN;
 
 BTN* BTN_init(BTN_type type);
diff --git a/src/06-mini-project/daemon/gpio/led.c b/src/06-mini-project/daemon/gpio/led.c
index b0e580c..7b797eb 100644
--- a/src/06-mini-project/daemon/gpio/led.c
+++ b/src/06-mini-project/daemon/gpio/led.c
@@ -67,6 +67,10 @@ LED* LED_init(LED_type type) {
     }
 
     led->gpio = f;
+    if (pthread_mutex_init(&led->mutex, NULL) != 0) {
+        close(f);
+        return NULL;
+    }
     return led;
 }
 
@@ -74,20 +78,25 @@ void LED_on(LED* led) {
     if (led == NULL) {
         return;
     }
+    pthread_mutex_lock(&led->mutex);
     pwrite(led->gpio, "1", sizeof("1"), 0);
+    pthread_mutex_unlock(&led->mutex);
 }
 
 void LED_off(LED* led) {
     if (led == NULL) {
         return;
     }
+    pthread_mutex_lock(&led->mutex);
     pwrite(led->gpio, "0", sizeof("0"), 0);
+    pthread_mutex_unlock(&led->mutex);
 }
 
 void LED_toggle(LED* led) {
     if (led == NULL) {
         return;
     }
+    pthread_mutex_lock(&led->mutex);
     char value[2];
     pread(led->gpio, value, sizeof(value), 0);
     if (value[0] == '0') {
diff --git a/src/06-mini-project/daemon/gpio/led.h b/src/06-mini-project/daemon/gpio/led.h
index 6b009a2..9f31acd 100644
--- a/src/06-mini-project/daemon/gpio/led.h
+++ b/src/06-mini-project/daemon/gpio/led.h
@@ -1,6 +1,8 @@
 #ifndef LED_H
 #define LED_H
 
+#include <pthread.h>
+
 #define GPIO_LED_STATUS "10"
 #define GPIO_LED_POWER  "362"
 
@@ -11,6 +13,7 @@ typedef enum {
 
 typedef struct {
     int gpio;
+    pthread_mutex_t mutex;
 } LED;
 
 LED* LED_init(LED_type type);