From 374647732c8c91fb6e27f4237f05325cd458f28d Mon Sep 17 00:00:00 2001
From: ismail <ismailsahillioglu@gmail.com>
Date: Wed, 27 Aug 2025 14:06:37 +0300
Subject: [PATCH] Fix possible integer underflow bug

Fixed a possible integer underflow bug that may cause the timer
to be set for an unexpectedly long duration.

Fixes #1091
---
 src/relay_chn_core.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/src/relay_chn_core.c b/src/relay_chn_core.c
index f062e1b..4119062 100644
--- a/src/relay_chn_core.c
+++ b/src/relay_chn_core.c
@@ -327,19 +327,27 @@ void relay_chn_issue_cmd(relay_chn_ctl_t* chn_ctl, relay_chn_cmd_t cmd)
                 // If the last run command is different from the current command, calculate the time passed 
                 // since the last run command stopped and decide whether to run the command immediately or wait
                 uint32_t last_run_cmd_time_ms = relay_chn_run_info_get_last_run_cmd_time_ms(chn_ctl->run_info);
-                uint32_t inertia_time_passed_ms = (uint32_t) (esp_timer_get_time() / 1000) - last_run_cmd_time_ms;
-                uint32_t inertia_time_ms = CONFIG_RELAY_CHN_OPPOSITE_INERTIA_MS - inertia_time_passed_ms;
-                if (inertia_time_ms > 0) {
-                    chn_ctl->pending_cmd = cmd;
-                    relay_chn_state_t new_state = cmd == RELAY_CHN_CMD_FORWARD 
-                            ? RELAY_CHN_STATE_FORWARD_PENDING : RELAY_CHN_STATE_REVERSE_PENDING;
-                    relay_chn_update_state(chn_ctl, new_state);
-                    // If the time passed is less than the opposite inertia time, wait for the remaining time
-                    relay_chn_start_esp_timer_once(chn_ctl->inertia_timer, inertia_time_ms);
-                }
-                else {
-                    // If the time passed is more than the opposite inertia time, run the command immediately
+                uint32_t current_time_ms = (uint32_t)(esp_timer_get_time() / 1000);
+                if (current_time_ms < last_run_cmd_time_ms) { // Timer overflow
+                    // If timer overflowed, it's been a long time. Run immediately.
                     relay_chn_dispatch_cmd(chn_ctl, cmd);
+                } else {
+                    uint32_t inertia_time_passed_ms = current_time_ms - last_run_cmd_time_ms;
+                    if (inertia_time_passed_ms < CONFIG_RELAY_CHN_OPPOSITE_INERTIA_MS) {
+                        uint32_t inertia_time_ms = CONFIG_RELAY_CHN_OPPOSITE_INERTIA_MS - inertia_time_passed_ms;
+                        chn_ctl->pending_cmd = cmd;
+                        relay_chn_state_t new_state = cmd == RELAY_CHN_CMD_FORWARD
+                                ? RELAY_CHN_STATE_FORWARD_PENDING : RELAY_CHN_STATE_REVERSE_PENDING;
+                        relay_chn_update_state(chn_ctl, new_state);
+                        // If the time passed is less than the opposite inertia time, wait for the remaining time
+                        if (relay_chn_start_esp_timer_once(chn_ctl->inertia_timer, inertia_time_ms) != ESP_OK) {
+                            ESP_LOGE(TAG, "Failed to start inertia timer for ch %d", chn_ctl->id);
+                            relay_chn_execute_idle(chn_ctl);
+                        }
+                    } else {
+                        // If the time passed is more than the opposite inertia time, run the command immediately
+                        relay_chn_dispatch_cmd(chn_ctl, cmd);
+                    }
                 }
             }
             break;