pin_control: fix error handling

pin_control/include/pin_control.h

@@ -13,6 +13,6 @@ int turn_on_all_pins();
 
 int turn_off_all_pins();
 
-int wait_for_button_press(int button_pin);
+int wait_for_button_press(const unsigned pins[static 5]);
 
 #endif /* GPIO_CONTROL_H */

pin_control/main.c

@@ -1,13 +0,0 @@
-#include "pin_control.h"
-
-int main() {
-    int button_pin = 5;
-    int button_response;
-
-
-    button_response = wait_for_button_press(button_pin);
-    printf("Button press detected on pin: %d\n", button_response);
-
-    cleanup_gpio();
-    return 0;
-}

pin_control/src/pin_control.c

@@ -1,6 +1,8 @@
 #include <stdio.h>
 #include <gpiod.h>
 
+#include <pin_control.h>
+
 // https://docs.kernel.org/driver-api/gpio/using-gpio.html
 
 #define GPIO_CHIP "gpiochip0"
@@ -8,45 +10,59 @@
 struct gpiod_chip *chip;
 
 int init_gpio() {
+    cleanup_gpio();
+
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_open_by_name.html
     chip = gpiod_chip_open_by_name(GPIO_CHIP);
     if (!chip) {
-        printf("Error opening GPIO chip");
+        perror("[pin_control] gpiod_chip_open_by_name(\"" GPIO_CHIP "\")");
         return -1;
     }
+
     return 0;
 }
 
 void cleanup_gpio() {
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_close.html
-    gpiod_chip_close(chip);
+    if (chip) {
+        gpiod_chip_close(chip);
+        chip = NULL;
+    }
 }
 
 static int set_pin_state(int pin, int state) {
+    int ret = -1;
+    if (!chip) {
+        perror("[pin_control] attempt to set GPIO line for invalid chip");
+        goto exit;
+    }
+
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_get_line.html
     struct gpiod_line *line = gpiod_chip_get_line(chip, pin);   // this may need an offset
     if (!line) {
-        printf("Error getting GPIO line");
-        return -1;
+        perror("[pin_control] gpiod_chip_get_line()");
+        goto exit;
     }
 
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_request_output.html
     if (gpiod_line_request_output(line, "house-leds", state) < 0) {
-        printf("Error setting GPIO line direction");
-        gpiod_line_release(line);
-        return -1;
+        perror("[pin_control] gpiod_line_request_output()");
+        goto exit_line;
     }
 
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_set_value.html
     if (gpiod_line_set_value(line, state) < 0) {
-        printf("Error setting GPIO line value");
-        gpiod_line_release(line);
-        return -1;
+        perror("[pin_control] gpiod_line_set_value()");
+        goto exit_line;
     }
 
+    ret = 0;
+
+exit_line:
     // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_release.html
     gpiod_line_release(line);
-    return 0;
+exit:
+    return ret;
 }
 
 int turn_on_pin(int pin) {
@@ -58,10 +74,10 @@ int turn_off_pin(int pin) {
 }
 
 int turn_on_all_pins() {
-    for (int pin = 0; pin <= 5; pin++) {
+    for (int pin = 0; pin <= 5; pin++)
         if (turn_on_pin(pin) < 0)
             return -1;
-    }
+
     return 0;
 }
 
@@ -80,7 +96,7 @@ static int button_presssed(int event, unsigned int pin, const struct timespec *
     return GPIOD_CTXLESS_EVENT_POLL_RET_STOP;
 }
 
-int wait_for_button_press(unsigned int pins[]) {
+int wait_for_button_press(const unsigned pins[static 5]) {
     // https://www.lane-fu.com/linuxmirror/libgpiod/doc/html/group______high__level____.html#ga3ac28eb59bbd31b8b2298f76047d377d
     
     int pressed_pin = -1;
@@ -90,15 +106,22 @@ int wait_for_button_press(unsigned int pins[]) {
         .tv_nsec = 0,
     };
 
-    return gpiod_ctxless_event_monitor_multiple(GPIO_CHIP,
-                                        GPIOD_CTXLESS_EVENT_FALLING_EDGE,
-                                        pins,
-                                        5,
-                                        true,
-                                        "house-leds",
-                                        &ts,     // big timout
-                                        NULL,
-                                        button_presssed,
-                                        &pressed_pin
-                                        );
+    int ret = gpiod_ctxless_event_monitor_multiple(
+        GPIO_CHIP,
+        GPIOD_CTXLESS_EVENT_FALLING_EDGE,
+        pins,
+        5,
+        true,
+        "house-leds",
+        &ts,     // big timout
+        NULL,
+        button_presssed,
+        &pressed_pin);
+
+    if (ret < 0) {
+        perror("[pin_control] gpiod_ctxless_event_monitor_multiple()");
+        return -1;
+    }
+
+    return pressed_pin;
 }