From 669923dedb0a13c2c8b834947863dd4d663249f6 Mon Sep 17 00:00:00 2001
From: Bartosz Golaszewski <bartekgola@gmail.com>
Date: Wed, 11 Jan 2017 10:52:13 +0100
Subject: [PATCH] iterators: improve error checking

Add new functions that allow to check if opening a gpiochip device
file from an iterator routine failed or if we're done iterating over
all gpiochips present on the system.

Use them in the relevant foreach macro and gpiodetect.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
---
 core.c       | 25 +++++++++++++++++++++++++
 gpiod.h      | 18 +++++++++++++++++-
 gpiodetect.c |  3 +++
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/core.c b/core.c
index ea24288..e7696d7 100644
--- a/core.c
+++ b/core.c
@@ -52,10 +52,17 @@ struct gpiod_line {
 	};
 };
 
+enum {
+	CHIP_ITER_INIT = 0,
+	CHIP_ITER_DONE,
+	CHIP_ITER_ERR,
+};
+
 struct gpiod_chip_iter
 {
 	DIR *dir;
 	struct gpiod_chip *current;
+	int state;
 };
 
 static const char dev_dir[] = "/dev/";
@@ -932,6 +939,8 @@ struct gpiod_chip_iter * gpiod_chip_iter_new(void)
 		return NULL;
 	}
 
+	new->state = CHIP_ITER_INIT;
+
 	return new;
 }
 
@@ -966,11 +975,27 @@ struct gpiod_chip * gpiod_chip_iter_next(struct gpiod_chip_iter *iter)
 		status = strncmp(dentry->d_name, cdev_prefix,
 				 sizeof(cdev_prefix) - 1);
 		if (status == 0) {
+			iter->state = CHIP_ITER_INIT;
+
 			chip = gpiod_chip_open_by_name(dentry->d_name);
+			if (!chip)
+				iter->state = CHIP_ITER_ERR;
+
 			iter->current = chip;
 			return iter->current;
 		}
 	}
 
+	iter->state = CHIP_ITER_DONE;
 	return NULL;
 }
+
+bool gpiod_chip_iter_done(struct gpiod_chip_iter *iter)
+{
+	return iter->state == CHIP_ITER_DONE;
+}
+
+bool gpiod_chip_iter_iserr(struct gpiod_chip_iter *iter)
+{
+	return iter->state == CHIP_ITER_ERR;
+}
diff --git a/gpiod.h b/gpiod.h
index ecba21a..5cf3254 100644
--- a/gpiod.h
+++ b/gpiod.h
@@ -704,9 +704,25 @@ gpiod_chip_iter_next(struct gpiod_chip_iter *iter) GPIOD_API;
  */
 #define gpiod_foreach_chip(iter, chip)					\
 	for ((chip) = gpiod_chip_iter_next(iter);			\
-	     (chip);							\
+	     !gpiod_chip_iter_done(iter);				\
 	     (chip) = gpiod_chip_iter_next(iter))
 
+/**
+ * @brief Check if we're done iterating over gpiochips on this iterator.
+ * @param iter The gpiochip iterator object.
+ * @return True if we've iterated over all chips, false otherwise.
+ */
+bool gpiod_chip_iter_done(struct gpiod_chip_iter *iter) GPIOD_API;
+
+/**
+ * @brief Check if we've encountered an error condition while opening a
+ *        gpiochip.
+ * @param iter The gpiochip iterator object.
+ * @return True if there was an error opening a gpiochip device file,
+ *         false otherwise.
+ */
+bool gpiod_chip_iter_iserr(struct gpiod_chip_iter *iter) GPIOD_API;
+
 /**
  * @brief GPIO line iterator structure.
  *
diff --git a/gpiodetect.c b/gpiodetect.c
index afb5479..aab022d 100644
--- a/gpiodetect.c
+++ b/gpiodetect.c
@@ -65,6 +65,9 @@ int main(int argc, char **argv)
 		die_perror("unable to access GPIO chips");
 
 	gpiod_foreach_chip(iter, chip) {
+		if (gpiod_chip_iter_iserr(iter))
+			die_perror("error accessing gpiochip");
+
 		printf("%s [%s] (%u lines)\n",
 		       gpiod_chip_name(chip),
 		       gpiod_chip_label(chip),
-- 
2.30.2