[PATCH 1/2] iio: generic_buffer: Cleanup when receiving signals

[Crestez Dan Leonard]

This will clean (disable buffer/trigger/channels) when doing something
like a CTRL-C. Otherwise restarting generic_buffer requires a manual
echo 0 > buffer/enable

This also drops all the code freeing string buffers at the end of main.
Memory is freed when the process exits anyway so there's no point in
cluttering the code with all those gotos.

Signed-off-by: Crestez Dan Leonard <leonard.crestez@xxxxxxxxx>
---
 tools/iio/generic_buffer.c | 162 ++++++++++++++++++++++++---------------------
 1 file changed, 88 insertions(+), 74 deletions(-)

diff --git a/tools/iio/generic_buffer.c b/tools/iio/generic_buffer.c
index 2429c78..e7bf477 100644
--- a/tools/iio/generic_buffer.c
+++ b/tools/iio/generic_buffer.c
@@ -32,6 +32,8 @@
 #include <endian.h>
 #include <getopt.h>
 #include <inttypes.h>
+#include <stdbool.h>
+#include <signal.h>
 #include "iio_utils.h"
 
 /**
@@ -254,6 +256,69 @@ void print_usage(void)
 		"  -w <n>     Set delay between reads in us (event-less mode)\n");
 }
 
+enum autochan autochannels = AUTOCHANNELS_DISABLED;
+char *dev_dir_name = NULL;
+char *buf_dir_name = NULL;
+bool current_trigger_set = false;
+
+void cleanup(void)
+{
+	int ret;
+
+	fprintf(stderr, "Cleanup\n");
+
+	/* Disable trigger */
+	if (dev_dir_name && current_trigger_set) {
+		/* Disconnect the trigger - just write a dummy name. */
+		ret = write_sysfs_string("trigger/current_trigger",
+					 dev_dir_name, "NULL");
+		if (ret < 0)
+			fprintf(stderr, "Failed to disable trigger: %s\n",
+				strerror(-ret));
+	}
+
+	/* Disable buffer */
+	if (buf_dir_name) {
+		ret = write_sysfs_int("enable", buf_dir_name, 0);
+		if (ret < 0)
+			fprintf(stderr, "Failed to disable buffer: %s\n",
+				strerror(-ret));
+	}
+
+	/* Disable channels if auto-enabled */
+	if (dev_dir_name && autochannels == AUTOCHANNELS_ACTIVE) {
+		ret = enable_disable_all_channels(dev_dir_name, 0);
+		if (ret)
+			fprintf(stderr, "Failed to disable all channels\n");
+	}
+}
+
+void sig_handler(int signum)
+{
+	fprintf(stderr, "Caught signal %d\n", signum);
+	exit(-signum);
+}
+
+void register_cleanup(void)
+{
+	struct sigaction sa = { .sa_handler = sig_handler };
+	const int signums[] = { SIGINT, SIGTERM, SIGABRT };
+	int ret, i;
+
+	ret = atexit(cleanup);
+	if (ret) {
+		perror("Failed to register atexit");
+		exit(-1);
+	}
+	for (i = 0; i < ARRAY_SIZE(signums); ++i) {
+		ret = sigaction(signums[i], &sa, NULL);
+		if (ret) {
+			perror("Failed to register signal handler");
+			exit(-1);
+		}
+	}
+}
+
 int main(int argc, char **argv)
 {
 	unsigned long num_loops = 2;
@@ -265,9 +330,7 @@ int main(int argc, char **argv)
 
 	int num_channels;
 	char *trigger_name = NULL, *device_name = NULL;
-	char *dev_dir_name, *buf_dir_name;
 
-	int datardytrigger = 1;
 	char *data;
 	ssize_t read_size;
 	int dev_num, trig_num;
@@ -275,11 +338,12 @@ int main(int argc, char **argv)
 	int scan_size;
 	int noevents = 0;
 	int notrigger = 0;
-	enum autochan autochannels = AUTOCHANNELS_DISABLED;
 	char *dummy;
 
 	struct iio_channel_info *channels;
 
+	register_cleanup();
+
 	while ((c = getopt(argc, argv, "ac:egl:n:t:w:")) != -1) {
 		switch (c) {
 		case 'a':
@@ -310,7 +374,6 @@ int main(int argc, char **argv)
 			break;
 		case 't':
 			trigger_name = optarg;
-			datardytrigger = 0;
 			break;
 		case 'w':
 			errno = 0;
@@ -352,10 +415,8 @@ int main(int argc, char **argv)
 			 */
 			ret = asprintf(&trigger_name,
 				       "%s-dev%d", device_name, dev_num);
-			if (ret < 0) {
-				ret = -ENOMEM;
-				goto error_free_dev_dir_name;
-			}
+			if (ret < 0)
+				return -ENOMEM;
 		}
 
 		/* Look for this "-devN" trigger */
@@ -365,18 +426,15 @@ int main(int argc, char **argv)
 			free(trigger_name);
 			ret = asprintf(&trigger_name,
 				       "%s-trigger", device_name);
-			if (ret < 0) {
-				ret = -ENOMEM;
-				goto error_free_dev_dir_name;
-			}
+			if (ret < 0)
+				return -ENOMEM;
 		}
 
 		trig_num = find_type_by_name(trigger_name, "trigger");
 		if (trig_num < 0) {
 			fprintf(stderr, "Failed to find the trigger %s\n",
 				trigger_name);
-			ret = trig_num;
-			goto error_free_triggername;
+			return trig_num;
 		}
 
 		printf("iio trigger number being used is %d\n", trig_num);
@@ -392,7 +450,7 @@ int main(int argc, char **argv)
 	if (ret) {
 		fprintf(stderr, "Problem reading scan element information\n"
 			"diag %s\n", dev_dir_name);
-		goto error_free_triggername;
+		return ret;
 	}
 	if (num_channels && autochannels == AUTOCHANNELS_ENABLED) {
 		fprintf(stderr, "Auto-channels selected but some channels "
@@ -407,7 +465,7 @@ int main(int argc, char **argv)
 		ret = enable_disable_all_channels(dev_dir_name, 1);
 		if (ret) {
 			fprintf(stderr, "Failed to enable all channels\n");
-			goto error_free_triggername;
+			return ret;
 		}
 
 		/* This flags that we need to disable the channels again */
@@ -419,12 +477,12 @@ int main(int argc, char **argv)
 			fprintf(stderr, "Problem reading scan element "
 				"information\n"
 				"diag %s\n", dev_dir_name);
-			goto error_disable_channels;
+		        return ret;
 		}
 		if (!num_channels) {
 			fprintf(stderr, "Still no channels after "
 				"auto-enabling, giving up\n");
-			goto error_disable_channels;
+		        return ret;
 		}
 	}
 
@@ -435,8 +493,7 @@ int main(int argc, char **argv)
 			FORMAT_SCAN_ELEMENTS_DIR
 			"/*_en or pass -a to autoenable channels and "
 			"try again.\n", dev_dir_name);
-		ret = -ENOENT;
-		goto error_free_triggername;
+		return -ENOENT;
 	}
 
 	/*
@@ -446,10 +503,8 @@ int main(int argc, char **argv)
 	 */
 	ret = asprintf(&buf_dir_name,
 		       "%siio:device%d/buffer", iio_dir, dev_num);
-	if (ret < 0) {
-		ret = -ENOMEM;
-		goto error_free_channels;
-	}
+	if (ret < 0)
+		return -ENOMEM;
 
 	if (!notrigger) {
 		printf("%s %s\n", dev_dir_name, trigger_name);
@@ -463,34 +518,35 @@ int main(int argc, char **argv)
 		if (ret < 0) {
 			fprintf(stderr,
 				"Failed to write current_trigger file\n");
-			goto error_free_buf_dir_name;
+			return ret;
 		}
+		current_trigger_set = true;
 	}
 
 	/* Setup ring buffer parameters */
 	ret = write_sysfs_int("length", buf_dir_name, buf_len);
 	if (ret < 0)
-		goto error_free_buf_dir_name;
+		return ret;
 
 	/* Enable the buffer */
 	ret = write_sysfs_int("enable", buf_dir_name, 1);
 	if (ret < 0) {
 		fprintf(stderr,
 			"Failed to enable buffer: %s\n", strerror(-ret));
-		goto error_free_buf_dir_name;
+		return ret;
 	}
 
 	scan_size = size_from_channelarray(channels, num_channels);
 	data = malloc(scan_size * buf_len);
 	if (!data) {
 		ret = -ENOMEM;
-		goto error_free_buf_dir_name;
+		return ret;
 	}
 
 	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
 	if (ret < 0) {
 		ret = -ENOMEM;
-		goto error_free_data;
+		return ret;
 	}
 
 	/* Attempt to open non blocking the access dev */
@@ -498,7 +554,7 @@ int main(int argc, char **argv)
 	if (fp == -1) { /* TODO: If it isn't there make the node */
 		ret = -errno;
 		fprintf(stderr, "Failed to open %s\n", buffer_access);
-		goto error_free_buffer_access;
+		return ret;
 	}
 
 	for (j = 0; j < num_loops; j++) {
@@ -510,8 +566,7 @@ int main(int argc, char **argv)
 
 			ret = poll(&pfd, 1, -1);
 			if (ret < 0) {
-				ret = -errno;
-				goto error_close_buffer_access;
+				return -errno;
 			} else if (ret == 0) {
 				continue;
 			}
@@ -536,46 +591,5 @@ int main(int argc, char **argv)
 				     num_channels);
 	}
 
-	/* Stop the buffer */
-	ret = write_sysfs_int("enable", buf_dir_name, 0);
-	if (ret < 0)
-		goto error_close_buffer_access;
-
-	if (!notrigger)
-		/* Disconnect the trigger - just write a dummy name. */
-		ret = write_sysfs_string("trigger/current_trigger",
-					 dev_dir_name, "NULL");
-		if (ret < 0)
-			fprintf(stderr, "Failed to write to %s\n",
-				dev_dir_name);
-
-error_close_buffer_access:
-	if (close(fp) == -1)
-		perror("Failed to close buffer");
-
-error_free_buffer_access:
-	free(buffer_access);
-error_free_data:
-	free(data);
-error_free_buf_dir_name:
-	free(buf_dir_name);
-error_free_channels:
-	for (i = num_channels - 1; i >= 0; i--) {
-		free(channels[i].name);
-		free(channels[i].generic_name);
-	}
-	free(channels);
-error_free_triggername:
-	if (datardytrigger)
-		free(trigger_name);
-error_disable_channels:
-	if (autochannels == AUTOCHANNELS_ACTIVE) {
-		ret = enable_disable_all_channels(dev_dir_name, 0);
-		if (ret)
-			fprintf(stderr, "Failed to disable all channels\n");
-	}
-error_free_dev_dir_name:
-	free(dev_dir_name);
-
-	return ret;
+	return 0;
 }
-- 
2.5.5