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SubjectRe: [PATCH 1/2] iio: generic_buffer: Cleanup when receiving signals
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On 20/05/16 16:55, Peter Meerwald-Stadler wrote:
>
>> 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.
>
> well, it helps to see that all memory has been released when looking for
> leaks :)
> e.g. valgrind becomes much less useful when the program exits with tons of
> memory still allocated
Beyond that we are looking at code here that will get cut and paste into other
peoples applications - they might not pick up that it doesn't clean up properly
after itself.

I'd much prefer to keep these explicit frees in place.

Jonathan
>
> functions and global variables could be static
>
>> ---
>> 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;
>> }
>>
>

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