On 1/8/19 12:38 PM, Dan Carpenter wrote:
> Hello Martin Kelly,
>
> The patch 55dda0abcf9d: "tools: iio: iio_generic_buffer: allow
> continuous looping" from May 17, 2018, leads to the following static
> checker warning:
>
> ./tools/iio/iio_generic_buffer.c:640 main()
> warn: unsigned 'num_loops' is never less than zero.
>
Thanks for catching this. How can I repro this so that I can make sure
the static analyzer is happy once I fix it?
> ./tools/iio/iio_generic_buffer.c
> 331 int main(int argc, char **argv)
> 332 {
> 333 unsigned long long num_loops = 2;
> ^^^^^^^^
>
> 334 unsigned long timedelay = 1000000;
> 335 unsigned long buf_len = 128;
> 336
> 337 ssize_t i;
> 338 unsigned long long j;
> 339 unsigned long toread;
> 340 int ret, c;
> 341 int fp = -1;
> 342
> 343 int num_channels = 0;
> 344 char *trigger_name = NULL, *device_name = NULL;
> 345
> 346 char *data = NULL;
> 347 ssize_t read_size;
> 348 int dev_num = -1, trig_num = -1;
> 349 char *buffer_access = NULL;
> 350 int scan_size;
> 351 int noevents = 0;
> 352 int notrigger = 0;
> 353 char *dummy;
> 354 bool force_autochannels = false;
> 355
> 356 struct iio_channel_info *channels = NULL;
> 357
>
> [ snip ]
>
> 632 /* Attempt to open non blocking the access dev */
> 633 fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
> 634 if (fp == -1) { /* TODO: If it isn't there make the node */
> 635 ret = -errno;
> 636 fprintf(stderr, "Failed to open %s\n", buffer_access);
> 637 goto error;
> 638 }
> 639
> --> 640 for (j = 0; j < num_loops || num_loops < 0; j++) {
> ^^^^^^^^^^^^^
> If num_loops is -1 then it's supposed to loop forever. It basically
> does, except for the static checker warning.
>
Yep, looks like -1 gets converted to ULONG_LONG_MAX and it loops for a
very long time but not forever. I will fix it soon.
> 641 if (!noevents) {
> 642 struct pollfd pfd = {
> 643 .fd = fp,
> 644 .events = POLLIN,
> 645 };
> 646
> 647 ret = poll(&pfd, 1, -1);
> 648 if (ret < 0) {
> 649 ret = -errno;
> 650 goto error;
> 651 } else if (ret == 0) {
> 652 continue;
> 653 }
> 654
> 655 toread = buf_len;
> 656 } else {
> 657 usleep(timedelay);
> 658 toread = 64;
> 659 }
>
> regards,
> dan carpenter
>
