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SubjectRe: [PATCH v2 11/11] tools: gpio: implement gpio-watch
śr., 4 gru 2019 o 23:42 Andy Shevchenko <andy.shevchenko@gmail.com> napisał(a):
>
> On Wed, Dec 4, 2019 at 7:19 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > Add a simple program that allows to test the new LINECHANGED_FD ioctl().
>
> > --- a/tools/gpio/.gitignore
> > +++ b/tools/gpio/.gitignore
> > @@ -1,4 +1,5 @@
> > gpio-event-mon
> > gpio-hammer
> > lsgpio
> > +gpio-watch
>
> Perhaps keep it sorted?
>

Sure I can do this.

> > +++ b/tools/gpio/gpio-watch.c
> > @@ -0,0 +1,112 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * gpio-watch - monitor unrequested lines for property changes using the
> > + * character device
> > + *
> > + * Copyright (C) 2019 BayLibre SAS
> > + * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > + */
> > +
> > +#include <ctype.h>
> > +#include <errno.h>
> > +#include <fcntl.h>
> > +#include <linux/gpio.h>
> > +#include <poll.h>
> > +#include <stdbool.h>
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <sys/ioctl.h>
> > +#include <unistd.h>
> > +
> > +static bool isnumber(const char *str)
> > +{
> > + size_t sz = strlen(str);
> > + int i;
> > +
> > + for (i = 0; i < sz; i++) {
> > + if (!isdigit(str[i]))
> > + return false;
> > + }
> > +
> > + return true;
> > +}
>
> strtoul() will do the same.
>
> char *p;
> unsigned long dummy; // do we need it?
> dummy = strtoul(..., &p);
> return *p == '\0';

Yeah strtoul does allow for error checking. I'll change this in v3.

>
> > +int main(int argc, char **argv)
> > +{
> > + struct gpioline_info_changed chg;
> > + struct gpioline_info req;
> > + struct pollfd pfd;
> > + int fd, i, j, ret;
> > + char *event;
> > + ssize_t rd;
> > +
> > + if (argc < 3)
> > + goto err_usage;
> > +
> > + fd = open(argv[1], O_RDWR | O_CLOEXEC);
> > + if (fd < 0) {
> > + perror("unable to open gpiochip");
> > + return EXIT_FAILURE;
> > + }
> > +
> > + for (i = 0, j = 2; i < argc - 2; i++, j++) {
> > + if (!isnumber(argv[j]))
> > + goto err_usage;
> > +
> > + memset(&req, 0, sizeof(req));
> > + req.line_offset = atoi(argv[j]);
>
> Oh, why not to call strtoul() directly?
>
> > +
> > + ret = ioctl(fd, GPIO_GET_LINEINFO_WATCH_IOCTL, &req);
> > + if (ret) {
> > + perror("unable to set up line watch");
>
> Don't you need to unwatch previously added ones?

Nah, we're exiting anyway, the fd will be released.

>
> > + return EXIT_FAILURE;
> > + }
> > + }
>
> > + for (;;) {
> > + ret = poll(&pfd, 1, 5000);
> > + if (ret < 0) {
> > + perror("error polling the linechanged fd");
> > + return EXIT_FAILURE;
> > + } else if (ret > 0) {
> > + memset(&chg, 0, sizeof(chg));
>
> > + rd = read(pfd.fd, &chg, sizeof(chg));
> > + if (rd < 0 || rd != sizeof(chg)) {
> > + if (rd != sizeof(chg))
> > + errno = EIO;
> > +
> > + perror("error reading line change event");
> > + return EXIT_FAILURE;
> > + }
>
> Shouldn't we handle the -EINTR?

Indeed we should. Will fix.

Bart

>
> > + }
> > + }
> > +
> > + return 0;
>
>
> --
> With Best Regards,
> Andy Shevchenko

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