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SubjectRe: [PATCH v2 11/11] tools: gpio: implement gpio-watch
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?

> +++ 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';

> +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?

> + 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?

> + }
> + }
> +
> + return 0;


--
With Best Regards,
Andy Shevchenko

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