1 files changed, 154 insertions, 0 deletions
diff --git a/src/shared/watchdog.c b/src/shared/watchdog.c
new file mode 100644
index 0000000..c423af6
--- /dev/null
+++ b/src/shared/watchdog.c
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <syslog.h>
+#include <unistd.h>
+#include <linux/watchdog.h>
+
+#include "fd-util.h"
+#include "log.h"
+#include "string-util.h"
+#include "time-util.h"
+#include "watchdog.h"
+
+static int watchdog_fd = -1;
+static char *watchdog_device = NULL;
+static usec_t watchdog_timeout = USEC_INFINITY;
+
+static int update_timeout(void) {
+        int r;
+
+        if (watchdog_fd < 0)
+                return 0;
+
+        if (watchdog_timeout == USEC_INFINITY)
+                return 0;
+        else if (watchdog_timeout == 0) {
+                int flags;
+
+                flags = WDIOS_DISABLECARD;
+                r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
+                if (r < 0)
+                        return log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
+        } else {
+                int sec, flags;
+                char buf[FORMAT_TIMESPAN_MAX];
+
+                sec = (int) DIV_ROUND_UP(watchdog_timeout, USEC_PER_SEC);
+                r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
+                if (r < 0)
+                        return log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
+
+                watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
+                log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout, 0));
+
+                flags = WDIOS_ENABLECARD;
+                r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
+                if (r < 0) {
+                        /* ENOTTY means the watchdog is always enabled so we're fine */
+                        log_full(errno == ENOTTY ? LOG_DEBUG : LOG_WARNING,
+                                 "Failed to enable hardware watchdog: %m");
+                        if (errno != ENOTTY)
+                                return -errno;
+                }
+
+                r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
+                if (r < 0)
+                        return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
+        }
+
+        return 0;
+}
+
+static int open_watchdog(void) {
+        struct watchdog_info ident;
+
+        if (watchdog_fd >= 0)
+                return 0;
+
+        watchdog_fd = open(watchdog_device ?: "/dev/watchdog",
+                           O_WRONLY|O_CLOEXEC);
+        if (watchdog_fd < 0)
+                return -errno;
+
+        if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) >= 0)
+                log_info("Hardware watchdog '%s', version %x",
+                         ident.identity,
+                         ident.firmware_version);
+
+        return update_timeout();
+}
+
+int watchdog_set_device(char *path) {
+        return free_and_strdup(&watchdog_device, path);
+}
+
+int watchdog_set_timeout(usec_t *usec) {
+        int r;
+
+        watchdog_timeout = *usec;
+
+        /* If we didn't open the watchdog yet and didn't get any
+         * explicit timeout value set, don't do anything */
+        if (watchdog_fd < 0 && watchdog_timeout == USEC_INFINITY)
+                return 0;
+
+        if (watchdog_fd < 0)
+                r = open_watchdog();
+        else
+                r = update_timeout();
+
+        *usec = watchdog_timeout;
+
+        return r;
+}
+
+int watchdog_ping(void) {
+        int r;
+
+        if (watchdog_fd < 0) {
+                r = open_watchdog();
+                if (r < 0)
+                        return r;
+        }
+
+        r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
+        if (r < 0)
+                return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
+
+        return 0;
+}
+
+void watchdog_close(bool disarm) {
+        int r;
+
+        if (watchdog_fd < 0)
+                return;
+
+        if (disarm) {
+                int flags;
+
+                /* Explicitly disarm it */
+                flags = WDIOS_DISABLECARD;
+                r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
+                if (r < 0)
+                        log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
+
+                /* To be sure, use magic close logic, too */
+                for (;;) {
+                        static const char v = 'V';
+
+                        if (write(watchdog_fd, &v, 1) > 0)
+                                break;
+
+                        if (errno != EINTR) {
+                                log_error_errno(errno, "Failed to disarm watchdog timer: %m");
+                                break;
+                        }
+                }
+        }
+
+        watchdog_fd = safe_close(watchdog_fd);
+}