gpioset: new option

Add an option allowing the program to detach from the controlling
terminal after setting values. This is useful for pulled-down/up pins
that we want to keep exported.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>

diff --git a/src/tools/gpioset.c b/src/tools/gpioset.c
index 1fc1f4c7fbcee13699cc58cb722611b5fe2dd2d8..be98fe8b2c5775eadfd1a28629b9dc526981bc5e 100644 (file)
--- a/src/tools/gpioset.c
+++ b/src/tools/gpioset.c
@@ -29,10 +29,11 @@ static const struct option longopts[] = {
        { "mode",               required_argument,      NULL,   'm' },
        { "sec",                required_argument,      NULL,   's' },
        { "usec",               required_argument,      NULL,   'u' },
+       { "background",         no_argument,            NULL,   'b' },
        { 0 },
 };
 
-static const char *const shortopts = "+hvlm:s:u:";
+static const char *const shortopts = "+hvlm:s:u:b";
 
 static void print_help(void)
 {
@@ -47,6 +48,7 @@ static void print_help(void)
        printf("                tell the program what to do after setting values\n");
        printf("  -s, --sec=SEC:\tspecify the number of seconds to wait (only valid for --mode=time)\n");
        printf("  -u, --usec=USEC:\tspecify the number of microseconds to wait (only valid for --mode=time)\n");
+       printf("  -b, --background:\tafter setting values: detach from the controlling terminal\n");
        printf("\n");
        printf("Modes:\n");
        printf("  exit:\tset values and exit immediately\n");
@@ -58,8 +60,20 @@ static void print_help(void)
 struct callback_data {
        /* Replace with a union once we have more modes using callback data. */
        struct timeval tv;
+       bool daemonize;
 };
 
+static void maybe_daemonize(bool daemonize)
+{
+       int status;
+
+       if (daemonize) {
+               status = daemon(0, 0);
+               if (status < 0)
+                       die("unable to daemonize: %s", strerror(errno));
+       }
+}
+
 static void wait_enter(void *data UNUSED)
 {
        getchar();
@@ -69,11 +83,13 @@ static void wait_time(void *data)
 {
        struct callback_data *cbdata = data;
 
+       maybe_daemonize(cbdata->daemonize);
        select(0, NULL, NULL, NULL, &cbdata->tv);
 }
 
-static void wait_signal(void *data UNUSED)
+static void wait_signal(void *data)
 {
+       struct callback_data *cbdata = data;
        int sigfd, status;
        struct pollfd pfd;
        sigset_t sigmask;
@@ -94,6 +110,8 @@ static void wait_signal(void *data UNUSED)
        pfd.fd = sigfd;
        pfd.events = POLLIN | POLLPRI;
 
+       maybe_daemonize(cbdata->daemonize);
+
        for (;;) {
                status = poll(&pfd, 1, 1000 /* one second */);
                if (status < 0)
@@ -204,6 +222,11 @@ int main(int argc, char **argv)
                                die("invalid time value in microseconds: %s",
                                    optarg);
                        break;
+               case 'b':
+                       if (mode->id != MODE_SIGNAL && mode->id != MODE_TIME)
+                               die("can't daemonize in this mode");
+                       cbdata.daemonize = true;
+                       break;
                case '?':
                        die("try %s --help", get_progname());
                default: