This implements the s6 readiness notification protocol[1]. When the daemon has started and is listening on its socket(s), it will emit a readiness notification on a user-specified file descriptor. systemd-based systems can also use the readiness notification, using the sdnotify-wrapper program[2]. [1]: https://skarnet.org/software/s6/s6-supervise.html [2]: https://skarnet.org/software/misc/sdnotify-wrapper.c Signed-off-by: Alyssa Ross <hi@alyssa.is> --- This is important for us in Spectrum to be able to run usbipd to export USB devices to other VMs. I plan to add this patch to linuxPackages.usbip in Spectrum nixpkgs. I might attempt to upstream it to Linux, but I'm not sure yet -- the s6 protocol is perfect for our needs but fairly obsure, so I'm not sure if they'd like it. tools/usb/usbip/src/usbipd.c | 70 ++++++++++++++++++++++++++++-------- 1 file changed, 55 insertions(+), 15 deletions(-) diff --git a/tools/usb/usbip/src/usbipd.c b/tools/usb/usbip/src/usbipd.c index 48398a78e88af..4ee41040735f4 100644 --- a/tools/usb/usbip/src/usbipd.c +++ b/tools/usb/usbip/src/usbipd.c @@ -22,6 +22,7 @@ #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/in.h> +#include <fcntl.h> #ifdef HAVE_LIBWRAP #include <tcpd.h> @@ -65,6 +66,10 @@ static const char usbipd_help_string[] = " -D, --daemon\n" " Run as a daemon process.\n" "\n" + " -nFD, --notify-fd FD\n" + " Once ready to receive connections, write a line feed\n" + " character to FD, then close it.\n" + "\n" " -d, --debug\n" " Print debugging information.\n" "\n" @@ -88,6 +93,30 @@ static void usbipd_help(void) printf("%s\n", usbipd_help_string); } +static int parse_notify_fd(char *arg) +{ + dbg("parsing notify-fd arg '%s'", arg); + char *end; + unsigned long int notify_fd = strtoul(arg, &end, 10); + + if (end == arg) { + err("notify-fd: could not parse '%s' as decimal integer", arg); + return -1; + } + + if (*end != '\0') { + err("notify-fd: garbage at end of '%s'", arg); + return -1; + } + + if (fcntl(notify_fd, F_GETFD) == -1) { + err("notify-fd: %s", strerror(errno)); + return -1; + } + + return notify_fd; +} + static int recv_request_import(int sockfd) { struct op_import_request req; @@ -488,7 +517,7 @@ static void remove_pid_file(void) } } -static int do_standalone_mode(int daemonize, int ipv4, int ipv6) +static int do_standalone_mode(int daemonize, int notify_fd, int ipv4, int ipv6) { struct addrinfo *ai_head; int sockfdlist[MAXSOCKFD]; @@ -543,6 +572,13 @@ static int do_standalone_mode(int daemonize, int ipv4, int ipv6) dbg("listening on %d address%s", nsockfd, (nsockfd == 1) ? "" : "es"); + if (notify_fd != -1) { + const char lf[] = { '\n' }; + if (write(notify_fd, lf, sizeof lf) == -1) + err("failed to notify readiness"); + close(notify_fd); + } + fds = calloc(nsockfd, sizeof(struct pollfd)); for (i = 0; i < nsockfd; i++) { fds[i].fd = sockfdlist[i]; @@ -586,17 +622,18 @@ static int do_standalone_mode(int daemonize, int ipv4, int ipv6) int main(int argc, char *argv[]) { static const struct option longopts[] = { - { "ipv4", no_argument, NULL, '4' }, - { "ipv6", no_argument, NULL, '6' }, - { "daemon", no_argument, NULL, 'D' }, - { "daemon", no_argument, NULL, 'D' }, - { "debug", no_argument, NULL, 'd' }, - { "device", no_argument, NULL, 'e' }, - { "pid", optional_argument, NULL, 'P' }, - { "tcp-port", required_argument, NULL, 't' }, - { "help", no_argument, NULL, 'h' }, - { "version", no_argument, NULL, 'v' }, - { NULL, 0, NULL, 0 } + { "ipv4", no_argument, NULL, '4' }, + { "ipv6", no_argument, NULL, '6' }, + { "daemon", no_argument, NULL, 'D' }, + { "daemon", no_argument, NULL, 'D' }, + { "notify-fd", required_argument, NULL, 'n' }, + { "debug", no_argument, NULL, 'd' }, + { "device", no_argument, NULL, 'e' }, + { "pid", optional_argument, NULL, 'P' }, + { "tcp-port", required_argument, NULL, 't' }, + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, 'v' }, + { NULL, 0, NULL, 0 } }; enum { @@ -605,7 +642,7 @@ int main(int argc, char *argv[]) cmd_version } cmd; - int daemonize = 0; + int daemonize = 0, notify_fd = -1; int ipv4 = 0, ipv6 = 0; int opt, rc = -1; @@ -620,7 +657,7 @@ int main(int argc, char *argv[]) cmd = cmd_standalone_mode; driver = &host_driver; for (;;) { - opt = getopt_long(argc, argv, "46DdeP::t:hv", longopts, NULL); + opt = getopt_long(argc, argv, "46Dn:deP::t:hv", longopts, NULL); if (opt == -1) break; @@ -635,6 +672,9 @@ int main(int argc, char *argv[]) case 'D': daemonize = 1; break; + case 'n': + notify_fd = parse_notify_fd(optarg); + break; case 'd': usbip_use_debug = 1; break; @@ -665,7 +705,7 @@ int main(int argc, char *argv[]) switch (cmd) { case cmd_standalone_mode: - rc = do_standalone_mode(daemonize, ipv4, ipv6); + rc = do_standalone_mode(daemonize, notify_fd, ipv4, ipv6); remove_pid_file(); break; case cmd_version: -- 2.27.0