1 files changed, 118 insertions, 0 deletions
diff --git a/doc/examples/daemon-depedencies/await-ready.c b/doc/examples/daemon-depedencies/await-ready.c
new file mode 100644
index 0000000..03df950
--- /dev/null
+++ b/doc/examples/daemon-depedencies/await-ready.c
@@ -0,0 +1,118 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/wait.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char arg[4098];
+static int argc;
+static char **argv;
+static int remaining = 0;
+static char *started = NULL;
+static char msg[BUS_MEMORY_SIZE];
+
+
+static void announce_wait(pid_t pid)
+{
+	bus_t bus;
+	int i;
+	t(bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY));
+	for (i = 1; i < argc; i++) {
+		if (!started[i]) {
+			sprintf(arg, "%ji awaiting-ready %s", (intmax_t)pid, argv[i]);
+			t(bus_write(&bus, arg));
+		}
+	}
+	t(bus_close(&bus));
+	return;
+
+fail:
+	perror("await-ready");
+}
+
+
+static int callback(const char *message, void *user_data)
+{
+	int i;
+	char *arg2;
+	char *arg3;
+	pid_t pid;
+	pid_t ppid;
+
+	if (!message) {
+		ppid = getppid();
+		pid = fork();
+		if (pid == 0) {
+			announce_wait(ppid);
+			exit(0);
+		} else {
+			(void) waitpid(pid, NULL, 0); /* Let's pretend everything will go swimmingly. */
+		}
+		return 1;
+	}
+
+	strncpy(msg, message, BUS_MEMORY_SIZE - 1);
+	msg[BUS_MEMORY_SIZE - 1] = 0;
+
+	arg2 = strchr(message, ' ');
+	if (!arg2)
+		return 1;
+	arg3 = strchr(++arg2, ' ');
+	if (!arg3)
+		return 1;
+	*arg3++ = 0;
+
+	if (strcmp(arg2, "ready"))
+		return 1;
+
+	for (i = 1; i < argc; i++)
+		if (!started[i] && !strcmp(argv[i], arg3))
+			started[i] = 1, remaining--;
+
+	return !!remaining;
+	(void) user_data;
+}
+
+
+int main(int argc_, char *argv_[])
+{
+	bus_t bus;
+	int i;
+
+	argc = argc_;
+	argv = argv_;
+
+	if (argc < 2)
+		return fprintf(stderr, "USAGE: %s daemon...", *argv), 2;
+	t(bus_open(&bus, getenv("BUS_INIT"), BUS_RDONLY));
+	started = calloc(argc - 1, sizeof(char));
+	t(started == NULL);
+
+	started[0] = 1;
+	for (i = 1; i < argc; i++) {
+		sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/ready-daemons\" >/dev/null", argv[i]);
+		if (!WEXITSTATUS(system(arg)))
+			started[i] = 1;
+		else
+		        remaining++;
+	}
+
+	if (remaining)
+		bus_read(&bus, callback, NULL);
+
+	bus_close(&bus);
+	free(started);
+	return 0;
+
+fail:
+	perror("await-ready");
+	bus_close(&bus);
+	free(started);
+	return 1;
+}
+