14 files changed, 610 insertions, 0 deletions

diff --git a/doc/examples/daemon-dependencies/.gitignore b/doc/examples/daemon-dependencies/.gitignore
new file mode 100644
index 0000000..0dac119
--- /dev/null
+++ b/doc/examples/daemon-dependencies/.gitignore
@@ -0,0 +1,10 @@
+run/
+announce
+await-ready
+await-started
+cleanup
+init
+require
+start-daemon
+test-daemon
+
diff --git a/doc/examples/daemon-dependencies/Makefile b/doc/examples/daemon-dependencies/Makefile
new file mode 100644
index 0000000..bf6fe88
--- /dev/null
+++ b/doc/examples/daemon-dependencies/Makefile
@@ -0,0 +1,14 @@
+COMMANDS = announce await-ready await-started cleanup init require start-daemon test-daemon
+
+all: ${COMMANDS}
+
+%: %.c
+	${CC} -Wall -Wextra -pedantic -std=c99 -lbus -o $@ $<
+
+clean:
+	-rm ${COMMANDS}
+	-rm -r run
+
+
+.PHONY: all clean
+
diff --git a/doc/examples/daemon-dependencies/README b/doc/examples/daemon-dependencies/README
new file mode 100644
index 0000000..a9f5783
--- /dev/null
+++ b/doc/examples/daemon-dependencies/README
@@ -0,0 +1,19 @@
+Use-case example.
+
+This example shows how bus can be used in a init
+system to provide "aggressivly" parallel startup
+of daemons.
+
+
+First of, run make to build this example.
+
+To start the example run ./init. It will print in
+red export-statement you may want to run i other
+terminals. You will need to select at least one
+daemon, for example you can run `./init d-ntp`.
+The available pretend daemons are: d-network,
+d-ntp and d-ssh.
+
+When you are done run ./cleanup with BUS_INIT
+exported with the value printed by ./init.
+
diff --git a/doc/examples/daemon-dependencies/announce.c b/doc/examples/daemon-dependencies/announce.c
new file mode 100644
index 0000000..d928adb
--- /dev/null
+++ b/doc/examples/daemon-dependencies/announce.c
@@ -0,0 +1,28 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char arg[4098];
+
+
+int
+main(int argc, char *argv[])
+{
+	bus_t bus;
+	if (argc < 3)
+		return fprintf(stderr, "USAGE: %s state daemon", *argv), 2;
+	t(bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY));
+	sprintf(arg, "%ji %s %s", (intmax_t)getppid(), argv[1], argv[2]);
+	t(bus_write(&bus, arg, 0));
+	t(bus_close(&bus));
+	return 0;
+
+fail:
+	perror("announce");
+	return 1;
+}
diff --git a/doc/examples/daemon-dependencies/await-ready.c b/doc/examples/daemon-dependencies/await-ready.c
new file mode 100644
index 0000000..fea2382
--- /dev/null
+++ b/doc/examples/daemon-dependencies/await-ready.c
@@ -0,0 +1,122 @@
+#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, 0));
+		}
+	}
+	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) {
+			if (fork() == 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(msg, ' ');
+	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, 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;
+}
+
diff --git a/doc/examples/daemon-dependencies/await-started.c b/doc/examples/daemon-dependencies/await-started.c
new file mode 100644
index 0000000..99ba14f
--- /dev/null
+++ b/doc/examples/daemon-dependencies/await-started.c
@@ -0,0 +1,127 @@
+#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-started %s", (intmax_t)pid, argv[i]);
+			t(bus_write(&bus, arg, 0));
+		}
+	}
+	t(bus_close(&bus));
+	return;
+
+fail:
+	perror("await-started");
+}
+
+
+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) {
+			if (fork() == 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(msg, ' ');
+	if (!arg2)
+		return 1;
+	arg3 = strchr(++arg2, ' ');
+	if (!arg3)
+		return 1;
+	*arg3++ = 0;
+
+	if (strcmp(arg2, "started") && 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, sizeof(char));
+	t(started == NULL);
+
+	started[0] = 1;
+	for (i = 1; i < argc; i++) {
+		sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/started-daemons\" >/dev/null", argv[i]);
+		if (!WEXITSTATUS(system(arg))) {
+			started[i] = 1;
+		} else {
+			sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/ready-daemons\" >/dev/null", argv[i]);
+			if (!WEXITSTATUS(system(arg)))
+				started[i] = 1;
+			else
+			        remaining++;
+		}
+	}
+
+	if (remaining)
+		bus_read(&bus, callback, NULL);
+
+	bus_close(&bus);
+	free(started);
+	return 0;
+
+fail:
+	perror("await-started");
+	bus_close(&bus);
+	free(started);
+	return 1;
+}
+
diff --git a/doc/examples/daemon-dependencies/cleanup.c b/doc/examples/daemon-dependencies/cleanup.c
new file mode 100644
index 0000000..f9ead6d
--- /dev/null
+++ b/doc/examples/daemon-dependencies/cleanup.c
@@ -0,0 +1,25 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+
+int
+main()
+{
+	char *bus_address = getenv("BUS_INIT");
+	if (!bus_address || !*bus_address) {
+		fprintf(stderr, "$BUS_INIT has not been set, its export statement "
+			"should have been printed in bold red by ./init\n");
+		return 1;
+	}
+	t(bus_unlink(bus_address));
+	return 0;
+
+fail:
+	perror("cleanup");
+	return 1;
+}
+
diff --git a/doc/examples/daemon-dependencies/d-network b/doc/examples/daemon-dependencies/d-network
new file mode 100755
index 0000000..1b8c7dd
--- /dev/null
+++ b/doc/examples/daemon-dependencies/d-network
@@ -0,0 +1,9 @@
+#!/bin/sh
+PATH=.:$PATH
+d=d-network
+
+echo $d: starting
+sleep 2
+echo $d: ready
+announce ready $d
+
diff --git a/doc/examples/daemon-dependencies/d-ntp b/doc/examples/daemon-dependencies/d-ntp
new file mode 100755
index 0000000..0f29c7c
--- /dev/null
+++ b/doc/examples/daemon-dependencies/d-ntp
@@ -0,0 +1,11 @@
+#!/bin/sh
+PATH=.:$PATH
+d=d-ntp
+
+require d-network
+echo $d: started
+announce started $d
+await-ready d-network
+echo $d: ready
+announce ready $d
+
diff --git a/doc/examples/daemon-dependencies/d-ssh b/doc/examples/daemon-dependencies/d-ssh
new file mode 100755
index 0000000..487354e
--- /dev/null
+++ b/doc/examples/daemon-dependencies/d-ssh
@@ -0,0 +1,13 @@
+#!/bin/sh
+PATH=.:$PATH
+d=d-ssh
+
+require d-network
+echo $d: starting
+sleep 1
+echo $d: started
+announce started $d
+sleep 1
+echo $d: ready
+announce ready $d
+
diff --git a/doc/examples/daemon-dependencies/init.c b/doc/examples/daemon-dependencies/init.c
new file mode 100644
index 0000000..b7182c6
--- /dev/null
+++ b/doc/examples/daemon-dependencies/init.c
@@ -0,0 +1,127 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char msg[BUS_MEMORY_SIZE];
+static int argc;
+static char **argv;
+static char arg[4098];
+
+
+static void
+start_daemons()
+{
+	int i;
+	for (i = 1; i < argc; i++)
+		if (fork() == 0)
+			execl("./start-daemon", "./start-daemon", argv[i], NULL); 
+}
+
+
+static int
+callback(const char *message, void *user_data)
+{
+	pid_t pid;
+	char *arg2;
+	char *arg3;
+	if (!message) {
+		pid = fork();
+		t(pid == -1);
+		if (pid == 0) {
+			if (fork() == 0) {
+				start_daemons();
+			}
+			exit(0);
+		} else {
+			(void) waitpid(pid, NULL, 0); /* Let's pretend everything will go swimmingly. */
+		}
+		return 1;
+	}
+
+	strncpy(msg, message, BUS_MEMORY_SIZE - 1);
+	msg[BUS_MEMORY_SIZE - 1] = 0;
+
+	pid = fork();
+	t(pid == -1);
+
+	if (pid == 0) {
+		if (fork() == 0) {
+			arg2 = strchr(msg, ' ');
+			if (arg2 == NULL)
+				exit(0);
+			arg3 = strchr(++arg2, ' ');
+			if (arg3 == NULL)
+				exit(0);
+			*arg3++ = 0;
+			if (!strcmp(arg2, "require")) {
+				execl("./start-daemon", "./start-daemon", arg3, NULL);
+			} else if (!strcmp(arg2, "awaiting-started")) {
+				execl("./test-daemon", "./test-daemon", arg3, "started", NULL);
+			} else if (!strcmp(arg2, "awaiting-ready") || !strcmp(arg2, "awaiting")) {
+				execl("./test-daemon", "./test-daemon", arg3, "ready", NULL);
+			} else if (!strcmp(arg2, "started")) {
+				sprintf(arg,
+					"grep '^%s\\$' < \"${XDG_RUNTIME_DIR}/started-daemons\" >/dev/null || "
+					"echo %s >> \"${XDG_RUNTIME_DIR}/started-daemons\"",
+					arg3, arg3);
+				execlp("sh", "sh", "-c", arg, NULL);
+			} else if (!strcmp(arg2, "ready")) {
+				sprintf(arg,
+					"grep '^%s\\$' < \"${XDG_RUNTIME_DIR}/ready-daemons\" >/dev/null || "
+					"echo %s >> \"${XDG_RUNTIME_DIR}/ready-daemons\"",
+					arg3, arg3);
+				execlp("sh", "sh", "-c", arg, NULL);
+			}
+		}
+		exit(0);
+	} else {
+		(void) waitpid(pid, NULL, 0); /* Let's pretend everything will go swimmingly. */
+	}
+
+	return 1;
+	(void) user_data;
+
+fail:
+	perror("init");
+	return -1;
+}
+
+
+int
+main(int argc_, char *argv_[])
+{
+	char *bus_address = NULL;
+	bus_t bus;
+	argv = argv_;
+	argc = argc_;
+	if (argc < 2) {
+		fprintf(stderr, "USAGE: %s daemon...\n", *argv);
+		return 1;
+	}
+	t(setenv("XDG_RUNTIME_DIR", "./run", 1));  /* Real init systems with not have the period. */
+	system("mkdir -p -- \"${XDG_RUNTIME_DIR}\"");
+	system("truncate -s 0 -- \"${XDG_RUNTIME_DIR}/started-daemons\"");
+	system("truncate -s 0 -- \"${XDG_RUNTIME_DIR}/ready-daemons\"");
+	t(bus_create(NULL, 1, &bus_address));
+	fprintf(stderr, "\033[00;01;31mexport BUS_INIT=%s\033[00m\n", bus_address);
+	fprintf(stderr, "\033[00;31mexport XDG_RUNTIME_DIR=./run\033[00m\n");
+	t(setenv("BUS_INIT", bus_address, 1));
+	t(bus_open(&bus, bus_address, BUS_RDONLY));
+	t(bus_read(&bus, callback, NULL));
+	bus_close(&bus);
+	free(bus_address);
+	return 0;
+
+fail:
+	perror("init");
+	bus_close(&bus);
+	free(bus_address);
+	return 1;
+}
+
diff --git a/doc/examples/daemon-dependencies/require.c b/doc/examples/daemon-dependencies/require.c
new file mode 100644
index 0000000..e378431
--- /dev/null
+++ b/doc/examples/daemon-dependencies/require.c
@@ -0,0 +1,38 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char arg[4098];
+
+
+int
+main(int argc, char *argv[])
+{
+	bus_t bus;
+	int i;
+	if (argc < 2)
+		return fprintf(stderr, "USAGE: %s daemon...", *argv), 2;
+	t(bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY));
+
+	for (i = 1; i < argc; i++) {
+		sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/started-daemons\" >/dev/null", argv[i]);
+		if (WEXITSTATUS(system(arg))) {
+			sprintf(arg, "%ji require %s", (intmax_t)getppid(), argv[i]);
+			t(bus_write(&bus, arg, 0));
+		}
+	}
+
+	bus_close(&bus);
+	return 0;
+
+fail:
+	perror("require");
+	bus_close(&bus);
+	return 1;
+}
+
diff --git a/doc/examples/daemon-dependencies/start-daemon.c b/doc/examples/daemon-dependencies/start-daemon.c
new file mode 100644
index 0000000..7c224d5
--- /dev/null
+++ b/doc/examples/daemon-dependencies/start-daemon.c
@@ -0,0 +1,32 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char arg[4098];
+
+
+int
+main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return fprintf(stderr, "This program should be called from ./init\n"), 2;
+
+	sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/started-daemons\" >/dev/null", argv[1]);
+	if (!WEXITSTATUS(system(arg)))
+		return 0;
+	sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/ready-daemons\" >/dev/null", argv[1]);
+	if (!WEXITSTATUS(system(arg)))
+		return 0;
+
+	sprintf(arg, "./%s", argv[1]);
+	execlp(arg, arg, NULL);
+	perror("start-daemon");
+	return 1;
+}
+
diff --git a/doc/examples/daemon-dependencies/test-daemon.c b/doc/examples/daemon-dependencies/test-daemon.c
new file mode 100644
index 0000000..32ee545
--- /dev/null
+++ b/doc/examples/daemon-dependencies/test-daemon.c
@@ -0,0 +1,35 @@
+#include <bus.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define t(stmt)  if (stmt) goto fail
+
+
+static char arg[4098];
+
+
+int
+main(int argc, char *argv[])
+{
+	bus_t bus;
+	if (argc != 3)
+		return fprintf(stderr, "This program should be called from ./init\n"), 2;
+retry:
+	sprintf(arg, "grep '^%s$' < \"${XDG_RUNTIME_DIR}/%s-daemons\" >/dev/null", argv[1], argv[2]);
+	if (!WEXITSTATUS(system(arg))) {
+		t(bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY));
+		sprintf(arg, "0 %s %s", argv[2], argv[1]);
+		t(bus_write(&bus, arg, 0));
+		bus_close(&bus);
+	} else if (!strcmp(argv[2], "started")) {
+		argv[2] = "ready";
+		goto retry;
+	}
+	return 0;
+
+fail:
+	perror("test-daemon");
+	return 1;
+}
+