Make sinit a bit more sane

stuff/sinit.c

@@ -1,49 +1,61 @@
+#include <err.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-static int
-spawn(const char *file, char *const argv[])
-{
-	pid_t pid;
+#define LEN(x) (sizeof (x) / sizeof *(x))
 
-	pid = fork();
-	if (pid < 0)
-		return pid;
-	if (pid == 0) {
-		setsid();
-		setpgid(0, 0);
-		execvp(file, argv);
-		_exit(errno == ENOENT ? 127 : 126);
-	}
-}
+typedef union {
+        int i;
+        unsigned int ui;
+        float f;
+        const void *v;
+} Arg;
+
+typedef struct {
+        const char *name;
+        void (*func)(const Arg *arg);
+        const Arg arg;
+} Command;
+
+static void cmdpoweroff(const Arg *);
+static void cmdreboot(const Arg *);
+static void dispatchcmd(int);
+static int spawn(const char *, char *const []);
+
+static const char *fifopath = "/var/run/init.fifo";
+static Command commands[] = {
+	{ "poweroff",   cmdpoweroff,   {0} },
+	{ "reboot",     cmdreboot,     {0} },
+};
 
 int
 main(void)
 {
-	const char *fifopath = "/var/run/init.fifo";
 	sigset_t set;
 	pid_t pid;
 	fd_set rfds;
-	char buf[BUFSIZ], *p;
-	int c;
-	int fd;
-	int n;
+	int c, fd, n;
 
-	if (getpid() != 1) return 1;
+	if (getpid() != 1)
+		return EXIT_FAILURE;
 
 	sigfillset(&set);
 	sigprocmask(SIG_BLOCK, &set, 0);
 
 	pid = fork();
-	if (pid < 0) return 1;
-	if (pid > 0) for (;;) wait(&c);
+	if (pid < 0)
+		return EXIT_FAILURE;
+	if (pid > 0)
+		for (;;)
+			wait(&c);
 
 	sigprocmask(SIG_UNBLOCK, &set, 0);
 
@@ -52,39 +64,80 @@ main(void)
 	unlink(fifopath);
 	umask(0);
 	mkfifo(fifopath, 0600);
+
 	fd = open(fifopath, O_RDWR | O_NONBLOCK);
-	while (1) {
-		FD_ZERO(&rfds);
-		FD_SET(fd, &rfds);
-		n = select(fd + 1, &rfds, NULL, NULL, NULL);
-		if (n <= 0)
-			continue;
-		if (FD_ISSET(fd, &rfds)) {
-			n = read(fd, buf, sizeof(buf) - 1);
-			if (n < 0 || n == 0)
+	if (fd >= 0) {
+		while (1) {
+			FD_ZERO(&rfds);
+			FD_SET(fd, &rfds);
+			n = select(fd + 1, &rfds, NULL, NULL, NULL);
+			if (n <= 0)
 				continue;
-			buf[n] = '\0';
-			p = strchr(buf, '\n');
-			if (p) *p = '\0';
-			if (strcmp(buf, "reboot") == 0) {
-				spawn("/bin/sh", (char *[]){
-						"sh",
-						"-c",
-						"/etc/rc.shutdown reboot",
-						NULL
-				});
-			}
-			if (strcmp(buf, "poweroff") == 0) {
-				spawn("/bin/sh", (char *[]){
-						"sh",
-						"-c",
-						"/etc/rc.shutdown poweroff",
-						NULL
-				});
-			}
+			if (FD_ISSET(fd, &rfds))
+				dispatchcmd(fd);
 		}
 	}
 
-	/* unreached */
-	return 0;
+	/* can't reach */
+	return EXIT_SUCCESS;
+}
+
+static void
+cmdpoweroff(const Arg *arg)
+{
+	spawn("/bin/sh", (char *[]){
+			"sh",
+			"-c",
+			"/etc/rc.shutdown poweroff",
+			NULL
+	});
+}
+
+static void
+cmdreboot(const Arg *arg)
+{
+	spawn("/bin/sh", (char *[]){
+			"sh",
+			"-c",
+			"/etc/rc.shutdown reboot",
+			NULL
+	});
+}
+
+static void
+dispatchcmd(int fd)
+{
+	int i;
+	char buf[BUFSIZ], *p;
+	ssize_t n;
+
+	n = read(fd, buf, sizeof(buf) - 1);
+	if (n <= 0)
+		return;
+	buf[n] = '\0';
+	p = strchr(buf, '\n');
+	if (p)
+		*p = '\0';
+	for (i = 0; i < LEN(commands); i++) {
+		if (strcmp(commands[i].name, buf) == 0) {
+			commands[i].func(&commands[i].arg);
+			break;
+		}
+	}
+}
+
+static int
+spawn(const char *file, char *const argv[])
+{
+	pid_t pid;
+
+	pid = fork();
+	if (pid < 0)
+		return -1;
+	if (pid == 0) {
+		setsid();
+		setpgid(0, 0);
+		execvp(file, argv);
+		_exit(errno == ENOENT ? 127 : 126);
+	}
 }