4rc: service manager that larps as functional

1 files changed, 66 insertions, 10 deletions

diff --git a/4rc/4rc.c b/4rc/4rc.c
index 68a5d9f..35a85d3 100644
--- a/4rc/4rc.c
+++ b/4rc/4rc.c
@@ -1,36 +1,52 @@
+#define _DEFAULT_SOURCE
 #define _POSIX_C_SOURCE 200809L
 
+#include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 void create_vfs(void) {
-	mkdir("/proc", 0755);
-	mkdir("/sys", 0755);
-	mkdir("/dev", 0755);
-	mkdir("/run", 0755);
+	if (mkdir("/proc", 0755) != 0 && errno != EEXIST) {
+		perror("proc");
+	}
+	if (mkdir("/sys", 0755) != 0 && errno != EEXIST) {
+		perror("sys");
+	}
+	if (mkdir("/dev", 0755) != 0 && errno != EEXIST) {
+		perror("dev");
+	}
+	if (mkdir("/run", 0755) != 0 && errno != EEXIST) {
+		perror("run");
+	}
 }
 
 void mount_vfs(void) {
 	if (mount("proc", "/proc", "proc",
-			  MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_RELATIME, NULL) != 0) {
+			  MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_RELATIME, NULL) != 0 &&
+		errno != EBUSY) {
 		perror("mount /proc");
 	}
 
 	if (mount("sys", "/sys", "sysfs",
-			  MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_RELATIME, NULL) != 0) {
+			  MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_RELATIME, NULL) != 0 &&
+		errno != EBUSY) {
 		perror("mount /sys");
 	}
 
 	if (mount("dev", "/dev", "devtmpfs", MS_NOSUID | MS_RELATIME, "mode=755") !=
-		0) {
+			0 &&
+		errno != EBUSY) {
 		perror("mount /dev");
 	}
 
 	if (mount("run", "/run", "tmpfs", MS_NOSUID | MS_NODEV | MS_RELATIME,
-			  "mode=755") != 0) {
+			  "mode=755") != 0 &&
+		errno != EBUSY) {
 		perror("mount /run");
 	}
 
@@ -38,19 +54,59 @@ void mount_vfs(void) {
 	mkdir("/dev/shm", 1777);
 
 	if (mount("devpts", "/dev/pts", "devpts",
-			  MS_NOSUID | MS_NOEXEC | MS_RELATIME, "gid=5,mode=620") != 0) {
+			  MS_NOSUID | MS_NOEXEC | MS_RELATIME, "gid=5,mode=620") != 0 &&
+		errno != EBUSY) {
 		perror("mount /dev/pts");
 	}
 
 	if (mount("shm", "/dev/shm", "tmpfs", MS_NOSUID | MS_NODEV | MS_RELATIME,
-			  "mode=1777") != 0) {
+			  "mode=1777") != 0 &&
+		errno != EBUSY) {
 		perror("mount /dev/shm");
 	}
 }
 
+void set_hostname(void) {
+	char buf[256];
+	int fd = open("/etc/hostname", O_RDONLY);
+
+	if (fd < 0) {
+		perror("open /etc/hostname");
+		return;
+	}
+
+	ssize_t bytes_read = read(fd, buf, sizeof(buf) - 1);
+	close(fd);
+
+	if (bytes_read > 0) {
+		buf[bytes_read] = '\0';
+		size_t len = strcspn(buf, "\r\n ");
+		buf[len] = '\0';
+
+		if (sethostname(buf, len) != 0) {
+			perror("sethostname");
+		}
+	}
+}
+
 int main(void) {
 	create_vfs();
 	mount_vfs();
 
+	int fd = open("/dev/console", O_RDWR);
+
+	if (fd >= 0) {
+		dup2(fd, 0);
+		dup2(fd, 1);
+		dup2(fd, 2);
+		if (fd > 2) {
+			close(fd);
+		}
+	} else {
+		perror("console");
+	}
+
+	set_hostname();
+
 	return 0;
 }