mount syscall and simple mount program

tools/mount/main.c

@@ -0,0 +1,44 @@
+#include <sys/mount.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+void usage(char *name) {
+	fprintf(stderr, "%s: usage: %s [-d device] mountpoint filesystem\n", name, name);
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[]) {
+	char *dev = NULL;
+	char *mountp = NULL;
+	char *fs = NULL;
+	bool devnext = false;
+
+	for (int i = 1; i < argc; ++i) {
+		if (strcmp(argv[i], "-d") == 0) {
+			devnext = true;
+			continue;
+		}
+
+		if (devnext) {
+			devnext = false;
+			dev = argv[i];
+		} else if (mountp == NULL)
+			mountp = argv[i];
+		else if (fs == NULL)
+			fs = argv[i];
+		else
+			usage(argv[0]);
+	}
+
+	if (mount == NULL || fs == NULL)
+		usage(argv[0]);
+
+	if (mount(dev, mountp, fs, 0, NULL) == -1) {
+		perror("mount failed");
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}