add directory bin

bin/rdev.c

@@ -0,0 +1,84 @@
+/* rdev.c  -  query/set root device. */
+
+/* usage: rdev [ boot-image ] [ root-device ] [ offset ] */
+
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+
+#define DEFAULT_OFFSET 508
+
+
+static void die(char *msg)
+{
+    perror(msg);
+    exit(1);
+}
+
+
+static char *find_dev(int number)
+{
+    DIR *dp;
+    struct dirent *dir;
+    static char name[PATH_MAX+1];
+    struct stat s;
+
+    if (!number) return "Boot device";
+    if ((dp = opendir("/dev")) == NULL) die("opendir /dev");
+    strcpy(name,"/dev/");
+    while (dir = readdir(dp)) {
+	strcpy(name+5,dir->d_name);
+	if (stat(name,&s) < 0) die(name);
+	if ((s.st_mode & S_IFMT) == S_IFBLK && s.st_rdev == number) return name;
+    }
+    sprintf(name,"0x%04x",number);
+    return name;
+}
+
+
+main(int argc,char **argv)
+{
+    int image,offset,dev_nr;
+    char *device;
+    struct stat s;
+
+    offset = DEFAULT_OFFSET;
+    device = NULL;
+    if (argc == 1 || argc > 4) {
+	if (stat("/",&s) < 0) die("/");
+	printf("%s /\n",find_dev(s.st_dev));
+	exit(0);
+    }
+    if (argc == 4) {
+	device = argv[2];
+	offset = atoi(argv[3]);
+    }
+    else {
+	if (argc == 3) {
+	    if (isdigit(*argv[2])) offset = atoi(argv[2]);
+	    else device = argv[2];
+	}
+    }
+    if (device) {
+	if (stat(device,&s) < 0) die(device);
+	if ((image = open(argv[1],O_WRONLY)) < 0) die(argv[1]);
+	if (lseek(image,offset,0) < 0) die("lseek");
+	if (write(image,&s.st_rdev,2) != 2) die(argv[1]);
+	if (close(image) < 0) die("close");
+    }
+    else {
+	if ((image = open(argv[1],O_RDONLY)) < 0) die(argv[1]);
+	if (lseek(image,offset,0) < 0) die("lseek");
+	dev_nr = 0;
+	if (read(image,&dev_nr,2) != 2) die(argv[1]);
+	if (close(image) < 0) die("close");
+	printf("Root device: %s\n",find_dev(dev_nr));
+    }
+    return 0;
+}