commands/printroot/printroot.c

   1 /* printroot - print root device on stdout      Author: Bruce Evans */
   2
   3 /* This program figures out what the root device is by doing a stat on it, and
   4  * then searching /dev until it finds an entry with the same device number.
   5  *
   6  *  9 Dec 1989  - clean up for 1.5 - full prototypes (BDE)
   7  * 15 Oct 1989  - avoid ACK cc bugs (BDE):
   8  *              - sizeof "foo" is 2 (from wrong type char *) instead of 4
   9  *              - char foo[10] = "bar"; allocates 4 bytes instead of 10
  10  *  1 Oct 1989  - Minor changes by Andy Tanenbaum
  11  *  5 Oct 1992  - Use readdir (kjb)
  12  * 26 Nov 1994  - Flag -r: print just the root device (kjb)
  13  */
  14
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17 #include <fcntl.h>
  18 #include <limits.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22 #include <minix/minlib.h>
  23 #include <dirent.h>
  24
  25 static char DEV_PATH[] = "/dev/";       /* #define would step on sizeof bug */
  26 static char MESSAGE[] = " / ";  /* ditto */
  27 #define UNKNOWN_DEV     "/dev/unknown"
  28 #define ROOT            "/"
  29 int rflag;
  30
  31 int main(int argc, char **argv);
  32 void done(char *name, int status);
  33
  34 int main(argc, argv)
  35 int argc;
  36 char **argv;
  37 {
  38   DIR *dp;
  39   struct dirent *entry;
  40   struct stat filestat, rootstat;
  41   static char namebuf[sizeof DEV_PATH + NAME_MAX];
  42
  43   rflag = (argc > 1 && strcmp(argv[1], "-r") == 0);
  44
  45   if (stat(ROOT, &rootstat) == 0 && (dp = opendir(DEV_PATH)) != (DIR *) NULL) {
  46         while ((entry = readdir(dp)) != (struct dirent *) NULL) {
  47                 strcpy(namebuf, DEV_PATH);
  48                 strcat(namebuf, entry->d_name);
  49                 if (stat(namebuf, &filestat) != 0) continue;
  50                 if ((filestat.st_mode & S_IFMT) != S_IFBLK) continue;
  51                 if (filestat.st_rdev != rootstat.st_dev) continue;
  52                 done(namebuf, 0);
  53         }
  54   }
  55   done(UNKNOWN_DEV, 1);
  56   return(0);                    /* not reached */
  57 }
  58
  59 void done(name, status)
  60 char *name;
  61 int status;
  62 {
  63   int v;
  64
  65   write(1, name, strlen(name));
  66   if (rflag) {
  67         write(1, "\n", 1);
  68         exit(status);
  69   }
  70   write(1, MESSAGE, sizeof MESSAGE - 1);
  71   v = fsversion(name, "printroot");     /* determine file system version */
  72   switch (v) {
  73         case FSVERSION_MFS1: write(1, "1 rw\n", 5);     break;
  74         case FSVERSION_MFS2: write(1, "2 rw\n", 5);     break;
  75         case FSVERSION_MFS3: write(1, "3 rw\n", 5);     break;
  76         case FSVERSION_EXT2: write(1, "ext2 rw\n", 8);  break;
  77         default: write(1, "0 rw\n", 5);                 break;
  78   }
  79   exit(status);
  80 }