misc/base_device.c

   1 /*
   2  * base_device.c
   3  *
   4  * Return the "base device" given a particular device; this is used to
   5  * assure that we only fsck one partition on a particular drive at any
   6  * one time.  Otherwise, the disk heads will be seeking all over the
   7  * place.  If the base device can not be determined, return NULL.
   8  *
   9  * The base_device() function returns an allocated string which must
  10  * be freed.
  11  *
  12  * Written by Theodore Ts'o, <tytso@mit.edu>
  13  *
  14  * Copyright (C) 2000 Theodore Ts'o.
  15  *
  16  * %Begin-Header%
  17  * This file may be redistributed under the terms of the GNU Public
  18  * License.
  19  * %End-Header%
  20  */
  21 #include <stdio.h>
  22 #if HAVE_UNISTD_H
  23 #include <unistd.h>
  24 #endif
  25 #if HAVE_STDLIB_H
  26 #include <stdlib.h>
  27 #endif
  28 #include <ctype.h>
  29 #include <string.h>
  30
  31 #include "fsck.h"
  32
  33 /*
  34  * Required for the uber-silly devfs /dev/ide/host1/bus2/target3/lun3
  35  * pathames.
  36  */
  37 static const char *devfs_hier[] = {
  38         "host", "bus", "target", "lun", 0
  39 };
  40
  41 char *base_device(const char *device)
  42 {
  43         char *str, *cp;
  44         const char **hier, *disk;
  45         int len;
  46
  47         str = malloc(strlen(device)+1);
  48         if (!str)
  49                 return NULL;
  50         strcpy(str, device);
  51         cp = str;
  52
  53         /* Skip over /dev/; if it's not present, give up. */
  54         if (strncmp(cp, "/dev/", 5) != 0)
  55                 goto errout;
  56         cp += 5;
  57
  58         /* Skip over /dev/dsk/... */
  59         if (strncmp(cp, "dsk/", 4) == 0)
  60                 cp += 4;
  61
  62         /*
  63          * For md devices, we treat them all as if they were all
  64          * on one disk, since we don't know how to parallelize them.
  65          */
  66         if (cp[0] == 'm' && cp[1] == 'd') {
  67                 *(cp+2) = 0;
  68                 return str;
  69         }
  70
  71         /* Handle DAC 960 devices */
  72         if (strncmp(cp, "rd/", 3) == 0) {
  73                 cp += 3;
  74                 if (cp[0] != 'c' || cp[2] != 'd' ||
  75                     !isdigit(cp[1]) || !isdigit(cp[3]))
  76                         goto errout;
  77                 *(cp+4) = 0;
  78                 return str;
  79         }
  80
  81         /* Now let's handle /dev/hd* and /dev/sd* devices.... */
  82         if ((cp[0] == 'h' || cp[0] == 's') && (cp[1] == 'd')) {
  83                 cp += 2;
  84                 /* If there's a single number after /dev/hd, skip it */
  85                 if (isdigit(*cp))
  86                         cp++;
  87                 /* What follows must be an alpha char, or give up */
  88                 if (!isalpha(*cp))
  89                         goto errout;
  90                 *(cp + 1) = 0;
  91                 return str;
  92         }
  93
  94         /* Now let's handle devfs (ugh) names */
  95         len = 0;
  96         if (strncmp(cp, "ide/", 4) == 0)
  97                 len = 4;
  98         if (strncmp(cp, "scsi/", 5) == 0)
  99                 len = 5;
 100         if (len) {
 101                 cp += len;
 102                 /*
 103                  * Now we proceed down the expected devfs hierarchy.
 104                  * i.e., .../host1/bus2/target3/lun4/...
 105                  * If we don't find the expected token, followed by
 106                  * some number of digits at each level, abort.
 107                  */
 108                 for (hier = devfs_hier; *hier; hier++) {
 109                         len = strlen(*hier);
 110                         if (strncmp(cp, *hier, len) != 0)
 111                                 goto errout;
 112                         cp += len;
 113                         while (*cp != '/' && *cp != 0) {
 114                                 if (!isdigit(*cp))
 115                                         goto errout;
 116                                 cp++;
 117                         }
 118                         cp++;
 119                 }
 120                 *(cp - 1) = 0;
 121                 return str;
 122         }
 123
 124         /* Now handle devfs /dev/disc or /dev/disk names */
 125         disk = 0;
 126         if (strncmp(cp, "discs/", 6) == 0)
 127                 disk = "disc";
 128         else if (strncmp(cp, "disks/", 6) == 0)
 129                 disk = "disk";
 130         if (disk) {
 131                 cp += 6;
 132                 if (strncmp(cp, disk, 4) != 0)
 133                         goto errout;
 134                 cp += 4;
 135                 while (*cp != '/' && *cp != 0) {
 136                         if (!isdigit(*cp))
 137                                 goto errout;
 138                         cp++;
 139                 }
 140                 *cp = 0;
 141                 return str;
 142         }
 143
 144 errout:
 145         free(str);
 146         return NULL;
 147 }
 148
 149 #ifdef DEBUG
 150 int main(int argc, char** argv)
 151 {
 152         const char *base;
 153         char  buf[256], *cp;
 154
 155         while (1) {
 156                 if (fgets(buf, sizeof(buf), stdin) == NULL)
 157                         break;
 158                 cp = strchr(buf, '\n');
 159                 if (cp)
 160                         *cp = 0;
 161                 cp = strchr(buf, '\t');
 162                 if (cp)
 163                         *cp = 0;
 164                 base = base_device(buf);
 165                 printf("%s\t%s\n", buf, base ? base : "NONE");
 166         }
 167         exit(0);
 168 }
 169 #endif