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