lib/libutil/getdevpath.c

   1 /*
   2  * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/types.h>
  36 #include <sys/stat.h>
  37
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #include <errno.h>
  43 #include <paths.h>
  44 #include <limits.h>
  45
  46 #include "libutil.h"
  47
  48 static void finddevlabel(char **pathp, const char *devname);
  49 static int xlatedevpath(char **pathp, struct stat *st);
  50 static char *dodequote(char *base);
  51
  52 /*
  53  * Acquire device path.
  54  *
  55  */
  56 char *
  57 getdevpath(const char *devname, int flags)
  58 {
  59         const char *ptr;
  60         struct stat st;
  61         char *path = NULL;
  62         int stgood = 0;
  63
  64         if (devname[0] == '/' || devname[0] == '.') {
  65                 asprintf(&path, "%s", devname);
  66         } else if ((ptr = strchr(devname, ':')) != NULL) {
  67                 asprintf(&path, "/dev/%*.*s/%s",
  68                         ptr - devname, ptr - devname, devname,
  69                         ptr + 1);
  70         } else {
  71                 asprintf(&path, "/dev/%s", devname);
  72                 if (lstat(path, &st) < 0) {
  73                         free(path);
  74                         path = NULL;
  75                         finddevlabel(&path, devname);
  76                 } else {
  77                         stgood = 1;
  78                 }
  79         }
  80
  81         /*
  82          * Translate softlinks if requested.  If the lstat() of the
  83          * pre-translated path fails NULL is expected to be returned.
  84          * lstat() is not called on the post-translated path.
  85          */
  86         if ((flags & GETDEVPATH_RAWDEV) && path) {
  87                 if (stgood == 0 && lstat(path, &st) == 0)
  88                         stgood = 1;
  89                 if (stgood)
  90                         stgood = xlatedevpath(&path, &st);
  91                 if (stgood == 0) {
  92                         free(path);
  93                         path = NULL;
  94                 }
  95
  96         }
  97         if (path == NULL)
  98                 errno = ENOENT;
  99         return(path);
 100 }
 101
 102 static void
 103 finddevlabel(char **pathp, const char *devname)
 104 {
 105         const char *prefix = _PATH_DEVTAB_PATHS;
 106         const char *ptr1;
 107         const char *ptr2;
 108         char *ptr3;
 109         char *dtpath;
 110         char *bufp;
 111         char buf[256];
 112         FILE *fp;
 113         size_t len;
 114
 115         while (*prefix && *pathp == NULL) {
 116                 ptr1 = strchr(prefix, ':');
 117                 len = (ptr1) ? (size_t)(ptr1 - prefix) : strlen(prefix);
 118                 asprintf(&dtpath, "%*.*s/devtab", len, len, prefix);
 119                 if ((fp = fopen(dtpath, "r")) != NULL) {
 120                         while (fgets(buf, sizeof(buf), fp) != NULL) {
 121                                 ptr1 = strtok_r(buf, " \t\r\n", &bufp);
 122                                 if (ptr1 == NULL || *ptr1 == 0 || *ptr1 == '#')
 123                                         continue;
 124                                 if (strcmp(devname, ptr1) != 0)
 125                                         continue;
 126                                 ptr2 = strtok_r(NULL, " \t\r\n", &bufp);
 127                                 ptr3 = strtok_r(NULL, " \t\r\n", &bufp);
 128                                 if (ptr2 == NULL || ptr3 == NULL)
 129                                         continue;
 130                                 if (*ptr2 == 0 || *ptr3 == 0)
 131                                         continue;
 132                                 ptr3 = dodequote(ptr3);
 133                                 if (strcmp(ptr2, "path") == 0) {
 134                                         asprintf(pathp, "%s", ptr3);
 135                                 } else {
 136                                         asprintf(pathp, "/dev/%s/%s",
 137                                                  ptr2, ptr3);
 138                                 }
 139                                 break;
 140                         }
 141                         fclose(fp);
 142                 }
 143                 free(dtpath);
 144                 prefix += len;
 145                 if (*prefix == ':')
 146                         ++prefix;
 147         }
 148 }
 149
 150 static int
 151 xlatedevpath(char **pathp, struct stat *st)
 152 {
 153         char *path;
 154         int n;
 155         int len;
 156
 157         /*
 158          * If not a softlink return unchanged.
 159          */
 160         if (!S_ISLNK(st->st_mode))
 161                 return(1);
 162
 163         /*
 164          * If the softlink isn't reasonable return bad (0)
 165          */
 166         len = (int)st->st_size;
 167         if (len < 0 || len > PATH_MAX)
 168                 return(0);
 169
 170         /*
 171          * Read the link, return if the result is not what we expected.
 172          */
 173         path = malloc(len + 1);
 174         n = readlink(*pathp, path, len);
 175         if (n < 0 || n > len) {
 176                 free(path);
 177                 return(0);
 178         }
 179
 180         /*
 181          * Success, replace (*pathp).
 182          */
 183         path[n] = 0;
 184         free(*pathp);
 185         *pathp = path;
 186         return(1);
 187 }
 188
 189 static char *
 190 dodequote(char *base)
 191 {
 192         int len = strlen(base);
 193
 194         if (len && base[0] == '\"' && base[len-1] == '\"') {
 195                 base[len - 1] = 0;
 196                 ++base;
 197         }
 198         return(base);
 199 }