lib/libhammer/misc.c

   1 /*
   2  * Copyright (c) 2011 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  * by Antonio Huete <tuxillo@quantumachine.net>
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <assert.h>
  37 #include <fcntl.h>
  38 #include <err.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include <sys/types.h>
  44 #include <sys/stat.h>
  45 #include <sys/mount.h>
  46 #include <unistd.h>
  47 #include <uuid.h>
  48
  49 #include "libhammer.h"
  50
  51 char *
  52 libhammer_find_pfs_mount(uuid_t *unique_uuid)
  53 {
  54         struct hammer_ioc_pseudofs_rw pfs;
  55         struct hammer_pseudofs_data pfsd;
  56         struct statfs *mntbuf;
  57         int mntsize;
  58         int curmount;
  59         int fd;
  60         size_t  mntbufsize;
  61         uuid_t uuid;
  62         char *retval;
  63
  64         retval = NULL;
  65
  66         /* Do not continue if there are no mounted filesystems */
  67         mntsize = getfsstat(NULL, 0, MNT_NOWAIT);
  68         if (mntsize <= 0)
  69                 return retval;
  70
  71         mntbufsize = mntsize * sizeof(struct statfs);
  72         mntbuf = _libhammer_malloc(mntbufsize);
  73
  74         mntsize = getfsstat(mntbuf, (long)mntbufsize, MNT_NOWAIT);
  75         curmount = mntsize - 1;
  76
  77         /*
  78          * Iterate all the mounted points looking for the PFS passed to
  79          * this function.
  80          */
  81         while(curmount >= 0) {
  82                 struct statfs *mnt = &mntbuf[curmount];
  83                 /*
  84                  * Discard any non null(5) or hammer(5) filesystems as synthetic
  85                  * filesystems like procfs(5) could accept ioctl calls and thus
  86                  * produce bogus results.
  87                  */
  88                 if ((strcmp("hammer", mnt->f_fstypename) != 0) &&
  89                     (strcmp("null", mnt->f_fstypename) != 0)) {
  90                         curmount--;
  91                         continue;
  92                 }
  93                 bzero(&pfs, sizeof(pfs));
  94                 bzero(&pfsd, sizeof(pfsd));
  95                 pfs.pfs_id = -1;
  96                 pfs.ondisk = &pfsd;
  97                 pfs.bytes = sizeof(struct hammer_pseudofs_data);
  98                 fd = open(mnt->f_mntonname, O_RDONLY);
  99                 if (fd < 0 || (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) < 0)) {
 100                         close(fd);
 101                         curmount--;
 102                         continue;
 103                 }
 104
 105                 memcpy(&uuid, &pfs.ondisk->unique_uuid, sizeof(uuid));
 106                 if (uuid_compare(unique_uuid, &uuid, NULL) == 0) {
 107                         retval = strdup(mnt->f_mntonname);
 108                         close(fd);
 109                         break;
 110                 }
 111
 112                 curmount--;
 113                 close(fd);
 114         }
 115         free(mntbuf);
 116
 117         return retval;
 118 }
 119
 120 /*
 121  * Find out the path that can be used to open(2) a PFS
 122  * when it is not mounted. It allocates *path so the
 123  * caller is in charge of freeing it up.
 124  */
 125 void
 126 libhammer_pfs_canonical_path(char * mtpt, libhammer_pfsinfo_t pip, char **path)
 127 {
 128         struct statfs st;
 129
 130         assert(pip != NULL);
 131         assert(mtpt != NULL);
 132
 133         if ((statfs(mtpt, &st) < 0) ||
 134             ((strcmp("hammer", st.f_fstypename) != 0) &&
 135             (strcmp("null", st.f_fstypename) != 0))) {
 136                 *path = NULL;
 137                 return;
 138         }
 139
 140         if (pip->ismaster)
 141                 asprintf(path, "%s/@@-1:%.5d", mtpt,
 142                     pip->pfs_id);
 143         else
 144                 asprintf(path, "%s/@@0x%016jx:%.5d", mtpt,
 145                     pip->end_tid, pip->pfs_id);
 146 }
 147
 148
 149 /*
 150  * Allocate len bytes of memory and return the pointer.
 151  * It'll exit in the case no memory could be allocated.
 152  *
 153  * To be used only by the library itself.
 154  */
 155 void *
 156 _libhammer_malloc(size_t len)
 157 {
 158         void *m;
 159
 160         m = calloc(len, sizeof(char));
 161         if (m == NULL)
 162                 errx(1, "Failed to allocate %zd bytes", len);
 163
 164         return (m);
 165 }