src/lxc/initutils.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include "initutils.h"
  25 #include "log.h"
  26
  27 lxc_log_define(lxc_initutils, lxc);
  28
  29 static int mount_fs(const char *source, const char *target, const char *type)
  30 {
  31         /* the umount may fail */
  32         if (umount(target))
  33                 WARN("failed to unmount %s : %s", target, strerror(errno));
  34
  35         if (mount(source, target, type, 0, NULL)) {
  36                 ERROR("failed to mount %s : %s", target, strerror(errno));
  37                 return -1;
  38         }
  39
  40         DEBUG("'%s' mounted on '%s'", source, target);
  41
  42         return 0;
  43 }
  44
  45 extern void lxc_setup_fs(void)
  46 {
  47         if (mount_fs("proc", "/proc", "proc"))
  48                 INFO("failed to remount proc");
  49
  50         /* if we can't mount /dev/shm, continue anyway */
  51         if (mount_fs("shmfs", "/dev/shm", "tmpfs"))
  52                 INFO("failed to mount /dev/shm");
  53
  54         /* If we were able to mount /dev/shm, then /dev exists */
  55         /* Sure, but it's read-only per config :) */
  56         if (access("/dev/mqueue", F_OK) && mkdir("/dev/mqueue", 0666)) {
  57                 DEBUG("failed to create '/dev/mqueue'");
  58                 return;
  59         }
  60
  61         /* continue even without posix message queue support */
  62         if (mount_fs("mqueue", "/dev/mqueue", "mqueue"))
  63                 INFO("failed to mount /dev/mqueue");
  64 }
  65
  66 static char *copy_global_config_value(char *p)
  67 {
  68         int len = strlen(p);
  69         char *retbuf;
  70
  71         if (len < 1)
  72                 return NULL;
  73         if (p[len-1] == '\n') {
  74                 p[len-1] = '\0';
  75                 len--;
  76         }
  77         retbuf = malloc(len+1);
  78         if (!retbuf)
  79                 return NULL;
  80         strcpy(retbuf, p);
  81         return retbuf;
  82 }
  83
  84 const char *lxc_global_config_value(const char *option_name)
  85 {
  86         static const char * const options[][2] = {
  87                 { "lxc.bdev.lvm.vg",        DEFAULT_VG      },
  88                 { "lxc.bdev.lvm.thin_pool", DEFAULT_THIN_POOL },
  89                 { "lxc.bdev.zfs.root",      DEFAULT_ZFSROOT },
  90                 { "lxc.lxcpath",            NULL            },
  91                 { "lxc.default_config",     NULL            },
  92                 { "lxc.cgroup.pattern",     NULL            },
  93                 { "lxc.cgroup.use",         NULL            },
  94                 { NULL, NULL },
  95         };
  96
  97         /* placed in the thread local storage pool for non-bionic targets */
  98 #ifdef HAVE_TLS
  99         static __thread const char *values[sizeof(options) / sizeof(options[0])] = { 0 };
 100 #else
 101         static const char *values[sizeof(options) / sizeof(options[0])] = { 0 };
 102 #endif
 103
 104         /* user_config_path is freed as soon as it is used */
 105         char *user_config_path = NULL;
 106
 107         /*
 108          * The following variables are freed at bottom unconditionally.
 109          * So NULL the value if it is to be returned to the caller
 110          */
 111         char *user_default_config_path = NULL;
 112         char *user_lxc_path = NULL;
 113         char *user_cgroup_pattern = NULL;
 114
 115         if (geteuid() > 0) {
 116                 const char *user_home = getenv("HOME");
 117                 if (!user_home)
 118                         user_home = "/";
 119
 120                 user_config_path = malloc(sizeof(char) * (22 + strlen(user_home)));
 121                 user_default_config_path = malloc(sizeof(char) * (26 + strlen(user_home)));
 122                 user_lxc_path = malloc(sizeof(char) * (19 + strlen(user_home)));
 123
 124                 sprintf(user_config_path, "%s/.config/lxc/lxc.conf", user_home);
 125                 sprintf(user_default_config_path, "%s/.config/lxc/default.conf", user_home);
 126                 sprintf(user_lxc_path, "%s/.local/share/lxc/", user_home);
 127                 user_cgroup_pattern = strdup("lxc/%n");
 128         }
 129         else {
 130                 user_config_path = strdup(LXC_GLOBAL_CONF);
 131                 user_default_config_path = strdup(LXC_DEFAULT_CONFIG);
 132                 user_lxc_path = strdup(LXCPATH);
 133                 user_cgroup_pattern = strdup(DEFAULT_CGROUP_PATTERN);
 134         }
 135
 136         const char * const (*ptr)[2];
 137         size_t i;
 138         char buf[1024], *p, *p2;
 139         FILE *fin = NULL;
 140
 141         for (i = 0, ptr = options; (*ptr)[0]; ptr++, i++) {
 142                 if (!strcmp(option_name, (*ptr)[0]))
 143                         break;
 144         }
 145         if (!(*ptr)[0]) {
 146                 free(user_config_path);
 147                 free(user_default_config_path);
 148                 free(user_lxc_path);
 149                 free(user_cgroup_pattern);
 150                 errno = EINVAL;
 151                 return NULL;
 152         }
 153
 154         if (values[i]) {
 155                 free(user_config_path);
 156                 free(user_default_config_path);
 157                 free(user_lxc_path);
 158                 free(user_cgroup_pattern);
 159                 return values[i];
 160         }
 161
 162         fin = fopen_cloexec(user_config_path, "r");
 163         free(user_config_path);
 164         if (fin) {
 165                 while (fgets(buf, 1024, fin)) {
 166                         if (buf[0] == '#')
 167                                 continue;
 168                         p = strstr(buf, option_name);
 169                         if (!p)
 170                                 continue;
 171                         /* see if there was just white space in front
 172                          * of the option name
 173                          */
 174                         for (p2 = buf; p2 < p; p2++) {
 175                                 if (*p2 != ' ' && *p2 != '\t')
 176                                         break;
 177                         }
 178                         if (p2 < p)
 179                                 continue;
 180                         p = strchr(p, '=');
 181                         if (!p)
 182                                 continue;
 183                         /* see if there was just white space after
 184                          * the option name
 185                          */
 186                         for (p2 += strlen(option_name); p2 < p; p2++) {
 187                                 if (*p2 != ' ' && *p2 != '\t')
 188                                         break;
 189                         }
 190                         if (p2 < p)
 191                                 continue;
 192                         p++;
 193                         while (*p && (*p == ' ' || *p == '\t')) p++;
 194                         if (!*p)
 195                                 continue;
 196
 197                         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 198                                 free(user_lxc_path);
 199                                 user_lxc_path = copy_global_config_value(p);
 200                                 remove_trailing_slashes(user_lxc_path);
 201                                 values[i] = user_lxc_path;
 202                                 user_lxc_path = NULL;
 203                                 goto out;
 204                         }
 205
 206                         values[i] = copy_global_config_value(p);
 207                         goto out;
 208                 }
 209         }
 210         /* could not find value, use default */
 211         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 212                 remove_trailing_slashes(user_lxc_path);
 213                 values[i] = user_lxc_path;
 214                 user_lxc_path = NULL;
 215         }
 216         else if (strcmp(option_name, "lxc.default_config") == 0) {
 217                 values[i] = user_default_config_path;
 218                 user_default_config_path = NULL;
 219         }
 220         else if (strcmp(option_name, "lxc.cgroup.pattern") == 0) {
 221                 values[i] = user_cgroup_pattern;
 222                 user_cgroup_pattern = NULL;
 223         }
 224         else
 225                 values[i] = (*ptr)[1];
 226
 227         /* special case: if default value is NULL,
 228          * and there is no config, don't view that
 229          * as an error... */
 230         if (!values[i])
 231                 errno = 0;
 232
 233 out:
 234         if (fin)
 235                 fclose(fin);
 236
 237         free(user_cgroup_pattern);
 238         free(user_default_config_path);
 239         free(user_lxc_path);
 240
 241         return values[i];
 242 }
 243
 244 extern void remove_trailing_slashes(char *p)
 245 {
 246         int l = strlen(p);
 247         while (--l >= 0 && (p[l] == '/' || p[l] == '\n'))
 248                 p[l] = '\0';
 249 }
 250
 251 FILE *fopen_cloexec(const char *path, const char *mode)
 252 {
 253         int open_mode = 0;
 254         int step = 0;
 255         int fd;
 256         int saved_errno = 0;
 257         FILE *ret;
 258
 259         if (!strncmp(mode, "r+", 2)) {
 260                 open_mode = O_RDWR;
 261                 step = 2;
 262         } else if (!strncmp(mode, "r", 1)) {
 263                 open_mode = O_RDONLY;
 264                 step = 1;
 265         } else if (!strncmp(mode, "w+", 2)) {
 266                 open_mode = O_RDWR | O_TRUNC | O_CREAT;
 267                 step = 2;
 268         } else if (!strncmp(mode, "w", 1)) {
 269                 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
 270                 step = 1;
 271         } else if (!strncmp(mode, "a+", 2)) {
 272                 open_mode = O_RDWR | O_CREAT | O_APPEND;
 273                 step = 2;
 274         } else if (!strncmp(mode, "a", 1)) {
 275                 open_mode = O_WRONLY | O_CREAT | O_APPEND;
 276                 step = 1;
 277         }
 278         for (; mode[step]; step++)
 279                 if (mode[step] == 'x')
 280                         open_mode |= O_EXCL;
 281         open_mode |= O_CLOEXEC;
 282
 283         fd = open(path, open_mode, 0666);
 284         if (fd < 0)
 285                 return NULL;
 286
 287         ret = fdopen(fd, mode);
 288         saved_errno = errno;
 289         if (!ret)
 290                 close(fd);
 291         errno = saved_errno;
 292         return ret;
 293 }