tools/virtiofsd/helper.c

   1 /*
   2  * FUSE: Filesystem in Userspace
   3  * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4  *
   5  * Helper functions to create (simple) standalone programs. With the
   6  * aid of these functions it should be possible to create full FUSE
   7  * file system by implementing nothing but the request handlers.
   8
   9  * This program can be distributed under the terms of the GNU LGPLv2.
  10  * See the file COPYING.LIB.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "fuse_i.h"
  15 #include "fuse_lowlevel.h"
  16 #include "fuse_misc.h"
  17 #include "fuse_opt.h"
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/param.h>
  26 #include <sys/time.h>
  27 #include <sys/resource.h>
  28 #include <unistd.h>
  29
  30 #define FUSE_HELPER_OPT(t, p)                       \
  31     {                                               \
  32         t, offsetof(struct fuse_cmdline_opts, p), 1 \
  33     }
  34 #define FUSE_HELPER_OPT_VALUE(t, p, v)              \
  35     {                                               \
  36         t, offsetof(struct fuse_cmdline_opts, p), v \
  37     }
  38
  39 static const struct fuse_opt fuse_helper_opts[] = {
  40     FUSE_HELPER_OPT("-h", show_help),
  41     FUSE_HELPER_OPT("--help", show_help),
  42     FUSE_HELPER_OPT("-V", show_version),
  43     FUSE_HELPER_OPT("--version", show_version),
  44     FUSE_HELPER_OPT("--print-capabilities", print_capabilities),
  45     FUSE_HELPER_OPT("-d", debug),
  46     FUSE_HELPER_OPT("debug", debug),
  47     FUSE_HELPER_OPT("-d", foreground),
  48     FUSE_HELPER_OPT("debug", foreground),
  49     FUSE_OPT_KEY("-d", FUSE_OPT_KEY_KEEP),
  50     FUSE_OPT_KEY("debug", FUSE_OPT_KEY_KEEP),
  51     FUSE_HELPER_OPT("-f", foreground),
  52     FUSE_HELPER_OPT_VALUE("--daemonize", foreground, 0),
  53     FUSE_HELPER_OPT("fsname=", nodefault_subtype),
  54     FUSE_OPT_KEY("fsname=", FUSE_OPT_KEY_KEEP),
  55     FUSE_HELPER_OPT("subtype=", nodefault_subtype),
  56     FUSE_OPT_KEY("subtype=", FUSE_OPT_KEY_KEEP),
  57     FUSE_HELPER_OPT("max_idle_threads=%u", max_idle_threads),
  58     FUSE_HELPER_OPT("--rlimit-nofile=%lu", rlimit_nofile),
  59     FUSE_HELPER_OPT("--syslog", syslog),
  60     FUSE_HELPER_OPT_VALUE("log_level=debug", log_level, FUSE_LOG_DEBUG),
  61     FUSE_HELPER_OPT_VALUE("log_level=info", log_level, FUSE_LOG_INFO),
  62     FUSE_HELPER_OPT_VALUE("log_level=warn", log_level, FUSE_LOG_WARNING),
  63     FUSE_HELPER_OPT_VALUE("log_level=err", log_level, FUSE_LOG_ERR),
  64     FUSE_OPT_END
  65 };
  66
  67 struct fuse_conn_info_opts {
  68     int atomic_o_trunc;
  69     int no_remote_posix_lock;
  70     int no_remote_flock;
  71     int splice_write;
  72     int splice_move;
  73     int splice_read;
  74     int no_splice_write;
  75     int no_splice_move;
  76     int no_splice_read;
  77     int auto_inval_data;
  78     int no_auto_inval_data;
  79     int no_readdirplus;
  80     int no_readdirplus_auto;
  81     int async_dio;
  82     int no_async_dio;
  83     int writeback_cache;
  84     int no_writeback_cache;
  85     int async_read;
  86     int sync_read;
  87     unsigned max_write;
  88     unsigned max_readahead;
  89     unsigned max_background;
  90     unsigned congestion_threshold;
  91     unsigned time_gran;
  92     int set_max_write;
  93     int set_max_readahead;
  94     int set_max_background;
  95     int set_congestion_threshold;
  96     int set_time_gran;
  97 };
  98
  99 #define CONN_OPTION(t, p, v)                          \
 100     {                                                 \
 101         t, offsetof(struct fuse_conn_info_opts, p), v \
 102     }
 103 static const struct fuse_opt conn_info_opt_spec[] = {
 104     CONN_OPTION("max_write=%u", max_write, 0),
 105     CONN_OPTION("max_write=", set_max_write, 1),
 106     CONN_OPTION("max_readahead=%u", max_readahead, 0),
 107     CONN_OPTION("max_readahead=", set_max_readahead, 1),
 108     CONN_OPTION("max_background=%u", max_background, 0),
 109     CONN_OPTION("max_background=", set_max_background, 1),
 110     CONN_OPTION("congestion_threshold=%u", congestion_threshold, 0),
 111     CONN_OPTION("congestion_threshold=", set_congestion_threshold, 1),
 112     CONN_OPTION("sync_read", sync_read, 1),
 113     CONN_OPTION("async_read", async_read, 1),
 114     CONN_OPTION("atomic_o_trunc", atomic_o_trunc, 1),
 115     CONN_OPTION("no_remote_lock", no_remote_posix_lock, 1),
 116     CONN_OPTION("no_remote_lock", no_remote_flock, 1),
 117     CONN_OPTION("no_remote_flock", no_remote_flock, 1),
 118     CONN_OPTION("no_remote_posix_lock", no_remote_posix_lock, 1),
 119     CONN_OPTION("splice_write", splice_write, 1),
 120     CONN_OPTION("no_splice_write", no_splice_write, 1),
 121     CONN_OPTION("splice_move", splice_move, 1),
 122     CONN_OPTION("no_splice_move", no_splice_move, 1),
 123     CONN_OPTION("splice_read", splice_read, 1),
 124     CONN_OPTION("no_splice_read", no_splice_read, 1),
 125     CONN_OPTION("auto_inval_data", auto_inval_data, 1),
 126     CONN_OPTION("no_auto_inval_data", no_auto_inval_data, 1),
 127     CONN_OPTION("readdirplus=no", no_readdirplus, 1),
 128     CONN_OPTION("readdirplus=yes", no_readdirplus, 0),
 129     CONN_OPTION("readdirplus=yes", no_readdirplus_auto, 1),
 130     CONN_OPTION("readdirplus=auto", no_readdirplus, 0),
 131     CONN_OPTION("readdirplus=auto", no_readdirplus_auto, 0),
 132     CONN_OPTION("async_dio", async_dio, 1),
 133     CONN_OPTION("no_async_dio", no_async_dio, 1),
 134     CONN_OPTION("writeback_cache", writeback_cache, 1),
 135     CONN_OPTION("no_writeback_cache", no_writeback_cache, 1),
 136     CONN_OPTION("time_gran=%u", time_gran, 0),
 137     CONN_OPTION("time_gran=", set_time_gran, 1),
 138     FUSE_OPT_END
 139 };
 140
 141
 142 void fuse_cmdline_help(void)
 143 {
 144     printf("    -h   --help                print help\n"
 145            "    -V   --version             print version\n"
 146            "    --print-capabilities       print vhost-user.json\n"
 147            "    -d   -o debug              enable debug output (implies -f)\n"
 148            "    --syslog                   log to syslog (default stderr)\n"
 149            "    -f                         foreground operation\n"
 150            "    --daemonize                run in background\n"
 151            "    -o cache=<mode>            cache mode. could be one of \"auto, "
 152            "always, none\"\n"
 153            "                               default: auto\n"
 154            "    -o flock|no_flock          enable/disable flock\n"
 155            "                               default: no_flock\n"
 156            "    -o log_level=<level>       log level, default to \"info\"\n"
 157            "                               level could be one of \"debug, "
 158            "info, warn, err\"\n"
 159            "    -o max_idle_threads        the maximum number of idle worker "
 160            "threads\n"
 161            "                               allowed (default: 10)\n"
 162            "    -o norace                  disable racy fallback\n"
 163            "                               default: false\n"
 164            "    -o posix_lock|no_posix_lock\n"
 165            "                               enable/disable remote posix lock\n"
 166            "                               default: posix_lock\n"
 167            "    -o readdirplus|no_readdirplus\n"
 168            "                               enable/disable readirplus\n"
 169            "                               default: readdirplus except with "
 170            "cache=none\n"
 171            "    -o timeout=<number>        I/O timeout (seconds)\n"
 172            "                               default: depends on cache= option.\n"
 173            "    -o writeback|no_writeback  enable/disable writeback cache\n"
 174            "                               default: no_writeback\n"
 175            "    -o xattr|no_xattr          enable/disable xattr\n"
 176            "                               default: no_xattr\n"
 177            "    -o modcaps=CAPLIST         Modify the list of capabilities\n"
 178            "                               e.g. -o modcaps=+sys_admin:-chown\n"
 179            "    --rlimit-nofile=<num>      set maximum number of file descriptors\n"
 180            "                               (0 leaves rlimit unchanged)\n"
 181            "                               default: min(1000000, fs.file-max - 16384)\n"
 182            "                                        if the current rlimit is lower\n"
 183            );
 184 }
 185
 186 static int fuse_helper_opt_proc(void *data, const char *arg, int key,
 187                                 struct fuse_args *outargs)
 188 {
 189     (void)data;
 190     (void)outargs;
 191
 192     switch (key) {
 193     case FUSE_OPT_KEY_NONOPT:
 194         fuse_log(FUSE_LOG_ERR, "fuse: invalid argument `%s'\n", arg);
 195         return -1;
 196
 197     default:
 198         /* Pass through unknown options */
 199         return 1;
 200     }
 201 }
 202
 203 static unsigned long get_default_rlimit_nofile(void)
 204 {
 205     g_autofree gchar *file_max_str = NULL;
 206     const rlim_t reserved_fds = 16384; /* leave at least this many fds free */
 207     rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
 208     rlim_t file_max;
 209     struct rlimit rlim;
 210
 211     /*
 212      * Reduce max_fds below the system-wide maximum, if necessary.  This
 213      * ensures there are fds available for other processes so we don't
 214      * cause resource exhaustion.
 215      */
 216     if (!g_file_get_contents("/proc/sys/fs/file-max", &file_max_str,
 217                              NULL, NULL)) {
 218         fuse_log(FUSE_LOG_ERR, "can't read /proc/sys/fs/file-max\n");
 219         exit(1);
 220     }
 221     file_max = g_ascii_strtoull(file_max_str, NULL, 10);
 222     if (file_max < 2 * reserved_fds) {
 223         fuse_log(FUSE_LOG_ERR,
 224                  "The fs.file-max sysctl is too low (%lu) to allow a "
 225                  "reasonable number of open files.\n",
 226                  (unsigned long)file_max);
 227         exit(1);
 228     }
 229     max_fds = MIN(file_max - reserved_fds, max_fds);
 230
 231     if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
 232         fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
 233         exit(1);
 234     }
 235
 236     if (rlim.rlim_cur >= max_fds) {
 237         return 0; /* we have more fds available than required! */
 238     }
 239     return max_fds;
 240 }
 241
 242 int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
 243 {
 244     memset(opts, 0, sizeof(struct fuse_cmdline_opts));
 245
 246     opts->max_idle_threads = 10;
 247     opts->rlimit_nofile = get_default_rlimit_nofile();
 248     opts->foreground = 1;
 249
 250     if (fuse_opt_parse(args, opts, fuse_helper_opts, fuse_helper_opt_proc) ==
 251         -1) {
 252         return -1;
 253     }
 254
 255     return 0;
 256 }
 257
 258
 259 int fuse_daemonize(int foreground)
 260 {
 261     int ret = 0, rett;
 262     if (!foreground) {
 263         int nullfd;
 264         int waiter[2];
 265         char completed;
 266
 267         if (pipe(waiter)) {
 268             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: pipe: %s\n",
 269                      strerror(errno));
 270             return -1;
 271         }
 272
 273         /*
 274          * demonize current process by forking it and killing the
 275          * parent.  This makes current process as a child of 'init'.
 276          */
 277         switch (fork()) {
 278         case -1:
 279             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: fork: %s\n",
 280                      strerror(errno));
 281             return -1;
 282         case 0:
 283             break;
 284         default:
 285             _exit(read(waiter[0], &completed,
 286                        sizeof(completed) != sizeof(completed)));
 287         }
 288
 289         if (setsid() == -1) {
 290             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: setsid: %s\n",
 291                      strerror(errno));
 292             return -1;
 293         }
 294
 295         ret = chdir("/");
 296
 297         nullfd = open("/dev/null", O_RDWR, 0);
 298         if (nullfd != -1) {
 299             rett = dup2(nullfd, 0);
 300             if (!ret) {
 301                 ret = rett;
 302             }
 303             rett = dup2(nullfd, 1);
 304             if (!ret) {
 305                 ret = rett;
 306             }
 307             rett = dup2(nullfd, 2);
 308             if (!ret) {
 309                 ret = rett;
 310             }
 311             if (nullfd > 2) {
 312                 close(nullfd);
 313             }
 314         }
 315
 316         /* Propagate completion of daemon initialization */
 317         completed = 1;
 318         rett = write(waiter[1], &completed, sizeof(completed));
 319         if (!ret) {
 320             ret = rett;
 321         }
 322         close(waiter[0]);
 323         close(waiter[1]);
 324     } else {
 325         ret = chdir("/");
 326     }
 327     return ret;
 328 }
 329
 330 void fuse_apply_conn_info_opts(struct fuse_conn_info_opts *opts,
 331                                struct fuse_conn_info *conn)
 332 {
 333     if (opts->set_max_write) {
 334         conn->max_write = opts->max_write;
 335     }
 336     if (opts->set_max_background) {
 337         conn->max_background = opts->max_background;
 338     }
 339     if (opts->set_congestion_threshold) {
 340         conn->congestion_threshold = opts->congestion_threshold;
 341     }
 342     if (opts->set_time_gran) {
 343         conn->time_gran = opts->time_gran;
 344     }
 345     if (opts->set_max_readahead) {
 346         conn->max_readahead = opts->max_readahead;
 347     }
 348
 349 #define LL_ENABLE(cond, cap) \
 350     if (cond)                \
 351         conn->want |= (cap)
 352 #define LL_DISABLE(cond, cap) \
 353     if (cond)                 \
 354         conn->want &= ~(cap)
 355
 356     LL_ENABLE(opts->splice_read, FUSE_CAP_SPLICE_READ);
 357     LL_DISABLE(opts->no_splice_read, FUSE_CAP_SPLICE_READ);
 358
 359     LL_ENABLE(opts->splice_write, FUSE_CAP_SPLICE_WRITE);
 360     LL_DISABLE(opts->no_splice_write, FUSE_CAP_SPLICE_WRITE);
 361
 362     LL_ENABLE(opts->splice_move, FUSE_CAP_SPLICE_MOVE);
 363     LL_DISABLE(opts->no_splice_move, FUSE_CAP_SPLICE_MOVE);
 364
 365     LL_ENABLE(opts->auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 366     LL_DISABLE(opts->no_auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 367
 368     LL_DISABLE(opts->no_readdirplus, FUSE_CAP_READDIRPLUS);
 369     LL_DISABLE(opts->no_readdirplus_auto, FUSE_CAP_READDIRPLUS_AUTO);
 370
 371     LL_ENABLE(opts->async_dio, FUSE_CAP_ASYNC_DIO);
 372     LL_DISABLE(opts->no_async_dio, FUSE_CAP_ASYNC_DIO);
 373
 374     LL_ENABLE(opts->writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 375     LL_DISABLE(opts->no_writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 376
 377     LL_ENABLE(opts->async_read, FUSE_CAP_ASYNC_READ);
 378     LL_DISABLE(opts->sync_read, FUSE_CAP_ASYNC_READ);
 379
 380     LL_DISABLE(opts->no_remote_posix_lock, FUSE_CAP_POSIX_LOCKS);
 381     LL_DISABLE(opts->no_remote_flock, FUSE_CAP_FLOCK_LOCKS);
 382 }
 383
 384 struct fuse_conn_info_opts *fuse_parse_conn_info_opts(struct fuse_args *args)
 385 {
 386     struct fuse_conn_info_opts *opts;
 387
 388     opts = calloc(1, sizeof(struct fuse_conn_info_opts));
 389     if (opts == NULL) {
 390         fuse_log(FUSE_LOG_ERR, "calloc failed\n");
 391         return NULL;
 392     }
 393     if (fuse_opt_parse(args, opts, conn_info_opt_spec, NULL) == -1) {
 394         free(opts);
 395         return NULL;
 396     }
 397     return opts;
 398 }