source3/modules/vfs_preopen.c

   1 /*
   2  * Force a readahead of files by opening them and reading the first bytes
   3  *
   4  * Copyright (C) Volker Lendecke 2008
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23 #include "smbd/smbd.h"
  24 #include "lib/sys_rw_data.h"
  25
  26 struct preopen_state;
  27
  28 struct preopen_helper {
  29         struct preopen_state *state;
  30         struct tevent_fd *fde;
  31         pid_t pid;
  32         int fd;
  33         bool busy;
  34 };
  35
  36 struct preopen_state {
  37         int num_helpers;
  38         struct preopen_helper *helpers;
  39
  40         size_t to_read;         /* How many bytes to read in children? */
  41         int queue_max;
  42
  43         char *template_fname;   /* Filename to be sent to children */
  44         size_t number_start;    /* start offset into "template_fname" */
  45         int num_digits;         /* How many digits is the number long? */
  46
  47         int fnum_sent;          /* last fname sent to children */
  48
  49         int fnum_queue_end;     /* last fname to be sent, based on
  50                                  * last open call + preopen:queuelen
  51                                  */
  52
  53         name_compare_entry *preopen_names;
  54 };
  55
  56 static void preopen_helper_destroy(struct preopen_helper *c)
  57 {
  58         int status;
  59         close(c->fd);
  60         c->fd = -1;
  61         kill(c->pid, SIGKILL);
  62         waitpid(c->pid, &status, 0);
  63         c->busy = true;
  64 }
  65
  66 static void preopen_queue_run(struct preopen_state *state)
  67 {
  68         char *pdelimiter;
  69         char delimiter;
  70
  71         pdelimiter = state->template_fname + state->number_start
  72                 + state->num_digits;
  73         delimiter = *pdelimiter;
  74
  75         while (state->fnum_sent < state->fnum_queue_end) {
  76
  77                 ssize_t written;
  78                 size_t to_write;
  79                 int helper;
  80
  81                 for (helper=0; helper<state->num_helpers; helper++) {
  82                         if (state->helpers[helper].busy) {
  83                                 continue;
  84                         }
  85                         break;
  86                 }
  87                 if (helper == state->num_helpers) {
  88                         /* everyone is busy */
  89                         return;
  90                 }
  91
  92                 snprintf(state->template_fname + state->number_start,
  93                          state->num_digits + 1,
  94                          "%.*lu", state->num_digits,
  95                          (long unsigned int)(state->fnum_sent + 1));
  96                 *pdelimiter = delimiter;
  97
  98                 to_write = talloc_get_size(state->template_fname);
  99                 written = write_data(state->helpers[helper].fd,
 100                                      state->template_fname, to_write);
 101                 state->helpers[helper].busy = true;
 102
 103                 if (written != to_write) {
 104                         preopen_helper_destroy(&state->helpers[helper]);
 105                 }
 106                 state->fnum_sent += 1;
 107         }
 108 }
 109
 110 static void preopen_helper_readable(struct tevent_context *ev,
 111                                     struct tevent_fd *fde, uint16_t flags,
 112                                     void *priv)
 113 {
 114         struct preopen_helper *helper = (struct preopen_helper *)priv;
 115         struct preopen_state *state = helper->state;
 116         ssize_t nread;
 117         char c;
 118
 119         if ((flags & TEVENT_FD_READ) == 0) {
 120                 return;
 121         }
 122
 123         nread = read(helper->fd, &c, 1);
 124         if (nread <= 0) {
 125                 preopen_helper_destroy(helper);
 126                 return;
 127         }
 128
 129         helper->busy = false;
 130
 131         preopen_queue_run(state);
 132 }
 133
 134 static int preopen_helpers_destructor(struct preopen_state *c)
 135 {
 136         int i;
 137
 138         for (i=0; i<c->num_helpers; i++) {
 139                 if (c->helpers[i].fd == -1) {
 140                         continue;
 141                 }
 142                 preopen_helper_destroy(&c->helpers[i]);
 143         }
 144
 145         return 0;
 146 }
 147
 148 static bool preopen_helper_open_one(int sock_fd, char **pnamebuf,
 149                                     size_t to_read, void *filebuf)
 150 {
 151         char *namebuf = *pnamebuf;
 152         ssize_t nread;
 153         char c = 0;
 154         int fd;
 155
 156         nread = 0;
 157
 158         while ((nread == 0) || (namebuf[nread-1] != '\0')) {
 159                 ssize_t thistime;
 160
 161                 thistime = read(sock_fd, namebuf + nread,
 162                                 talloc_get_size(namebuf) - nread);
 163                 if (thistime <= 0) {
 164                         return false;
 165                 }
 166
 167                 nread += thistime;
 168
 169                 if (nread == talloc_get_size(namebuf)) {
 170                         namebuf = talloc_realloc(
 171                                 NULL, namebuf, char,
 172                                 talloc_get_size(namebuf) * 2);
 173                         if (namebuf == NULL) {
 174                                 return false;
 175                         }
 176                         *pnamebuf = namebuf;
 177                 }
 178         }
 179
 180         fd = open(namebuf, O_RDONLY);
 181         if (fd == -1) {
 182                 goto done;
 183         }
 184         nread = read(fd, filebuf, to_read);
 185         close(fd);
 186
 187  done:
 188         (void)write(sock_fd, &c, 1);
 189         return true;
 190 }
 191
 192 static bool preopen_helper(int fd, size_t to_read)
 193 {
 194         char *namebuf;
 195         void *readbuf;
 196
 197         namebuf = talloc_array(NULL, char, 1024);
 198         if (namebuf == NULL) {
 199                 return false;
 200         }
 201
 202         readbuf = talloc_size(NULL, to_read);
 203         if (readbuf == NULL) {
 204                 TALLOC_FREE(namebuf);
 205                 return false;
 206         }
 207
 208         while (preopen_helper_open_one(fd, &namebuf, to_read, readbuf)) {
 209                 ;
 210         }
 211
 212         TALLOC_FREE(readbuf);
 213         TALLOC_FREE(namebuf);
 214         return false;
 215 }
 216
 217 static NTSTATUS preopen_init_helper(struct preopen_helper *h)
 218 {
 219         int fdpair[2];
 220         NTSTATUS status;
 221
 222         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 223                 status = map_nt_error_from_unix(errno);
 224                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 225                 return status;
 226         }
 227
 228         h->pid = fork();
 229
 230         if (h->pid == -1) {
 231                 return map_nt_error_from_unix(errno);
 232         }
 233
 234         if (h->pid == 0) {
 235                 close(fdpair[0]);
 236                 preopen_helper(fdpair[1], h->state->to_read);
 237                 exit(0);
 238         }
 239         close(fdpair[1]);
 240         h->fd = fdpair[0];
 241         h->fde = tevent_add_fd(server_event_context(), h->state, h->fd,
 242                               TEVENT_FD_READ, preopen_helper_readable, h);
 243         if (h->fde == NULL) {
 244                 close(h->fd);
 245                 h->fd = -1;
 246                 return NT_STATUS_NO_MEMORY;
 247         }
 248         h->busy = false;
 249         return NT_STATUS_OK;
 250 }
 251
 252 static NTSTATUS preopen_init_helpers(TALLOC_CTX *mem_ctx, size_t to_read,
 253                                      int num_helpers, int queue_max,
 254                                      struct preopen_state **presult)
 255 {
 256         struct preopen_state *result;
 257         int i;
 258
 259         result = talloc(mem_ctx, struct preopen_state);
 260         if (result == NULL) {
 261                 return NT_STATUS_NO_MEMORY;
 262         }
 263
 264         result->num_helpers = num_helpers;
 265         result->helpers = talloc_array(result, struct preopen_helper,
 266                                        num_helpers);
 267         if (result->helpers == NULL) {
 268                 TALLOC_FREE(result);
 269                 return NT_STATUS_NO_MEMORY;
 270         }
 271
 272         result->to_read = to_read;
 273         result->queue_max = queue_max;
 274         result->template_fname = NULL;
 275         result->fnum_sent = 0;
 276
 277         for (i=0; i<num_helpers; i++) {
 278                 result->helpers[i].state = result;
 279                 result->helpers[i].fd = -1;
 280         }
 281
 282         talloc_set_destructor(result, preopen_helpers_destructor);
 283
 284         for (i=0; i<num_helpers; i++) {
 285                 preopen_init_helper(&result->helpers[i]);
 286         }
 287
 288         *presult = result;
 289         return NT_STATUS_OK;
 290 }
 291
 292 static void preopen_free_helpers(void **ptr)
 293 {
 294         TALLOC_FREE(*ptr);
 295 }
 296
 297 static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
 298 {
 299         struct preopen_state *state;
 300         NTSTATUS status;
 301         const char *namelist;
 302
 303         if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
 304                 SMB_VFS_HANDLE_GET_DATA(handle, state, struct preopen_state,
 305                                         return NULL);
 306                 return state;
 307         }
 308
 309         namelist = lp_parm_const_string(SNUM(handle->conn), "preopen", "names",
 310                                         NULL);
 311
 312         if (namelist == NULL) {
 313                 return NULL;
 314         }
 315
 316         status = preopen_init_helpers(
 317                 NULL,
 318                 lp_parm_int(SNUM(handle->conn), "preopen", "num_bytes", 1),
 319                 lp_parm_int(SNUM(handle->conn), "preopen", "helpers", 1),
 320                 lp_parm_int(SNUM(handle->conn), "preopen", "queuelen", 10),
 321                 &state);
 322         if (!NT_STATUS_IS_OK(status)) {
 323                 return NULL;
 324         }
 325
 326         set_namearray(&state->preopen_names, namelist);
 327
 328         if (state->preopen_names == NULL) {
 329                 TALLOC_FREE(state);
 330                 return NULL;
 331         }
 332
 333         if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
 334                 SMB_VFS_HANDLE_SET_DATA(handle, state, preopen_free_helpers,
 335                                         struct preopen_state, return NULL);
 336         }
 337
 338         return state;
 339 }
 340
 341 static bool preopen_parse_fname(const char *fname, unsigned long *pnum,
 342                                 size_t *pstart_idx, int *pnum_digits)
 343 {
 344         const char *p;
 345         char *q = NULL;
 346         unsigned long num;
 347
 348         p = strrchr_m(fname, '/');
 349         if (p == NULL) {
 350                 p = fname;
 351         }
 352
 353         p += 1;
 354         while (p[0] != '\0') {
 355                 if (isdigit(p[0]) && isdigit(p[1]) && isdigit(p[2])) {
 356                         break;
 357                 }
 358                 p += 1;
 359         }
 360         if (*p == '\0') {
 361                 /* no digits around */
 362                 return false;
 363         }
 364
 365         num = strtoul(p, (char **)&q, 10);
 366
 367         if (num+1 < num) {
 368                 /* overflow */
 369                 return false;
 370         }
 371
 372         *pnum = num;
 373         *pstart_idx = (p - fname);
 374         *pnum_digits = (q - p);
 375         return true;
 376 }
 377
 378 static int preopen_open(vfs_handle_struct *handle,
 379                         struct smb_filename *smb_fname, files_struct *fsp,
 380                         int flags, mode_t mode)
 381 {
 382         struct preopen_state *state;
 383         int res;
 384         unsigned long num;
 385
 386         DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
 387
 388         state = preopen_state_get(handle);
 389         if (state == NULL) {
 390                 return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 391         }
 392
 393         res = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 394         if (res == -1) {
 395                 return -1;
 396         }
 397
 398         if (flags != O_RDONLY) {
 399                 return res;
 400         }
 401
 402         if (!is_in_path(smb_fname->base_name, state->preopen_names, true)) {
 403                 DEBUG(10, ("%s does not match the preopen:names list\n",
 404                            smb_fname_str_dbg(smb_fname)));
 405                 return res;
 406         }
 407
 408         TALLOC_FREE(state->template_fname);
 409         state->template_fname = talloc_asprintf(
 410                 state, "%s/%s", fsp->conn->cwd, smb_fname->base_name);
 411
 412         if (state->template_fname == NULL) {
 413                 return res;
 414         }
 415
 416         if (!preopen_parse_fname(state->template_fname, &num,
 417                                  &state->number_start, &state->num_digits)) {
 418                 TALLOC_FREE(state->template_fname);
 419                 return res;
 420         }
 421
 422         if (num > state->fnum_sent) {
 423                 /*
 424                  * Helpers were too slow, there's no point in reading
 425                  * files in helpers that we already read in the
 426                  * parent.
 427                  */
 428                 state->fnum_sent = num;
 429         }
 430
 431         if ((state->fnum_queue_end != 0) /* Something was started earlier */
 432             && (num < (state->fnum_queue_end - state->queue_max))) {
 433                 /*
 434                  * "num" is before the queue we announced. This means
 435                  * a new run is started.
 436                  */
 437                 state->fnum_sent = num;
 438         }
 439
 440         state->fnum_queue_end = num + state->queue_max;
 441
 442         preopen_queue_run(state);
 443
 444         return res;
 445 }
 446
 447 static struct vfs_fn_pointers vfs_preopen_fns = {
 448         .open_fn = preopen_open
 449 };
 450
 451 NTSTATUS vfs_preopen_init(void);
 452 NTSTATUS vfs_preopen_init(void)
 453 {
 454         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 455                                 "preopen", &vfs_preopen_fns);
 456 }