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/util/sys_rw.h"
  25 #include "lib/util/sys_rw_data.h"
  26
  27 struct preopen_state;
  28
  29 struct preopen_helper {
  30         struct preopen_state *state;
  31         struct tevent_fd *fde;
  32         pid_t pid;
  33         int fd;
  34         bool busy;
  35 };
  36
  37 struct preopen_state {
  38         int num_helpers;
  39         struct preopen_helper *helpers;
  40
  41         size_t to_read;         /* How many bytes to read in children? */
  42         int queue_max;
  43
  44         char *template_fname;   /* Filename to be sent to children */
  45         size_t number_start;    /* start offset into "template_fname" */
  46         int num_digits;         /* How many digits is the number long? */
  47
  48         int fnum_sent;          /* last fname sent to children */
  49
  50         int fnum_queue_end;     /* last fname to be sent, based on
  51                                  * last open call + preopen:queuelen
  52                                  */
  53
  54         name_compare_entry *preopen_names;
  55 };
  56
  57 static void preopen_helper_destroy(struct preopen_helper *c)
  58 {
  59         int status;
  60         close(c->fd);
  61         c->fd = -1;
  62         kill(c->pid, SIGKILL);
  63         waitpid(c->pid, &status, 0);
  64         c->busy = true;
  65 }
  66
  67 static void preopen_queue_run(struct preopen_state *state)
  68 {
  69         char *pdelimiter;
  70         char delimiter;
  71
  72         pdelimiter = state->template_fname + state->number_start
  73                 + state->num_digits;
  74         delimiter = *pdelimiter;
  75
  76         while (state->fnum_sent < state->fnum_queue_end) {
  77
  78                 ssize_t written;
  79                 size_t to_write;
  80                 int helper;
  81
  82                 for (helper=0; helper<state->num_helpers; helper++) {
  83                         if (state->helpers[helper].busy) {
  84                                 continue;
  85                         }
  86                         break;
  87                 }
  88                 if (helper == state->num_helpers) {
  89                         /* everyone is busy */
  90                         return;
  91                 }
  92
  93                 snprintf(state->template_fname + state->number_start,
  94                          state->num_digits + 1,
  95                          "%.*lu", state->num_digits,
  96                          (long unsigned int)(state->fnum_sent + 1));
  97                 *pdelimiter = delimiter;
  98
  99                 to_write = talloc_get_size(state->template_fname);
 100                 written = write_data(state->helpers[helper].fd,
 101                                      state->template_fname, to_write);
 102                 state->helpers[helper].busy = true;
 103
 104                 if (written != to_write) {
 105                         preopen_helper_destroy(&state->helpers[helper]);
 106                 }
 107                 state->fnum_sent += 1;
 108         }
 109 }
 110
 111 static void preopen_helper_readable(struct tevent_context *ev,
 112                                     struct tevent_fd *fde, uint16_t flags,
 113                                     void *priv)
 114 {
 115         struct preopen_helper *helper = (struct preopen_helper *)priv;
 116         struct preopen_state *state = helper->state;
 117         ssize_t nread;
 118         char c;
 119
 120         if ((flags & TEVENT_FD_READ) == 0) {
 121                 return;
 122         }
 123
 124         nread = read(helper->fd, &c, 1);
 125         if (nread <= 0) {
 126                 preopen_helper_destroy(helper);
 127                 return;
 128         }
 129
 130         helper->busy = false;
 131
 132         preopen_queue_run(state);
 133 }
 134
 135 static int preopen_helpers_destructor(struct preopen_state *c)
 136 {
 137         int i;
 138
 139         for (i=0; i<c->num_helpers; i++) {
 140                 if (c->helpers[i].fd == -1) {
 141                         continue;
 142                 }
 143                 preopen_helper_destroy(&c->helpers[i]);
 144         }
 145
 146         return 0;
 147 }
 148
 149 static bool preopen_helper_open_one(int sock_fd, char **pnamebuf,
 150                                     size_t to_read, void *filebuf)
 151 {
 152         char *namebuf = *pnamebuf;
 153         ssize_t nread;
 154         char c = 0;
 155         int fd;
 156
 157         nread = 0;
 158
 159         while ((nread == 0) || (namebuf[nread-1] != '\0')) {
 160                 ssize_t thistime;
 161
 162                 thistime = read(sock_fd, namebuf + nread,
 163                                 talloc_get_size(namebuf) - nread);
 164                 if (thistime <= 0) {
 165                         return false;
 166                 }
 167
 168                 nread += thistime;
 169
 170                 if (nread == talloc_get_size(namebuf)) {
 171                         namebuf = talloc_realloc(
 172                                 NULL, namebuf, char,
 173                                 talloc_get_size(namebuf) * 2);
 174                         if (namebuf == NULL) {
 175                                 return false;
 176                         }
 177                         *pnamebuf = namebuf;
 178                 }
 179         }
 180
 181         fd = open(namebuf, O_RDONLY);
 182         if (fd == -1) {
 183                 goto done;
 184         }
 185         nread = read(fd, filebuf, to_read);
 186         close(fd);
 187
 188  done:
 189         sys_write_v(sock_fd, &c, 1);
 190         return true;
 191 }
 192
 193 static bool preopen_helper(int fd, size_t to_read)
 194 {
 195         char *namebuf;
 196         void *readbuf;
 197
 198         namebuf = talloc_array(NULL, char, 1024);
 199         if (namebuf == NULL) {
 200                 return false;
 201         }
 202
 203         readbuf = talloc_size(NULL, to_read);
 204         if (readbuf == NULL) {
 205                 TALLOC_FREE(namebuf);
 206                 return false;
 207         }
 208
 209         while (preopen_helper_open_one(fd, &namebuf, to_read, readbuf)) {
 210                 ;
 211         }
 212
 213         TALLOC_FREE(readbuf);
 214         TALLOC_FREE(namebuf);
 215         return false;
 216 }
 217
 218 static NTSTATUS preopen_init_helper(struct preopen_helper *h)
 219 {
 220         int fdpair[2];
 221         NTSTATUS status;
 222
 223         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 224                 status = map_nt_error_from_unix(errno);
 225                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 226                 return status;
 227         }
 228
 229         h->pid = fork();
 230
 231         if (h->pid == -1) {
 232                 return map_nt_error_from_unix(errno);
 233         }
 234
 235         if (h->pid == 0) {
 236                 close(fdpair[0]);
 237                 preopen_helper(fdpair[1], h->state->to_read);
 238                 exit(0);
 239         }
 240         close(fdpair[1]);
 241         h->fd = fdpair[0];
 242         h->fde = tevent_add_fd(server_event_context(), h->state, h->fd,
 243                               TEVENT_FD_READ, preopen_helper_readable, h);
 244         if (h->fde == NULL) {
 245                 close(h->fd);
 246                 h->fd = -1;
 247                 return NT_STATUS_NO_MEMORY;
 248         }
 249         h->busy = false;
 250         return NT_STATUS_OK;
 251 }
 252
 253 static NTSTATUS preopen_init_helpers(TALLOC_CTX *mem_ctx, size_t to_read,
 254                                      int num_helpers, int queue_max,
 255                                      struct preopen_state **presult)
 256 {
 257         struct preopen_state *result;
 258         int i;
 259
 260         result = talloc(mem_ctx, struct preopen_state);
 261         if (result == NULL) {
 262                 return NT_STATUS_NO_MEMORY;
 263         }
 264
 265         result->num_helpers = num_helpers;
 266         result->helpers = talloc_array(result, struct preopen_helper,
 267                                        num_helpers);
 268         if (result->helpers == NULL) {
 269                 TALLOC_FREE(result);
 270                 return NT_STATUS_NO_MEMORY;
 271         }
 272
 273         result->to_read = to_read;
 274         result->queue_max = queue_max;
 275         result->template_fname = NULL;
 276         result->fnum_sent = 0;
 277
 278         for (i=0; i<num_helpers; i++) {
 279                 result->helpers[i].state = result;
 280                 result->helpers[i].fd = -1;
 281         }
 282
 283         talloc_set_destructor(result, preopen_helpers_destructor);
 284
 285         for (i=0; i<num_helpers; i++) {
 286                 preopen_init_helper(&result->helpers[i]);
 287         }
 288
 289         *presult = result;
 290         return NT_STATUS_OK;
 291 }
 292
 293 static void preopen_free_helpers(void **ptr)
 294 {
 295         TALLOC_FREE(*ptr);
 296 }
 297
 298 static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
 299 {
 300         struct preopen_state *state;
 301         NTSTATUS status;
 302         const char *namelist;
 303
 304         if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
 305                 SMB_VFS_HANDLE_GET_DATA(handle, state, struct preopen_state,
 306                                         return NULL);
 307                 return state;
 308         }
 309
 310         namelist = lp_parm_const_string(SNUM(handle->conn), "preopen", "names",
 311                                         NULL);
 312
 313         if (namelist == NULL) {
 314                 return NULL;
 315         }
 316
 317         status = preopen_init_helpers(
 318                 NULL,
 319                 lp_parm_int(SNUM(handle->conn), "preopen", "num_bytes", 1),
 320                 lp_parm_int(SNUM(handle->conn), "preopen", "helpers", 1),
 321                 lp_parm_int(SNUM(handle->conn), "preopen", "queuelen", 10),
 322                 &state);
 323         if (!NT_STATUS_IS_OK(status)) {
 324                 return NULL;
 325         }
 326
 327         set_namearray(&state->preopen_names, namelist);
 328
 329         if (state->preopen_names == NULL) {
 330                 TALLOC_FREE(state);
 331                 return NULL;
 332         }
 333
 334         if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
 335                 SMB_VFS_HANDLE_SET_DATA(handle, state, preopen_free_helpers,
 336                                         struct preopen_state, return NULL);
 337         }
 338
 339         return state;
 340 }
 341
 342 static bool preopen_parse_fname(const char *fname, unsigned long *pnum,
 343                                 size_t *pstart_idx, int *pnum_digits)
 344 {
 345         const char *p;
 346         char *q = NULL;
 347         unsigned long num;
 348
 349         p = strrchr_m(fname, '/');
 350         if (p == NULL) {
 351                 p = fname;
 352         }
 353
 354         p += 1;
 355         while (p[0] != '\0') {
 356                 if (isdigit(p[0]) && isdigit(p[1]) && isdigit(p[2])) {
 357                         break;
 358                 }
 359                 p += 1;
 360         }
 361         if (*p == '\0') {
 362                 /* no digits around */
 363                 return false;
 364         }
 365
 366         num = strtoul(p, (char **)&q, 10);
 367
 368         if (num+1 < num) {
 369                 /* overflow */
 370                 return false;
 371         }
 372
 373         *pnum = num;
 374         *pstart_idx = (p - fname);
 375         *pnum_digits = (q - p);
 376         return true;
 377 }
 378
 379 static int preopen_open(vfs_handle_struct *handle,
 380                         struct smb_filename *smb_fname, files_struct *fsp,
 381                         int flags, mode_t mode)
 382 {
 383         struct preopen_state *state;
 384         int res;
 385         unsigned long num;
 386
 387         DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
 388
 389         state = preopen_state_get(handle);
 390         if (state == NULL) {
 391                 return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 392         }
 393
 394         res = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 395         if (res == -1) {
 396                 return -1;
 397         }
 398
 399         if (flags != O_RDONLY) {
 400                 return res;
 401         }
 402
 403         if (!is_in_path(smb_fname->base_name, state->preopen_names, true)) {
 404                 DEBUG(10, ("%s does not match the preopen:names list\n",
 405                            smb_fname_str_dbg(smb_fname)));
 406                 return res;
 407         }
 408
 409         TALLOC_FREE(state->template_fname);
 410         state->template_fname = talloc_asprintf(
 411                 state, "%s/%s", fsp->conn->cwd, smb_fname->base_name);
 412
 413         if (state->template_fname == NULL) {
 414                 return res;
 415         }
 416
 417         if (!preopen_parse_fname(state->template_fname, &num,
 418                                  &state->number_start, &state->num_digits)) {
 419                 TALLOC_FREE(state->template_fname);
 420                 return res;
 421         }
 422
 423         if (num > state->fnum_sent) {
 424                 /*
 425                  * Helpers were too slow, there's no point in reading
 426                  * files in helpers that we already read in the
 427                  * parent.
 428                  */
 429                 state->fnum_sent = num;
 430         }
 431
 432         if ((state->fnum_queue_end != 0) /* Something was started earlier */
 433             && (num < (state->fnum_queue_end - state->queue_max))) {
 434                 /*
 435                  * "num" is before the queue we announced. This means
 436                  * a new run is started.
 437                  */
 438                 state->fnum_sent = num;
 439         }
 440
 441         state->fnum_queue_end = num + state->queue_max;
 442
 443         preopen_queue_run(state);
 444
 445         return res;
 446 }
 447
 448 static struct vfs_fn_pointers vfs_preopen_fns = {
 449         .open_fn = preopen_open
 450 };
 451
 452 NTSTATUS vfs_preopen_init(void);
 453 NTSTATUS vfs_preopen_init(void)
 454 {
 455         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 456                                 "preopen", &vfs_preopen_fns);
 457 }