source/locking/shmem.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    Shared memory functions
   5    Copyright (C) Erik Devriendt 1996-1998
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21 */
  22
  23 #include "includes.h"
  24
  25
  26 #ifdef HAVE_SHARED_MMAP
  27
  28
  29 extern int DEBUGLEVEL;
  30
  31
  32 #define SMB_SHM_MAGIC 0x53484100
  33 /* = "SHM" in hex */
  34
  35 #define SMB_SHM_VERSION 2
  36
  37 /* we need world read for smbstatus to function correctly */
  38 #ifdef SECURE_SHARE_MODES
  39 #define SHM_FILE_MODE 0600
  40 #else
  41 #define SHM_FILE_MODE 0644
  42 #endif
  43
  44 #define SHMEM_HASH_SIZE 13
  45
  46
  47 /* WARNING : offsets are used because mmap() does not guarantee that all processes have the
  48    shared memory mapped to the same address */
  49
  50 struct SmbShmHeader
  51 {
  52    int smb_shm_magic;
  53    int smb_shm_version;
  54    int total_size;      /* in bytes */
  55    BOOL consistent;
  56    int first_free_off;
  57    int userdef_off;    /* a userdefined offset. can be used to store root of tree or list */
  58    struct {             /* a cell is a range of bytes of sizeof(struct SmbShmBlockDesc) size */
  59       int cells_free;
  60       int cells_used;
  61       int cells_system; /* number of cells used as allocated block descriptors */
  62    } statistics;
  63 };
  64
  65 #define SMB_SHM_NOT_FREE_OFF (-1)
  66 struct SmbShmBlockDesc
  67 {
  68    int next;    /* offset of next block in the free list or SMB_SHM_NOT_FREE_OFF when block in use  */
  69    int          size;   /* user size in BlockDescSize units */
  70 };
  71
  72 #define EOList_Addr     (struct SmbShmBlockDesc *)( 0 )
  73 #define EOList_Off      0
  74
  75 #define CellSize        sizeof(struct SmbShmBlockDesc)
  76
  77 /* HeaderSize aligned on 8 byte boundary */
  78 #define AlignedHeaderSize       ((sizeof(struct SmbShmHeader)+7) & ~7)
  79
  80 static int  smb_shm_fd = -1;
  81 static pstring smb_shm_processreg_name = "";
  82
  83 static struct SmbShmHeader *smb_shm_header_p = (struct SmbShmHeader *)0;
  84 static int smb_shm_times_locked = 0;
  85
  86 static BOOL smb_shm_initialize_called = False;
  87
  88 static int read_only;
  89
  90 static BOOL smb_shm_global_lock(void)
  91 {
  92    if (smb_shm_fd < 0)
  93    {
  94       DEBUG(0,("ERROR smb_shm_global_lock : bad smb_shm_fd (%d)\n",smb_shm_fd));
  95       return False;
  96    }
  97
  98    smb_shm_times_locked++;
  99
 100    if(smb_shm_times_locked > 1)
 101    {
 102       DEBUG(5,("smb_shm_global_lock : locked %d times\n",smb_shm_times_locked));
 103       return True;
 104    }
 105
 106    if (read_only)
 107            return True;
 108
 109    /* Do an exclusive wait lock on the first byte of the file */
 110    if (fcntl_lock(smb_shm_fd, SMB_F_SETLKW, 0, 1, F_WRLCK) == False)
 111    {
 112       DEBUG(0,("ERROR smb_shm_global_lock : fcntl_lock failed with code %s\n",strerror(errno)));
 113       smb_shm_times_locked--;
 114       return False;
 115    }
 116
 117    return True;
 118
 119 }
 120
 121 static BOOL smb_shm_global_unlock(void)
 122 {
 123    if (smb_shm_fd < 0)
 124    {
 125       DEBUG(0,("ERROR smb_shm_global_unlock : bad smb_shm_fd (%d)\n",smb_shm_fd));
 126       return False;
 127    }
 128
 129    if(smb_shm_times_locked == 0)
 130    {
 131       DEBUG(0,("ERROR smb_shm_global_unlock : shmem not locked\n"));
 132       return False;
 133    }
 134
 135    smb_shm_times_locked--;
 136
 137    if(smb_shm_times_locked > 0)
 138    {
 139       DEBUG(5,("smb_shm_global_unlock : still locked %d times\n",smb_shm_times_locked));
 140       return True;
 141    }
 142
 143    if (read_only)
 144            return True;
 145
 146    /* Do a wait unlock on the first byte of the file */
 147    if (fcntl_lock(smb_shm_fd, SMB_F_SETLKW, 0, 1, F_UNLCK) == False)
 148    {
 149       DEBUG(0,("ERROR smb_shm_global_unlock : fcntl_lock failed with code %s\n",strerror(errno)));
 150       smb_shm_times_locked++;
 151       return False;
 152    }
 153
 154    return True;
 155
 156 }
 157
 158
 159 static void *smb_shm_offset2addr(int offset)
 160 {
 161    if (offset == 0 )
 162       return (void *)(0);
 163
 164    if (!smb_shm_header_p)
 165       return (void *)(0);
 166
 167    return (void *)((char *)smb_shm_header_p + offset );
 168 }
 169
 170 static int smb_shm_addr2offset(void *addr)
 171 {
 172    if (!addr)
 173       return 0;
 174
 175    if (!smb_shm_header_p)
 176       return 0;
 177
 178    return (int)((char *)addr - (char *)smb_shm_header_p);
 179 }
 180
 181
 182
 183 static int smb_shm_alloc(int size)
 184 {
 185    unsigned num_cells ;
 186    struct SmbShmBlockDesc *scanner_p;
 187    struct SmbShmBlockDesc *prev_p;
 188    struct SmbShmBlockDesc *new_p;
 189    int result_offset;
 190
 191
 192    if( !smb_shm_header_p )
 193    {
 194       /* not mapped yet */
 195       DEBUG(0,("ERROR smb_shm_alloc : shmem not mapped\n"));
 196       return 0;
 197    }
 198
 199    smb_shm_global_lock();
 200
 201    if( !smb_shm_header_p->consistent)
 202    {
 203       DEBUG(0,("ERROR smb_shm_alloc : shmem not consistent\n"));
 204       smb_shm_global_unlock();
 205       return 0;
 206    }
 207
 208
 209    /* calculate the number of cells */
 210    num_cells = (size + CellSize -1) / CellSize;
 211
 212    /* set start of scan */
 213    prev_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(smb_shm_header_p->first_free_off);
 214    scanner_p =  prev_p ;
 215
 216    /* scan the free list to find a matching free space */
 217    while ( ( scanner_p != EOList_Addr ) && ( scanner_p->size < num_cells ) )
 218    {
 219       prev_p = scanner_p;
 220       scanner_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(scanner_p->next);
 221    }
 222
 223    /* at this point scanner point to a block header or to the end of the list */
 224    if ( scanner_p == EOList_Addr )
 225    {
 226       DEBUG(0,("ERROR smb_shm_alloc : alloc of %d bytes failed, no free space found\n",size));
 227       smb_shm_global_unlock();
 228       return (0);
 229    }
 230
 231    /* going to modify shared mem */
 232    smb_shm_header_p->consistent = False;
 233
 234    /* if we found a good one : scanner == the good one */
 235    if ( scanner_p->size <= num_cells + 2 )
 236    {
 237       /* there is no use in making a new one, it will be too small anyway
 238       *  we will link out scanner
 239       */
 240       if ( prev_p == scanner_p )
 241       {
 242          smb_shm_header_p->first_free_off = scanner_p->next ;
 243       }
 244       else
 245       {
 246          prev_p->next = scanner_p->next ;
 247       }
 248       smb_shm_header_p->statistics.cells_free -= scanner_p->size;
 249       smb_shm_header_p->statistics.cells_used += scanner_p->size;
 250    }
 251    else
 252    {
 253       /* Make a new one */
 254       new_p = scanner_p + 1 + num_cells;
 255       new_p->size = scanner_p->size - num_cells - 1;
 256       new_p->next = scanner_p->next;
 257       scanner_p->size = num_cells;
 258       scanner_p->next = smb_shm_addr2offset(new_p);
 259
 260       if ( prev_p       != scanner_p )
 261       {
 262          prev_p->next      = smb_shm_addr2offset(new_p)  ;
 263       }
 264       else
 265       {
 266          smb_shm_header_p->first_free_off = smb_shm_addr2offset(new_p)  ;
 267       }
 268       smb_shm_header_p->statistics.cells_free -= num_cells+1;
 269       smb_shm_header_p->statistics.cells_used += num_cells;
 270       smb_shm_header_p->statistics.cells_system += 1;
 271    }
 272
 273    result_offset = smb_shm_addr2offset( &(scanner_p[1]) );
 274    scanner_p->next =    SMB_SHM_NOT_FREE_OFF ;
 275
 276    /* end modification of shared mem */
 277    smb_shm_header_p->consistent = True;
 278
 279    DEBUG(6,("smb_shm_alloc : request for %d bytes, allocated %d bytes at offset %d\n",size,scanner_p->size*CellSize,result_offset ));
 280
 281    smb_shm_global_unlock();
 282    return ( result_offset );
 283 }
 284
 285
 286
 287
 288 /*
 289  * Function to create the hash table for the share mode entries. Called
 290  * when smb shared memory is global locked.
 291  */
 292 static BOOL smb_shm_create_hash_table( unsigned int size )
 293 {
 294   size *= sizeof(int);
 295
 296   smb_shm_global_lock();
 297   smb_shm_header_p->userdef_off = smb_shm_alloc( size );
 298
 299   if(smb_shm_header_p->userdef_off == 0)
 300     {
 301       DEBUG(0,("smb_shm_create_hash_table: Failed to create hash table of size %d\n",size));
 302       smb_shm_global_unlock();
 303       return False;
 304     }
 305
 306   /* Clear hash buckets. */
 307   memset( smb_shm_offset2addr(smb_shm_header_p->userdef_off), '\0', size);
 308   smb_shm_global_unlock();
 309   return True;
 310 }
 311
 312 static BOOL smb_shm_register_process(char *processreg_file, pid_t pid, BOOL *other_processes)
 313 {
 314   int smb_shm_processes_fd = -1;
 315   int nb_read;
 316   pid_t other_pid;
 317   SMB_OFF_T seek_back = -((SMB_OFF_T)sizeof(other_pid));
 318   SMB_OFF_T free_slot = -1;
 319   SMB_OFF_T erased_slot;
 320
 321   smb_shm_processes_fd = sys_open(processreg_file,
 322                               read_only?O_RDONLY:(O_RDWR|O_CREAT),
 323                               SHM_FILE_MODE);
 324
 325   if ( smb_shm_processes_fd < 0 )
 326   {
 327      DEBUG(0, ("ERROR smb_shm_register_process : processreg_file \
 328 open failed with code %s\n",strerror(errno)));
 329      return False;
 330   }
 331
 332   *other_processes = False;
 333
 334   while ((nb_read = read(smb_shm_processes_fd, &other_pid, sizeof(other_pid))) > 0)
 335   {
 336     if(other_pid)
 337     {
 338       if(process_exists(other_pid))
 339         *other_processes = True;
 340       else
 341       {
 342         /* erase old pid */
 343         DEBUG(5,("smb_shm_register_process : erasing stale record \
 344 for pid %d (seek_back = %.0f)\n", (int)other_pid, (double)seek_back));
 345         other_pid = (pid_t)0;
 346         if((erased_slot = sys_lseek(smb_shm_processes_fd,
 347                                     seek_back, SEEK_CUR)) == -1)
 348         {
 349           DEBUG(0, ("ERROR smb_shm_register_process : sys_lseek failed \
 350 with error %s\n", strerror(errno)));
 351           close(smb_shm_processes_fd);
 352           return False;
 353         }
 354
 355         if(write(smb_shm_processes_fd, &other_pid, sizeof(other_pid)) == -1)
 356         {
 357            DEBUG(0, ("ERROR smb_shm_register_process : write failed \
 358 with error %s\n", strerror(errno)));
 359            close(smb_shm_processes_fd);
 360            return False;
 361         }
 362
 363         if(free_slot < 0)
 364           free_slot = erased_slot;
 365       }
 366     }
 367     else
 368     {
 369       if(free_slot < 0)
 370       {
 371         if((free_slot = sys_lseek(smb_shm_processes_fd,
 372                                   seek_back, SEEK_CUR))==-1)
 373         {
 374           DEBUG(0, ("ERROR smb_shm_register_process : sys_lseek \
 375 failed with error %s\n", strerror(errno)));
 376           close(smb_shm_processes_fd);
 377           return False;
 378         }
 379       } /* end if free_slot */
 380     } /* end else */
 381   } /* end if other_pid */
 382
 383   if (nb_read < 0)
 384   {
 385     DEBUG(0,("ERROR smb_shm_register_process : processreg_file read \
 386 failed with code %s\n",strerror(errno)));
 387     close(smb_shm_processes_fd);
 388     return False;
 389   }
 390
 391   if(free_slot < 0)
 392   {
 393     if((free_slot = sys_lseek(smb_shm_processes_fd, 0, SEEK_END)) == -1)
 394     {
 395       DEBUG(0,("ERROR smb_shm_register_process : sys_lseek failed with code %s\n",strerror(errno)));
 396       close(smb_shm_processes_fd);
 397       return False;
 398     }
 399   }
 400
 401   DEBUG(5,("smb_shm_register_process : writing record for pid %d at offset %.0f\n",
 402          (int)pid, (double)free_slot));
 403
 404   if(sys_lseek(smb_shm_processes_fd, free_slot, SEEK_SET) == -1)
 405   {
 406     DEBUG(0,("ERROR smb_shm_register_process : sys_lseek failed with code %s\n",strerror(errno)));
 407     close(smb_shm_processes_fd);
 408     return False;
 409   }
 410
 411   if(write(smb_shm_processes_fd, &pid, sizeof(pid)) == -1)
 412   {
 413     DEBUG(0,("ERROR smb_shm_register_process : processreg_file write failed with code %s\n",strerror(errno)));
 414     close(smb_shm_processes_fd);
 415     return False;
 416   }
 417
 418   close(smb_shm_processes_fd);
 419
 420   return True;
 421 }
 422
 423 static BOOL smb_shm_unregister_process(char *processreg_file, pid_t pid)
 424 {
 425    int smb_shm_processes_fd = -1;
 426    int nb_read;
 427    pid_t other_pid;
 428    SMB_OFF_T seek_back = -((SMB_OFF_T)sizeof(other_pid));
 429    BOOL found = False;
 430
 431
 432    smb_shm_processes_fd = sys_open(processreg_file, O_RDWR, 0);
 433    if ( smb_shm_processes_fd < 0 )
 434    {
 435       DEBUG(0,("ERROR smb_shm_unregister_process : processreg_file open failed with code %s\n",strerror(errno)));
 436       return False;
 437    }
 438
 439    while ((nb_read = read(smb_shm_processes_fd, &other_pid, sizeof(other_pid))) > 0)
 440    {
 441       DEBUG(5,("smb_shm_unregister_process : read record for pid %d\n",(int)other_pid));
 442       if(other_pid == pid)
 443       {
 444         /* erase pid */
 445         DEBUG(5,("smb_shm_unregister_process : erasing record for pid %d (seek_val = %.0f)\n",
 446                      (int)other_pid, (double)seek_back));
 447         other_pid = (pid_t)0;
 448         if(sys_lseek(smb_shm_processes_fd, seek_back, SEEK_CUR) == -1)
 449         {
 450           DEBUG(0,("ERROR smb_shm_unregister_process : processreg_file sys_lseek failed with code %s\n",strerror(errno)));
 451           close(smb_shm_processes_fd);
 452           return False;
 453         }
 454         if(write(smb_shm_processes_fd, &other_pid, sizeof(other_pid)) < 0)
 455         {
 456           DEBUG(0,("ERROR smb_shm_unregister_process : processreg_file write failed with code %s\n",strerror(errno)));
 457           close(smb_shm_processes_fd);
 458           return False;
 459         }
 460
 461         found = True;
 462         break;
 463       }
 464    }
 465    if (nb_read < 0)
 466    {
 467       DEBUG(0,("ERROR smb_shm_unregister_process : processreg_file read failed with code %s\n",strerror(errno)));
 468       close(smb_shm_processes_fd);
 469       return False;
 470    }
 471
 472    if(!found)
 473    {
 474       DEBUG(0,("ERROR smb_shm_unregister_process : couldn't find pid %d in file %s\n",
 475             (int)pid,processreg_file));
 476       close(smb_shm_processes_fd);
 477       return False;
 478    }
 479
 480
 481    close(smb_shm_processes_fd);
 482
 483    return True;
 484 }
 485
 486
 487 static BOOL smb_shm_validate_header(int size)
 488 {
 489    if( !smb_shm_header_p )
 490    {
 491       /* not mapped yet */
 492       DEBUG(0,("ERROR smb_shm_validate_header : shmem not mapped\n"));
 493       return False;
 494    }
 495
 496    if(smb_shm_header_p->smb_shm_magic != SMB_SHM_MAGIC)
 497    {
 498       DEBUG(0,("ERROR smb_shm_validate_header : bad magic\n"));
 499       return False;
 500    }
 501    if(smb_shm_header_p->smb_shm_version != SMB_SHM_VERSION)
 502    {
 503       DEBUG(0,("ERROR smb_shm_validate_header : bad version %X\n",smb_shm_header_p->smb_shm_version));
 504       return False;
 505    }
 506
 507    if(smb_shm_header_p->total_size != size)
 508    {
 509       DEBUG(0,("ERROR smb_shm_validate_header : shmem size mismatch (old = %d, new = %d)\n",smb_shm_header_p->total_size,size));
 510       return False;
 511    }
 512
 513    if(!smb_shm_header_p->consistent)
 514    {
 515       DEBUG(0,("ERROR smb_shm_validate_header : shmem not consistent\n"));
 516       return False;
 517    }
 518    return True;
 519 }
 520
 521 static BOOL smb_shm_initialize(int size)
 522 {
 523    struct SmbShmBlockDesc * first_free_block_p;
 524
 525    DEBUG(5,("smb_shm_initialize : initializing shmem file of size %d\n",size));
 526
 527    if( !smb_shm_header_p )
 528    {
 529       /* not mapped yet */
 530       DEBUG(0,("ERROR smb_shm_initialize : shmem not mapped\n"));
 531       return False;
 532    }
 533
 534    smb_shm_header_p->smb_shm_magic = SMB_SHM_MAGIC;
 535    smb_shm_header_p->smb_shm_version = SMB_SHM_VERSION;
 536    smb_shm_header_p->total_size = size;
 537    smb_shm_header_p->first_free_off = AlignedHeaderSize;
 538    smb_shm_header_p->userdef_off = 0;
 539
 540    first_free_block_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(smb_shm_header_p->first_free_off);
 541    first_free_block_p->next = EOList_Off;
 542    first_free_block_p->size = ( size - AlignedHeaderSize - CellSize ) / CellSize ;
 543
 544    smb_shm_header_p->statistics.cells_free = first_free_block_p->size;
 545    smb_shm_header_p->statistics.cells_used = 0;
 546    smb_shm_header_p->statistics.cells_system = 1;
 547
 548    smb_shm_header_p->consistent = True;
 549
 550    smb_shm_initialize_called = True;
 551
 552    return True;
 553 }
 554
 555 static void smb_shm_solve_neighbors(struct SmbShmBlockDesc *head_p )
 556 {
 557    struct SmbShmBlockDesc *next_p;
 558
 559    /* Check if head_p and head_p->next are neighbors and if so join them */
 560    if ( head_p == EOList_Addr ) return ;
 561    if ( head_p->next == EOList_Off ) return ;
 562
 563    next_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(head_p->next);
 564    if ( ( head_p + head_p->size + 1 ) == next_p)
 565    {
 566       head_p->size += next_p->size +1 ; /* adapt size */
 567       head_p->next = next_p->next         ; /* link out */
 568
 569       smb_shm_header_p->statistics.cells_free += 1;
 570       smb_shm_header_p->statistics.cells_system -= 1;
 571    }
 572 }
 573
 574
 575
 576 static BOOL smb_shm_close( void )
 577 {
 578
 579    if(smb_shm_initialize_called == False)
 580      return True;
 581
 582    DEBUG(5,("smb_shm_close\n"));
 583    if(smb_shm_times_locked > 0)
 584       DEBUG(0,("WARNING smb_shm_close : shmem was still locked %d times\n",smb_shm_times_locked));;
 585    if ((smb_shm_header_p != NULL) &&
 586               (munmap((caddr_t)smb_shm_header_p, smb_shm_header_p->total_size) < 0))
 587    {
 588       DEBUG(0,("ERROR smb_shm_close : munmap failed with code %s\n",strerror(errno)));
 589    }
 590
 591    smb_shm_global_lock();
 592    DEBUG(5,("calling smb_shm_unregister_process(%s, %d)\n",
 593          smb_shm_processreg_name, (int)getpid()));
 594    smb_shm_unregister_process(smb_shm_processreg_name, getpid());
 595    smb_shm_global_unlock();
 596
 597    close(smb_shm_fd);
 598
 599    smb_shm_fd = -1;
 600    smb_shm_processreg_name[0] = '\0';
 601
 602    smb_shm_header_p = (struct SmbShmHeader *)0;
 603    smb_shm_times_locked = 0;
 604
 605    return True;
 606 }
 607
 608
 609 static BOOL smb_shm_free(int offset)
 610 {
 611    struct SmbShmBlockDesc *header_p  ; /*       pointer to header of block to free */
 612    struct SmbShmBlockDesc *scanner_p ; /*       used to scan the list                      */
 613    struct SmbShmBlockDesc *prev_p          ; /* holds previous in the list                 */
 614
 615    if( !smb_shm_header_p )
 616    {
 617       /* not mapped yet */
 618       DEBUG(0,("ERROR smb_shm_free : shmem not mapped\n"));
 619       return False;
 620    }
 621
 622    smb_shm_global_lock();
 623
 624    if( !smb_shm_header_p->consistent)
 625    {
 626       DEBUG(0,("ERROR smb_shm_free : shmem not consistent\n"));
 627       smb_shm_global_unlock();
 628       return False;
 629    }
 630
 631    header_p = ( (struct SmbShmBlockDesc *)smb_shm_offset2addr(offset) - 1); /* make pointer to header of block */
 632
 633    if (header_p->next != SMB_SHM_NOT_FREE_OFF)
 634    {
 635       DEBUG(0,("ERROR smb_shm_free : bad offset (%d)\n",offset));
 636       smb_shm_global_unlock();
 637       return False;
 638    }
 639
 640    /* find a place in the free_list to put the header in */
 641
 642    /* set scanner and previous pointer to start of list */
 643    prev_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(smb_shm_header_p->first_free_off);
 644    scanner_p = prev_p ;
 645
 646    while ( ( scanner_p != EOList_Addr) && (scanner_p < header_p) ) /* while we didn't scan past its position */
 647    {
 648       prev_p = scanner_p ;
 649       scanner_p = (struct SmbShmBlockDesc *)smb_shm_offset2addr(scanner_p->next);
 650    }
 651
 652    smb_shm_header_p->consistent = False;
 653
 654    DEBUG(6,("smb_shm_free : freeing %d bytes at offset %d\n",header_p->size*CellSize,offset));
 655
 656    /* zero the area being freed - this allows us to find bugs faster */
 657    memset(smb_shm_offset2addr(offset), 0, header_p->size*CellSize);
 658
 659    if ( scanner_p == prev_p )
 660    {
 661       smb_shm_header_p->statistics.cells_free += header_p->size;
 662       smb_shm_header_p->statistics.cells_used -= header_p->size;
 663
 664       /* we must free it at the beginning of the list */
 665       smb_shm_header_p->first_free_off = smb_shm_addr2offset(header_p);                                          /*     set     the free_list_pointer to this block_header */
 666
 667       /* scanner is the one that was first in the list */
 668       header_p->next = smb_shm_addr2offset(scanner_p);
 669       smb_shm_solve_neighbors( header_p ); /* if neighbors then link them */
 670
 671       smb_shm_header_p->consistent = True;
 672       smb_shm_global_unlock();
 673       return True;
 674    }
 675    else
 676    {
 677       smb_shm_header_p->statistics.cells_free += header_p->size;
 678       smb_shm_header_p->statistics.cells_used -= header_p->size;
 679
 680       prev_p->next = smb_shm_addr2offset(header_p);
 681       header_p->next = smb_shm_addr2offset(scanner_p);
 682       smb_shm_solve_neighbors(header_p) ;
 683       smb_shm_solve_neighbors(prev_p) ;
 684
 685       smb_shm_header_p->consistent = True;
 686       smb_shm_global_unlock();
 687       return True;
 688    }
 689 }
 690
 691 static int smb_shm_get_userdef_off(void)
 692 {
 693    if (!smb_shm_header_p)
 694       return 0;
 695    else
 696       return smb_shm_header_p->userdef_off;
 697 }
 698
 699 /*******************************************************************
 700   Lock a particular hash bucket entry.
 701   ******************************************************************/
 702 static BOOL smb_shm_lock_hash_entry( unsigned int entry)
 703 {
 704   int start = (smb_shm_header_p->userdef_off + (entry * sizeof(int)));
 705
 706   if (smb_shm_fd < 0)
 707     {
 708       DEBUG(0,("ERROR smb_shm_lock_hash_entry : bad smb_shm_fd (%d)\n",smb_shm_fd));
 709       return False;
 710     }
 711
 712   if (read_only)
 713           return True;
 714
 715   /* Do an exclusive wait lock on the 4 byte region mapping into this entry  */
 716   if (fcntl_lock(smb_shm_fd, SMB_F_SETLKW, start, sizeof(int), F_WRLCK) == False)
 717     {
 718       DEBUG(0,("ERROR smb_shm_lock_hash_entry : fcntl_lock failed with code %s\n",strerror(errno)));
 719       return False;
 720     }
 721
 722   DEBUG(9,("smb_shm_lock_hash_entry: locked hash bucket %d\n", entry));
 723   return True;
 724 }
 725
 726 /*******************************************************************
 727   Unlock a particular hash bucket entry.
 728   ******************************************************************/
 729 static BOOL smb_shm_unlock_hash_entry( unsigned int entry )
 730 {
 731   int start = (smb_shm_header_p->userdef_off + (entry * sizeof(int)));
 732
 733   if (smb_shm_fd < 0)
 734     {
 735       DEBUG(0,("ERROR smb_shm_unlock_hash_entry : bad smb_shm_fd (%d)\n",smb_shm_fd));
 736       return False;
 737     }
 738
 739   if (read_only)
 740           return True;
 741
 742   /* Do a wait lock on the 4 byte region mapping into this entry  */
 743   if (fcntl_lock(smb_shm_fd, SMB_F_SETLKW, start, sizeof(int), F_UNLCK) == False)
 744     {
 745       DEBUG(0,("ERROR smb_shm_unlock_hash_entry : fcntl_lock failed with code %s\n",strerror(errno)));
 746       return False;
 747     }
 748
 749   DEBUG(9,("smb_shm_unlock_hash_entry: unlocked hash bucket %d\n", entry));
 750   return True;
 751 }
 752
 753 /*******************************************************************
 754   Gather statistics on shared memory usage.
 755   ******************************************************************/
 756 static BOOL smb_shm_get_usage(int *bytes_free,
 757                    int *bytes_used,
 758                    int *bytes_overhead)
 759 {
 760    if( !smb_shm_header_p )
 761    {
 762       /* not mapped yet */
 763       DEBUG(0,("ERROR smb_shm_free : shmem not mapped\n"));
 764       return False;
 765    }
 766    *bytes_free = smb_shm_header_p->statistics.cells_free * CellSize;
 767    *bytes_used = smb_shm_header_p->statistics.cells_used * CellSize;
 768    *bytes_overhead = smb_shm_header_p->statistics.cells_system * CellSize + AlignedHeaderSize;
 769
 770    return True;
 771 }
 772
 773 /*******************************************************************
 774 hash a number into a hash_entry
 775   ******************************************************************/
 776 static unsigned smb_shm_hash_size(void)
 777 {
 778         return SHMEM_HASH_SIZE;
 779 }
 780
 781 static struct shmem_ops shmops = {
 782         smb_shm_close,
 783         smb_shm_alloc,
 784         smb_shm_free,
 785         smb_shm_get_userdef_off,
 786         smb_shm_offset2addr,
 787         smb_shm_addr2offset,
 788         smb_shm_lock_hash_entry,
 789         smb_shm_unlock_hash_entry,
 790         smb_shm_get_usage,
 791         smb_shm_hash_size,
 792 };
 793
 794 /*******************************************************************
 795   open the shared memory
 796   ******************************************************************/
 797 struct shmem_ops *smb_shm_open(int ronly)
 798 {
 799   pstring file_name;
 800   SMB_OFF_T filesize;
 801   BOOL created_new = False;
 802   BOOL other_processes = True;
 803   SMB_OFF_T size = (SMB_OFF_T)lp_shmem_size();
 804
 805   read_only = ronly;
 806
 807   pstrcpy(file_name,lp_lockdir());
 808   if (!directory_exist(file_name,NULL)) {
 809     if (read_only)
 810       return NULL;
 811     mkdir(file_name,0755);
 812   }
 813   trim_string(file_name,"","/");
 814   if (!*file_name)
 815     return(False);
 816   pstrcat(file_name, "/SHARE_MEM_FILE");
 817
 818   DEBUG(5,("smb_shm_open : using shmem file %s to be of size %.0f\n",
 819         file_name,(double)size));
 820
 821   smb_shm_fd = sys_open(file_name, read_only?O_RDONLY:(O_RDWR|O_CREAT),
 822                     SHM_FILE_MODE);
 823
 824   if ( smb_shm_fd < 0 )
 825   {
 826     DEBUG(0,("ERROR smb_shm_open : open failed with code %s\n",strerror(errno)));
 827     return NULL;
 828   }
 829
 830   if (!smb_shm_global_lock())
 831   {
 832     DEBUG(0,("ERROR smb_shm_open : can't do smb_shm_global_lock\n"));
 833     return NULL;
 834   }
 835
 836   if( (filesize = sys_lseek(smb_shm_fd, 0, SEEK_END)) == -1)
 837   {
 838     DEBUG(0,("ERROR smb_shm_open : sys_lseek failed with code %s\n",
 839           strerror(errno)));
 840     smb_shm_global_unlock();
 841     close(smb_shm_fd);
 842     return NULL;
 843   }
 844
 845   /*
 846    * Return the file offset to 0 to save on later seeks.
 847    */
 848   if(sys_lseek(smb_shm_fd,0,SEEK_SET) == -1)
 849   {
 850     DEBUG(0,("ERROR smb_shm_open : sys_lseek failed with code %s\n",
 851           strerror(errno)));
 852     smb_shm_global_unlock();
 853     close(smb_shm_fd);
 854     return NULL;
 855   }
 856
 857   if (filesize == 0)
 858   {
 859     /*
 860      * We just created a new one.
 861      */
 862     created_new = True;
 863   }
 864
 865   /*
 866    * To find out if some other process is already mapping the file,
 867    * we use a registration file containing the processids of the file
 868    * mapping processes.
 869    */
 870
 871   /* construct processreg file name */
 872   pstrcpy(smb_shm_processreg_name, file_name);
 873   pstrcat(smb_shm_processreg_name, ".processes");
 874
 875   if (!read_only && !smb_shm_register_process(smb_shm_processreg_name,
 876                                               getpid(), &other_processes))
 877   {
 878     smb_shm_global_unlock();
 879     close(smb_shm_fd);
 880     return NULL;
 881   }
 882
 883   if (!read_only && (created_new || !other_processes))
 884   {
 885     /* we just created a new one, or are the first opener, lets set it size */
 886     if( sys_ftruncate(smb_shm_fd, size) <0)
 887     {
 888       DEBUG(0,("ERROR smb_shm_open : ftruncate failed with code %s\n",
 889             strerror(errno)));
 890       smb_shm_unregister_process(smb_shm_processreg_name, getpid());
 891       smb_shm_global_unlock();
 892       close(smb_shm_fd);
 893       return NULL;
 894     }
 895
 896     /* paranoia */
 897     if(sys_lseek(smb_shm_fd,0,SEEK_SET) == -1)
 898     {
 899       DEBUG(0,("ERROR smb_shm_open : sys_lseek failed with code %s\n",
 900             strerror(errno)));
 901       smb_shm_unregister_process(smb_shm_processreg_name, getpid());
 902       smb_shm_global_unlock();
 903       close(smb_shm_fd);
 904       return NULL;
 905     }
 906
 907     filesize = size;
 908   }
 909
 910   if (size != filesize )
 911   {
 912     /* the existing file has a different size and we are not the first opener.
 913       Since another process is still using it, we will use the file size */
 914     DEBUG(0,("WARNING smb_shm_open : filesize (%.0f) != expected \
 915 size (%.0f), using filesize\n", (double)filesize, (double)size));
 916
 917     size = filesize;
 918   }
 919
 920   smb_shm_header_p = (struct SmbShmHeader *)sys_mmap(NULL, size,
 921                                read_only?PROT_READ: (PROT_READ | PROT_WRITE),
 922                                MAP_FILE | MAP_SHARED, smb_shm_fd, (SMB_OFF_T)0);
 923
 924   /*
 925    * WARNING, smb_shm_header_p can be different for different
 926    * processes mapping the same file !
 927    */
 928   if (smb_shm_header_p  == (struct SmbShmHeader *)(-1))
 929   {
 930     DEBUG(0,("ERROR smb_shm_open : mmap failed with code %s\n",strerror(errno)));
 931     smb_shm_unregister_process(smb_shm_processreg_name, getpid());
 932     smb_shm_global_unlock();
 933     close(smb_shm_fd);
 934     return NULL;
 935   }
 936
 937
 938   if (!read_only && (created_new || !other_processes))
 939   {
 940     smb_shm_initialize(size);
 941     /* Create the hash buckets for the share file entries. */
 942     smb_shm_create_hash_table(SHMEM_HASH_SIZE);
 943   }
 944   else if (!smb_shm_validate_header(size) )
 945   {
 946     /* existing file is corrupt, samba admin should remove it by hand */
 947     DEBUG(0,("ERROR smb_shm_open : corrupt shared mem file, remove it manually\n"));
 948     munmap((caddr_t)smb_shm_header_p, size);
 949     smb_shm_unregister_process(smb_shm_processreg_name, getpid());
 950     smb_shm_global_unlock();
 951     close(smb_shm_fd);
 952     return NULL;
 953   }
 954
 955   smb_shm_global_unlock();
 956   return &shmops;
 957 }
 958
 959
 960 #else /* HAVE_SHARED_MMAP */
 961  int shmem_dummy_procedure(void)
 962 {return 0;}
 963 #endif /* HAVE_SHARED_MMAP */