source/smbd/dir.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    Directory handling routines
   5    Copyright (C) Andrew Tridgell 1992-1997
   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 #include "includes.h"
  23
  24 extern int DEBUGLEVEL;
  25 extern connection_struct Connections[];
  26
  27 /*
  28    This module implements directory related functions for Samba.
  29 */
  30
  31
  32
  33 uint32 dircounter = 0;
  34
  35
  36 #define NUMDIRPTRS 256
  37
  38
  39 static struct dptr_struct
  40 {
  41   int pid;
  42   int cnum;
  43   uint32 lastused;
  44   void *ptr;
  45   BOOL valid;
  46   BOOL finished;
  47   BOOL expect_close;
  48   char *wcard; /* Field only used for lanman2 trans2_findfirst/next searches */
  49   uint16 attr; /* Field only used for lanman2 trans2_findfirst/next searches */
  50   char *path;
  51 }
  52 dirptrs[NUMDIRPTRS];
  53
  54
  55 static int dptrs_open = 0;
  56
  57 /****************************************************************************
  58 initialise the dir array
  59 ****************************************************************************/
  60 void init_dptrs(void)
  61 {
  62   static BOOL dptrs_init=False;
  63   int i;
  64
  65   if (dptrs_init) return;
  66   for (i=0;i<NUMDIRPTRS;i++)
  67     {
  68       dirptrs[i].valid = False;
  69       dirptrs[i].wcard = NULL;
  70       dirptrs[i].ptr = NULL;
  71       string_init(&dirptrs[i].path,"");
  72     }
  73   dptrs_init = True;
  74 }
  75
  76 /****************************************************************************
  77 idle a dptr - the directory is closed but the control info is kept
  78 ****************************************************************************/
  79 static void dptr_idle(int key)
  80 {
  81   if (dirptrs[key].valid && dirptrs[key].ptr) {
  82     DEBUG(4,("Idling dptr key %d\n",key));
  83     dptrs_open--;
  84     CloseDir(dirptrs[key].ptr);
  85     dirptrs[key].ptr = NULL;
  86   }
  87 }
  88
  89 /****************************************************************************
  90 idle the oldest dptr
  91 ****************************************************************************/
  92 static void dptr_idleoldest(void)
  93 {
  94   int i;
  95   uint32 old=dircounter+1;
  96   int oldi= -1;
  97   for (i=0;i<NUMDIRPTRS;i++)
  98     if (dirptrs[i].valid && dirptrs[i].ptr && dirptrs[i].lastused < old) {
  99       old = dirptrs[i].lastused;
 100       oldi = i;
 101     }
 102   if (oldi != -1)
 103     dptr_idle(oldi);
 104   else
 105     DEBUG(0,("No dptrs available to idle??\n"));
 106 }
 107
 108 /****************************************************************************
 109 get the dir ptr for a dir index
 110 ****************************************************************************/
 111 static void *dptr_get(int key,uint32 lastused)
 112 {
 113   if (dirptrs[key].valid) {
 114     if (lastused) dirptrs[key].lastused = lastused;
 115     if (!dirptrs[key].ptr) {
 116       if (dptrs_open >= MAXDIR)
 117         dptr_idleoldest();
 118       DEBUG(4,("Reopening dptr key %d\n",key));
 119       if ((dirptrs[key].ptr = OpenDir(dirptrs[key].path)))
 120         dptrs_open++;
 121     }
 122     return(dirptrs[key].ptr);
 123   }
 124   return(NULL);
 125 }
 126
 127 /****************************************************************************
 128 get the dir path for a dir index
 129 ****************************************************************************/
 130 char *dptr_path(int key)
 131 {
 132   if (dirptrs[key].valid)
 133     return(dirptrs[key].path);
 134   return(NULL);
 135 }
 136
 137 /****************************************************************************
 138 get the dir wcard for a dir index (lanman2 specific)
 139 ****************************************************************************/
 140 char *dptr_wcard(int key)
 141 {
 142   if (dirptrs[key].valid)
 143     return(dirptrs[key].wcard);
 144   return(NULL);
 145 }
 146
 147 /****************************************************************************
 148 set the dir wcard for a dir index (lanman2 specific)
 149 Returns 0 on ok, 1 on fail.
 150 ****************************************************************************/
 151 BOOL dptr_set_wcard(int key, char *wcard)
 152 {
 153   if (dirptrs[key].valid) {
 154     dirptrs[key].wcard = wcard;
 155     return True;
 156   }
 157   return False;
 158 }
 159
 160 /****************************************************************************
 161 set the dir attrib for a dir index (lanman2 specific)
 162 Returns 0 on ok, 1 on fail.
 163 ****************************************************************************/
 164 BOOL dptr_set_attr(int key, uint16 attr)
 165 {
 166   if (dirptrs[key].valid) {
 167     dirptrs[key].attr = attr;
 168     return True;
 169   }
 170   return False;
 171 }
 172
 173 /****************************************************************************
 174 get the dir attrib for a dir index (lanman2 specific)
 175 ****************************************************************************/
 176 uint16 dptr_attr(int key)
 177 {
 178   if (dirptrs[key].valid)
 179     return(dirptrs[key].attr);
 180   return(0);
 181 }
 182
 183 /****************************************************************************
 184 close a dptr
 185 ****************************************************************************/
 186 void dptr_close(int key)
 187 {
 188   /* OS/2 seems to use -1 to indicate "close all directories" */
 189   if (key == -1) {
 190     int i;
 191     for (i=0;i<NUMDIRPTRS;i++)
 192       dptr_close(i);
 193     return;
 194   }
 195
 196   if (key < 0 || key >= NUMDIRPTRS) {
 197     DEBUG(3,("Invalid key %d given to dptr_close\n",key));
 198     return;
 199   }
 200
 201   if (dirptrs[key].valid) {
 202     DEBUG(4,("closing dptr key %d\n",key));
 203     if (dirptrs[key].ptr) {
 204       CloseDir(dirptrs[key].ptr);
 205       dptrs_open--;
 206     }
 207     /* Lanman 2 specific code */
 208     if (dirptrs[key].wcard)
 209       free(dirptrs[key].wcard);
 210     dirptrs[key].valid = False;
 211     string_set(&dirptrs[key].path,"");
 212   }
 213 }
 214
 215 /****************************************************************************
 216 close all dptrs for a cnum
 217 ****************************************************************************/
 218 void dptr_closecnum(int cnum)
 219 {
 220   int i;
 221   for (i=0;i<NUMDIRPTRS;i++)
 222     if (dirptrs[i].valid && dirptrs[i].cnum == cnum)
 223       dptr_close(i);
 224 }
 225
 226 /****************************************************************************
 227 idle all dptrs for a cnum
 228 ****************************************************************************/
 229 void dptr_idlecnum(int cnum)
 230 {
 231   int i;
 232   for (i=0;i<NUMDIRPTRS;i++)
 233     if (dirptrs[i].valid && dirptrs[i].cnum == cnum && dirptrs[i].ptr)
 234       dptr_idle(i);
 235 }
 236
 237 /****************************************************************************
 238 close a dptr that matches a given path, only if it matches the pid also
 239 ****************************************************************************/
 240 void dptr_closepath(char *path,int pid)
 241 {
 242   int i;
 243   for (i=0;i<NUMDIRPTRS;i++)
 244     if (dirptrs[i].valid && pid == dirptrs[i].pid &&
 245         strequal(dirptrs[i].path,path))
 246       dptr_close(i);
 247 }
 248
 249 /****************************************************************************
 250   start a directory listing
 251 ****************************************************************************/
 252 static BOOL start_dir(int cnum,char *directory)
 253 {
 254   DEBUG(5,("start_dir cnum=%d dir=%s\n",cnum,directory));
 255
 256   if (!check_name(directory,cnum))
 257     return(False);
 258
 259   if (! *directory)
 260     directory = ".";
 261
 262   Connections[cnum].dirptr = OpenDir(directory);
 263   if (Connections[cnum].dirptr) {
 264     dptrs_open++;
 265     string_set(&Connections[cnum].dirpath,directory);
 266     return(True);
 267   }
 268
 269   return(False);
 270 }
 271
 272
 273 /****************************************************************************
 274 create a new dir ptr
 275 ****************************************************************************/
 276 int dptr_create(int cnum,char *path, BOOL expect_close,int pid)
 277 {
 278   int i;
 279   uint32 old;
 280   int oldi;
 281
 282   if (!start_dir(cnum,path))
 283     return(-1);
 284
 285   if (dptrs_open >= MAXDIR)
 286     dptr_idleoldest();
 287
 288   for (i=0;i<NUMDIRPTRS;i++)
 289     if (!dirptrs[i].valid)
 290       break;
 291   if (i == NUMDIRPTRS) i = -1;
 292
 293
 294   /* as a 2nd option, grab the oldest not marked for expect_close */
 295   if (i == -1) {
 296     old=dircounter+1;
 297     oldi= -1;
 298     for (i=0;i<NUMDIRPTRS;i++)
 299       if (!dirptrs[i].expect_close && dirptrs[i].lastused < old) {
 300         old = dirptrs[i].lastused;
 301         oldi = i;
 302       }
 303     i = oldi;
 304   }
 305
 306   /* a 3rd option - grab the oldest one */
 307   if (i == -1) {
 308     old=dircounter+1;
 309     oldi= -1;
 310     for (i=0;i<NUMDIRPTRS;i++)
 311       if (dirptrs[i].lastused < old) {
 312         old = dirptrs[i].lastused;
 313         oldi = i;
 314       }
 315     i = oldi;
 316   }
 317
 318   if (i == -1) {
 319     DEBUG(0,("Error - all dirptrs in use??\n"));
 320     return(-1);
 321   }
 322
 323   if (dirptrs[i].valid)
 324     dptr_close(i);
 325
 326   dirptrs[i].ptr = Connections[cnum].dirptr;
 327   string_set(&dirptrs[i].path,path);
 328   dirptrs[i].lastused = dircounter++;
 329   dirptrs[i].finished = False;
 330   dirptrs[i].cnum = cnum;
 331   dirptrs[i].pid = pid;
 332   dirptrs[i].expect_close = expect_close;
 333   dirptrs[i].wcard = NULL; /* Only used in lanman2 searches */
 334   dirptrs[i].attr = 0; /* Only used in lanman2 searches */
 335   dirptrs[i].valid = True;
 336
 337   DEBUG(3,("creating new dirptr %d for path %s, expect_close = %d\n",
 338            i,path,expect_close));
 339
 340   return(i);
 341 }
 342
 343 #define DPTR_MASK ((uint32)(((uint32)1)<<31))
 344
 345 /****************************************************************************
 346 fill the 5 byte server reserved dptr field
 347 ****************************************************************************/
 348 BOOL dptr_fill(char *buf1,unsigned int key)
 349 {
 350   unsigned char *buf = (unsigned char *)buf1;
 351   void *p = dptr_get(key,0);
 352   uint32 offset;
 353   if (!p) {
 354     DEBUG(1,("filling null dirptr %d\n",key));
 355     return(False);
 356   }
 357   offset = TellDir(p);
 358   DEBUG(6,("fill on key %d dirptr 0x%x now at %d\n",key,p,offset));
 359   buf[0] = key;
 360   SIVAL(buf,1,offset | DPTR_MASK);
 361   return(True);
 362 }
 363
 364
 365 /****************************************************************************
 366 return True is the offset is at zero
 367 ****************************************************************************/
 368 BOOL dptr_zero(char *buf)
 369 {
 370   return((IVAL(buf,1)&~DPTR_MASK) == 0);
 371 }
 372
 373 /****************************************************************************
 374 fetch the dir ptr and seek it given the 5 byte server field
 375 ****************************************************************************/
 376 void *dptr_fetch(char *buf,int *num)
 377 {
 378   unsigned int key = *(unsigned char *)buf;
 379   void *p = dptr_get(key,dircounter++);
 380   uint32 offset;
 381   if (!p) {
 382     DEBUG(3,("fetched null dirptr %d\n",key));
 383     return(NULL);
 384   }
 385   *num = key;
 386   offset = IVAL(buf,1)&~DPTR_MASK;
 387   SeekDir(p,offset);
 388   DEBUG(3,("fetching dirptr %d for path %s at offset %d\n",
 389            key,dptr_path(key),offset));
 390   return(p);
 391 }
 392
 393 /****************************************************************************
 394 fetch the dir ptr and seek it given the lanman2 parameter block
 395 ****************************************************************************/
 396 void *dptr_fetch_lanman2(char *params,int dptr_num)
 397 {
 398   void *p = dptr_get(dptr_num,dircounter++);
 399   uint32 resume_key = SVAL(params,6);
 400   BOOL uses_resume_key = BITSETW(params+10,2);
 401   BOOL continue_bit = BITSETW(params+10,3);
 402
 403   if (!p) {
 404     DEBUG(3,("fetched null dirptr %d\n",dptr_num));
 405     return(NULL);
 406   }
 407   if(uses_resume_key && !continue_bit)
 408     SeekDir(p,resume_key);
 409   DEBUG(3,("fetching dirptr %d for path %s\n",dptr_num,dptr_path(dptr_num)));
 410   return(p);
 411 }
 412
 413 /****************************************************************************
 414 check a filetype for being valid
 415 ****************************************************************************/
 416 BOOL dir_check_ftype(int cnum,int mode,struct stat *st,int dirtype)
 417 {
 418   if (((mode & ~dirtype) & (aHIDDEN | aSYSTEM | aDIR)) != 0)
 419     return False;
 420   return True;
 421 }
 422
 423 /****************************************************************************
 424   get a directory entry
 425 ****************************************************************************/
 426 BOOL get_dir_entry(int cnum,char *mask,int dirtype,char *fname,int *size,int *mode,time_t *date,BOOL check_descend)
 427 {
 428   char *dname;
 429   BOOL found = False;
 430   struct stat sbuf;
 431   pstring path;
 432   pstring pathreal;
 433   BOOL isrootdir;
 434   pstring filename;
 435   BOOL matched;
 436
 437   *path = *pathreal = *filename = 0;
 438
 439   isrootdir = (strequal(Connections[cnum].dirpath,"./") ||
 440                strequal(Connections[cnum].dirpath,".") ||
 441                strequal(Connections[cnum].dirpath,"/"));
 442
 443   if (!Connections[cnum].dirptr)
 444     return(False);
 445
 446   while (!found)
 447     {
 448       dname = ReadDirName(Connections[cnum].dirptr);
 449
 450       DEBUG(6,("readdir on dirptr 0x%x now at offset %d\n",
 451             Connections[cnum].dirptr,TellDir(Connections[cnum].dirptr)));
 452
 453       if (dname == NULL)
 454         return(False);
 455
 456       matched = False;
 457
 458       strcpy(filename,dname);
 459
 460       if ((strcmp(filename,mask) == 0) ||
 461           (name_map_mangle(filename,True,SNUM(cnum)) &&
 462            mask_match(filename,mask,False,False)))
 463         {
 464           if (isrootdir && (strequal(filename,"..") || strequal(filename,".")))
 465             continue;
 466
 467           strcpy(fname,filename);
 468           *path = 0;
 469           strcpy(path,Connections[cnum].dirpath);
 470           strcat(path,"/");
 471           strcpy(pathreal,path);
 472           strcat(path,fname);
 473           strcat(pathreal,dname);
 474           if (sys_stat(pathreal,&sbuf) != 0)
 475             {
 476               DEBUG(5,("Couldn't stat 1 [%s]\n",path));
 477               continue;
 478             }
 479
 480           if (check_descend &&
 481               !strequal(fname,".") && !strequal(fname,".."))
 482             continue;
 483
 484           *mode = dos_mode(cnum,pathreal,&sbuf);
 485
 486           if (!dir_check_ftype(cnum,*mode,&sbuf,dirtype)) {
 487             DEBUG(5,("[%s] attribs didn't match %x\n",filename,dirtype));
 488             continue;
 489           }
 490
 491           *size = sbuf.st_size;
 492           *date = sbuf.st_mtime;
 493
 494           DEBUG(5,("get_dir_entry found %s fname=%s\n",pathreal,fname));
 495
 496           found = True;
 497         }
 498     }
 499
 500   return(found);
 501 }
 502
 503
 504
 505 typedef struct
 506 {
 507   int pos;
 508   int numentries;
 509   int mallocsize;
 510   char *data;
 511   char *current;
 512 } Dir;
 513
 514
 515 /*******************************************************************
 516 open a directory
 517 ********************************************************************/
 518 void *OpenDir(char *name)
 519 {
 520   Dir *dirp;
 521   char *n;
 522   void *p = sys_opendir(name);
 523   int used=0;
 524
 525   if (!p) return(NULL);
 526   dirp = (Dir *)malloc(sizeof(Dir));
 527   if (!dirp) {
 528     closedir(p);
 529     return(NULL);
 530   }
 531   dirp->pos = dirp->numentries = dirp->mallocsize = 0;
 532   dirp->data = dirp->current = NULL;
 533
 534   while ((n = readdirname(p))) {
 535     int l = strlen(n)+1;
 536     /* If it's a vetoed file, pretend it doesn't even exist */
 537     if(is_vetoed_name(n))
 538       continue;
 539     if (used + l > dirp->mallocsize) {
 540       int s = MAX(used+l,used+2000);
 541       char *r;
 542       r = (char *)Realloc(dirp->data,s);
 543       if (!r) {
 544         DEBUG(0,("Out of memory in OpenDir\n"));
 545         break;
 546       }
 547       dirp->data = r;
 548       dirp->mallocsize = s;
 549       dirp->current = dirp->data;
 550     }
 551     strcpy(dirp->data+used,n);
 552     used += l;
 553     dirp->numentries++;
 554   }
 555
 556   closedir(p);
 557   return((void *)dirp);
 558 }
 559
 560
 561 /*******************************************************************
 562 close a directory
 563 ********************************************************************/
 564 void CloseDir(void *p)
 565 {
 566   Dir *dirp = (Dir *)p;
 567   if (!dirp) return;
 568   if (dirp->data) free(dirp->data);
 569   free(dirp);
 570 }
 571
 572 /*******************************************************************
 573 read from a directory
 574 ********************************************************************/
 575 char *ReadDirName(void *p)
 576 {
 577   char *ret;
 578   Dir *dirp = (Dir *)p;
 579
 580   if (!dirp || !dirp->current || dirp->pos >= dirp->numentries) return(NULL);
 581
 582   ret = dirp->current;
 583   dirp->current = skip_string(dirp->current,1);
 584   dirp->pos++;
 585
 586   return(ret);
 587 }
 588
 589
 590 /*******************************************************************
 591 seek a dir
 592 ********************************************************************/
 593 BOOL SeekDir(void *p,int pos)
 594 {
 595   Dir *dirp = (Dir *)p;
 596
 597   if (!dirp) return(False);
 598
 599   if (pos < dirp->pos) {
 600     dirp->current = dirp->data;
 601     dirp->pos = 0;
 602   }
 603
 604   while (dirp->pos < pos && ReadDirName(p)) ;
 605
 606   return(dirp->pos == pos);
 607 }
 608
 609 /*******************************************************************
 610 tell a dir position
 611 ********************************************************************/
 612 int TellDir(void *p)
 613 {
 614   Dir *dirp = (Dir *)p;
 615
 616   if (!dirp) return(-1);
 617
 618   return(dirp->pos);
 619 }
 620
 621
 622 static int dir_cache_size = 0;
 623 static struct dir_cache {
 624   struct dir_cache *next;
 625   struct dir_cache *prev;
 626   char *path;
 627   char *name;
 628   char *dname;
 629   int snum;
 630 } *dir_cache = NULL;
 631
 632 /*******************************************************************
 633 add an entry to the directory cache
 634 ********************************************************************/
 635 void DirCacheAdd(char *path,char *name,char *dname,int snum)
 636 {
 637   int count;
 638   struct dir_cache *entry = (struct dir_cache *)malloc(sizeof(*entry));
 639   if (!entry) return;
 640   entry->path = strdup(path);
 641   entry->name = strdup(name);
 642   entry->dname = strdup(dname);
 643   entry->snum = snum;
 644   if (!entry->path || !entry->name || !entry->dname) return;
 645
 646   entry->next = dir_cache;
 647   entry->prev = NULL;
 648   if (entry->next) entry->next->prev = entry;
 649   dir_cache = entry;
 650
 651   DEBUG(4,("Added dir cache entry %s %s -> %s\n",path,name,dname));
 652
 653   if (dir_cache_size == DIRCACHESIZE) {
 654     for (entry=dir_cache, count=1;
 655          entry->next && count < dir_cache_size + 1;
 656          entry=entry->next, count++) ;
 657     if (entry->next || count != dir_cache_size + 1) {
 658       DEBUG(0,("DirCache bug - please report %d %d\n",dir_cache_size,count));
 659     }
 660     free(entry->path);
 661     free(entry->name);
 662     free(entry->dname);
 663     if (entry->prev) entry->prev->next = entry->next;
 664     free(entry);
 665   } else {
 666     dir_cache_size++;
 667   }
 668 }
 669
 670
 671 /*******************************************************************
 672 check for an entry in the directory cache
 673 ********************************************************************/
 674 char *DirCacheCheck(char *path,char *name,int snum)
 675 {
 676   struct dir_cache *entry;
 677
 678   for (entry=dir_cache; entry; entry=entry->next) {
 679     if (entry->snum == snum &&
 680         strcmp(path,entry->path) == 0 &&
 681         strcmp(name,entry->name) == 0) {
 682       DEBUG(4,("Got dir cache hit on %s %s -> %s\n",path,name,entry->dname));
 683       return(entry->dname);
 684     }
 685   }
 686
 687   return(NULL);
 688 }
 689
 690 /*******************************************************************
 691 flush entries in the dir_cache
 692 ********************************************************************/
 693 void DirCacheFlush(int snum)
 694 {
 695   struct dir_cache *entry,*next;
 696
 697   for (entry=dir_cache; entry; entry=next) {
 698     if (entry->snum == snum) {
 699       free(entry->path);
 700       free(entry->dname);
 701       free(entry->name);
 702       next = entry->next;
 703       if (entry->prev) entry->prev->next = entry->next;
 704       if (entry->next) entry->next->prev = entry->prev;
 705       if (dir_cache == entry) dir_cache = entry->next;
 706       free(entry);
 707       dir_cache_size--;
 708     } else {
 709       next = entry->next;
 710     }
 711   }
 712 }
 713
 714
 715 #ifdef REPLACE_GETWD
 716 /* This is getcwd.c from bash.  It is needed in Interactive UNIX.  To
 717  * add support for another OS you need to determine which of the
 718  * conditional compilation macros you need to define.  All the options
 719  * are defined for Interactive UNIX.
 720  */
 721 #ifdef ISC
 722 #define HAVE_UNISTD_H
 723 #define USGr3
 724 #define USG
 725 #endif
 726
 727 #if defined (HAVE_UNISTD_H)
 728 #  include <unistd.h>
 729 #endif
 730
 731 #if defined (__STDC__)
 732 #  define CONST const
 733 #  define PTR void *
 734 #else /* !__STDC__ */
 735 #  define CONST
 736 #  define PTR char *
 737 #endif /* !__STDC__ */
 738
 739 #if !defined (PATH_MAX)
 740 #  if defined (MAXPATHLEN)
 741 #    define PATH_MAX MAXPATHLEN
 742 #  else /* !MAXPATHLEN */
 743 #    define PATH_MAX 1024
 744 #  endif /* !MAXPATHLEN */
 745 #endif /* !PATH_MAX */
 746
 747 #if defined (_POSIX_VERSION) || defined (USGr3) || defined (HAVE_DIRENT_H)
 748 #  if !defined (HAVE_DIRENT)
 749 #    define HAVE_DIRENT
 750 #  endif /* !HAVE_DIRENT */
 751 #endif /* _POSIX_VERSION || USGr3 || HAVE_DIRENT_H */
 752
 753 #if defined (HAVE_DIRENT)
 754 #  define D_NAMLEN(d)   (strlen ((d)->d_name))
 755 #else
 756 #  define D_NAMLEN(d)   ((d)->d_namlen)
 757 #endif /* ! (_POSIX_VERSION || USGr3) */
 758
 759 #if defined (USG) || defined (USGr3)
 760 #  define d_fileno d_ino
 761 #endif
 762
 763 #if !defined (alloca)
 764 extern char *alloca ();
 765 #endif /* alloca */
 766
 767 /* Get the pathname of the current working directory,
 768    and put it in SIZE bytes of BUF.  Returns NULL if the
 769    directory couldn't be determined or SIZE was too small.
 770    If successful, returns BUF.  In GNU, if BUF is NULL,
 771    an array is allocated with `malloc'; the array is SIZE
 772    bytes long, unless SIZE <= 0, in which case it is as
 773    big as necessary.  */
 774 #if defined (__STDC__)
 775 char *
 776 getcwd (char *buf, size_t size)
 777 #else /* !__STDC__ */
 778 char *
 779 getcwd (buf, size)
 780      char *buf;
 781      int size;
 782 #endif /* !__STDC__ */
 783 {
 784   static CONST char dots[]
 785     = "../../../../../../../../../../../../../../../../../../../../../../../\
 786 ../../../../../../../../../../../../../../../../../../../../../../../../../../\
 787 ../../../../../../../../../../../../../../../../../../../../../../../../../..";
 788   CONST char *dotp, *dotlist;
 789   size_t dotsize;
 790   dev_t rootdev, thisdev;
 791   ino_t rootino, thisino;
 792   char path[PATH_MAX + 1];
 793   register char *pathp;
 794   char *pathbuf;
 795   size_t pathsize;
 796   struct stat st;
 797
 798   if (buf != NULL && size == 0)
 799     {
 800       errno = EINVAL;
 801       return ((char *)NULL);
 802     }
 803
 804   pathsize = sizeof (path);
 805   pathp = &path[pathsize];
 806   *--pathp = '\0';
 807   pathbuf = path;
 808
 809   if (stat (".", &st) < 0)
 810     return ((char *)NULL);
 811   thisdev = st.st_dev;
 812   thisino = st.st_ino;
 813
 814   if (stat ("/", &st) < 0)
 815     return ((char *)NULL);
 816   rootdev = st.st_dev;
 817   rootino = st.st_ino;
 818
 819   dotsize = sizeof (dots) - 1;
 820   dotp = &dots[sizeof (dots)];
 821   dotlist = dots;
 822   while (!(thisdev == rootdev && thisino == rootino))
 823     {
 824       register DIR *dirstream;
 825       register struct dirent *d;
 826       dev_t dotdev;
 827       ino_t dotino;
 828       char mount_point;
 829       int namlen;
 830
 831       /* Look at the parent directory.  */
 832       if (dotp == dotlist)
 833         {
 834           /* My, what a deep directory tree you have, Grandma.  */
 835           char *new;
 836           if (dotlist == dots)
 837             {
 838               new = malloc (dotsize * 2 + 1);
 839               if (new == NULL)
 840                 goto lose;
 841               memcpy (new, dots, dotsize);
 842             }
 843           else
 844             {
 845               new = realloc ((PTR) dotlist, dotsize * 2 + 1);
 846               if (new == NULL)
 847                 goto lose;
 848             }
 849           memcpy (&new[dotsize], new, dotsize);
 850           dotp = &new[dotsize];
 851           dotsize *= 2;
 852           new[dotsize] = '\0';
 853           dotlist = new;
 854         }
 855
 856       dotp -= 3;
 857
 858       /* Figure out if this directory is a mount point.  */
 859       if (stat (dotp, &st) < 0)
 860         goto lose;
 861       dotdev = st.st_dev;
 862       dotino = st.st_ino;
 863       mount_point = dotdev != thisdev;
 864
 865       /* Search for the last directory.  */
 866       dirstream = opendir(dotp);
 867       if (dirstream == NULL)
 868         goto lose;
 869       while ((d = (struct dirent *)readdir(dirstream)) != NULL)
 870         {
 871           if (d->d_name[0] == '.' &&
 872               (d->d_name[1] == '\0' ||
 873                 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
 874             continue;
 875           if (mount_point || d->d_fileno == thisino)
 876             {
 877               char *name;
 878
 879               namlen = D_NAMLEN(d);
 880               name = (char *)
 881                 alloca (dotlist + dotsize - dotp + 1 + namlen + 1);
 882               memcpy (name, dotp, dotlist + dotsize - dotp);
 883               name[dotlist + dotsize - dotp] = '/';
 884               memcpy (&name[dotlist + dotsize - dotp + 1],
 885                       d->d_name, namlen + 1);
 886               if (lstat (name, &st) < 0)
 887                 {
 888                   int save = errno;
 889                   closedir(dirstream);
 890                   errno = save;
 891                   goto lose;
 892                 }
 893               if (st.st_dev == thisdev && st.st_ino == thisino)
 894                 break;
 895             }
 896         }
 897       if (d == NULL)
 898         {
 899           int save = errno;
 900           closedir(dirstream);
 901           errno = save;
 902           goto lose;
 903         }
 904       else
 905         {
 906           size_t space;
 907
 908           while ((space = pathp - pathbuf) <= namlen)
 909             {
 910               char *new;
 911
 912               if (pathbuf == path)
 913                 {
 914                   new = malloc (pathsize * 2);
 915                   if (!new)
 916                     goto lose;
 917                 }
 918               else
 919                 {
 920                   new = realloc ((PTR) pathbuf, (pathsize * 2));
 921                   if (!new)
 922                     goto lose;
 923                   pathp = new + space;
 924                 }
 925               (void) memcpy (new + pathsize + space, pathp, pathsize - space);
 926               pathp = new + pathsize + space;
 927               pathbuf = new;
 928               pathsize *= 2;
 929             }
 930
 931           pathp -= namlen;
 932           (void) memcpy (pathp, d->d_name, namlen);
 933           *--pathp = '/';
 934           closedir(dirstream);
 935         }
 936
 937       thisdev = dotdev;
 938       thisino = dotino;
 939     }
 940
 941   if (pathp == &path[sizeof(path) - 1])
 942     *--pathp = '/';
 943
 944   if (dotlist != dots)
 945     free ((PTR) dotlist);
 946
 947   {
 948     size_t len = pathbuf + pathsize - pathp;
 949     if (buf == NULL)
 950       {
 951         if (len < (size_t) size)
 952           len = size;
 953         buf = (char *) malloc (len);
 954         if (buf == NULL)
 955           goto lose2;
 956       }
 957     else if ((size_t) size < len)
 958       {
 959         errno = ERANGE;
 960         goto lose2;
 961       }
 962     (void) memcpy((PTR) buf, (PTR) pathp, len);
 963   }
 964
 965   if (pathbuf != path)
 966     free (pathbuf);
 967
 968   return (buf);
 969
 970  lose:
 971   if ((dotlist != dots) && dotlist)
 972     {
 973       int e = errno;
 974       free ((PTR) dotlist);
 975       errno = e;
 976     }
 977
 978  lose2:
 979   if ((pathbuf != path) && pathbuf)
 980     {
 981       int e = errno;
 982       free ((PTR) pathbuf);
 983       errno = e;
 984     }
 985   return ((char *)NULL);
 986 }
 987 #endif