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1 /*      $NetBSD: walk.c,v 1.24 2008/12/28 21:51:46 christos Exp $       */
2
3 /*
4  * Copyright (c) 2001 Wasabi Systems, Inc.
5  * All rights reserved.
6  *
7  * Written by Luke Mewburn for Wasabi Systems, Inc.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *      This product includes software developed for the NetBSD Project by
20  *      Wasabi Systems, Inc.
21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22  *    or promote products derived from this software without specific prior
23  *    written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35  * POSSIBILITY OF SUCH DAMAGE.
36  */
37
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
41
42 #include <sys/param.h>
43 #include <sys/time.h>
44
45 #include <assert.h>
46 #include <errno.h>
47 #include <fcntl.h>
48 #include <stdio.h>
49 #include <dirent.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <unistd.h>
53 #include <sys/stat.h>
54
55 #include "makefs.h"
56 #include "mtree.h"
57 #include "extern.h"
58
59 static  void     apply_specdir(const char *, NODE *, fsnode *, int);
60 static  void     apply_specentry(const char *, NODE *, fsnode *);
61 static  fsnode  *create_fsnode(const char *, const char *, const char *,
62                                struct stat *);
63
64
65 /*
66  * walk_dir --
67  *      build a tree of fsnodes from `root' and `dir', with a parent
68  *      fsnode of `parent' (which may be NULL for the root of the tree).
69  *      append the tree to a fsnode of `join' if it is not NULL.
70  *      each "level" is a directory, with the "." entry guaranteed to be
71  *      at the start of the list, and without ".." entries.
72  */
73 fsnode *
74 walk_dir(const char *root, const char *dir, fsnode *parent, fsnode *join)
75 {
76         fsnode          *first, *cur, *prev, *last;
77         DIR             *dirp;
78         struct dirent   *dent;
79         char            path[MAXPATHLEN + 1];
80         struct stat     stbuf;
81         char            *name, *rp;
82         int             dot, len;
83
84         assert(root != NULL);
85         assert(dir != NULL);
86
87         len = snprintf(path, sizeof(path), "%s/%s", root, dir);
88         if (len >= (int)sizeof(path))
89                 errx(1, "Pathname too long.");
90         if (debug & DEBUG_WALK_DIR)
91                 printf("walk_dir: %s %p\n", path, parent);
92         if ((dirp = opendir(path)) == NULL)
93                 err(1, "Can't opendir `%s'", path);
94         rp = path + strlen(root) + 1;
95         if (join != NULL) {
96                 first = cur = join;
97                 while (cur->next != NULL)
98                         cur = cur->next;
99                 prev = cur;
100         } else
101                 first = prev = NULL;
102         last = prev;
103         while ((dent = readdir(dirp)) != NULL) {
104                 name = dent->d_name;
105                 dot = 0;
106                 if (name[0] == '.')
107                         switch (name[1]) {
108                         case '\0':      /* "." */
109                                 if (join != NULL)
110                                         continue;
111                                 dot = 1;
112                                 break;
113                         case '.':       /* ".." */
114                                 if (name[2] == '\0')
115                                         continue;
116                                 /* FALLTHROUGH */
117                         default:
118                                 dot = 0;
119                         }
120                 if (debug & DEBUG_WALK_DIR_NODE)
121                         printf("scanning %s/%s/%s\n", root, dir, name);
122                 if (snprintf(path + len, sizeof(path) - len, "/%s", name) >=
123                     (int)sizeof(path) - len)
124                         errx(1, "Pathname too long.");
125                 if (lstat(path, &stbuf) == -1)
126                         err(1, "Can't lstat `%s'", path);
127 #ifdef S_ISSOCK
128                 if (S_ISSOCK(stbuf.st_mode & S_IFMT)) {
129                         if (debug & DEBUG_WALK_DIR_NODE)
130                                 printf("  skipping socket %s\n", path);
131                         continue;
132                 }
133 #endif
134
135                 if (join != NULL) {
136                         cur = join->next;
137                         for (;;) {
138                                 if (cur == NULL || strcmp(cur->name, name) == 0)
139                                         break;
140                                 if (cur == last) {
141                                         cur = NULL;
142                                         break;
143                                 }
144                                 cur = cur->next;
145                         }
146                         if (cur != NULL) {
147                                 if (S_ISDIR(cur->type) &&
148                                     S_ISDIR(stbuf.st_mode)) {
149                                         if (debug & DEBUG_WALK_DIR_NODE)
150                                                 printf("merging %s with %p\n",
151                                                     path, cur->child);
152                                         cur->child = walk_dir(root, rp, cur,
153                                             cur->child);
154                                         continue;
155                                 }
156                                 errx(1, "Can't merge %s `%s' with existing %s",
157                                     inode_type(stbuf.st_mode), path,
158                                     inode_type(cur->type));
159                         }
160                 }
161
162                 cur = create_fsnode(root, dir, name, &stbuf);
163                 cur->parent = parent;
164                 if (dot) {
165                                 /* ensure "." is at the start of the list */
166                         cur->next = first;
167                         first = cur;
168                         if (! prev)
169                                 prev = cur;
170                         cur->first = first;
171                 } else {                        /* not "." */
172                         if (prev)
173                                 prev->next = cur;
174                         prev = cur;
175                         if (!first)
176                                 first = cur;
177                         cur->first = first;
178                         if (S_ISDIR(cur->type)) {
179                                 cur->child = walk_dir(root, rp, cur, NULL);
180                                 continue;
181                         }
182                 }
183                 if (stbuf.st_nlink > 1) {
184                         fsinode *curino;
185
186                         curino = link_check(cur->inode);
187                         if (curino != NULL) {
188                                 free(cur->inode);
189                                 cur->inode = curino;
190                                 cur->inode->nlink++;
191                                 if (debug & DEBUG_WALK_DIR_LINKCHECK)
192                                         printf("link_check: found [%llu, %llu]\n",
193                                             (unsigned long long)curino->st.st_dev,
194                                             (unsigned long long)curino->st.st_ino);
195                         }
196                 }
197                 if (S_ISLNK(cur->type)) {
198                         char    slink[PATH_MAX+1];
199                         int     llen;
200
201                         llen = readlink(path, slink, sizeof(slink) - 1);
202                         if (llen == -1)
203                                 err(1, "Readlink `%s'", path);
204                         slink[llen] = '\0';
205                         if ((cur->symlink = strdup(slink)) == NULL)
206                                 err(1, "Memory allocation error");
207                 }
208         }
209         assert(first != NULL);
210         if (join == NULL)
211                 for (cur = first->next; cur != NULL; cur = cur->next)
212                         cur->first = first;
213         if (closedir(dirp) == -1)
214                 err(1, "Can't closedir `%s/%s'", root, dir);
215         return (first);
216 }
217
218 static fsnode *
219 create_fsnode(const char *root, const char *path, const char *name,
220     struct stat *stbuf)
221 {
222         fsnode *cur;
223
224         if ((cur = calloc(1, sizeof(fsnode))) == NULL ||
225             (cur->path = strdup(path)) == NULL ||
226             (cur->name = strdup(name)) == NULL ||
227             (cur->inode = calloc(1, sizeof(fsinode))) == NULL)
228                 err(1, "Memory allocation error");
229         cur->root = root;
230         cur->type = stbuf->st_mode & S_IFMT;
231         cur->inode->nlink = 1;
232         cur->inode->st = *stbuf;
233         if (stampst.st_ino) {
234                 cur->inode->st.st_atime = stampst.st_atime;
235                 cur->inode->st.st_mtime = stampst.st_mtime;
236                 cur->inode->st.st_ctime = stampst.st_ctime;
237 #if HAVE_STRUCT_STAT_ST_MTIMENSEC
238                 cur->inode->st.st_atimensec = stampst.st_atimensec;
239                 cur->inode->st.st_mtimensec = stampst.st_mtimensec;
240                 cur->inode->st.st_ctimensec = stampst.st_ctimensec;
241 #endif
242 #if HAVE_STRUCT_STAT_BIRTHTIME
243                 cur->inode->st.st_birthtime = stampst.st_birthtime;
244                 cur->inode->st.st_birthtimensec = stampst.st_birthtimensec;
245 #endif
246         }
247         return (cur);
248 }
249
250 /*
251  * free_fsnodes --
252  *      Removes node from tree and frees it and all of
253  *   its descendants.
254  */
255 void
256 free_fsnodes(fsnode *node)
257 {
258         fsnode  *cur, *next;
259
260         assert(node != NULL);
261
262         /* for ".", start with actual parent node */
263         if (node->first == node) {
264                 assert(node->name[0] == '.' && node->name[1] == '\0');
265                 if (node->parent) {
266                         assert(node->parent->child == node);
267                         node = node->parent;
268                 }
269         }
270
271         /* Find ourselves in our sibling list and unlink */
272         if (node->first != node) {
273                 for (cur = node->first; cur->next; cur = cur->next) {
274                         if (cur->next == node) {
275                                 cur->next = node->next;
276                                 node->next = NULL;
277                                 break;
278                         }
279                 }
280         }
281
282         for (cur = node; cur != NULL; cur = next) {
283                 next = cur->next;
284                 if (cur->child) {
285                         cur->child->parent = NULL;
286                         free_fsnodes(cur->child);
287                 }
288                 if (cur->inode->nlink-- == 1)
289                         free(cur->inode);
290                 if (cur->symlink)
291                         free(cur->symlink);
292                 free(cur->path);
293                 free(cur->name);
294                 free(cur);
295         }
296 }
297
298 /*
299  * apply_specfile --
300  *      read in the mtree(8) specfile, and apply it to the tree
301  *      at dir,parent. parameters in parent on equivalent types
302  *      will be changed to those found in specfile, and missing
303  *      entries will be added.
304  */
305 void
306 apply_specfile(const char *specfile, const char *dir, fsnode *parent, int speconly)
307 {
308         struct timeval   start;
309         FILE    *fp;
310         NODE    *root;
311
312         assert(specfile != NULL);
313         assert(parent != NULL);
314
315         if (debug & DEBUG_APPLY_SPECFILE)
316                 printf("apply_specfile: %s, %s %p\n", specfile, dir, parent);
317
318                                 /* read in the specfile */
319         if ((fp = fopen(specfile, "r")) == NULL)
320                 err(1, "Can't open `%s'", specfile);
321         TIMER_START(start);
322         root = spec(fp);
323         TIMER_RESULTS(start, "spec");
324         if (fclose(fp) == EOF)
325                 err(1, "Can't close `%s'", specfile);
326
327                                 /* perform some sanity checks */
328         if (root == NULL)
329                 errx(1, "Specfile `%s' did not contain a tree", specfile);
330         assert(strcmp(root->name, ".") == 0);
331         assert(root->type == F_DIR);
332
333                                 /* merge in the changes */
334         apply_specdir(dir, root, parent, speconly);
335
336 }
337
338 static void
339 apply_specdir(const char *dir, NODE *specnode, fsnode *dirnode, int speconly)
340 {
341         char     path[MAXPATHLEN + 1];
342         NODE    *curnode;
343         fsnode  *curfsnode;
344
345         assert(specnode != NULL);
346         assert(dirnode != NULL);
347
348         if (debug & DEBUG_APPLY_SPECFILE)
349                 printf("apply_specdir: %s %p %p\n", dir, specnode, dirnode);
350
351         if (specnode->type != F_DIR)
352                 errx(1, "Specfile node `%s/%s' is not a directory",
353                     dir, specnode->name);
354         if (dirnode->type != S_IFDIR)
355                 errx(1, "Directory node `%s/%s' is not a directory",
356                     dir, dirnode->name);
357
358         apply_specentry(dir, specnode, dirnode);
359
360         /* Remove any filesystem nodes not found in specfile */
361         /* XXX inefficient.  This is O^2 in each dir and it would
362          * have been better never to have walked this part of the tree
363          * to begin with
364          */
365         if (speconly) {
366                 fsnode *next;
367                 assert(dirnode->name[0] == '.' && dirnode->name[1] == '\0');
368                 for (curfsnode = dirnode->next; curfsnode != NULL; curfsnode = next) {
369                         next = curfsnode->next;
370                         for (curnode = specnode->child; curnode != NULL;
371                              curnode = curnode->next) {
372                                 if (strcmp(curnode->name, curfsnode->name) == 0)
373                                         break;
374                         }
375                         if (curnode == NULL) {
376                                 if (debug & DEBUG_APPLY_SPECONLY) {
377                                         printf("apply_specdir: trimming %s/%s %p\n", dir, curfsnode->name, curfsnode);
378                                 }
379                                 free_fsnodes(curfsnode);
380                         }
381                 }
382         }
383
384                         /* now walk specnode->child matching up with dirnode */
385         for (curnode = specnode->child; curnode != NULL;
386             curnode = curnode->next) {
387                 if (debug & DEBUG_APPLY_SPECENTRY)
388                         printf("apply_specdir:  spec %s\n",
389                             curnode->name);
390                 for (curfsnode = dirnode->next; curfsnode != NULL;
391                     curfsnode = curfsnode->next) {
392 #if 0   /* too verbose for now */
393                         if (debug & DEBUG_APPLY_SPECENTRY)
394                                 printf("apply_specdir:  dirent %s\n",
395                                     curfsnode->name);
396 #endif
397                         if (strcmp(curnode->name, curfsnode->name) == 0)
398                                 break;
399                 }
400                 if (snprintf(path, sizeof(path), "%s/%s",
401                     dir, curnode->name) >= sizeof(path))
402                         errx(1, "Pathname too long.");
403                 if (curfsnode == NULL) {        /* need new entry */
404                         struct stat     stbuf;
405
406                                             /*
407                                              * don't add optional spec entries
408                                              * that lack an existing fs entry
409                                              */
410                         if ((curnode->flags & F_OPT) &&
411                             lstat(path, &stbuf) == -1)
412                                         continue;
413
414                                         /* check that enough info is provided */
415 #define NODETEST(t, m)                                                  \
416                         if (!(t))                                       \
417                                 errx(1, "`%s': %s not provided", path, m)
418                         NODETEST(curnode->flags & F_TYPE, "type");
419                         NODETEST(curnode->flags & F_MODE, "mode");
420                                 /* XXX: require F_TIME ? */
421                         NODETEST(curnode->flags & F_GID ||
422                             curnode->flags & F_GNAME, "group");
423                         NODETEST(curnode->flags & F_UID ||
424                             curnode->flags & F_UNAME, "user");
425 /*                      if (curnode->type == F_BLOCK || curnode->type == F_CHAR)
426                                 NODETEST(curnode->flags & F_DEV,
427                                     "device number");*/
428 #undef NODETEST
429
430                         if (debug & DEBUG_APPLY_SPECFILE)
431                                 printf("apply_specdir: adding %s\n",
432                                     curnode->name);
433                                         /* build minimal fsnode */
434                         memset(&stbuf, 0, sizeof(stbuf));
435                         stbuf.st_mode = nodetoino(curnode->type);
436                         stbuf.st_nlink = 1;
437                         stbuf.st_mtime = stbuf.st_atime =
438                             stbuf.st_ctime = start_time.tv_sec;
439 #if HAVE_STRUCT_STAT_ST_MTIMENSEC
440                         stbuf.st_mtimensec = stbuf.st_atimensec =
441                             stbuf.st_ctimensec = start_time.tv_nsec;
442 #endif
443                         curfsnode = create_fsnode(".", ".", curnode->name,
444                             &stbuf);
445                         curfsnode->parent = dirnode->parent;
446                         curfsnode->first = dirnode;
447                         curfsnode->next = dirnode->next;
448                         dirnode->next = curfsnode;
449                         if (curfsnode->type == S_IFDIR) {
450                                         /* for dirs, make "." entry as well */
451                                 curfsnode->child = create_fsnode(".", ".", ".",
452                                     &stbuf);
453                                 curfsnode->child->parent = curfsnode;
454                                 curfsnode->child->first = curfsnode->child;
455                         }
456                         if (curfsnode->type == S_IFLNK) {
457                                 assert(curnode->slink != NULL);
458                                         /* for symlinks, copy the target */
459                                 if ((curfsnode->symlink =
460                                     strdup(curnode->slink)) == NULL)
461                                         err(1, "Memory allocation error");
462                         }
463                 }
464                 apply_specentry(dir, curnode, curfsnode);
465                 if (curnode->type == F_DIR) {
466                         if (curfsnode->type != S_IFDIR)
467                                 errx(1, "`%s' is not a directory", path);
468                         assert (curfsnode->child != NULL);
469                         apply_specdir(path, curnode, curfsnode->child, speconly);
470                 }
471         }
472 }
473
474 static void
475 apply_specentry(const char *dir, NODE *specnode, fsnode *dirnode)
476 {
477
478         assert(specnode != NULL);
479         assert(dirnode != NULL);
480
481         if (nodetoino(specnode->type) != dirnode->type)
482                 errx(1, "`%s/%s' type mismatch: specfile %s, tree %s",
483                     dir, specnode->name, inode_type(nodetoino(specnode->type)),
484                     inode_type(dirnode->type));
485
486         if (debug & DEBUG_APPLY_SPECENTRY)
487                 printf("apply_specentry: %s/%s\n", dir, dirnode->name);
488
489 #define ASEPRINT(t, b, o, n) \
490                 if (debug & DEBUG_APPLY_SPECENTRY) \
491                         printf("\t\t\tchanging %s from " b " to " b "\n", \
492                             t, o, n)
493
494         if (specnode->flags & (F_GID | F_GNAME)) {
495                 ASEPRINT("gid", "%d",
496                     dirnode->inode->st.st_gid, specnode->st_gid);
497                 dirnode->inode->st.st_gid = specnode->st_gid;
498         }
499         if (specnode->flags & F_MODE) {
500                 ASEPRINT("mode", "%#o",
501                     dirnode->inode->st.st_mode & ALLPERMS, specnode->st_mode);
502                 dirnode->inode->st.st_mode &= ~ALLPERMS;
503                 dirnode->inode->st.st_mode |= (specnode->st_mode & ALLPERMS);
504         }
505                 /* XXX: ignoring F_NLINK for now */
506         if (specnode->flags & F_SIZE) {
507                 ASEPRINT("size", "%lld",
508                     (long long)dirnode->inode->st.st_size,
509                     (long long)specnode->st_size);
510                 dirnode->inode->st.st_size = specnode->st_size;
511         }
512         if (specnode->flags & F_SLINK) {
513                 assert(dirnode->symlink != NULL);
514                 assert(specnode->slink != NULL);
515                 ASEPRINT("symlink", "%s", dirnode->symlink, specnode->slink);
516                 free(dirnode->symlink);
517                 if ((dirnode->symlink = strdup(specnode->slink)) == NULL)
518                         err(1, "Memory allocation error");
519         }
520         if (specnode->flags & F_TIME) {
521                 ASEPRINT("time", "%ld",
522                     (long)dirnode->inode->st.st_mtime,
523                     (long)specnode->st_mtimespec.tv_sec);
524                 dirnode->inode->st.st_mtime =           specnode->st_mtimespec.tv_sec;
525                 dirnode->inode->st.st_atime =           specnode->st_mtimespec.tv_sec;
526                 dirnode->inode->st.st_ctime =           start_time.tv_sec;
527 #if HAVE_STRUCT_STAT_ST_MTIMENSEC
528                 dirnode->inode->st.st_mtimensec =       specnode->st_mtimespec.tv_nsec;
529                 dirnode->inode->st.st_atimensec =       specnode->st_mtimespec.tv_nsec;
530                 dirnode->inode->st.st_ctimensec =       start_time.tv_nsec;
531 #endif
532         }
533         if (specnode->flags & (F_UID | F_UNAME)) {
534                 ASEPRINT("uid", "%d",
535                     dirnode->inode->st.st_uid, specnode->st_uid);
536                 dirnode->inode->st.st_uid = specnode->st_uid;
537         }
538 #if HAVE_STRUCT_STAT_ST_FLAGS
539         if (specnode->flags & F_FLAGS) {
540                 ASEPRINT("flags", "%#lX",
541                     (unsigned long)dirnode->inode->st.st_flags,
542                     (unsigned long)specnode->st_flags);
543                 dirnode->inode->st.st_flags = specnode->st_flags;
544         }
545 #endif
546 /*      if (specnode->flags & F_DEV) {
547                 ASEPRINT("rdev", "%#llx",
548                     (unsigned long long)dirnode->inode->st.st_rdev,
549                     (unsigned long long)specnode->st_rdev);
550                 dirnode->inode->st.st_rdev = specnode->st_rdev;
551         }*/
552 #undef ASEPRINT
553
554         dirnode->flags |= FSNODE_F_HASSPEC;
555 }
556
557
558 /*
559  * dump_fsnodes --
560  *      dump the fsnodes from `cur'
561  */
562 void
563 dump_fsnodes(fsnode *root)
564 {
565         fsnode  *cur;
566         char    path[MAXPATHLEN + 1];
567
568         printf("dump_fsnodes: %s %p\n", root->path, root);
569         for (cur = root; cur != NULL; cur = cur->next) {
570                 if (snprintf(path, sizeof(path), "%s/%s", cur->path,
571                     cur->name) >= (int)sizeof(path))
572                         errx(1, "Pathname too long.");
573
574                 if (debug & DEBUG_DUMP_FSNODES_VERBOSE)
575                         printf("cur=%8p parent=%8p first=%8p ",
576                             cur, cur->parent, cur->first);
577                 printf("%7s: %s", inode_type(cur->type), path);
578                 if (S_ISLNK(cur->type)) {
579                         assert(cur->symlink != NULL);
580                         printf(" -> %s", cur->symlink);
581                 } else {
582                         assert (cur->symlink == NULL);
583                 }
584                 if (cur->inode->nlink > 1)
585                         printf(", nlinks=%d", cur->inode->nlink);
586                 putchar('\n');
587
588                 if (cur->child) {
589                         assert (cur->type == S_IFDIR);
590                         dump_fsnodes(cur->child);
591                 }
592         }
593         printf("dump_fsnodes: finished %s/%s\n", root->path, root->name);
594 }
595
596
597 /*
598  * inode_type --
599  *      for a given inode type `mode', return a descriptive string.
600  *      for most cases, uses inotype() from mtree/misc.c
601  */
602 const char *
603 inode_type(mode_t mode)
604 {
605         if (S_ISREG(mode))
606                 return ("file");
607         if (S_ISLNK(mode))
608                 return ("symlink");
609         if (S_ISDIR(mode))
610                 return ("dir");
611         if (S_ISLNK(mode))
612                 return ("link");
613         if (S_ISFIFO(mode))
614                 return ("fifo");
615         if (S_ISSOCK(mode))
616                 return ("socket");
617         /* XXX should not happen but handle them */
618         if (S_ISCHR(mode))
619                 return ("char");
620         if (S_ISBLK(mode))
621                 return ("block");
622         return ("unknown");
623 }
624
625
626 /*
627  * link_check --
628  *      return pointer to fsinode matching `entry's st_ino & st_dev if it exists,
629  *      otherwise add `entry' to table and return NULL
630  */
631 /* This was borrowed from du.c and tweaked to keep an fsnode 
632  * pointer instead. -- dbj@netbsd.org
633  */
634 fsinode *
635 link_check(fsinode *entry)
636 {
637         static struct entry {
638                 fsinode *data;
639         } *htable;
640         static int htshift;  /* log(allocated size) */
641         static int htmask;   /* allocated size - 1 */
642         static int htused;   /* 2*number of insertions */
643         int h, h2;
644         uint64_t tmp;
645         /* this constant is (1<<64)/((1+sqrt(5))/2)
646          * aka (word size)/(golden ratio)
647          */
648         const uint64_t HTCONST = 11400714819323198485ULL;
649         const int HTBITS = 64;
650         
651         /* Never store zero in hashtable */
652         assert(entry);
653
654         /* Extend hash table if necessary, keep load under 0.5 */
655         if (htused<<1 >= htmask) {
656                 struct entry *ohtable;
657
658                 if (!htable)
659                         htshift = 10;   /* starting hashtable size */
660                 else
661                         htshift++;   /* exponential hashtable growth */
662
663                 htmask  = (1 << htshift) - 1;
664                 htused = 0;
665
666                 ohtable = htable;
667                 htable = calloc(htmask+1, sizeof(*htable));
668                 if (!htable)
669                         err(1, "Memory allocation error");
670
671                 /* populate newly allocated hashtable */
672                 if (ohtable) {
673                         int i;
674                         for (i = 0; i <= htmask>>1; i++)
675                                 if (ohtable[i].data)
676                                         link_check(ohtable[i].data);
677                         free(ohtable);
678                 }
679         }
680
681         /* multiplicative hashing */
682         tmp = entry->st.st_dev;
683         tmp <<= HTBITS>>1;
684         tmp |=  entry->st.st_ino;
685         tmp *= HTCONST;
686         h  = tmp >> (HTBITS - htshift);
687         h2 = 1 | ( tmp >> (HTBITS - (htshift<<1) - 1)); /* must be odd */
688         
689         /* open address hashtable search with double hash probing */
690         while (htable[h].data) {
691                 if ((htable[h].data->st.st_ino == entry->st.st_ino) &&
692                     (htable[h].data->st.st_dev == entry->st.st_dev)) {
693                         return htable[h].data;
694                 }
695                 h = (h + h2) & htmask;
696         }
697
698         /* Insert the current entry into hashtable */
699         htable[h].data = entry;
700         htused++;
701         return NULL;
702 }