1/*- 2 * Copyright (c) 2003-2004 Tim Kientzle 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27/*- 28 * There is a single list of "tree_entry" items that represent 29 * filesystem objects that require further attention. Non-directories 30 * are not kept in memory: they are pulled from readdir(), returned to 31 * the client, then freed as soon as possible. Any directory entry to 32 * be traversed gets pushed onto the stack. 33 * 34 * There is surprisingly little information that needs to be kept for 35 * each item on the stack. Just the name, depth (represented here as the 36 * string length of the parent directory's pathname), and some markers 37 * indicating how to get back to the parent (via chdir("..") for a 38 * regular dir or via fchdir(2) for a symlink). 39 */ 40 41#include <sys/stat.h> 42#include <dirent.h> 43#include <fcntl.h> 44#include <stdlib.h> 45#include <string.h> 46#include <unistd.h> 47 48#include "tree.h" 49 50/* 51 * TODO: 52 * 1) Loop checking. 53 * 3) Arbitrary logical traversals by closing/reopening intermediate fds. 54 */ 55 56struct tree_entry { 57 struct tree_entry *next; 58 char *name; 59 size_t dirname_length; 60 int fd; 61 int flags; 62}; 63 64/* Definitions for tree_entry.flags bitmap. */ 65#define isDir 1 /* This entry is a regular directory. */ 66#define isDirLink 2 /* This entry is a symbolic link to a directory. */ 67#define needsTraversal 4 /* This entry hasn't yet been traversed. */ 68 69/* 70 * Local data for this package. 71 */ 72struct tree { 73 struct tree_entry *stack; 74 DIR *d; 75 int initialDirFd; 76 int flags; 77 78 char *buff; 79 char *basename; 80 size_t buff_length; 81 size_t path_length; 82 size_t dirname_length; 83 84 int depth; 85 int openCount; 86 int maxOpenCount; 87 88 struct stat lst; 89 struct stat st; 90}; 91 92/* Definitions for tree.flags bitmap. */ 93#define needsReturn 8 /* Marks first entry as not having been returned yet. */ 94#define hasStat 16 /* The st entry is set. */ 95#define hasLstat 32 /* The lst entry is set. */ 96 97 98#define HAVE_DIRENT_D_NAMLEN 1 99#ifdef HAVE_DIRENT_D_NAMLEN 100/* BSD extension; avoids need for a strlen() call. */ 101#define D_NAMELEN(dp) (dp)->d_namlen 102#else 103#define D_NAMELEN(dp) (strlen((dp)->d_name)) 104#endif 105 106#if 0 107static void 108dumpStack(struct tree *t) 109{ 110 struct tree_entry *te; 111 112 printf("\tbuff: %s\n", t->buff); 113 printf("\tpwd: "); fflush(stdout); system("pwd"); 114 printf("\tstack:\n"); 115 for (te = t->stack; te != NULL; te = te->next) { 116 printf("\t\tte->name: %s %s\n", te->name, te->flags & needsTraversal ? "" : "*"); 117 } 118} 119#endif 120 121/* 122 * Add a directory path to the current stack. 123 */ 124static void 125tree_add(struct tree *t, const char *path) 126{ 127 struct tree_entry *te; 128 129 te = malloc(sizeof(*te)); 130 memset(te, 0, sizeof(*te)); 131 te->next = t->stack; 132 t->stack = te; 133 te->fd = -1; 134 te->name = strdup(path); 135 te->flags = needsTraversal; 136 te->dirname_length = t->dirname_length; 137} 138 139/* 140 * Append a name to the current path. 141 */ 142static void 143tree_append(struct tree *t, const char *name, size_t name_length) 144{ 145 if (t->buff != NULL) 146 t->buff[t->dirname_length] = '\0'; 147 148 /* Resize pathname buffer as needed. */ 149 while (name_length + 1 + t->dirname_length >= t->buff_length) { 150 t->buff_length *= 2; 151 if (t->buff_length < 1024) 152 t->buff_length = 1024; 153 t->buff = realloc(t->buff, t->buff_length); 154 } 155 t->basename = t->buff + t->dirname_length; 156 t->path_length = t->dirname_length + name_length; 157 if (t->dirname_length > 0) { 158 *t->basename++ = '/'; 159 t->path_length ++; 160 } 161 strcpy(t->basename, name); 162} 163 164/* 165 * Open a directory tree for traversal. 166 */ 167struct tree * 168tree_open(const char *path) 169{ 170 struct tree *t; 171 172 t = malloc(sizeof(*t)); 173 memset(t, 0, sizeof(*t)); 174 tree_append(t, path, strlen(path)); 175 t->initialDirFd = open(".", O_RDONLY); 176 /* 177 * During most of the traversal, items are set up and then 178 * returned immediately from tree_next(). That doesn't work 179 * for the very first entry, so we set a flag for this special 180 * case. 181 */ 182 t->flags = needsReturn; 183 return (t); 184} 185 186/* 187 * We've finished a directory; ascend back to the parent. 188 */ 189static void 190tree_ascend(struct tree *t) 191{ 192 struct tree_entry *te; 193 194 te = t->stack; 195 t->depth--; 196 if (te->flags & isDirLink) { 197 fchdir(te->fd); 198 close(te->fd); 199 t->openCount--; 200 } else { 201 chdir(".."); 202 } 203} 204 205/* 206 * Pop the working stack. 207 */ 208static void 209tree_pop(struct tree *t) 210{ 211 struct tree_entry *te; 212 213 te = t->stack; 214 t->stack = te->next; 215 t->dirname_length = te->dirname_length; 216 free(te->name); 217 free(te); 218} 219 220/* 221 * Get the next item in the tree traversal. 222 */ 223int 224tree_next(struct tree *t) 225{ 226 struct dirent *de = NULL; 227 228 /* Handle the startup case by returning the initial entry. */ 229 if (t->flags & needsReturn) { 230 t->flags &= ~needsReturn; 231 return (1); 232 } 233 234 while (t->stack != NULL) { 235 /* If there's an open dir, get the next entry from there. */ 236 while (t->d != NULL) { 237 de = readdir(t->d); 238 if (de == NULL) { 239 closedir(t->d); 240 t->d = NULL; 241 } else if (de->d_name[0] == '.' 242 && de->d_name[1] == '\0') { 243 /* Skip '.' */ 244 } else if (de->d_name[0] == '.' 245 && de->d_name[1] == '.' 246 && de->d_name[2] == '\0') { 247 /* Skip '..' */ 248 } else { 249 /* 250 * Append the path to the current path 251 * and return it. 252 */ 253 tree_append(t, de->d_name, D_NAMELEN(de)); 254 t->flags &= ~hasLstat; 255 t->flags &= ~hasStat; 256 return (1); 257 } 258 } 259 260 /* If the current dir needs to be traversed, set it up. */ 261 if (t->stack->flags & needsTraversal) { 262 tree_append(t, t->stack->name, strlen(t->stack->name)); 263 t->stack->flags &= ~needsTraversal; 264 /* If it is a link, set up fd for the ascent. */ 265 if (t->stack->flags & isDirLink) { 266 t->stack->fd = open(".", O_RDONLY); 267 t->openCount++; 268 if (t->openCount > t->maxOpenCount) 269 t->maxOpenCount = t->openCount; 270 } 271 if (chdir(t->stack->name) == 0) { 272 t->depth++; 273 t->dirname_length = t->path_length; 274 t->d = opendir("."); 275 } else 276 tree_pop(t); 277 continue; 278 } 279 280 /* We've done everything necessary for the top stack entry. */ 281 tree_ascend(t); 282 tree_pop(t); 283 } 284 return (0); 285} 286 287/* 288 * Called by the client to mark the directory just returned from 289 * tree_next() as needing to be visited. 290 */ 291void 292tree_descend(struct tree *t) 293{ 294 const struct stat *s = tree_current_lstat(t); 295 296 if (S_ISDIR(s->st_mode)) { 297 tree_add(t, t->basename); 298 t->stack->flags |= isDir; 299 } 300 301 if (S_ISLNK(s->st_mode) && S_ISDIR(tree_current_stat(t)->st_mode)) { 302 tree_add(t, t->basename); 303 t->stack->flags |= isDirLink; 304 } 305} 306 307/* 308 * Get the stat() data for the entry just returned from tree_next(). 309 */ 310const struct stat * 311tree_current_stat(struct tree *t) 312{ 313 if (!(t->flags & hasStat)) { 314 stat(t->basename, &t->st); 315 t->flags |= hasStat; 316 } 317 return (&t->st); 318} 319 320/* 321 * Get the lstat() data for the entry just returned from tree_next(). 322 */ 323const struct stat * 324tree_current_lstat(struct tree *t) 325{ 326 if (!(t->flags & hasLstat)) { 327 lstat(t->basename, &t->lst); 328 t->flags |= hasLstat; 329 } 330 return (&t->lst); 331} 332 333/* 334 * Return the access path for the entry just returned from tree_next(). 335 */ 336const char * 337tree_current_access_path(struct tree *t) 338{ 339 return (t->basename); 340} 341 342/* 343 * Return the full path for the entry just returned from tree_next(). 344 */ 345const char * 346tree_current_path(struct tree *t) 347{ 348 return (t->buff); 349} 350 351/* 352 * Return the length of the path for the entry just returned from tree_next(). 353 */ 354size_t 355tree_current_pathlen(struct tree *t) 356{ 357 return (t->path_length); 358} 359 360/* 361 * Return the nesting depth of the entry just returned from tree_next(). 362 */ 363int 364tree_current_depth(struct tree *t) 365{ 366 return (t->depth); 367} 368 369/* 370 * Terminate the traversal and release any resources. 371 */ 372void 373tree_close(struct tree *t) 374{ 375 /* Release anything remaining in the stack. */ 376 while (t->stack != NULL) 377 tree_pop(t); 378 if (t->buff) 379 free(t->buff); 380 /* chdir() back to where we started. */ 381 if (t->initialDirFd >= 0) { 382 fchdir(t->initialDirFd); 383 close(t->initialDirFd); 384 t->initialDirFd = -1; 385 } 386 free(t); 387} 388 389 390#if 0 391/* Main function for testing. */ 392#include <stdio.h> 393 394int main(int argc, char **argv) 395{ 396 size_t max_path_len = 0; 397 int max_depth = 0; 398 399 system("pwd"); 400 while (*++argv) { 401 struct tree *t = tree_open(*argv); 402 while (tree_next(t)) { 403 size_t path_len = tree_current_pathlen(t); 404 int depth = tree_current_depth(t); 405 if (path_len > max_path_len) 406 max_path_len = path_len; 407 if (depth > max_depth) 408 max_depth = depth; 409 printf("%s\n", tree_current_path(t)); 410 if (S_ISDIR(tree_current_lstat(t)->st_mode)) 411 tree_descend(t); /* Descend into every dir. */ 412 } 413 tree_close(t); 414 printf("Max path length: %d\n", max_path_len); 415 printf("Max depth: %d\n", max_depth); 416 printf("Final open count: %d\n", t->openCount); 417 printf("Max open count: %d\n", t->maxOpenCount); 418 fflush(stdout); 419 system("pwd"); 420 } 421 return (0); 422} 423#endif 424