1 /* $NetBSD: cd.c,v 1.29 2002/11/24 22:35:39 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Kenneth Almquist. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "@(#)cd.c 8.2 (Berkeley) 5/4/95"; 43 #else 44 __RCSID("$NetBSD: cd.c,v 1.29 2002/11/24 22:35:39 christos Exp $"); 45 #endif 46 #endif /* not lint */ 47 48 #include <sys/types.h> 49 #include <sys/stat.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <errno.h> 54 55 /* 56 * The cd and pwd commands. 57 */ 58 59 #include "shell.h" 60 #include "var.h" 61 #include "nodes.h" /* for jobs.h */ 62 #include "jobs.h" 63 #include "options.h" 64 #include "output.h" 65 #include "memalloc.h" 66 #include "error.h" 67 #include "exec.h" 68 #include "redir.h" 69 #include "mystring.h" 70 #include "show.h" 71 #include "cd.h" 72 73 STATIC int docd(char *, int); 74 STATIC char *getcomponent(void); 75 STATIC void updatepwd(char *); 76 77 char *curdir = NULL; /* current working directory */ 78 char *prevdir; /* previous working directory */ 79 STATIC char *cdcomppath; 80 81 int 82 cdcmd(int argc, char **argv) 83 { 84 const char *dest; 85 const char *path; 86 char *p, *d; 87 struct stat statb; 88 int print = 0; 89 90 nextopt(nullstr); 91 92 /* Try (quite hard) to have 'curdir' defined, nothing has set 93 it on entry to the shell, but we want 'cd fred; cd -' to work. */ 94 getpwd(1); 95 dest = *argptr; 96 if (dest == NULL) { 97 dest = bltinlookup("HOME", 1); 98 if (dest == NULL) 99 error("HOME not set"); 100 } else { 101 if (argptr[1]) { 102 /* Do 'ksh' style substitution */ 103 if (!curdir) 104 error("PWD not set"); 105 p = strstr(curdir, dest); 106 if (!p) 107 error("bad substitution"); 108 d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1); 109 memcpy(d, curdir, p - curdir); 110 strcpy(d + (p - curdir), argptr[1]); 111 strcat(d, p + strlen(dest)); 112 dest = d; 113 print = 1; 114 } 115 } 116 117 if (*dest == '\0') 118 dest = "."; 119 if (dest[0] == '-' && dest[1] == '\0') { 120 dest = prevdir ? prevdir : curdir; 121 print = 1; 122 if (dest) 123 print = 1; 124 else 125 dest = "."; 126 } 127 if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL) 128 path = nullstr; 129 while ((p = padvance(&path, dest)) != NULL) { 130 if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) { 131 if (!print) { 132 /* 133 * XXX - rethink 134 */ 135 if (p[0] == '.' && p[1] == '/' && p[2] != '\0') 136 p += 2; 137 print = strcmp(p, dest); 138 } 139 if (docd(p, print) >= 0) 140 return 0; 141 142 } 143 } 144 error("can't cd to %s", dest); 145 /* NOTREACHED */ 146 } 147 148 149 /* 150 * Actually do the chdir. In an interactive shell, print the 151 * directory name if "print" is nonzero. 152 */ 153 154 STATIC int 155 docd(char *dest, int print) 156 { 157 char *p; 158 char *q; 159 char *component; 160 struct stat statb; 161 int first; 162 int badstat; 163 164 TRACE(("docd(\"%s\", %d) called\n", dest, print)); 165 166 /* 167 * Check each component of the path. If we find a symlink or 168 * something we can't stat, clear curdir to force a getcwd() 169 * next time we get the value of the current directory. 170 */ 171 badstat = 0; 172 cdcomppath = stalloc(strlen(dest) + 1); 173 scopy(dest, cdcomppath); 174 STARTSTACKSTR(p); 175 if (*dest == '/') { 176 STPUTC('/', p); 177 cdcomppath++; 178 } 179 first = 1; 180 while ((q = getcomponent()) != NULL) { 181 if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0')) 182 continue; 183 if (! first) 184 STPUTC('/', p); 185 first = 0; 186 component = q; 187 while (*q) 188 STPUTC(*q++, p); 189 if (equal(component, "..")) 190 continue; 191 STACKSTRNUL(p); 192 if ((lstat(stackblock(), &statb) < 0) 193 || (S_ISLNK(statb.st_mode))) { 194 /* print = 1; */ 195 badstat = 1; 196 break; 197 } 198 } 199 200 INTOFF; 201 if (chdir(dest) < 0) { 202 INTON; 203 return -1; 204 } 205 updatepwd(badstat ? NULL : dest); 206 INTON; 207 if (print && iflag && curdir) 208 out1fmt("%s\n", curdir); 209 return 0; 210 } 211 212 213 /* 214 * Get the next component of the path name pointed to by cdcomppath. 215 * This routine overwrites the string pointed to by cdcomppath. 216 */ 217 218 STATIC char * 219 getcomponent() 220 { 221 char *p; 222 char *start; 223 224 if ((p = cdcomppath) == NULL) 225 return NULL; 226 start = cdcomppath; 227 while (*p != '/' && *p != '\0') 228 p++; 229 if (*p == '\0') { 230 cdcomppath = NULL; 231 } else { 232 *p++ = '\0'; 233 cdcomppath = p; 234 } 235 return start; 236 } 237 238 239 240 /* 241 * Update curdir (the name of the current directory) in response to a 242 * cd command. We also call hashcd to let the routines in exec.c know 243 * that the current directory has changed. 244 */ 245 246 STATIC void 247 updatepwd(char *dir) 248 { 249 char *new; 250 char *p; 251 252 hashcd(); /* update command hash table */ 253 254 /* 255 * If our argument is NULL, we don't know the current directory 256 * any more because we traversed a symbolic link or something 257 * we couldn't stat(). 258 */ 259 if (dir == NULL || curdir == NULL) { 260 if (prevdir) 261 ckfree(prevdir); 262 INTOFF; 263 prevdir = curdir; 264 curdir = NULL; 265 getpwd(1); 266 INTON; 267 if (curdir) 268 setvar("PWD", curdir, VEXPORT); 269 else 270 unsetvar("PWD", 0); 271 return; 272 } 273 cdcomppath = stalloc(strlen(dir) + 1); 274 scopy(dir, cdcomppath); 275 STARTSTACKSTR(new); 276 if (*dir != '/') { 277 p = curdir; 278 while (*p) 279 STPUTC(*p++, new); 280 if (p[-1] == '/') 281 STUNPUTC(new); 282 } 283 while ((p = getcomponent()) != NULL) { 284 if (equal(p, "..")) { 285 while (new > stackblock() && (STUNPUTC(new), *new) != '/'); 286 } else if (*p != '\0' && ! equal(p, ".")) { 287 STPUTC('/', new); 288 while (*p) 289 STPUTC(*p++, new); 290 } 291 } 292 if (new == stackblock()) 293 STPUTC('/', new); 294 STACKSTRNUL(new); 295 INTOFF; 296 if (prevdir) 297 ckfree(prevdir); 298 prevdir = curdir; 299 curdir = savestr(stackblock()); 300 setvar("PWD", curdir, VEXPORT); 301 INTON; 302 } 303 304 305 306 int 307 pwdcmd(int argc, char **argv) 308 { 309 getpwd(0); 310 out1str(curdir); 311 out1c('\n'); 312 return 0; 313 } 314 315 316 317 318 #define MAXPWD 256 319 320 /* 321 * Find out what the current directory is. If we already know the current 322 * directory, this routine returns immediately. 323 */ 324 void 325 getpwd(int noerror) 326 { 327 char *pwd; 328 struct stat stdot, stpwd; 329 static int first = 1; 330 int i; 331 332 if (curdir) 333 return; 334 335 if (first) { 336 pwd = getenv("PWD"); 337 if (pwd && *pwd == '/' && stat(".", &stdot) != -1 && 338 stat(pwd, &stpwd) != -1 && 339 stdot.st_dev == stpwd.st_dev && 340 stdot.st_ino == stpwd.st_ino) { 341 curdir = savestr(pwd); 342 return; 343 } 344 } 345 first = 0; 346 347 /* 348 * Things are a bit complicated here; we could have just used 349 * getcwd, but traditionally getcwd is implemented using popen 350 * to /bin/pwd. This creates a problem for us, since we cannot 351 * keep track of the job if it is being ran behind our backs. 352 * So we re-implement getcwd(), and we suppress interrupts 353 * throughout the process. This is not completely safe, since 354 * the user can still break out of it by killing the pwd program. 355 * We still try to use getcwd for systems that we know have a 356 * c implementation of getcwd, that does not open a pipe to 357 * /bin/pwd. 358 */ 359 #if defined(__NetBSD__) || defined(__SVR4) 360 361 for (i = MAXPWD;; i *= 2) { 362 pwd = stalloc(i); 363 if (getcwd(pwd, i) != NULL) 364 break; 365 stunalloc(pwd); 366 if (errno == ERANGE) 367 continue; 368 if (!noerror) 369 error("getcwd() failed: %s", strerror(errno)); 370 pwd = 0; 371 break; 372 } 373 374 if (pwd) 375 curdir = savestr(pwd); 376 #else 377 { 378 char *p; 379 int status; 380 struct job *jp; 381 int pip[2]; 382 char buf[MAXPWD]; 383 384 INTOFF; 385 if (pipe(pip) < 0) 386 error("Pipe call failed"); 387 jp = makejob((union node *)NULL, 1); 388 if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) { 389 (void) close(pip[0]); 390 if (pip[1] != 1) { 391 close(1); 392 copyfd(pip[1], 1); 393 close(pip[1]); 394 } 395 (void) execl("/bin/pwd", "pwd", (char *)0); 396 error("Cannot exec /bin/pwd"); 397 } 398 (void) close(pip[1]); 399 pip[1] = -1; 400 p = buf; 401 while ((i = read(pip[0], p, buf + MAXPWD - p)) > 0 402 || (i == -1 && errno == EINTR)) { 403 if (i > 0) 404 p += i; 405 } 406 (void) close(pip[0]); 407 pip[0] = -1; 408 status = waitforjob(jp); 409 if (status != 0) 410 error((char *)0); 411 if (i < 0 || p == buf || p[-1] != '\n') { 412 if (noerror) { 413 INTON; 414 return; 415 } 416 error("pwd command failed"); 417 } 418 p[-1] = '\0'; 419 } 420 curdir = savestr(buf); 421 INTON; 422 #endif 423 } 424