1 /* $NetBSD: cd.c,v 1.47 2016/12/26 02:27:57 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)cd.c 8.2 (Berkeley) 5/4/95"; 39 #else 40 __RCSID("$NetBSD: cd.c,v 1.47 2016/12/26 02:27:57 christos Exp $"); 41 #endif 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 #include <errno.h> 50 51 /* 52 * The cd and pwd commands. 53 */ 54 55 #include "shell.h" 56 #include "var.h" 57 #include "nodes.h" /* for jobs.h */ 58 #include "jobs.h" 59 #include "options.h" 60 #include "builtins.h" 61 #include "output.h" 62 #include "memalloc.h" 63 #include "error.h" 64 #include "exec.h" 65 #include "redir.h" 66 #include "mystring.h" 67 #include "show.h" 68 #include "cd.h" 69 70 STATIC int docd(const char *, int); 71 STATIC char *getcomponent(void); 72 STATIC void updatepwd(const char *); 73 STATIC void find_curdir(int noerror); 74 75 char *curdir = NULL; /* current working directory */ 76 char *prevdir; /* previous working directory */ 77 STATIC char *cdcomppath; 78 79 int 80 cdcmd(int argc, char **argv) 81 { 82 const char *dest; 83 const char *path, *p; 84 char *d; 85 struct stat statb; 86 int print = cdprint; /* set -cdprint to enable */ 87 88 while (nextopt("P") != '\0') 89 ; 90 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 */ 95 getpwd(1); 96 dest = *argptr; 97 if (dest == NULL) { 98 dest = bltinlookup("HOME", 1); 99 if (dest == NULL) 100 error("HOME not set"); 101 } else { 102 if (argptr[1]) { 103 /* Do 'ksh' style substitution */ 104 if (!curdir) 105 error("PWD not set"); 106 p = strstr(curdir, dest); 107 if (!p) 108 error("bad substitution"); 109 d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1); 110 memcpy(d, curdir, p - curdir); 111 strcpy(d + (p - curdir), argptr[1]); 112 strcat(d, p + strlen(dest)); 113 dest = d; 114 print = 1; 115 } 116 } 117 118 if (dest[0] == '-' && dest[1] == '\0') { 119 dest = prevdir ? prevdir : curdir; 120 print = 1; 121 } 122 if (*dest == '\0') 123 dest = "."; 124 p = dest; 125 if (*p == '.' && *++p == '.') 126 p++; 127 if (*p == 0 || *p == '/' || (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 print = strcmp(p + 2, dest); 137 else 138 print = strcmp(p, dest); 139 } 140 if (docd(p, print) >= 0) 141 return 0; 142 143 } 144 } 145 error("can't cd to %s", dest); 146 /* NOTREACHED */ 147 } 148 149 150 /* 151 * Actually do the chdir. In an interactive shell, print the 152 * directory name if "print" is nonzero. 153 */ 154 155 STATIC int 156 docd(const char *dest, int print) 157 { 158 char *p; 159 char *q; 160 char *component; 161 struct stat statb; 162 int first; 163 int badstat; 164 165 TRACE(("docd(\"%s\", %d) called\n", dest, print)); 166 167 /* 168 * Check each component of the path. If we find a symlink or 169 * something we can't stat, clear curdir to force a getcwd() 170 * next time we get the value of the current directory. 171 */ 172 badstat = 0; 173 cdcomppath = stalloc(strlen(dest) + 1); 174 scopy(dest, cdcomppath); 175 STARTSTACKSTR(p); 176 if (*dest == '/') { 177 STPUTC('/', p); 178 cdcomppath++; 179 } 180 first = 1; 181 while ((q = getcomponent()) != NULL) { 182 if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0')) 183 continue; 184 if (! first) 185 STPUTC('/', p); 186 first = 0; 187 component = q; 188 while (*q) 189 STPUTC(*q++, p); 190 if (equal(component, "..")) 191 continue; 192 STACKSTRNUL(p); 193 if (lstat(stackblock(), &statb) < 0) { 194 badstat = 1; 195 break; 196 } 197 } 198 199 INTOFF; 200 if (chdir(dest) < 0) { 201 INTON; 202 return -1; 203 } 204 updatepwd(badstat ? NULL : dest); 205 INTON; 206 if (print && iflag == 1 && curdir) 207 out1fmt("%s\n", curdir); 208 return 0; 209 } 210 211 212 /* 213 * Get the next component of the path name pointed to by cdcomppath. 214 * This routine overwrites the string pointed to by cdcomppath. 215 */ 216 217 STATIC char * 218 getcomponent(void) 219 { 220 char *p; 221 char *start; 222 223 if ((p = cdcomppath) == NULL) 224 return NULL; 225 start = cdcomppath; 226 while (*p != '/' && *p != '\0') 227 p++; 228 if (*p == '\0') { 229 cdcomppath = NULL; 230 } else { 231 *p++ = '\0'; 232 cdcomppath = p; 233 } 234 return start; 235 } 236 237 238 239 /* 240 * Update curdir (the name of the current directory) in response to a 241 * cd command. We also call hashcd to let the routines in exec.c know 242 * that the current directory has changed. 243 */ 244 245 STATIC void 246 updatepwd(const char *dir) 247 { 248 char *new; 249 char *p; 250 251 hashcd(); /* update command hash table */ 252 253 /* 254 * If our argument is NULL, we don't know the current directory 255 * any more because we traversed a symbolic link or something 256 * we couldn't stat(). 257 */ 258 if (dir == NULL || curdir == NULL) { 259 if (prevdir) 260 ckfree(prevdir); 261 INTOFF; 262 prevdir = curdir; 263 curdir = NULL; 264 getpwd(1); 265 INTON; 266 if (curdir) { 267 setvar("OLDPWD", prevdir, VEXPORT); 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("OLDPWD", prevdir, VEXPORT); 301 setvar("PWD", curdir, VEXPORT); 302 INTON; 303 } 304 305 /* 306 * Posix says the default should be 'pwd -L' (as below), however 307 * the 'cd' command (above) does something much nearer to the 308 * posix 'cd -P' (not the posix default of 'cd -L'). 309 * If 'cd' is changed to support -P/L then the default here 310 * needs to be revisited if the historic behaviour is to be kept. 311 */ 312 313 int 314 pwdcmd(int argc, char **argv) 315 { 316 int i; 317 char opt = 'L'; 318 319 while ((i = nextopt("LP")) != '\0') 320 opt = i; 321 if (*argptr) 322 error("unexpected argument"); 323 324 if (opt == 'L') 325 getpwd(0); 326 else 327 find_curdir(0); 328 329 setvar("OLDPWD", prevdir, VEXPORT); 330 setvar("PWD", curdir, VEXPORT); 331 out1str(curdir); 332 out1c('\n'); 333 return 0; 334 } 335 336 337 338 void 339 initpwd(void) 340 { 341 getpwd(1); 342 if (curdir) 343 setvar("PWD", curdir, VEXPORT); 344 else 345 sh_warnx("Cannot determine current working directory"); 346 } 347 348 #define MAXPWD 256 349 350 /* 351 * Find out what the current directory is. If we already know the current 352 * directory, this routine returns immediately. 353 */ 354 void 355 getpwd(int noerror) 356 { 357 char *pwd; 358 struct stat stdot, stpwd; 359 static int first = 1; 360 361 if (curdir) 362 return; 363 364 if (first) { 365 first = 0; 366 pwd = getenv("PWD"); 367 if (pwd && *pwd == '/' && stat(".", &stdot) != -1 && 368 stat(pwd, &stpwd) != -1 && 369 stdot.st_dev == stpwd.st_dev && 370 stdot.st_ino == stpwd.st_ino) { 371 curdir = savestr(pwd); 372 return; 373 } 374 } 375 376 find_curdir(noerror); 377 378 return; 379 } 380 381 STATIC void 382 find_curdir(int noerror) 383 { 384 int i; 385 char *pwd; 386 387 /* 388 * Things are a bit complicated here; we could have just used 389 * getcwd, but traditionally getcwd is implemented using popen 390 * to /bin/pwd. This creates a problem for us, since we cannot 391 * keep track of the job if it is being ran behind our backs. 392 * So we re-implement getcwd(), and we suppress interrupts 393 * throughout the process. This is not completely safe, since 394 * the user can still break out of it by killing the pwd program. 395 * We still try to use getcwd for systems that we know have a 396 * c implementation of getcwd, that does not open a pipe to 397 * /bin/pwd. 398 */ 399 #if defined(__NetBSD__) || defined(__SVR4) 400 401 for (i = MAXPWD;; i *= 2) { 402 pwd = stalloc(i); 403 if (getcwd(pwd, i) != NULL) { 404 curdir = savestr(pwd); 405 return; 406 } 407 stunalloc(pwd); 408 if (errno == ERANGE) 409 continue; 410 if (!noerror) 411 error("getcwd() failed: %s", strerror(errno)); 412 return; 413 } 414 #else 415 { 416 char *p; 417 int status; 418 struct job *jp; 419 int pip[2]; 420 421 pwd = stalloc(MAXPWD); 422 INTOFF; 423 if (pipe(pip) < 0) 424 error("Pipe call failed"); 425 jp = makejob(NULL, 1); 426 if (forkshell(jp, NULL, FORK_NOJOB) == 0) { 427 (void) close(pip[0]); 428 movefd(pip[1], 1); 429 (void) execl("/bin/pwd", "pwd", (char *)0); 430 error("Cannot exec /bin/pwd"); 431 } 432 (void) close(pip[1]); 433 pip[1] = -1; 434 p = pwd; 435 while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0 436 || (i == -1 && errno == EINTR)) { 437 if (i > 0) 438 p += i; 439 } 440 (void) close(pip[0]); 441 pip[0] = -1; 442 status = waitforjob(jp); 443 if (status != 0) 444 error((char *)0); 445 if (i < 0 || p == pwd || p[-1] != '\n') { 446 if (noerror) { 447 INTON; 448 return; 449 } 450 error("pwd command failed"); 451 } 452 p[-1] = '\0'; 453 INTON; 454 curdir = savestr(pwd); 455 return; 456 } 457 #endif 458 } 459