bin/sh/cd.c

   1 /*      $NetBSD: cd.c,v 1.44 2011/08/31 16:24:54 plunky 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 1.44 2011/08/31 16:24:54 plunky 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                     || (S_ISLNK(statb.st_mode)))  {
 195                         /* print = 1; */
 196                         badstat = 1;
 197                         break;
 198                 }
 199         }
 200
 201         INTOFF;
 202         if (chdir(dest) < 0) {
 203                 INTON;
 204                 return -1;
 205         }
 206         updatepwd(badstat ? NULL : dest);
 207         INTON;
 208         if (print && iflag == 1 && curdir)
 209                 out1fmt("%s\n", curdir);
 210         return 0;
 211 }
 212
 213
 214 /*
 215  * Get the next component of the path name pointed to by cdcomppath.
 216  * This routine overwrites the string pointed to by cdcomppath.
 217  */
 218
 219 STATIC char *
 220 getcomponent(void)
 221 {
 222         char *p;
 223         char *start;
 224
 225         if ((p = cdcomppath) == NULL)
 226                 return NULL;
 227         start = cdcomppath;
 228         while (*p != '/' && *p != '\0')
 229                 p++;
 230         if (*p == '\0') {
 231                 cdcomppath = NULL;
 232         } else {
 233                 *p++ = '\0';
 234                 cdcomppath = p;
 235         }
 236         return start;
 237 }
 238
 239
 240
 241 /*
 242  * Update curdir (the name of the current directory) in response to a
 243  * cd command.  We also call hashcd to let the routines in exec.c know
 244  * that the current directory has changed.
 245  */
 246
 247 STATIC void
 248 updatepwd(const char *dir)
 249 {
 250         char *new;
 251         char *p;
 252
 253         hashcd();                               /* update command hash table */
 254
 255         /*
 256          * If our argument is NULL, we don't know the current directory
 257          * any more because we traversed a symbolic link or something
 258          * we couldn't stat().
 259          */
 260         if (dir == NULL || curdir == NULL)  {
 261                 if (prevdir)
 262                         ckfree(prevdir);
 263                 INTOFF;
 264                 prevdir = curdir;
 265                 curdir = NULL;
 266                 getpwd(1);
 267                 INTON;
 268                 if (curdir) {
 269                         setvar("OLDPWD", prevdir, VEXPORT);
 270                         setvar("PWD", curdir, VEXPORT);
 271                 } else
 272                         unsetvar("PWD", 0);
 273                 return;
 274         }
 275         cdcomppath = stalloc(strlen(dir) + 1);
 276         scopy(dir, cdcomppath);
 277         STARTSTACKSTR(new);
 278         if (*dir != '/') {
 279                 p = curdir;
 280                 while (*p)
 281                         STPUTC(*p++, new);
 282                 if (p[-1] == '/')
 283                         STUNPUTC(new);
 284         }
 285         while ((p = getcomponent()) != NULL) {
 286                 if (equal(p, "..")) {
 287                         while (new > stackblock() && (STUNPUTC(new), *new) != '/');
 288                 } else if (*p != '\0' && ! equal(p, ".")) {
 289                         STPUTC('/', new);
 290                         while (*p)
 291                                 STPUTC(*p++, new);
 292                 }
 293         }
 294         if (new == stackblock())
 295                 STPUTC('/', new);
 296         STACKSTRNUL(new);
 297         INTOFF;
 298         if (prevdir)
 299                 ckfree(prevdir);
 300         prevdir = curdir;
 301         curdir = savestr(stackblock());
 302         setvar("OLDPWD", prevdir, VEXPORT);
 303         setvar("PWD", curdir, VEXPORT);
 304         INTON;
 305 }
 306
 307 /*
 308  * Posix says the default should be 'pwd -L' (as below), however
 309  * the 'cd' command (above) does something much nearer to the
 310  * posix 'cd -P' (not the posix default of 'cd -L').
 311  * If 'cd' is changed to support -P/L then the default here
 312  * needs to be revisited if the historic behaviour is to be kept.
 313  */
 314
 315 int
 316 pwdcmd(int argc, char **argv)
 317 {
 318         int i;
 319         char opt = 'L';
 320
 321         while ((i = nextopt("LP")) != '\0')
 322                 opt = i;
 323         if (*argptr)
 324                 error("unexpected argument");
 325
 326         if (opt == 'L')
 327                 getpwd(0);
 328         else
 329                 find_curdir(0);
 330
 331         setvar("OLDPWD", prevdir, VEXPORT);
 332         setvar("PWD", curdir, VEXPORT);
 333         out1str(curdir);
 334         out1c('\n');
 335         return 0;
 336 }
 337
 338
 339
 340 void
 341 initpwd(void)
 342 {
 343         getpwd(1);
 344         if (curdir)
 345                 setvar("PWD", curdir, VEXPORT);
 346         else
 347                 sh_warnx("Cannot determine current working directory");
 348 }
 349
 350 #define MAXPWD 256
 351
 352 /*
 353  * Find out what the current directory is. If we already know the current
 354  * directory, this routine returns immediately.
 355  */
 356 void
 357 getpwd(int noerror)
 358 {
 359         char *pwd;
 360         struct stat stdot, stpwd;
 361         static int first = 1;
 362
 363         if (curdir)
 364                 return;
 365
 366         if (first) {
 367                 first = 0;
 368                 pwd = getenv("PWD");
 369                 if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
 370                     stat(pwd, &stpwd) != -1 &&
 371                     stdot.st_dev == stpwd.st_dev &&
 372                     stdot.st_ino == stpwd.st_ino) {
 373                         curdir = savestr(pwd);
 374                         return;
 375                 }
 376         }
 377
 378         find_curdir(noerror);
 379
 380         return;
 381 }
 382
 383 STATIC void
 384 find_curdir(int noerror)
 385 {
 386         int i;
 387         char *pwd;
 388
 389         /*
 390          * Things are a bit complicated here; we could have just used
 391          * getcwd, but traditionally getcwd is implemented using popen
 392          * to /bin/pwd. This creates a problem for us, since we cannot
 393          * keep track of the job if it is being ran behind our backs.
 394          * So we re-implement getcwd(), and we suppress interrupts
 395          * throughout the process. This is not completely safe, since
 396          * the user can still break out of it by killing the pwd program.
 397          * We still try to use getcwd for systems that we know have a
 398          * c implementation of getcwd, that does not open a pipe to
 399          * /bin/pwd.
 400          */
 401 #if defined(__NetBSD__) || defined(__SVR4) || defined(__minix)
 402
 403         for (i = MAXPWD;; i *= 2) {
 404                 pwd = stalloc(i);
 405                 if (getcwd(pwd, i) != NULL) {
 406                         curdir = savestr(pwd);
 407                         return;
 408                 }
 409                 stunalloc(pwd);
 410                 if (errno == ERANGE)
 411                         continue;
 412                 if (!noerror)
 413                         error("getcwd() failed: %s", strerror(errno));
 414                 return;
 415         }
 416 #else
 417         {
 418                 char *p;
 419                 int status;
 420                 struct job *jp;
 421                 int pip[2];
 422
 423                 pwd = stalloc(MAXPWD);
 424                 INTOFF;
 425                 if (pipe(pip) < 0)
 426                         error("Pipe call failed");
 427                 jp = makejob(NULL, 1);
 428                 if (forkshell(jp, NULL, FORK_NOJOB) == 0) {
 429                         (void) close(pip[0]);
 430                         if (pip[1] != 1) {
 431                                 close(1);
 432                                 copyfd(pip[1], 1, 1);
 433                                 close(pip[1]);
 434                         }
 435                         (void) execl("/bin/pwd", "pwd", (char *)0);
 436                         error("Cannot exec /bin/pwd");
 437                 }
 438                 (void) close(pip[1]);
 439                 pip[1] = -1;
 440                 p = pwd;
 441                 while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
 442                      || (i == -1 && errno == EINTR)) {
 443                         if (i > 0)
 444                                 p += i;
 445                 }
 446                 (void) close(pip[0]);
 447                 pip[0] = -1;
 448                 status = waitforjob(jp);
 449                 if (status != 0)
 450                         error((char *)0);
 451                 if (i < 0 || p == pwd || p[-1] != '\n') {
 452                         if (noerror) {
 453                                 INTON;
 454                                 return;
 455                         }
 456                         error("pwd command failed");
 457                 }
 458                 p[-1] = '\0';
 459                 INTON;
 460                 curdir = savestr(pwd);
 461                 return;
 462         }
 463 #endif
 464 }