src/ash/cd.c

   1 /*      $NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl 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 #ifdef HAVE_SYS_CDEFS_H
  36 #include <sys/cdefs.h>
  37 #endif
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)cd.c        8.2 (Berkeley) 5/4/95";
  41 #else
  42 __RCSID("$NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/types.h>
  47 #include <sys/stat.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51 #include <errno.h>
  52
  53 /*
  54  * The cd and pwd commands.
  55  */
  56
  57 #include "shell.h"
  58 #include "var.h"
  59 #include "nodes.h"      /* for jobs.h */
  60 #include "jobs.h"
  61 #include "options.h"
  62 #include "output.h"
  63 #include "memalloc.h"
  64 #include "error.h"
  65 #include "exec.h"
  66 #include "redir.h"
  67 #include "mystring.h"
  68 #include "show.h"
  69 #include "cd.h"
  70
  71 STATIC int docd(char *, int);
  72 STATIC char *getcomponent(void);
  73 STATIC void updatepwd(char *);
  74 STATIC void find_curdir(int noerror);
  75
  76 char *curdir = NULL;            /* current working directory */
  77 char *prevdir;                  /* previous working directory */
  78 STATIC char *cdcomppath;
  79
  80 int
  81 cdcmd(int argc, char **argv)
  82 {
  83         const char *dest;
  84         const char *path;
  85         char *p, *d;
  86         struct stat statb;
  87         int print = cdprint;    /* set -cdprint to enable */
  88
  89         nextopt(nullstr);
  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         if (IS_ROOT(dest) || (path = bltinlookup("CDPATH", 1)) == NULL)
 125                 path = nullstr;
 126         while ((p = padvance(&path, dest)) != NULL) {
 127                 if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
 128                         if (!print) {
 129                                 /*
 130                                  * XXX - rethink
 131                                  */
 132                                 if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
 133                                         p += 2;
 134                                 print = strcmp(p, dest);
 135                         }
 136                         if (docd(p, print) >= 0)
 137                                 return 0;
 138
 139                 }
 140         }
 141         error("can't cd to %s", dest);
 142         /* NOTREACHED */
 143 }
 144
 145
 146 /*
 147  * Actually do the chdir.  In an interactive shell, print the
 148  * directory name if "print" is nonzero.
 149  */
 150
 151 STATIC int
 152 docd(char *dest, int print)
 153 {
 154         char *p;
 155         char *q;
 156         char *component;
 157         struct stat statb;
 158         int first;
 159         int badstat;
 160
 161         TRACE(("docd(\"%s\", %d) called\n", dest, print));
 162
 163         /*
 164          *  Check each component of the path. If we find a symlink or
 165          *  something we can't stat, clear curdir to force a getcwd()
 166          *  next time we get the value of the current directory.
 167          */
 168         badstat = 0;
 169         cdcomppath = stalloc(strlen(dest) + 1);
 170         scopy(dest, cdcomppath);
 171         STARTSTACKSTR(p);
 172         if (IS_ROOT(dest)) {
 173                 STPUTC('/', p);
 174                 cdcomppath++;
 175         }
 176         first = 1;
 177         while ((q = getcomponent()) != NULL) {
 178                 if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
 179                         continue;
 180                 if (! first)
 181                         STPUTC('/', p);
 182                 first = 0;
 183                 component = q;
 184                 while (*q)
 185                         STPUTC(*q++, p);
 186                 if (equal(component, ".."))
 187                         continue;
 188                 STACKSTRNUL(p);
 189                 if ((lstat(stackblock(), &statb) < 0)
 190                     || (S_ISLNK(statb.st_mode)))  {
 191                         /* print = 1; */
 192                         badstat = 1;
 193                         break;
 194                 }
 195         }
 196
 197         INTOFF;
 198         if (chdir(dest) < 0) {
 199                 INTON;
 200                 return -1;
 201         }
 202         updatepwd(badstat ? NULL : dest);
 203         INTON;
 204         if (print && iflag && curdir)
 205                 out1fmt("%s\n", curdir);
 206         return 0;
 207 }
 208
 209
 210 /*
 211  * Get the next component of the path name pointed to by cdcomppath.
 212  * This routine overwrites the string pointed to by cdcomppath.
 213  */
 214
 215 STATIC char *
 216 getcomponent()
 217 {
 218         char *p;
 219         char *start;
 220
 221         if ((p = cdcomppath) == NULL)
 222                 return NULL;
 223         start = cdcomppath;
 224         while (*p != '/' && *p != '\0')
 225                 p++;
 226         if (*p == '\0') {
 227                 cdcomppath = NULL;
 228         } else {
 229                 *p++ = '\0';
 230                 cdcomppath = p;
 231         }
 232         return start;
 233 }
 234
 235
 236
 237 /*
 238  * Update curdir (the name of the current directory) in response to a
 239  * cd command.  We also call hashcd to let the routines in exec.c know
 240  * that the current directory has changed.
 241  */
 242
 243 STATIC void
 244 updatepwd(char *dir)
 245 {
 246         char *new;
 247         char *p;
 248
 249         hashcd();                               /* update command hash table */
 250
 251         /*
 252          * If our argument is NULL, we don't know the current directory
 253          * any more because we traversed a symbolic link or something
 254          * we couldn't stat().
 255          */
 256         if (dir == NULL || curdir == NULL)  {
 257                 if (prevdir)
 258                         ckfree(prevdir);
 259                 INTOFF;
 260                 prevdir = curdir;
 261                 curdir = NULL;
 262                 getpwd(1);
 263                 INTON;
 264                 if (curdir)
 265                         setvar("PWD", curdir, VEXPORT);
 266                 else
 267                         unsetvar("PWD", 0);
 268                 return;
 269         }
 270         cdcomppath = stalloc(strlen(dir) + 1);
 271         scopy(dir, cdcomppath);
 272         STARTSTACKSTR(new);
 273         if (!IS_ROOT(dir)) {
 274                 p = curdir;
 275                 while (*p)
 276                         STPUTC(*p++, new);
 277                 if (p[-1] == '/')
 278                         STUNPUTC(new);
 279         }
 280         while ((p = getcomponent()) != NULL) {
 281                 if (equal(p, "..")) {
 282                         while (new > stackblock() && (STUNPUTC(new), *new) != '/');
 283                 } else if (*p != '\0' && ! equal(p, ".")) {
 284                         STPUTC('/', new);
 285                         while (*p)
 286                                 STPUTC(*p++, new);
 287                 }
 288         }
 289         if (new == stackblock())
 290                 STPUTC('/', new);
 291         STACKSTRNUL(new);
 292         INTOFF;
 293         if (prevdir)
 294                 ckfree(prevdir);
 295         prevdir = curdir;
 296         curdir = savestr(stackblock());
 297         setvar("PWD", curdir, VEXPORT);
 298         INTON;
 299 }
 300
 301 /*
 302  * Posix says the default should be 'pwd -L' (as below), however
 303  * the 'cd' command (above) does something much nearer to the
 304  * posix 'cd -P' (not the posix default of 'cd -L').
 305  * If 'cd' is changed to support -P/L then the default here
 306  * needs to be revisited if the historic behaviour is to be kept.
 307  */
 308
 309 int
 310 pwdcmd(int argc, char **argv)
 311 {
 312         int i;
 313         char opt = 'L';
 314
 315         while ((i = nextopt("LP")) != '\0')
 316                 opt = i;
 317         if (*argptr)
 318                 error("unexpected argument");
 319
 320         if (opt == 'L')
 321                 getpwd(0);
 322         else
 323                 find_curdir(0);
 324
 325         setvar("PWD", curdir, VEXPORT);
 326         out1str(curdir);
 327         out1c('\n');
 328         return 0;
 329 }
 330
 331
 332
 333
 334 #define MAXPWD 256
 335
 336 /*
 337  * Find out what the current directory is. If we already know the current
 338  * directory, this routine returns immediately.
 339  */
 340 void
 341 getpwd(int noerror)
 342 {
 343         char *pwd;
 344         struct stat stdot, stpwd;
 345         static int first = 1;
 346
 347         if (curdir)
 348                 return;
 349
 350         if (first) {
 351                 first = 0;
 352                 pwd = getenv("PWD");
 353                 if (pwd && IS_ROOT(pwd) && stat(".", &stdot) != -1 &&
 354                     stat(pwd, &stpwd) != -1 &&
 355                     stdot.st_dev == stpwd.st_dev &&
 356                     stdot.st_ino == stpwd.st_ino) {
 357                         curdir = savestr(pwd);
 358                         return;
 359                 }
 360         }
 361
 362         find_curdir(noerror);
 363
 364         return;
 365 }
 366
 367 STATIC void
 368 find_curdir(int noerror)
 369 {
 370         int i;
 371         char *pwd;
 372
 373         /*
 374          * Things are a bit complicated here; we could have just used
 375          * getcwd, but traditionally getcwd is implemented using popen
 376          * to /bin/pwd. This creates a problem for us, since we cannot
 377          * keep track of the job if it is being ran behind our backs.
 378          * So we re-implement getcwd(), and we suppress interrupts
 379          * throughout the process. This is not completely safe, since
 380          * the user can still break out of it by killing the pwd program.
 381          * We still try to use getcwd for systems that we know have a
 382          * c implementation of getcwd, that does not open a pipe to
 383          * /bin/pwd.
 384          */
 385 #if defined(__NetBSD__) || defined(__SVR4) || defined(__INNOTEK_LIBC__) || 1 /* bird: nobody spawns pwd any more (we hope). */
 386
 387         for (i = MAXPWD;; i *= 2) {
 388                 pwd = stalloc(i);
 389                 if (getcwd(pwd, i) != NULL) {
 390                         curdir = savestr(pwd);
 391                         return;
 392                 }
 393                 stunalloc(pwd);
 394                 if (errno == ERANGE)
 395                         continue;
 396                 if (!noerror)
 397                         error("getcwd() failed: %s", strerror(errno));
 398                 return;
 399         }
 400 #else
 401         {
 402                 char *p;
 403                 int status;
 404                 struct job *jp;
 405                 int pip[2];
 406
 407                 pwd = stalloc(MAXPWD);
 408                 INTOFF;
 409                 if (pipe(pip) < 0)
 410                         error("Pipe call failed");
 411                 jp = makejob((union node *)NULL, 1);
 412                 if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
 413                         (void) close(pip[0]);
 414                         if (pip[1] != 1) {
 415                                 close(1);
 416                                 copyfd(pip[1], 1);
 417                                 close(pip[1]);
 418                         }
 419                         (void) execl("/bin/pwd", "pwd", (char *)0);
 420                         error("Cannot exec /bin/pwd");
 421                 }
 422                 (void) close(pip[1]);
 423                 pip[1] = -1;
 424                 p = pwd;
 425                 while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
 426                      || (i == -1 && errno == EINTR)) {
 427                         if (i > 0)
 428                                 p += i;
 429                 }
 430                 (void) close(pip[0]);
 431                 pip[0] = -1;
 432                 status = waitforjob(jp);
 433                 if (status != 0)
 434                         error((char *)0);
 435                 if (i < 0 || p == pwd || p[-1] != '\n') {
 436                         if (noerror) {
 437                                 INTON;
 438                                 return;
 439                         }
 440                         error("pwd command failed");
 441                 }
 442                 p[-1] = '\0';
 443                 INTON;
 444                 curdir = savestr(pwd);
 445                 return;
 446         }
 447 #endif
 448 }