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dir.c revision 1.20
      1 /* $NetBSD: dir.c,v 1.20 2002/08/12 02:37:26 itojun Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 1980, 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 #if 0
     39 static char sccsid[] = "@(#)dir.c	8.1 (Berkeley) 5/31/93";
     40 #else
     41 __RCSID("$NetBSD: dir.c,v 1.20 2002/08/12 02:37:26 itojun Exp $");
     42 #endif
     43 #endif /* not lint */
     44 
     45 #include <sys/param.h>
     46 #include <sys/stat.h>
     47 
     48 #include <errno.h>
     49 #include <stdarg.h>
     50 #include <stdlib.h>
     51 #include <string.h>
     52 #include <unistd.h>
     53 
     54 #include "csh.h"
     55 #include "dir.h"
     56 #include "extern.h"
     57 
     58 /* Directory management. */
     59 
     60 static struct directory *dfind(Char *);
     61 static Char *dfollow(Char *);
     62 static void printdirs(void);
     63 static Char *dgoto(Char *);
     64 static void skipargs(Char ***, char *);
     65 static void dnewcwd(struct directory *);
     66 static void dset(Char *);
     67 
     68 struct directory dhead;		/* "head" of loop */
     69 int printd;			/* force name to be printed */
     70 
     71 static int dirflag = 0;
     72 
     73 /*
     74  * dinit - initialize current working directory
     75  */
     76 void
     77 dinit(Char *hp)
     78 {
     79     static const char emsg[] = "csh: Trying to start from \"%s\"\n";
     80     char path[MAXPATHLEN];
     81     struct directory *dp;
     82     const char *ecp;
     83     Char *cp;
     84 
     85     /* Don't believe the login shell home, because it may be a symlink */
     86     ecp = getcwd(path, MAXPATHLEN);
     87     if (ecp == NULL || *ecp == '\0') {
     88 	(void)fprintf(csherr, "csh: %s\n", strerror(errno));
     89 	if (hp && *hp) {
     90 	    ecp = short2str(hp);
     91 	    if (chdir(ecp) == -1)
     92 		cp = NULL;
     93 	    else
     94 		cp = hp;
     95 	    (void)fprintf(csherr, emsg, vis_str(hp));
     96 	}
     97 	else
     98 	    cp = NULL;
     99 	if (cp == NULL) {
    100 	    (void)fprintf(csherr, emsg, "/");
    101 	    if (chdir("/") == -1) {
    102 		/* I am not even try to print an error message! */
    103 		xexit(1);
    104 	    }
    105 	    cp = SAVE("/");
    106 	}
    107     }
    108     else {
    109 	struct stat swd, shp;
    110 
    111 	/*
    112 	 * See if $HOME is the working directory we got and use that
    113 	 */
    114 	if (hp && *hp &&
    115 	    stat(ecp, &swd) != -1 && stat(short2str(hp), &shp) != -1 &&
    116 	    swd.st_dev == shp.st_dev && swd.st_ino == shp.st_ino)
    117 	    cp = hp;
    118 	else {
    119 	    const char *cwd;
    120 
    121 	    /*
    122 	     * use PWD if we have it (for subshells)
    123 	     */
    124 	    if ((cwd = getenv("PWD")) != NULL) {
    125 		if (stat(cwd, &shp) != -1 && swd.st_dev == shp.st_dev &&
    126 		    swd.st_ino == shp.st_ino)
    127 		    ecp = cwd;
    128 	    }
    129 	    cp = dcanon(SAVE(ecp), STRNULL);
    130 	}
    131     }
    132 
    133     dp = (struct directory *)xcalloc(1, sizeof(struct directory));
    134     dp->di_name = Strsave(cp);
    135     dp->di_count = 0;
    136     dhead.di_next = dhead.di_prev = dp;
    137     dp->di_next = dp->di_prev = &dhead;
    138     printd = 0;
    139     dnewcwd(dp);
    140 }
    141 
    142 static void
    143 dset(Char *dp)
    144 {
    145     Char **vec;
    146 
    147     /*
    148      * Don't call set() directly cause if the directory contains ` or
    149      * other junk characters glob will fail.
    150      */
    151 
    152     vec = (Char **)xmalloc((size_t)(2 * sizeof(Char **)));
    153     vec[0] = Strsave(dp);
    154     vec[1] = 0;
    155     setq(STRcwd, vec, &shvhed);
    156     Setenv(STRPWD, dp);
    157 }
    158 
    159 #define DIR_LONG 1
    160 #define DIR_VERT 2
    161 #define DIR_LINE 4
    162 
    163 static void
    164 skipargs(Char ***v, char *str)
    165 {
    166     Char  **n, *s;
    167 
    168     n = *v;
    169     dirflag = 0;
    170     for (n++; *n != NULL && (*n)[0] == '-'; n++)
    171 	for (s = &((*n)[1]); *s; s++)
    172 	    switch (*s) {
    173 	    case 'l':
    174 		dirflag |= DIR_LONG;
    175 		break;
    176 	    case 'n':
    177 		dirflag |= DIR_LINE;
    178 		break;
    179 	    case 'v':
    180 		dirflag |= DIR_VERT;
    181 		break;
    182 	    default:
    183 		stderror(ERR_DIRUS, vis_str(**v), str);
    184 		/* NOTREACHED */
    185 	    }
    186     *v = n;
    187 }
    188 
    189 /*
    190  * dodirs - list all directories in directory loop
    191  */
    192 void
    193 /*ARGSUSED*/
    194 dodirs(Char **v, struct command *t)
    195 {
    196     skipargs(&v, "");
    197 
    198     if (*v != NULL)
    199 	stderror(ERR_DIRUS, "dirs", "");
    200     printdirs();
    201 }
    202 
    203 static void
    204 printdirs(void)
    205 {
    206     struct directory *dp;
    207     Char *hp, *s;
    208     int cur, idx, len;
    209 
    210     hp = value(STRhome);
    211     if (*hp == '\0')
    212 	hp = NULL;
    213     dp = dcwd;
    214     idx = 0;
    215     cur = 0;
    216     do {
    217 	if (dp == &dhead)
    218 	    continue;
    219 	if (dirflag & DIR_VERT) {
    220 	    (void)fprintf(cshout, "%d\t", idx++);
    221 	    cur = 0;
    222 	}
    223 	if (!(dirflag & DIR_LONG) && hp != NULL && !eq(hp, STRslash) &&
    224 	    (len = Strlen(hp), Strncmp(hp, dp->di_name, len) == 0) &&
    225 	    (dp->di_name[len] == '\0' || dp->di_name[len] == '/'))
    226 	    len = Strlen(s = (dp->di_name + len)) + 2;
    227 	else
    228 	    len = Strlen(s = dp->di_name) + 1;
    229 
    230 	cur += len;
    231 	if ((dirflag & DIR_LINE) && cur >= 80 - 1 && len < 80) {
    232 	    (void)fprintf(cshout, "\n");
    233 	    cur = len;
    234 	}
    235 	(void) fprintf(cshout, "%s%s%c", (s != dp->di_name)? "~" : "",
    236 	    vis_str(s), (dirflag & DIR_VERT) ? '\n' : ' ');
    237     } while ((dp = dp->di_prev) != dcwd);
    238     if (!(dirflag & DIR_VERT))
    239 	(void)fprintf(cshout, "\n");
    240 }
    241 
    242 void
    243 dtildepr(Char *home, Char *dir)
    244 {
    245     if (!eq(home, STRslash) && prefix(home, dir))
    246 	(void)fprintf(cshout, "~%s", vis_str(dir + Strlen(home)));
    247     else
    248 	(void)fprintf(cshout, "%s", vis_str(dir));
    249 }
    250 
    251 void
    252 dtilde(void)
    253 {
    254     struct directory *d;
    255 
    256     d = dcwd;
    257     do {
    258 	if (d == &dhead)
    259 	    continue;
    260 	d->di_name = dcanon(d->di_name, STRNULL);
    261     } while ((d = d->di_prev) != dcwd);
    262 
    263     dset(dcwd->di_name);
    264 }
    265 
    266 
    267 /* dnormalize():
    268  *	If the name starts with . or .. then we might need to normalize
    269  *	it depending on the symbolic link flags
    270  */
    271 Char *
    272 dnormalize(Char *cp)
    273 {
    274 #define UC (unsigned char)
    275 #define ISDOT(c) (UC(c)[0] == '.' && ((UC(c)[1] == '\0') || (UC(c)[1] == '/')))
    276 #define ISDOTDOT(c) (UC(c)[0] == '.' && ISDOT(&((c)[1])))
    277     if ((unsigned char) cp[0] == '/')
    278 	return (Strsave(cp));
    279 
    280     if (adrof(STRignore_symlinks)) {
    281 	int     dotdot = 0;
    282 	Char   *dp, *cwd;
    283 
    284 	cwd = (Char *)xmalloc((size_t)((Strlen(dcwd->di_name) + 3) *
    285 	    sizeof(Char)));
    286 	(void)Strcpy(cwd, dcwd->di_name);
    287 
    288 	/*
    289 	 * Ignore . and count ..'s
    290 	 */
    291 	while (*cp) {
    292 	    if (ISDOT(cp)) {
    293 		if (*++cp)
    294 		    cp++;
    295 	    }
    296 	    else if (ISDOTDOT(cp)) {
    297 		dotdot++;
    298 		cp += 2;
    299 		if (*cp)
    300 		    cp++;
    301 	    }
    302 	    else
    303 		break;
    304 	}
    305 	while (dotdot > 0) {
    306 	    dp = Strrchr(cwd, '/');
    307 	    if (dp) {
    308 		*dp = '\0';
    309 		dotdot--;
    310 	    }
    311 	    else
    312 		break;
    313 	}
    314 
    315 	if (*cp) {
    316 	    cwd[dotdot = Strlen(cwd)] = '/';
    317 	    cwd[dotdot + 1] = '\0';
    318 	    dp = Strspl(cwd, cp);
    319 	    xfree((ptr_t) cwd);
    320 	    return dp;
    321 	}
    322 	else {
    323 	    if (!*cwd) {
    324 		cwd[0] = '/';
    325 		cwd[1] = '\0';
    326 	    }
    327 	    return cwd;
    328 	}
    329     }
    330     return Strsave(cp);
    331 }
    332 
    333 /*
    334  * dochngd - implement chdir command.
    335  */
    336 void
    337 /*ARGSUSED*/
    338 dochngd(Char **v, struct command *t)
    339 {
    340     struct directory *dp;
    341     Char *cp;
    342 
    343     skipargs(&v, " [<dir>]");
    344     printd = 0;
    345     if (*v == NULL) {
    346 	if ((cp = value(STRhome)) == NULL || *cp == 0)
    347 	    stderror(ERR_NAME | ERR_NOHOMEDIR);
    348 	if (chdir(short2str(cp)) < 0)
    349 	    stderror(ERR_NAME | ERR_CANTCHANGE);
    350 	cp = Strsave(cp);
    351     }
    352     else if (v[1] != NULL)
    353 	stderror(ERR_NAME | ERR_TOOMANY);
    354     else if ((dp = dfind(*v)) != 0) {
    355 	char   *tmp;
    356 
    357 	printd = 1;
    358 	if (chdir(tmp = short2str(dp->di_name)) < 0)
    359 	    stderror(ERR_SYSTEM, tmp, strerror(errno));
    360 	dcwd->di_prev->di_next = dcwd->di_next;
    361 	dcwd->di_next->di_prev = dcwd->di_prev;
    362 	dfree(dcwd);
    363 	dnewcwd(dp);
    364 	return;
    365     }
    366     else
    367 	cp = dfollow(*v);
    368     dp = (struct directory *)xcalloc(1, sizeof(struct directory));
    369     dp->di_name = cp;
    370     dp->di_count = 0;
    371     dp->di_next = dcwd->di_next;
    372     dp->di_prev = dcwd->di_prev;
    373     dp->di_prev->di_next = dp;
    374     dp->di_next->di_prev = dp;
    375     dfree(dcwd);
    376     dnewcwd(dp);
    377 }
    378 
    379 static Char *
    380 dgoto(Char *cp)
    381 {
    382     Char *dp;
    383 
    384     if (*cp != '/') {
    385 	Char *p, *q;
    386 	int cwdlen;
    387 
    388 	for (p = dcwd->di_name; *p++;)
    389 	    continue;
    390 	if ((cwdlen = p - dcwd->di_name - 1) == 1)	/* root */
    391 	    cwdlen = 0;
    392 	for (p = cp; *p++;)
    393 	    continue;
    394 	dp = (Char *)xmalloc((size_t)((cwdlen + (p - cp) + 1) * sizeof(Char)));
    395 	for (p = dp, q = dcwd->di_name; (*p++ = *q++) != '\0';)
    396 	    continue;
    397 	if (cwdlen)
    398 	    p[-1] = '/';
    399 	else
    400 	    p--;		/* don't add a / after root */
    401 	for (q = cp; (*p++ = *q++) != '\0';)
    402 	    continue;
    403 	xfree((ptr_t) cp);
    404 	cp = dp;
    405 	dp += cwdlen;
    406     }
    407     else
    408 	dp = cp;
    409 
    410     cp = dcanon(cp, dp);
    411     return cp;
    412 }
    413 
    414 /*
    415  * dfollow - change to arg directory; fall back on cdpath if not valid
    416  */
    417 static Char *
    418 dfollow(Char *cp)
    419 {
    420     char ebuf[MAXPATHLEN];
    421     struct varent *c;
    422     Char *dp;
    423     int serrno;
    424 
    425     cp = globone(cp, G_ERROR);
    426     /*
    427      * if we are ignoring symlinks, try to fix relatives now.
    428      */
    429     dp = dnormalize(cp);
    430     if (chdir(short2str(dp)) >= 0) {
    431 	xfree((ptr_t) cp);
    432 	return dgoto(dp);
    433     }
    434     else {
    435 	xfree((ptr_t) dp);
    436 	if (chdir(short2str(cp)) >= 0)
    437 	    return dgoto(cp);
    438 	serrno = errno;
    439     }
    440 
    441     if (cp[0] != '/' && !prefix(STRdotsl, cp) && !prefix(STRdotdotsl, cp)
    442 	&& (c = adrof(STRcdpath))) {
    443 	Char  **cdp;
    444 	Char *p;
    445 	Char    buf[MAXPATHLEN];
    446 
    447 	for (cdp = c->vec; *cdp; cdp++) {
    448 	    for (dp = buf, p = *cdp; (*dp++ = *p++) != '\0';)
    449 		continue;
    450 	    dp[-1] = '/';
    451 	    for (p = cp; (*dp++ = *p++) != '\0';)
    452 		continue;
    453 	    if (chdir(short2str(buf)) >= 0) {
    454 		printd = 1;
    455 		xfree((ptr_t) cp);
    456 		cp = Strsave(buf);
    457 		return dgoto(cp);
    458 	    }
    459 	}
    460     }
    461     dp = value(cp);
    462     if ((dp[0] == '/' || dp[0] == '.') && chdir(short2str(dp)) >= 0) {
    463 	xfree((ptr_t) cp);
    464 	cp = Strsave(dp);
    465 	printd = 1;
    466 	return dgoto(cp);
    467     }
    468     (void)strcpy(ebuf, short2str(cp));
    469     xfree((ptr_t) cp);
    470     stderror(ERR_SYSTEM, ebuf, strerror(serrno));
    471     /* NOTREACHED */
    472 }
    473 
    474 /*
    475  * dopushd - push new directory onto directory stack.
    476  *	with no arguments exchange top and second.
    477  *	with numeric argument (+n) bring it to top.
    478  */
    479 void
    480 /*ARGSUSED*/
    481 dopushd(Char **v, struct command *t)
    482 {
    483     struct directory *dp;
    484 
    485     skipargs(&v, " [<dir>|+<n>]");
    486     printd = 1;
    487     if (*v == NULL) {
    488 	char   *tmp;
    489 
    490 	if ((dp = dcwd->di_prev) == &dhead)
    491 	    dp = dhead.di_prev;
    492 	if (dp == dcwd)
    493 	    stderror(ERR_NAME | ERR_NODIR);
    494 	if (chdir(tmp = short2str(dp->di_name)) < 0)
    495 	    stderror(ERR_SYSTEM, tmp, strerror(errno));
    496 	dp->di_prev->di_next = dp->di_next;
    497 	dp->di_next->di_prev = dp->di_prev;
    498 	dp->di_next = dcwd->di_next;
    499 	dp->di_prev = dcwd;
    500 	dcwd->di_next->di_prev = dp;
    501 	dcwd->di_next = dp;
    502     }
    503     else if (v[1] != NULL)
    504 	stderror(ERR_NAME | ERR_TOOMANY);
    505     else if ((dp = dfind(*v)) != NULL) {
    506 	char   *tmp;
    507 
    508 	if (chdir(tmp = short2str(dp->di_name)) < 0)
    509 	    stderror(ERR_SYSTEM, tmp, strerror(errno));
    510     }
    511     else {
    512 	Char *ccp;
    513 
    514 	ccp = dfollow(*v);
    515 	dp = (struct directory *)xcalloc(1, sizeof(struct directory));
    516 	dp->di_name = ccp;
    517 	dp->di_count = 0;
    518 	dp->di_prev = dcwd;
    519 	dp->di_next = dcwd->di_next;
    520 	dcwd->di_next = dp;
    521 	dp->di_next->di_prev = dp;
    522     }
    523     dnewcwd(dp);
    524 }
    525 
    526 /*
    527  * dfind - find a directory if specified by numeric (+n) argument
    528  */
    529 static struct directory *
    530 dfind(Char *cp)
    531 {
    532     struct directory *dp;
    533     Char *ep;
    534     int i;
    535 
    536     if (*cp++ != '+')
    537 	return (0);
    538     for (ep = cp; Isdigit(*ep); ep++)
    539 	continue;
    540     if (*ep)
    541 	return (0);
    542     i = getn(cp);
    543     if (i <= 0)
    544 	return (0);
    545     for (dp = dcwd; i != 0; i--) {
    546 	if ((dp = dp->di_prev) == &dhead)
    547 	    dp = dp->di_prev;
    548 	if (dp == dcwd)
    549 	    stderror(ERR_NAME | ERR_DEEP);
    550     }
    551     return (dp);
    552 }
    553 
    554 /*
    555  * dopopd - pop a directory out of the directory stack
    556  *	with a numeric argument just discard it.
    557  */
    558 void
    559 /*ARGSUSED*/
    560 dopopd(Char **v, struct command *t)
    561 {
    562     struct directory *dp, *p = NULL;
    563 
    564     skipargs(&v, " [+<n>]");
    565     printd = 1;
    566     if (*v == NULL)
    567 	dp = dcwd;
    568     else if (v[1] != NULL)
    569 	stderror(ERR_NAME | ERR_TOOMANY);
    570     else if ((dp = dfind(*v)) == 0)
    571 	stderror(ERR_NAME | ERR_BADDIR);
    572     if (dp->di_prev == &dhead && dp->di_next == &dhead)
    573 	stderror(ERR_NAME | ERR_EMPTY);
    574     if (dp == dcwd) {
    575 	char *tmp;
    576 
    577 	if ((p = dp->di_prev) == &dhead)
    578 	    p = dhead.di_prev;
    579 	if (chdir(tmp = short2str(p->di_name)) < 0)
    580 	    stderror(ERR_SYSTEM, tmp, strerror(errno));
    581     }
    582     dp->di_prev->di_next = dp->di_next;
    583     dp->di_next->di_prev = dp->di_prev;
    584     if (dp == dcwd)
    585 	dnewcwd(p);
    586     else {
    587 	printdirs();
    588     }
    589     dfree(dp);
    590 }
    591 
    592 /*
    593  * dfree - free the directory (or keep it if it still has ref count)
    594  */
    595 void
    596 dfree(struct directory *dp)
    597 {
    598 
    599     if (dp->di_count != 0) {
    600 	dp->di_next = dp->di_prev = 0;
    601     }
    602     else {
    603 	xfree((char *) dp->di_name);
    604 	xfree((ptr_t) dp);
    605     }
    606 }
    607 
    608 /*
    609  * dcanon - canonicalize the pathname, removing excess ./ and ../ etc.
    610  *	we are of course assuming that the file system is standardly
    611  *	constructed (always have ..'s, directories have links)
    612  */
    613 Char *
    614 dcanon(Char *cp, Char *p)
    615 {
    616     Char slink[MAXPATHLEN];
    617     char tlink[MAXPATHLEN];
    618     Char *newcp, *sp;
    619     Char *p1, *p2;	/* general purpose */
    620     int cc;
    621     bool slash;
    622 
    623     /*
    624      * christos: if the path given does not start with a slash prepend cwd. If
    625      * cwd does not start with a path or the result would be too long abort().
    626      */
    627     if (*cp != '/') {
    628 	Char tmpdir[MAXPATHLEN];
    629 
    630 	p1 = value(STRcwd);
    631 	if (p1 == NULL || *p1 != '/')
    632 	    abort();
    633 	if (Strlen(p1) + Strlen(cp) + 1 >= MAXPATHLEN)
    634 	    abort();
    635 	(void)Strcpy(tmpdir, p1);
    636 	(void)Strcat(tmpdir, STRslash);
    637 	(void)Strcat(tmpdir, cp);
    638 	xfree((ptr_t) cp);
    639 	cp = p = Strsave(tmpdir);
    640     }
    641 
    642     while (*p) {		/* for each component */
    643 	sp = p;			/* save slash address */
    644 	while (*++p == '/')	/* flush extra slashes */
    645 	    continue;
    646 	if (p != ++sp)
    647 	    for (p1 = sp, p2 = p; (*p1++ = *p2++) != '\0';)
    648 		continue;
    649 	p = sp;			/* save start of component */
    650 	slash = 0;
    651 	while (*++p)		/* find next slash or end of path */
    652 	    if (*p == '/') {
    653 		slash = 1;
    654 		*p = 0;
    655 		break;
    656 	    }
    657 
    658 	if (*sp == '\0') {	/* if component is null */
    659 	    if (--sp == cp)	/* if path is one char (i.e. /) */
    660 		break;
    661 	    else
    662 		*sp = '\0';
    663 	} else if (sp[0] == '.' && sp[1] == 0) {
    664 	    if (slash) {
    665 		for (p1 = sp, p2 = p + 1; (*p1++ = *p2++) != '\0';)
    666 		    continue;
    667 		p = --sp;
    668 	    }
    669 	    else if (--sp != cp)
    670 		*sp = '\0';
    671 	}
    672 	else if (sp[0] == '.' && sp[1] == '.' && sp[2] == 0) {
    673 	    /*
    674 	     * We have something like "yyy/xxx/..", where "yyy" can be null or
    675 	     * a path starting at /, and "xxx" is a single component. Before
    676 	     * compressing "xxx/..", we want to expand "yyy/xxx", if it is a
    677 	     * symbolic link.
    678 	     */
    679 	    *--sp = 0;		/* form the pathname for readlink */
    680 	    if (sp != cp && !adrof(STRignore_symlinks) &&
    681 		(cc = readlink(short2str(cp), tlink,
    682 			       sizeof tlink)) >= 0) {
    683 		(void)Strcpy(slink, str2short(tlink));
    684 		slink[cc] = '\0';
    685 
    686 		if (slash)
    687 		    *p = '/';
    688 		/*
    689 		 * Point p to the '/' in "/..", and restore the '/'.
    690 		 */
    691 		*(p = sp) = '/';
    692 		/*
    693 		 * find length of p
    694 		 */
    695 		for (p1 = p; *p1++;)
    696 		    continue;
    697 		if (*slink != '/') {
    698 		    /*
    699 		     * Relative path, expand it between the "yyy/" and the
    700 		     * "/..". First, back sp up to the character past "yyy/".
    701 		     */
    702 		    while (*--sp != '/')
    703 			continue;
    704 		    sp++;
    705 		    *sp = 0;
    706 		    /*
    707 		     * New length is "yyy/" + slink + "/.." and rest
    708 		     */
    709 		    p1 = newcp = (Char *)xmalloc(
    710 		        (size_t)(((sp - cp) + cc + (p1 - p)) * sizeof(Char)));
    711 		    /*
    712 		     * Copy new path into newcp
    713 		     */
    714 		    for (p2 = cp; (*p1++ = *p2++) != '\0';)
    715 			continue;
    716 		    for (p1--, p2 = slink; (*p1++ = *p2++) != '\0';)
    717 			continue;
    718 		    for (p1--, p2 = p; (*p1++ = *p2++) != '\0';)
    719 			continue;
    720 		    /*
    721 		     * Restart canonicalization at expanded "/xxx".
    722 		     */
    723 		    p = sp - cp - 1 + newcp;
    724 		}
    725 		else {
    726 		    /*
    727 		     * New length is slink + "/.." and rest
    728 		     */
    729 		    p1 = newcp = (Char *)xmalloc(
    730 		        (size_t)((cc + (p1 - p)) * sizeof(Char)));
    731 		    /*
    732 		     * Copy new path into newcp
    733 		     */
    734 		    for (p2 = slink; (*p1++ = *p2++) != '\0';)
    735 			continue;
    736 		    for (p1--, p2 = p; (*p1++ = *p2++) != '\0';)
    737 			continue;
    738 		    /*
    739 		     * Restart canonicalization at beginning
    740 		     */
    741 		    p = newcp;
    742 		}
    743 		xfree((ptr_t) cp);
    744 		cp = newcp;
    745 		continue;	/* canonicalize the link */
    746 	    }
    747 	    *sp = '/';
    748 	    if (sp != cp)
    749 		while (*--sp != '/')
    750 		    continue;
    751 	    if (slash) {
    752 		for (p1 = sp + 1, p2 = p + 1; (*p1++ = *p2++) != '\0';)
    753 		    continue;
    754 		p = sp;
    755 	    }
    756 	    else if (cp == sp)
    757 		*++sp = '\0';
    758 	    else
    759 		*sp = '\0';
    760 	}
    761 	else {			/* normal dir name (not . or .. or nothing) */
    762 
    763 	    if (sp != cp && adrof(STRchase_symlinks) &&
    764 		!adrof(STRignore_symlinks) &&
    765 		(cc = readlink(short2str(cp), tlink, sizeof(tlink))) >= 0) {
    766 		(void)Strcpy(slink, str2short(tlink));
    767 		slink[cc] = '\0';
    768 
    769 		/*
    770 		 * restore the '/'.
    771 		 */
    772 		if (slash)
    773 		    *p = '/';
    774 
    775 		/*
    776 		 * point sp to p (rather than backing up).
    777 		 */
    778 		sp = p;
    779 
    780 		/*
    781 		 * find length of p
    782 		 */
    783 		for (p1 = p; *p1++;)
    784 		    continue;
    785 		if (*slink != '/') {
    786 		    /*
    787 		     * Relative path, expand it between the "yyy/" and the
    788 		     * remainder. First, back sp up to the character past
    789 		     * "yyy/".
    790 		     */
    791 		    while (*--sp != '/')
    792 			continue;
    793 		    sp++;
    794 		    *sp = 0;
    795 		    /*
    796 		     * New length is "yyy/" + slink + "/.." and rest
    797 		     */
    798 		    p1 = newcp = (Char *)xmalloc(
    799 		        (size_t)(((sp - cp) + cc + (p1 - p)) * sizeof(Char)));
    800 		    /*
    801 		     * Copy new path into newcp
    802 		     */
    803 		    for (p2 = cp; (*p1++ = *p2++) != '\0';)
    804 			continue;
    805 		    for (p1--, p2 = slink; (*p1++ = *p2++) != '\0';)
    806 			continue;
    807 		    for (p1--, p2 = p; (*p1++ = *p2++) != '\0';)
    808 			continue;
    809 		    /*
    810 		     * Restart canonicalization at expanded "/xxx".
    811 		     */
    812 		    p = sp - cp - 1 + newcp;
    813 		}
    814 		else {
    815 		    /*
    816 		     * New length is slink + the rest
    817 		     */
    818 		    p1 = newcp = (Char *)xmalloc(
    819 		        (size_t)((cc + (p1 - p)) * sizeof(Char)));
    820 		    /*
    821 		     * Copy new path into newcp
    822 		     */
    823 		    for (p2 = slink; (*p1++ = *p2++) != '\0';)
    824 			continue;
    825 		    for (p1--, p2 = p; (*p1++ = *p2++) != '\0';)
    826 			continue;
    827 		    /*
    828 		     * Restart canonicalization at beginning
    829 		     */
    830 		    p = newcp;
    831 		}
    832 		xfree((ptr_t) cp);
    833 		cp = newcp;
    834 		continue;	/* canonicalize the link */
    835 	    }
    836 	    if (slash)
    837 		*p = '/';
    838 	}
    839     }
    840 
    841     /*
    842      * fix home...
    843      */
    844     p1 = value(STRhome);
    845     cc = Strlen(p1);
    846     /*
    847      * See if we're not in a subdir of STRhome
    848      */
    849     if (p1 && *p1 == '/' &&
    850 	(Strncmp(p1, cp, cc) != 0 || (cp[cc] != '/' && cp[cc] != '\0'))) {
    851 	static ino_t home_ino;
    852 	static dev_t home_dev = NODEV;
    853 	static Char *home_ptr = NULL;
    854 	struct stat statbuf;
    855 
    856 	/*
    857 	 * Get dev and ino of STRhome
    858 	 */
    859 	if (home_ptr != p1 &&
    860 	    stat(short2str(p1), &statbuf) != -1) {
    861 	    home_dev = statbuf.st_dev;
    862 	    home_ino = statbuf.st_ino;
    863 	    home_ptr = p1;
    864 	}
    865 	/*
    866 	 * Start comparing dev & ino backwards
    867 	 */
    868 	p2 = Strcpy(slink, cp);
    869 	for (sp = NULL; *p2 && stat(short2str(p2), &statbuf) != -1;) {
    870 	    if (statbuf.st_dev == home_dev &&
    871 		statbuf.st_ino == home_ino) {
    872 		sp = (Char *) - 1;
    873 		break;
    874 	    }
    875 	    if ((sp = Strrchr(p2, '/')) != NULL)
    876 		*sp = '\0';
    877 	}
    878 	/*
    879 	 * See if we found it
    880 	 */
    881 	if (*p2 && sp == (Char *) -1) {
    882 	    /*
    883 	     * Use STRhome to make '~' work
    884 	     */
    885 	    newcp = Strspl(p1, cp + Strlen(p2));
    886 	    xfree((ptr_t) cp);
    887 	    cp = newcp;
    888 	}
    889     }
    890     return cp;
    891 }
    892 
    893 
    894 /*
    895  * dnewcwd - make a new directory in the loop the current one
    896  */
    897 static void
    898 dnewcwd(struct directory *dp)
    899 {
    900     dcwd = dp;
    901     dset(dcwd->di_name);
    902     if (printd && !(adrof(STRpushdsilent)))
    903 	printdirs();
    904 }
    905