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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.22

1.22    ! lukem       1: /*     $NetBSD: getcwd.c,v 1.21 1999/08/10 13:03:11 fvdl Exp $ */
1.4       cgd         2:
1.1       cgd         3: /*
1.8       perry       4:  * Copyright (c) 1989, 1991, 1993, 1995
1.4       cgd         5:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         6:  *
1.8       perry       7:  * This code is derived from software contributed to Berkeley by
                      8:  * Jan-Simon Pendry.
                      9:  *
1.1       cgd        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:
1.6       christos   39: #include <sys/cdefs.h>
1.1       cgd        40: #if defined(LIBC_SCCS) && !defined(lint)
1.4       cgd        41: #if 0
1.8       perry      42: static char sccsid[] = "@(#)getcwd.c   8.5 (Berkeley) 2/7/95";
1.4       cgd        43: #else
1.22    ! lukem      44: __RCSID("$NetBSD: getcwd.c,v 1.21 1999/08/10 13:03:11 fvdl Exp $");
1.4       cgd        45: #endif
1.1       cgd        46: #endif /* LIBC_SCCS and not lint */
                     47:
1.7       jtc        48: #include "namespace.h"
1.1       cgd        49: #include <sys/param.h>
                     50: #include <sys/stat.h>
1.8       perry      51:
1.22    ! lukem      52: #include <assert.h>
1.8       perry      53: #include <dirent.h>
1.1       cgd        54: #include <errno.h>
1.8       perry      55: #include <fcntl.h>
1.1       cgd        56: #include <stdio.h>
                     57: #include <stdlib.h>
                     58: #include <string.h>
                     59: #include <unistd.h>
1.17      sommerfe   60:
                     61: #include "extern.h"
1.7       jtc        62:
                     63: #ifdef __weak_alias
                     64: __weak_alias(getcwd,_getcwd);
1.9       perry      65: __weak_alias(realpath,_realpath);
1.7       jtc        66: #endif
1.1       cgd        67:
                     68: #define        ISDOT(dp) \
                     69:        (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6       christos   70:            (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1       cgd        71:
1.8       perry      72:
1.15      christos   73: #if defined(__SVR4) || defined(__svr4__)
                     74: #define d_fileno d_ino
                     75: #endif
                     76:
1.8       perry      77: /*
                     78:  * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
                     79:  *
                     80:  * Find the real name of path, by removing all ".", ".." and symlink
                     81:  * components.  Returns (resolved) on success, or (NULL) on failure,
                     82:  * in which case the path which caused trouble is left in (resolved).
                     83:  */
                     84: char *
                     85: realpath(path, resolved)
                     86:        const char *path;
                     87:        char *resolved;
                     88: {
                     89:        struct stat sb;
1.21      fvdl       90:        int fd, n, rootd, serrno, nlnk = 0;
1.8       perry      91:        char *p, *q, wbuf[MAXPATHLEN];
1.22    ! lukem      92:
        !            93:        _DIAGASSERT(path != NULL);
        !            94:        _DIAGASSERT(resolved != NULL);
        !            95: #ifdef _DIAGNOSTIC
        !            96:        if (path == NULL || *path == '\0') {
        !            97:                errno = ENOENT;
        !            98:                return (NULL);
        !            99:        }
        !           100:        if (resolved == NULL) {
        !           101:                errno = EINVAL;
        !           102:                return (NULL);
        !           103:        }
        !           104: #endif
1.8       perry     105:
                    106:        /* Save the starting point. */
                    107:        if ((fd = open(".", O_RDONLY)) < 0) {
                    108:                (void)strcpy(resolved, ".");
                    109:                return (NULL);
                    110:        }
                    111:
                    112:        /*
                    113:         * Find the dirname and basename from the path to be resolved.
                    114:         * Change directory to the dirname component.
                    115:         * lstat the basename part.
                    116:         *     if it is a symlink, read in the value and loop.
                    117:         *     if it is a directory, then change to that directory.
                    118:         * get the current directory name and append the basename.
                    119:         */
                    120:        (void)strncpy(resolved, path, MAXPATHLEN - 1);
                    121:        resolved[MAXPATHLEN - 1] = '\0';
                    122: loop:
                    123:        q = strrchr(resolved, '/');
                    124:        if (q != NULL) {
                    125:                p = q + 1;
                    126:                if (q == resolved)
                    127:                        q = "/";
                    128:                else {
                    129:                        do {
                    130:                                --q;
                    131:                        } while (q > resolved && *q == '/');
                    132:                        q[1] = '\0';
                    133:                        q = resolved;
                    134:                }
                    135:                if (chdir(q) < 0)
                    136:                        goto err1;
                    137:        } else
                    138:                p = resolved;
                    139:
                    140:        /* Deal with the last component. */
                    141:        if (lstat(p, &sb) == 0) {
                    142:                if (S_ISLNK(sb.st_mode)) {
1.21      fvdl      143:                        if (nlnk++ >= MAXSYMLINKS) {
                    144:                                errno = ELOOP;
                    145:                                goto err1;
                    146:                        }
1.8       perry     147:                        n = readlink(p, resolved, MAXPATHLEN);
                    148:                        if (n < 0)
                    149:                                goto err1;
                    150:                        resolved[n] = '\0';
                    151:                        goto loop;
                    152:                }
                    153:                if (S_ISDIR(sb.st_mode)) {
                    154:                        if (chdir(p) < 0)
                    155:                                goto err1;
                    156:                        p = "";
                    157:                }
                    158:        }
                    159:
                    160:        /*
                    161:         * Save the last component name and get the full pathname of
                    162:         * the current directory.
                    163:         */
1.9       perry     164:        (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8       perry     165:
                    166:        /*
                    167:         * Call the inernal internal version of getcwd which
                    168:         * does a physical search rather than using the $PWD short-cut
                    169:         */
1.12      lukem     170:        if (getcwd(resolved, MAXPATHLEN) == 0)
1.8       perry     171:                goto err1;
                    172:
                    173:        /*
                    174:         * Join the two strings together, ensuring that the right thing
                    175:         * happens if the last component is empty, or the dirname is root.
                    176:         */
                    177:        if (resolved[0] == '/' && resolved[1] == '\0')
                    178:                rootd = 1;
                    179:        else
                    180:                rootd = 0;
                    181:
                    182:        if (*wbuf) {
                    183:                if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
                    184:                        errno = ENAMETOOLONG;
                    185:                        goto err1;
                    186:                }
                    187:                if (rootd == 0)
1.9       perry     188:                        (void)strcat(resolved, "/"); /* XXX: strcat is safe */
                    189:                (void)strcat(resolved, wbuf);   /* XXX: strcat is safe */
1.8       perry     190:        }
                    191:
                    192:        /* Go back to where we came from. */
                    193:        if (fchdir(fd) < 0) {
                    194:                serrno = errno;
                    195:                goto err2;
                    196:        }
                    197:
                    198:        /* It's okay if the close fails, what's an fd more or less? */
                    199:        (void)close(fd);
                    200:        return (resolved);
                    201:
                    202: err1:  serrno = errno;
                    203:        (void)fchdir(fd);
                    204: err2:  (void)close(fd);
                    205:        errno = serrno;
                    206:        return (NULL);
                    207: }
                    208:
1.16      sommerfe  209: #ifdef OLD_GETCWD
                    210:
1.12      lukem     211: char *
                    212: getcwd(pt, size)
1.8       perry     213:        char *pt;
                    214:        size_t size;
                    215: {
1.10      perry     216:        struct dirent *dp;
                    217:        DIR *dir;
                    218:        dev_t dev;
                    219:        ino_t ino;
                    220:        int first;
                    221:        char *bpt, *bup;
1.1       cgd       222:        struct stat s;
                    223:        dev_t root_dev;
                    224:        ino_t root_ino;
                    225:        size_t ptsize, upsize;
                    226:        int save_errno;
                    227:        char *ept, *eup, *up;
1.15      christos  228:        size_t dlen;
1.1       cgd       229:
                    230:        /*
                    231:         * If no buffer specified by the user, allocate one as necessary.
                    232:         * If a buffer is specified, the size has to be non-zero.  The path
                    233:         * is built from the end of the buffer backwards.
                    234:         */
                    235:        if (pt) {
                    236:                ptsize = 0;
                    237:                if (!size) {
                    238:                        errno = EINVAL;
1.4       cgd       239:                        return (NULL);
1.1       cgd       240:                }
                    241:                ept = pt + size;
                    242:        } else {
1.4       cgd       243:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    244:                        return (NULL);
1.1       cgd       245:                ept = pt + ptsize;
                    246:        }
                    247:        bpt = ept - 1;
                    248:        *bpt = '\0';
                    249:
                    250:        /*
                    251:         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
                    252:         * Should always be enough (it's 340 levels).  If it's not, allocate
1.8       perry     253:         * as necessary.  Special case the first stat, it's ".", not "..".
1.1       cgd       254:         */
1.4       cgd       255:        if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1       cgd       256:                goto err;
                    257:        eup = up + MAXPATHLEN;
                    258:        bup = up;
                    259:        up[0] = '.';
                    260:        up[1] = '\0';
                    261:
                    262:        /* Save root values, so know when to stop. */
                    263:        if (stat("/", &s))
                    264:                goto err;
                    265:        root_dev = s.st_dev;
                    266:        root_ino = s.st_ino;
                    267:
                    268:        errno = 0;                      /* XXX readdir has no error return. */
                    269:
                    270:        for (first = 1;; first = 0) {
                    271:                /* Stat the current level. */
                    272:                if (lstat(up, &s))
                    273:                        goto err;
                    274:
                    275:                /* Save current node values. */
                    276:                ino = s.st_ino;
                    277:                dev = s.st_dev;
                    278:
                    279:                /* Check for reaching root. */
                    280:                if (root_dev == dev && root_ino == ino) {
                    281:                        *--bpt = '/';
                    282:                        /*
                    283:                         * It's unclear that it's a requirement to copy the
                    284:                         * path to the beginning of the buffer, but it's always
                    285:                         * been that way and stuff would probably break.
                    286:                         */
1.14      perry     287:                        memmove(pt, bpt,  (size_t)(ept - bpt));
1.1       cgd       288:                        free(up);
1.4       cgd       289:                        return (pt);
1.1       cgd       290:                }
                    291:
                    292:                /*
                    293:                 * Build pointer to the parent directory, allocating memory
                    294:                 * as necessary.  Max length is 3 for "../", the largest
                    295:                 * possible component name, plus a trailing NULL.
                    296:                 */
                    297:                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
1.4       cgd       298:                        if ((up = realloc(up, upsize *= 2)) == NULL)
1.1       cgd       299:                                goto err;
1.4       cgd       300:                        bup = up;
1.1       cgd       301:                        eup = up + upsize;
                    302:                }
                    303:                *bup++ = '.';
                    304:                *bup++ = '.';
                    305:                *bup = '\0';
                    306:
                    307:                /* Open and stat parent directory. */
                    308:                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                    309:                        goto err;
                    310:
                    311:                /* Add trailing slash for next directory. */
                    312:                *bup++ = '/';
                    313:
                    314:                /*
                    315:                 * If it's a mount point, have to stat each element because
                    316:                 * the inode number in the directory is for the entry in the
                    317:                 * parent directory, not the inode number of the mounted file.
                    318:                 */
                    319:                save_errno = 0;
                    320:                if (s.st_dev == dev) {
                    321:                        for (;;) {
                    322:                                if (!(dp = readdir(dir)))
                    323:                                        goto notfound;
1.15      christos  324:                                if (dp->d_fileno == ino) {
1.19      christos  325: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  326:                                        dlen = strlen(dp->d_name);
                    327: #else
                    328:                                        dlen = dp->d_namlen;
                    329: #endif
1.1       cgd       330:                                        break;
1.15      christos  331:                                }
1.1       cgd       332:                        }
                    333:                } else
                    334:                        for (;;) {
                    335:                                if (!(dp = readdir(dir)))
                    336:                                        goto notfound;
                    337:                                if (ISDOT(dp))
                    338:                                        continue;
1.19      christos  339: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  340:                                dlen = strlen(dp->d_name);
                    341: #else
                    342:                                dlen = dp->d_namlen;
                    343: #endif
                    344:                                memmove(bup, dp->d_name, dlen + 1);
1.1       cgd       345:
                    346:                                /* Save the first error for later. */
                    347:                                if (lstat(up, &s)) {
                    348:                                        if (!save_errno)
                    349:                                                save_errno = errno;
                    350:                                        errno = 0;
                    351:                                        continue;
                    352:                                }
                    353:                                if (s.st_dev == dev && s.st_ino == ino)
                    354:                                        break;
                    355:                        }
                    356:
                    357:                /*
                    358:                 * Check for length of the current name, preceding slash,
                    359:                 * leading slash.
                    360:                 */
1.15      christos  361:                if (bpt - pt <= dlen + (first ? 1 : 2)) {
1.1       cgd       362:                        size_t len, off;
                    363:
                    364:                        if (!ptsize) {
                    365:                                errno = ERANGE;
                    366:                                goto err;
                    367:                        }
                    368:                        off = bpt - pt;
                    369:                        len = ept - bpt;
1.4       cgd       370:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1       cgd       371:                                goto err;
                    372:                        bpt = pt + off;
                    373:                        ept = pt + ptsize;
1.14      perry     374:                        memmove(ept - len, bpt, len);
1.1       cgd       375:                        bpt = ept - len;
                    376:                }
                    377:                if (!first)
                    378:                        *--bpt = '/';
1.15      christos  379:                bpt -= dlen;
                    380:                memmove(bpt, dp->d_name, dlen);
1.1       cgd       381:                (void)closedir(dir);
                    382:
                    383:                /* Truncate any file name. */
                    384:                *bup = '\0';
                    385:        }
                    386:
                    387: notfound:
                    388:        /*
                    389:         * If readdir set errno, use it, not any saved error; otherwise,
                    390:         * didn't find the current directory in its parent directory, set
                    391:         * errno to ENOENT.
                    392:         */
                    393:        if (!errno)
                    394:                errno = save_errno ? save_errno : ENOENT;
                    395:        /* FALLTHROUGH */
                    396: err:
                    397:        if (ptsize)
                    398:                free(pt);
                    399:        free(up);
1.4       cgd       400:        return (NULL);
1.1       cgd       401: }
1.16      sommerfe  402:
                    403: #else /* New getcwd */
                    404:
                    405: char *
                    406: getcwd(pt, size)
                    407:        char *pt;
                    408:        size_t size;
                    409: {
1.18      christos  410:        size_t ptsize, bufsize;
                    411:        int len;
1.16      sommerfe  412:
                    413:        /*
                    414:         * If no buffer specified by the user, allocate one as necessary.
                    415:         * If a buffer is specified, the size has to be non-zero.  The path
                    416:         * is built from the end of the buffer backwards.
                    417:         */
                    418:        if (pt) {
                    419:                ptsize = 0;
                    420:                if (!size) {
                    421:                        errno = EINVAL;
                    422:                        return (NULL);
                    423:                }
                    424:                bufsize = size;
                    425:        } else {
                    426:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    427:                        return (NULL);
                    428:                bufsize = ptsize;
                    429:        }
1.18      christos  430:        for (;;) {
1.16      sommerfe  431:                len = __getcwd(pt, bufsize);
                    432:                if ((len < 0) && (size == 0) && (errno == ERANGE)) {
1.20      sommerfe  433:                        if (ptsize > (MAXPATHLEN*4))
                    434:                                return NULL;
1.16      sommerfe  435:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
                    436:                                return NULL;
                    437:                        bufsize = ptsize;
                    438:                        continue;
                    439:                }
1.18      christos  440:                break;
                    441:        }
1.16      sommerfe  442:        if (len < 0)
                    443:                return NULL;
                    444:        else
                    445:                return pt;
                    446: }
                    447:
                    448: #endif

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