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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.30

1.30    ! itojun      1: /*     $NetBSD: getcwd.c,v 1.29 2003/08/03 04:12:01 itojun 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
1.30    ! itojun     44: __RCSID("$NetBSD: getcwd.c,v 1.29 2003/08/03 04:12:01 itojun 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
1.24      mycroft    64: __weak_alias(getcwd,_getcwd)
                     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);
1.8       perry      95:
                     96:        /* Save the starting point. */
                     97:        if ((fd = open(".", O_RDONLY)) < 0) {
1.28      itojun     98:                (void)strlcpy(resolved, ".", MAXPATHLEN);
1.8       perry      99:                return (NULL);
                    100:        }
                    101:
                    102:        /*
                    103:         * Find the dirname and basename from the path to be resolved.
                    104:         * Change directory to the dirname component.
                    105:         * lstat the basename part.
                    106:         *     if it is a symlink, read in the value and loop.
                    107:         *     if it is a directory, then change to that directory.
                    108:         * get the current directory name and append the basename.
                    109:         */
1.27      itojun    110:        (void)strlcpy(resolved, path, MAXPATHLEN);
1.8       perry     111: loop:
                    112:        q = strrchr(resolved, '/');
                    113:        if (q != NULL) {
                    114:                p = q + 1;
                    115:                if (q == resolved)
                    116:                        q = "/";
                    117:                else {
                    118:                        do {
                    119:                                --q;
                    120:                        } while (q > resolved && *q == '/');
                    121:                        q[1] = '\0';
                    122:                        q = resolved;
                    123:                }
                    124:                if (chdir(q) < 0)
                    125:                        goto err1;
                    126:        } else
                    127:                p = resolved;
                    128:
                    129:        /* Deal with the last component. */
                    130:        if (lstat(p, &sb) == 0) {
                    131:                if (S_ISLNK(sb.st_mode)) {
1.21      fvdl      132:                        if (nlnk++ >= MAXSYMLINKS) {
                    133:                                errno = ELOOP;
                    134:                                goto err1;
                    135:                        }
1.26      provos    136:                        n = readlink(p, resolved, MAXPATHLEN-1);
1.8       perry     137:                        if (n < 0)
                    138:                                goto err1;
                    139:                        resolved[n] = '\0';
                    140:                        goto loop;
                    141:                }
                    142:                if (S_ISDIR(sb.st_mode)) {
                    143:                        if (chdir(p) < 0)
                    144:                                goto err1;
                    145:                        p = "";
                    146:                }
                    147:        }
                    148:
                    149:        /*
                    150:         * Save the last component name and get the full pathname of
                    151:         * the current directory.
                    152:         */
1.25      groo      153:        (void)strlcpy(wbuf, p, sizeof(wbuf));
1.8       perry     154:
                    155:        /*
                    156:         * Call the inernal internal version of getcwd which
                    157:         * does a physical search rather than using the $PWD short-cut
                    158:         */
1.12      lukem     159:        if (getcwd(resolved, MAXPATHLEN) == 0)
1.8       perry     160:                goto err1;
                    161:
                    162:        /*
                    163:         * Join the two strings together, ensuring that the right thing
                    164:         * happens if the last component is empty, or the dirname is root.
                    165:         */
                    166:        if (resolved[0] == '/' && resolved[1] == '\0')
                    167:                rootd = 1;
                    168:        else
                    169:                rootd = 0;
                    170:
                    171:        if (*wbuf) {
1.29      itojun    172:                if (strlen(resolved) + strlen(wbuf) + (rootd ? 0 : 1) + 1 >
                    173:                    MAXPATHLEN) {
1.8       perry     174:                        errno = ENAMETOOLONG;
                    175:                        goto err1;
                    176:                }
                    177:                if (rootd == 0)
1.30    ! itojun    178:                        (void)strlcat(resolved, "/", MAXPATHLEN);
        !           179:                (void)strlcat(resolved, wbuf, MAXPATHLEN);
1.8       perry     180:        }
                    181:
                    182:        /* Go back to where we came from. */
                    183:        if (fchdir(fd) < 0) {
                    184:                serrno = errno;
                    185:                goto err2;
                    186:        }
                    187:
                    188:        /* It's okay if the close fails, what's an fd more or less? */
                    189:        (void)close(fd);
                    190:        return (resolved);
                    191:
                    192: err1:  serrno = errno;
                    193:        (void)fchdir(fd);
                    194: err2:  (void)close(fd);
                    195:        errno = serrno;
                    196:        return (NULL);
                    197: }
                    198:
1.16      sommerfe  199: #ifdef OLD_GETCWD
                    200:
1.12      lukem     201: char *
                    202: getcwd(pt, size)
1.8       perry     203:        char *pt;
                    204:        size_t size;
                    205: {
1.10      perry     206:        struct dirent *dp;
                    207:        DIR *dir;
                    208:        dev_t dev;
                    209:        ino_t ino;
                    210:        int first;
                    211:        char *bpt, *bup;
1.1       cgd       212:        struct stat s;
                    213:        dev_t root_dev;
                    214:        ino_t root_ino;
                    215:        size_t ptsize, upsize;
                    216:        int save_errno;
                    217:        char *ept, *eup, *up;
1.15      christos  218:        size_t dlen;
1.1       cgd       219:
                    220:        /*
                    221:         * If no buffer specified by the user, allocate one as necessary.
                    222:         * If a buffer is specified, the size has to be non-zero.  The path
                    223:         * is built from the end of the buffer backwards.
                    224:         */
                    225:        if (pt) {
                    226:                ptsize = 0;
                    227:                if (!size) {
                    228:                        errno = EINVAL;
1.4       cgd       229:                        return (NULL);
1.1       cgd       230:                }
                    231:                ept = pt + size;
                    232:        } else {
1.4       cgd       233:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    234:                        return (NULL);
1.1       cgd       235:                ept = pt + ptsize;
                    236:        }
                    237:        bpt = ept - 1;
                    238:        *bpt = '\0';
                    239:
                    240:        /*
                    241:         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
                    242:         * Should always be enough (it's 340 levels).  If it's not, allocate
1.8       perry     243:         * as necessary.  Special case the first stat, it's ".", not "..".
1.1       cgd       244:         */
1.4       cgd       245:        if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1       cgd       246:                goto err;
                    247:        eup = up + MAXPATHLEN;
                    248:        bup = up;
                    249:        up[0] = '.';
                    250:        up[1] = '\0';
                    251:
                    252:        /* Save root values, so know when to stop. */
                    253:        if (stat("/", &s))
                    254:                goto err;
                    255:        root_dev = s.st_dev;
                    256:        root_ino = s.st_ino;
                    257:
                    258:        errno = 0;                      /* XXX readdir has no error return. */
                    259:
                    260:        for (first = 1;; first = 0) {
                    261:                /* Stat the current level. */
                    262:                if (lstat(up, &s))
                    263:                        goto err;
                    264:
                    265:                /* Save current node values. */
                    266:                ino = s.st_ino;
                    267:                dev = s.st_dev;
                    268:
                    269:                /* Check for reaching root. */
                    270:                if (root_dev == dev && root_ino == ino) {
                    271:                        *--bpt = '/';
                    272:                        /*
                    273:                         * It's unclear that it's a requirement to copy the
                    274:                         * path to the beginning of the buffer, but it's always
                    275:                         * been that way and stuff would probably break.
                    276:                         */
1.14      perry     277:                        memmove(pt, bpt,  (size_t)(ept - bpt));
1.1       cgd       278:                        free(up);
1.4       cgd       279:                        return (pt);
1.1       cgd       280:                }
                    281:
                    282:                /*
                    283:                 * Build pointer to the parent directory, allocating memory
                    284:                 * as necessary.  Max length is 3 for "../", the largest
                    285:                 * possible component name, plus a trailing NULL.
                    286:                 */
                    287:                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
1.4       cgd       288:                        if ((up = realloc(up, upsize *= 2)) == NULL)
1.1       cgd       289:                                goto err;
1.4       cgd       290:                        bup = up;
1.1       cgd       291:                        eup = up + upsize;
                    292:                }
                    293:                *bup++ = '.';
                    294:                *bup++ = '.';
                    295:                *bup = '\0';
                    296:
                    297:                /* Open and stat parent directory. */
                    298:                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                    299:                        goto err;
                    300:
                    301:                /* Add trailing slash for next directory. */
                    302:                *bup++ = '/';
                    303:
                    304:                /*
                    305:                 * If it's a mount point, have to stat each element because
                    306:                 * the inode number in the directory is for the entry in the
                    307:                 * parent directory, not the inode number of the mounted file.
                    308:                 */
                    309:                save_errno = 0;
                    310:                if (s.st_dev == dev) {
                    311:                        for (;;) {
                    312:                                if (!(dp = readdir(dir)))
                    313:                                        goto notfound;
1.15      christos  314:                                if (dp->d_fileno == ino) {
1.19      christos  315: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  316:                                        dlen = strlen(dp->d_name);
                    317: #else
                    318:                                        dlen = dp->d_namlen;
                    319: #endif
1.1       cgd       320:                                        break;
1.15      christos  321:                                }
1.1       cgd       322:                        }
                    323:                } else
                    324:                        for (;;) {
                    325:                                if (!(dp = readdir(dir)))
                    326:                                        goto notfound;
                    327:                                if (ISDOT(dp))
                    328:                                        continue;
1.19      christos  329: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  330:                                dlen = strlen(dp->d_name);
                    331: #else
                    332:                                dlen = dp->d_namlen;
                    333: #endif
                    334:                                memmove(bup, dp->d_name, dlen + 1);
1.1       cgd       335:
                    336:                                /* Save the first error for later. */
                    337:                                if (lstat(up, &s)) {
                    338:                                        if (!save_errno)
                    339:                                                save_errno = errno;
                    340:                                        errno = 0;
                    341:                                        continue;
                    342:                                }
                    343:                                if (s.st_dev == dev && s.st_ino == ino)
                    344:                                        break;
                    345:                        }
                    346:
                    347:                /*
                    348:                 * Check for length of the current name, preceding slash,
                    349:                 * leading slash.
                    350:                 */
1.15      christos  351:                if (bpt - pt <= dlen + (first ? 1 : 2)) {
1.1       cgd       352:                        size_t len, off;
                    353:
                    354:                        if (!ptsize) {
                    355:                                errno = ERANGE;
                    356:                                goto err;
                    357:                        }
                    358:                        off = bpt - pt;
                    359:                        len = ept - bpt;
1.4       cgd       360:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1       cgd       361:                                goto err;
                    362:                        bpt = pt + off;
                    363:                        ept = pt + ptsize;
1.14      perry     364:                        memmove(ept - len, bpt, len);
1.1       cgd       365:                        bpt = ept - len;
                    366:                }
                    367:                if (!first)
                    368:                        *--bpt = '/';
1.15      christos  369:                bpt -= dlen;
                    370:                memmove(bpt, dp->d_name, dlen);
1.1       cgd       371:                (void)closedir(dir);
                    372:
                    373:                /* Truncate any file name. */
                    374:                *bup = '\0';
                    375:        }
                    376:
                    377: notfound:
                    378:        /*
                    379:         * If readdir set errno, use it, not any saved error; otherwise,
                    380:         * didn't find the current directory in its parent directory, set
                    381:         * errno to ENOENT.
                    382:         */
                    383:        if (!errno)
                    384:                errno = save_errno ? save_errno : ENOENT;
                    385:        /* FALLTHROUGH */
                    386: err:
                    387:        if (ptsize)
                    388:                free(pt);
                    389:        free(up);
1.4       cgd       390:        return (NULL);
1.1       cgd       391: }
1.16      sommerfe  392:
                    393: #else /* New getcwd */
                    394:
                    395: char *
                    396: getcwd(pt, size)
                    397:        char *pt;
                    398:        size_t size;
                    399: {
1.18      christos  400:        size_t ptsize, bufsize;
                    401:        int len;
1.16      sommerfe  402:
                    403:        /*
                    404:         * If no buffer specified by the user, allocate one as necessary.
                    405:         * If a buffer is specified, the size has to be non-zero.  The path
                    406:         * is built from the end of the buffer backwards.
                    407:         */
                    408:        if (pt) {
                    409:                ptsize = 0;
                    410:                if (!size) {
                    411:                        errno = EINVAL;
                    412:                        return (NULL);
                    413:                }
                    414:                bufsize = size;
                    415:        } else {
                    416:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    417:                        return (NULL);
                    418:                bufsize = ptsize;
                    419:        }
1.18      christos  420:        for (;;) {
1.16      sommerfe  421:                len = __getcwd(pt, bufsize);
                    422:                if ((len < 0) && (size == 0) && (errno == ERANGE)) {
1.20      sommerfe  423:                        if (ptsize > (MAXPATHLEN*4))
                    424:                                return NULL;
1.16      sommerfe  425:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
                    426:                                return NULL;
                    427:                        bufsize = ptsize;
                    428:                        continue;
                    429:                }
1.18      christos  430:                break;
                    431:        }
1.16      sommerfe  432:        if (len < 0)
                    433:                return NULL;
                    434:        else
                    435:                return pt;
                    436: }
                    437:
                    438: #endif

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