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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.12

1.12    ! lukem       1: /*     $NetBSD: getcwd.c,v 1.11 1998/02/26 02:49:21 perry 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
1.12    ! lukem      44: __RCSID("$NetBSD: getcwd.c,v 1.11 1998/02/26 02:49:21 perry 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:
                     52: #include <dirent.h>
1.1       cgd        53: #include <errno.h>
1.8       perry      54: #include <fcntl.h>
1.1       cgd        55: #include <stdio.h>
                     56: #include <stdlib.h>
                     57: #include <string.h>
                     58: #include <unistd.h>
1.7       jtc        59:
                     60: #ifdef __weak_alias
                     61: __weak_alias(getcwd,_getcwd);
1.9       perry      62: __weak_alias(realpath,_realpath);
1.7       jtc        63: #endif
1.1       cgd        64:
                     65: #define        ISDOT(dp) \
                     66:        (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6       christos   67:            (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1       cgd        68:
1.8       perry      69:
                     70: /*
                     71:  * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
                     72:  *
                     73:  * Find the real name of path, by removing all ".", ".." and symlink
                     74:  * components.  Returns (resolved) on success, or (NULL) on failure,
                     75:  * in which case the path which caused trouble is left in (resolved).
                     76:  */
                     77: char *
                     78: realpath(path, resolved)
                     79:        const char *path;
                     80:        char *resolved;
                     81: {
                     82:        struct stat sb;
                     83:        int fd, n, rootd, serrno;
                     84:        char *p, *q, wbuf[MAXPATHLEN];
                     85:
                     86:        /* Save the starting point. */
                     87:        if ((fd = open(".", O_RDONLY)) < 0) {
                     88:                (void)strcpy(resolved, ".");
                     89:                return (NULL);
                     90:        }
                     91:
                     92:        /*
                     93:         * Find the dirname and basename from the path to be resolved.
                     94:         * Change directory to the dirname component.
                     95:         * lstat the basename part.
                     96:         *     if it is a symlink, read in the value and loop.
                     97:         *     if it is a directory, then change to that directory.
                     98:         * get the current directory name and append the basename.
                     99:         */
                    100:        (void)strncpy(resolved, path, MAXPATHLEN - 1);
                    101:        resolved[MAXPATHLEN - 1] = '\0';
                    102: loop:
                    103:        q = strrchr(resolved, '/');
                    104:        if (q != NULL) {
                    105:                p = q + 1;
                    106:                if (q == resolved)
                    107:                        q = "/";
                    108:                else {
                    109:                        do {
                    110:                                --q;
                    111:                        } while (q > resolved && *q == '/');
                    112:                        q[1] = '\0';
                    113:                        q = resolved;
                    114:                }
                    115:                if (chdir(q) < 0)
                    116:                        goto err1;
                    117:        } else
                    118:                p = resolved;
                    119:
                    120:        /* Deal with the last component. */
                    121:        if (lstat(p, &sb) == 0) {
                    122:                if (S_ISLNK(sb.st_mode)) {
                    123:                        n = readlink(p, resolved, MAXPATHLEN);
                    124:                        if (n < 0)
                    125:                                goto err1;
                    126:                        resolved[n] = '\0';
                    127:                        goto loop;
                    128:                }
                    129:                if (S_ISDIR(sb.st_mode)) {
                    130:                        if (chdir(p) < 0)
                    131:                                goto err1;
                    132:                        p = "";
                    133:                }
                    134:        }
                    135:
                    136:        /*
                    137:         * Save the last component name and get the full pathname of
                    138:         * the current directory.
                    139:         */
1.9       perry     140:        (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8       perry     141:
                    142:        /*
                    143:         * Call the inernal internal version of getcwd which
                    144:         * does a physical search rather than using the $PWD short-cut
                    145:         */
1.12    ! lukem     146:        if (getcwd(resolved, MAXPATHLEN) == 0)
1.8       perry     147:                goto err1;
                    148:
                    149:        /*
                    150:         * Join the two strings together, ensuring that the right thing
                    151:         * happens if the last component is empty, or the dirname is root.
                    152:         */
                    153:        if (resolved[0] == '/' && resolved[1] == '\0')
                    154:                rootd = 1;
                    155:        else
                    156:                rootd = 0;
                    157:
                    158:        if (*wbuf) {
                    159:                if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
                    160:                        errno = ENAMETOOLONG;
                    161:                        goto err1;
                    162:                }
                    163:                if (rootd == 0)
1.9       perry     164:                        (void)strcat(resolved, "/"); /* XXX: strcat is safe */
                    165:                (void)strcat(resolved, wbuf);   /* XXX: strcat is safe */
1.8       perry     166:        }
                    167:
                    168:        /* Go back to where we came from. */
                    169:        if (fchdir(fd) < 0) {
                    170:                serrno = errno;
                    171:                goto err2;
                    172:        }
                    173:
                    174:        /* It's okay if the close fails, what's an fd more or less? */
                    175:        (void)close(fd);
                    176:        return (resolved);
                    177:
                    178: err1:  serrno = errno;
                    179:        (void)fchdir(fd);
                    180: err2:  (void)close(fd);
                    181:        errno = serrno;
                    182:        return (NULL);
                    183: }
                    184:
1.12    ! lukem     185: char *
        !           186: getcwd(pt, size)
1.8       perry     187:        char *pt;
                    188:        size_t size;
                    189: {
1.10      perry     190:        struct dirent *dp;
                    191:        DIR *dir;
                    192:        dev_t dev;
                    193:        ino_t ino;
                    194:        int first;
                    195:        char *bpt, *bup;
1.1       cgd       196:        struct stat s;
                    197:        dev_t root_dev;
                    198:        ino_t root_ino;
                    199:        size_t ptsize, upsize;
                    200:        int save_errno;
                    201:        char *ept, *eup, *up;
                    202:
                    203:        /*
                    204:         * If no buffer specified by the user, allocate one as necessary.
                    205:         * If a buffer is specified, the size has to be non-zero.  The path
                    206:         * is built from the end of the buffer backwards.
                    207:         */
                    208:        if (pt) {
                    209:                ptsize = 0;
                    210:                if (!size) {
                    211:                        errno = EINVAL;
1.4       cgd       212:                        return (NULL);
1.1       cgd       213:                }
                    214:                ept = pt + size;
                    215:        } else {
1.4       cgd       216:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    217:                        return (NULL);
1.1       cgd       218:                ept = pt + ptsize;
                    219:        }
                    220:        bpt = ept - 1;
                    221:        *bpt = '\0';
                    222:
                    223:        /*
                    224:         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
                    225:         * Should always be enough (it's 340 levels).  If it's not, allocate
1.8       perry     226:         * as necessary.  Special case the first stat, it's ".", not "..".
1.1       cgd       227:         */
1.4       cgd       228:        if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1       cgd       229:                goto err;
                    230:        eup = up + MAXPATHLEN;
                    231:        bup = up;
                    232:        up[0] = '.';
                    233:        up[1] = '\0';
                    234:
                    235:        /* Save root values, so know when to stop. */
                    236:        if (stat("/", &s))
                    237:                goto err;
                    238:        root_dev = s.st_dev;
                    239:        root_ino = s.st_ino;
                    240:
                    241:        errno = 0;                      /* XXX readdir has no error return. */
                    242:
                    243:        for (first = 1;; first = 0) {
                    244:                /* Stat the current level. */
                    245:                if (lstat(up, &s))
                    246:                        goto err;
                    247:
                    248:                /* Save current node values. */
                    249:                ino = s.st_ino;
                    250:                dev = s.st_dev;
                    251:
                    252:                /* Check for reaching root. */
                    253:                if (root_dev == dev && root_ino == ino) {
                    254:                        *--bpt = '/';
                    255:                        /*
                    256:                         * It's unclear that it's a requirement to copy the
                    257:                         * path to the beginning of the buffer, but it's always
                    258:                         * been that way and stuff would probably break.
                    259:                         */
1.11      perry     260:                        bcopy(bpt, pt, (size_t)(ept - bpt));
1.1       cgd       261:                        free(up);
1.4       cgd       262:                        return (pt);
1.1       cgd       263:                }
                    264:
                    265:                /*
                    266:                 * Build pointer to the parent directory, allocating memory
                    267:                 * as necessary.  Max length is 3 for "../", the largest
                    268:                 * possible component name, plus a trailing NULL.
                    269:                 */
                    270:                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
1.4       cgd       271:                        if ((up = realloc(up, upsize *= 2)) == NULL)
1.1       cgd       272:                                goto err;
1.4       cgd       273:                        bup = up;
1.1       cgd       274:                        eup = up + upsize;
                    275:                }
                    276:                *bup++ = '.';
                    277:                *bup++ = '.';
                    278:                *bup = '\0';
                    279:
                    280:                /* Open and stat parent directory. */
                    281:                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                    282:                        goto err;
                    283:
                    284:                /* Add trailing slash for next directory. */
                    285:                *bup++ = '/';
                    286:
                    287:                /*
                    288:                 * If it's a mount point, have to stat each element because
                    289:                 * the inode number in the directory is for the entry in the
                    290:                 * parent directory, not the inode number of the mounted file.
                    291:                 */
                    292:                save_errno = 0;
                    293:                if (s.st_dev == dev) {
                    294:                        for (;;) {
                    295:                                if (!(dp = readdir(dir)))
                    296:                                        goto notfound;
                    297:                                if (dp->d_fileno == ino)
                    298:                                        break;
                    299:                        }
                    300:                } else
                    301:                        for (;;) {
                    302:                                if (!(dp = readdir(dir)))
                    303:                                        goto notfound;
                    304:                                if (ISDOT(dp))
                    305:                                        continue;
1.11      perry     306:                                bcopy(dp->d_name, bup,
                    307:                                    (size_t)(dp->d_namlen + 1));
1.1       cgd       308:
                    309:                                /* Save the first error for later. */
                    310:                                if (lstat(up, &s)) {
                    311:                                        if (!save_errno)
                    312:                                                save_errno = errno;
                    313:                                        errno = 0;
                    314:                                        continue;
                    315:                                }
                    316:                                if (s.st_dev == dev && s.st_ino == ino)
                    317:                                        break;
                    318:                        }
                    319:
                    320:                /*
                    321:                 * Check for length of the current name, preceding slash,
                    322:                 * leading slash.
                    323:                 */
                    324:                if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
                    325:                        size_t len, off;
                    326:
                    327:                        if (!ptsize) {
                    328:                                errno = ERANGE;
                    329:                                goto err;
                    330:                        }
                    331:                        off = bpt - pt;
                    332:                        len = ept - bpt;
1.4       cgd       333:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1       cgd       334:                                goto err;
                    335:                        bpt = pt + off;
                    336:                        ept = pt + ptsize;
1.5       jtc       337:                        bcopy(bpt, ept - len, len);
1.1       cgd       338:                        bpt = ept - len;
                    339:                }
                    340:                if (!first)
                    341:                        *--bpt = '/';
                    342:                bpt -= dp->d_namlen;
1.11      perry     343:                bcopy(dp->d_name, bpt, (size_t)dp->d_namlen);
1.1       cgd       344:                (void)closedir(dir);
                    345:
                    346:                /* Truncate any file name. */
                    347:                *bup = '\0';
                    348:        }
                    349:
                    350: notfound:
                    351:        /*
                    352:         * If readdir set errno, use it, not any saved error; otherwise,
                    353:         * didn't find the current directory in its parent directory, set
                    354:         * errno to ENOENT.
                    355:         */
                    356:        if (!errno)
                    357:                errno = save_errno ? save_errno : ENOENT;
                    358:        /* FALLTHROUGH */
                    359: err:
                    360:        if (ptsize)
                    361:                free(pt);
                    362:        free(up);
1.4       cgd       363:        return (NULL);
1.1       cgd       364: }

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