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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.19

1.19    ! christos    1: /*     $NetBSD: getcwd.c,v 1.18 1999/05/03 14:33:50 christos 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
1.19    ! christos   44: __RCSID("$NetBSD: getcwd.c,v 1.18 1999/05/03 14:33:50 christos 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>
1.17      sommerfe   59:
                     60: #include "extern.h"
1.7       jtc        61:
                     62: #ifdef __weak_alias
                     63: __weak_alias(getcwd,_getcwd);
1.9       perry      64: __weak_alias(realpath,_realpath);
1.7       jtc        65: #endif
1.1       cgd        66:
                     67: #define        ISDOT(dp) \
                     68:        (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6       christos   69:            (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1       cgd        70:
1.8       perry      71:
1.15      christos   72: #if defined(__SVR4) || defined(__svr4__)
                     73: #define d_fileno d_ino
                     74: #endif
                     75:
1.8       perry      76: /*
                     77:  * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
                     78:  *
                     79:  * Find the real name of path, by removing all ".", ".." and symlink
                     80:  * components.  Returns (resolved) on success, or (NULL) on failure,
                     81:  * in which case the path which caused trouble is left in (resolved).
                     82:  */
                     83: char *
                     84: realpath(path, resolved)
                     85:        const char *path;
                     86:        char *resolved;
                     87: {
                     88:        struct stat sb;
                     89:        int fd, n, rootd, serrno;
                     90:        char *p, *q, wbuf[MAXPATHLEN];
                     91:
                     92:        /* Save the starting point. */
                     93:        if ((fd = open(".", O_RDONLY)) < 0) {
                     94:                (void)strcpy(resolved, ".");
                     95:                return (NULL);
                     96:        }
                     97:
                     98:        /*
                     99:         * Find the dirname and basename from the path to be resolved.
                    100:         * Change directory to the dirname component.
                    101:         * lstat the basename part.
                    102:         *     if it is a symlink, read in the value and loop.
                    103:         *     if it is a directory, then change to that directory.
                    104:         * get the current directory name and append the basename.
                    105:         */
                    106:        (void)strncpy(resolved, path, MAXPATHLEN - 1);
                    107:        resolved[MAXPATHLEN - 1] = '\0';
                    108: loop:
                    109:        q = strrchr(resolved, '/');
                    110:        if (q != NULL) {
                    111:                p = q + 1;
                    112:                if (q == resolved)
                    113:                        q = "/";
                    114:                else {
                    115:                        do {
                    116:                                --q;
                    117:                        } while (q > resolved && *q == '/');
                    118:                        q[1] = '\0';
                    119:                        q = resolved;
                    120:                }
                    121:                if (chdir(q) < 0)
                    122:                        goto err1;
                    123:        } else
                    124:                p = resolved;
                    125:
                    126:        /* Deal with the last component. */
                    127:        if (lstat(p, &sb) == 0) {
                    128:                if (S_ISLNK(sb.st_mode)) {
                    129:                        n = readlink(p, resolved, MAXPATHLEN);
                    130:                        if (n < 0)
                    131:                                goto err1;
                    132:                        resolved[n] = '\0';
                    133:                        goto loop;
                    134:                }
                    135:                if (S_ISDIR(sb.st_mode)) {
                    136:                        if (chdir(p) < 0)
                    137:                                goto err1;
                    138:                        p = "";
                    139:                }
                    140:        }
                    141:
                    142:        /*
                    143:         * Save the last component name and get the full pathname of
                    144:         * the current directory.
                    145:         */
1.9       perry     146:        (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8       perry     147:
                    148:        /*
                    149:         * Call the inernal internal version of getcwd which
                    150:         * does a physical search rather than using the $PWD short-cut
                    151:         */
1.12      lukem     152:        if (getcwd(resolved, MAXPATHLEN) == 0)
1.8       perry     153:                goto err1;
                    154:
                    155:        /*
                    156:         * Join the two strings together, ensuring that the right thing
                    157:         * happens if the last component is empty, or the dirname is root.
                    158:         */
                    159:        if (resolved[0] == '/' && resolved[1] == '\0')
                    160:                rootd = 1;
                    161:        else
                    162:                rootd = 0;
                    163:
                    164:        if (*wbuf) {
                    165:                if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
                    166:                        errno = ENAMETOOLONG;
                    167:                        goto err1;
                    168:                }
                    169:                if (rootd == 0)
1.9       perry     170:                        (void)strcat(resolved, "/"); /* XXX: strcat is safe */
                    171:                (void)strcat(resolved, wbuf);   /* XXX: strcat is safe */
1.8       perry     172:        }
                    173:
                    174:        /* Go back to where we came from. */
                    175:        if (fchdir(fd) < 0) {
                    176:                serrno = errno;
                    177:                goto err2;
                    178:        }
                    179:
                    180:        /* It's okay if the close fails, what's an fd more or less? */
                    181:        (void)close(fd);
                    182:        return (resolved);
                    183:
                    184: err1:  serrno = errno;
                    185:        (void)fchdir(fd);
                    186: err2:  (void)close(fd);
                    187:        errno = serrno;
                    188:        return (NULL);
                    189: }
                    190:
1.16      sommerfe  191: #ifdef OLD_GETCWD
                    192:
1.12      lukem     193: char *
                    194: getcwd(pt, size)
1.8       perry     195:        char *pt;
                    196:        size_t size;
                    197: {
1.10      perry     198:        struct dirent *dp;
                    199:        DIR *dir;
                    200:        dev_t dev;
                    201:        ino_t ino;
                    202:        int first;
                    203:        char *bpt, *bup;
1.1       cgd       204:        struct stat s;
                    205:        dev_t root_dev;
                    206:        ino_t root_ino;
                    207:        size_t ptsize, upsize;
                    208:        int save_errno;
                    209:        char *ept, *eup, *up;
1.15      christos  210:        size_t dlen;
1.1       cgd       211:
                    212:        /*
                    213:         * If no buffer specified by the user, allocate one as necessary.
                    214:         * If a buffer is specified, the size has to be non-zero.  The path
                    215:         * is built from the end of the buffer backwards.
                    216:         */
                    217:        if (pt) {
                    218:                ptsize = 0;
                    219:                if (!size) {
                    220:                        errno = EINVAL;
1.4       cgd       221:                        return (NULL);
1.1       cgd       222:                }
                    223:                ept = pt + size;
                    224:        } else {
1.4       cgd       225:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    226:                        return (NULL);
1.1       cgd       227:                ept = pt + ptsize;
                    228:        }
                    229:        bpt = ept - 1;
                    230:        *bpt = '\0';
                    231:
                    232:        /*
                    233:         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
                    234:         * Should always be enough (it's 340 levels).  If it's not, allocate
1.8       perry     235:         * as necessary.  Special case the first stat, it's ".", not "..".
1.1       cgd       236:         */
1.4       cgd       237:        if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1       cgd       238:                goto err;
                    239:        eup = up + MAXPATHLEN;
                    240:        bup = up;
                    241:        up[0] = '.';
                    242:        up[1] = '\0';
                    243:
                    244:        /* Save root values, so know when to stop. */
                    245:        if (stat("/", &s))
                    246:                goto err;
                    247:        root_dev = s.st_dev;
                    248:        root_ino = s.st_ino;
                    249:
                    250:        errno = 0;                      /* XXX readdir has no error return. */
                    251:
                    252:        for (first = 1;; first = 0) {
                    253:                /* Stat the current level. */
                    254:                if (lstat(up, &s))
                    255:                        goto err;
                    256:
                    257:                /* Save current node values. */
                    258:                ino = s.st_ino;
                    259:                dev = s.st_dev;
                    260:
                    261:                /* Check for reaching root. */
                    262:                if (root_dev == dev && root_ino == ino) {
                    263:                        *--bpt = '/';
                    264:                        /*
                    265:                         * It's unclear that it's a requirement to copy the
                    266:                         * path to the beginning of the buffer, but it's always
                    267:                         * been that way and stuff would probably break.
                    268:                         */
1.14      perry     269:                        memmove(pt, bpt,  (size_t)(ept - bpt));
1.1       cgd       270:                        free(up);
1.4       cgd       271:                        return (pt);
1.1       cgd       272:                }
                    273:
                    274:                /*
                    275:                 * Build pointer to the parent directory, allocating memory
                    276:                 * as necessary.  Max length is 3 for "../", the largest
                    277:                 * possible component name, plus a trailing NULL.
                    278:                 */
                    279:                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
1.4       cgd       280:                        if ((up = realloc(up, upsize *= 2)) == NULL)
1.1       cgd       281:                                goto err;
1.4       cgd       282:                        bup = up;
1.1       cgd       283:                        eup = up + upsize;
                    284:                }
                    285:                *bup++ = '.';
                    286:                *bup++ = '.';
                    287:                *bup = '\0';
                    288:
                    289:                /* Open and stat parent directory. */
                    290:                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                    291:                        goto err;
                    292:
                    293:                /* Add trailing slash for next directory. */
                    294:                *bup++ = '/';
                    295:
                    296:                /*
                    297:                 * If it's a mount point, have to stat each element because
                    298:                 * the inode number in the directory is for the entry in the
                    299:                 * parent directory, not the inode number of the mounted file.
                    300:                 */
                    301:                save_errno = 0;
                    302:                if (s.st_dev == dev) {
                    303:                        for (;;) {
                    304:                                if (!(dp = readdir(dir)))
                    305:                                        goto notfound;
1.15      christos  306:                                if (dp->d_fileno == ino) {
1.19    ! christos  307: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  308:                                        dlen = strlen(dp->d_name);
                    309: #else
                    310:                                        dlen = dp->d_namlen;
                    311: #endif
1.1       cgd       312:                                        break;
1.15      christos  313:                                }
1.1       cgd       314:                        }
                    315:                } else
                    316:                        for (;;) {
                    317:                                if (!(dp = readdir(dir)))
                    318:                                        goto notfound;
                    319:                                if (ISDOT(dp))
                    320:                                        continue;
1.19    ! christos  321: #if defined(__SVR4) || defined(__svr4__) || defined(__linux__)
1.15      christos  322:                                dlen = strlen(dp->d_name);
                    323: #else
                    324:                                dlen = dp->d_namlen;
                    325: #endif
                    326:                                memmove(bup, dp->d_name, dlen + 1);
1.1       cgd       327:
                    328:                                /* Save the first error for later. */
                    329:                                if (lstat(up, &s)) {
                    330:                                        if (!save_errno)
                    331:                                                save_errno = errno;
                    332:                                        errno = 0;
                    333:                                        continue;
                    334:                                }
                    335:                                if (s.st_dev == dev && s.st_ino == ino)
                    336:                                        break;
                    337:                        }
                    338:
                    339:                /*
                    340:                 * Check for length of the current name, preceding slash,
                    341:                 * leading slash.
                    342:                 */
1.15      christos  343:                if (bpt - pt <= dlen + (first ? 1 : 2)) {
1.1       cgd       344:                        size_t len, off;
                    345:
                    346:                        if (!ptsize) {
                    347:                                errno = ERANGE;
                    348:                                goto err;
                    349:                        }
                    350:                        off = bpt - pt;
                    351:                        len = ept - bpt;
1.4       cgd       352:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1       cgd       353:                                goto err;
                    354:                        bpt = pt + off;
                    355:                        ept = pt + ptsize;
1.14      perry     356:                        memmove(ept - len, bpt, len);
1.1       cgd       357:                        bpt = ept - len;
                    358:                }
                    359:                if (!first)
                    360:                        *--bpt = '/';
1.15      christos  361:                bpt -= dlen;
                    362:                memmove(bpt, dp->d_name, dlen);
1.1       cgd       363:                (void)closedir(dir);
                    364:
                    365:                /* Truncate any file name. */
                    366:                *bup = '\0';
                    367:        }
                    368:
                    369: notfound:
                    370:        /*
                    371:         * If readdir set errno, use it, not any saved error; otherwise,
                    372:         * didn't find the current directory in its parent directory, set
                    373:         * errno to ENOENT.
                    374:         */
                    375:        if (!errno)
                    376:                errno = save_errno ? save_errno : ENOENT;
                    377:        /* FALLTHROUGH */
                    378: err:
                    379:        if (ptsize)
                    380:                free(pt);
                    381:        free(up);
1.4       cgd       382:        return (NULL);
1.1       cgd       383: }
1.16      sommerfe  384:
                    385: #else /* New getcwd */
                    386:
                    387: char *
                    388: getcwd(pt, size)
                    389:        char *pt;
                    390:        size_t size;
                    391: {
1.18      christos  392:        size_t ptsize, bufsize;
                    393:        int len;
1.16      sommerfe  394:
                    395:        /*
                    396:         * If no buffer specified by the user, allocate one as necessary.
                    397:         * If a buffer is specified, the size has to be non-zero.  The path
                    398:         * is built from the end of the buffer backwards.
                    399:         */
                    400:        if (pt) {
                    401:                ptsize = 0;
                    402:                if (!size) {
                    403:                        errno = EINVAL;
                    404:                        return (NULL);
                    405:                }
                    406:                bufsize = size;
                    407:        } else {
                    408:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    409:                        return (NULL);
                    410:                bufsize = ptsize;
                    411:        }
1.18      christos  412:        for (;;) {
1.16      sommerfe  413:                len = __getcwd(pt, bufsize);
                    414:                if ((len < 0) && (size == 0) && (errno == ERANGE)) {
                    415:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
                    416:                                return NULL;
                    417:                        bufsize = ptsize;
                    418:                        continue;
                    419:                }
1.18      christos  420:                break;
                    421:        }
1.16      sommerfe  422:        if (len < 0)
                    423:                return NULL;
                    424:        else
                    425:                return pt;
                    426: }
                    427:
                    428: #endif

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