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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.15

1.15    ! christos    1: /*     $NetBSD: getcwd.c,v 1.14 1998/08/26 00:38:40 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
1.15    ! christos   44: __RCSID("$NetBSD: getcwd.c,v 1.14 1998/08/26 00:38:40 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:
1.15    ! christos   70: #if defined(__SVR4) || defined(__svr4__)
        !            71: #define d_fileno d_ino
        !            72: #endif
        !            73:
1.8       perry      74: /*
                     75:  * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
                     76:  *
                     77:  * Find the real name of path, by removing all ".", ".." and symlink
                     78:  * components.  Returns (resolved) on success, or (NULL) on failure,
                     79:  * in which case the path which caused trouble is left in (resolved).
                     80:  */
                     81: char *
                     82: realpath(path, resolved)
                     83:        const char *path;
                     84:        char *resolved;
                     85: {
                     86:        struct stat sb;
                     87:        int fd, n, rootd, serrno;
                     88:        char *p, *q, wbuf[MAXPATHLEN];
                     89:
                     90:        /* Save the starting point. */
                     91:        if ((fd = open(".", O_RDONLY)) < 0) {
                     92:                (void)strcpy(resolved, ".");
                     93:                return (NULL);
                     94:        }
                     95:
                     96:        /*
                     97:         * Find the dirname and basename from the path to be resolved.
                     98:         * Change directory to the dirname component.
                     99:         * lstat the basename part.
                    100:         *     if it is a symlink, read in the value and loop.
                    101:         *     if it is a directory, then change to that directory.
                    102:         * get the current directory name and append the basename.
                    103:         */
                    104:        (void)strncpy(resolved, path, MAXPATHLEN - 1);
                    105:        resolved[MAXPATHLEN - 1] = '\0';
                    106: loop:
                    107:        q = strrchr(resolved, '/');
                    108:        if (q != NULL) {
                    109:                p = q + 1;
                    110:                if (q == resolved)
                    111:                        q = "/";
                    112:                else {
                    113:                        do {
                    114:                                --q;
                    115:                        } while (q > resolved && *q == '/');
                    116:                        q[1] = '\0';
                    117:                        q = resolved;
                    118:                }
                    119:                if (chdir(q) < 0)
                    120:                        goto err1;
                    121:        } else
                    122:                p = resolved;
                    123:
                    124:        /* Deal with the last component. */
                    125:        if (lstat(p, &sb) == 0) {
                    126:                if (S_ISLNK(sb.st_mode)) {
                    127:                        n = readlink(p, resolved, MAXPATHLEN);
                    128:                        if (n < 0)
                    129:                                goto err1;
                    130:                        resolved[n] = '\0';
                    131:                        goto loop;
                    132:                }
                    133:                if (S_ISDIR(sb.st_mode)) {
                    134:                        if (chdir(p) < 0)
                    135:                                goto err1;
                    136:                        p = "";
                    137:                }
                    138:        }
                    139:
                    140:        /*
                    141:         * Save the last component name and get the full pathname of
                    142:         * the current directory.
                    143:         */
1.9       perry     144:        (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8       perry     145:
                    146:        /*
                    147:         * Call the inernal internal version of getcwd which
                    148:         * does a physical search rather than using the $PWD short-cut
                    149:         */
1.12      lukem     150:        if (getcwd(resolved, MAXPATHLEN) == 0)
1.8       perry     151:                goto err1;
                    152:
                    153:        /*
                    154:         * Join the two strings together, ensuring that the right thing
                    155:         * happens if the last component is empty, or the dirname is root.
                    156:         */
                    157:        if (resolved[0] == '/' && resolved[1] == '\0')
                    158:                rootd = 1;
                    159:        else
                    160:                rootd = 0;
                    161:
                    162:        if (*wbuf) {
                    163:                if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
                    164:                        errno = ENAMETOOLONG;
                    165:                        goto err1;
                    166:                }
                    167:                if (rootd == 0)
1.9       perry     168:                        (void)strcat(resolved, "/"); /* XXX: strcat is safe */
                    169:                (void)strcat(resolved, wbuf);   /* XXX: strcat is safe */
1.8       perry     170:        }
                    171:
                    172:        /* Go back to where we came from. */
                    173:        if (fchdir(fd) < 0) {
                    174:                serrno = errno;
                    175:                goto err2;
                    176:        }
                    177:
                    178:        /* It's okay if the close fails, what's an fd more or less? */
                    179:        (void)close(fd);
                    180:        return (resolved);
                    181:
                    182: err1:  serrno = errno;
                    183:        (void)fchdir(fd);
                    184: err2:  (void)close(fd);
                    185:        errno = serrno;
                    186:        return (NULL);
                    187: }
                    188:
1.12      lukem     189: char *
                    190: getcwd(pt, size)
1.8       perry     191:        char *pt;
                    192:        size_t size;
                    193: {
1.10      perry     194:        struct dirent *dp;
                    195:        DIR *dir;
                    196:        dev_t dev;
                    197:        ino_t ino;
                    198:        int first;
                    199:        char *bpt, *bup;
1.1       cgd       200:        struct stat s;
                    201:        dev_t root_dev;
                    202:        ino_t root_ino;
                    203:        size_t ptsize, upsize;
                    204:        int save_errno;
                    205:        char *ept, *eup, *up;
1.15    ! christos  206:        size_t dlen;
1.1       cgd       207:
                    208:        /*
                    209:         * If no buffer specified by the user, allocate one as necessary.
                    210:         * If a buffer is specified, the size has to be non-zero.  The path
                    211:         * is built from the end of the buffer backwards.
                    212:         */
                    213:        if (pt) {
                    214:                ptsize = 0;
                    215:                if (!size) {
                    216:                        errno = EINVAL;
1.4       cgd       217:                        return (NULL);
1.1       cgd       218:                }
                    219:                ept = pt + size;
                    220:        } else {
1.4       cgd       221:                if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
                    222:                        return (NULL);
1.1       cgd       223:                ept = pt + ptsize;
                    224:        }
                    225:        bpt = ept - 1;
                    226:        *bpt = '\0';
                    227:
                    228:        /*
                    229:         * Allocate bytes (1024 - malloc space) for the string of "../"'s.
                    230:         * Should always be enough (it's 340 levels).  If it's not, allocate
1.8       perry     231:         * as necessary.  Special case the first stat, it's ".", not "..".
1.1       cgd       232:         */
1.4       cgd       233:        if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1       cgd       234:                goto err;
                    235:        eup = up + MAXPATHLEN;
                    236:        bup = up;
                    237:        up[0] = '.';
                    238:        up[1] = '\0';
                    239:
                    240:        /* Save root values, so know when to stop. */
                    241:        if (stat("/", &s))
                    242:                goto err;
                    243:        root_dev = s.st_dev;
                    244:        root_ino = s.st_ino;
                    245:
                    246:        errno = 0;                      /* XXX readdir has no error return. */
                    247:
                    248:        for (first = 1;; first = 0) {
                    249:                /* Stat the current level. */
                    250:                if (lstat(up, &s))
                    251:                        goto err;
                    252:
                    253:                /* Save current node values. */
                    254:                ino = s.st_ino;
                    255:                dev = s.st_dev;
                    256:
                    257:                /* Check for reaching root. */
                    258:                if (root_dev == dev && root_ino == ino) {
                    259:                        *--bpt = '/';
                    260:                        /*
                    261:                         * It's unclear that it's a requirement to copy the
                    262:                         * path to the beginning of the buffer, but it's always
                    263:                         * been that way and stuff would probably break.
                    264:                         */
1.14      perry     265:                        memmove(pt, bpt,  (size_t)(ept - bpt));
1.1       cgd       266:                        free(up);
1.4       cgd       267:                        return (pt);
1.1       cgd       268:                }
                    269:
                    270:                /*
                    271:                 * Build pointer to the parent directory, allocating memory
                    272:                 * as necessary.  Max length is 3 for "../", the largest
                    273:                 * possible component name, plus a trailing NULL.
                    274:                 */
                    275:                if (bup + 3  + MAXNAMLEN + 1 >= eup) {
1.4       cgd       276:                        if ((up = realloc(up, upsize *= 2)) == NULL)
1.1       cgd       277:                                goto err;
1.4       cgd       278:                        bup = up;
1.1       cgd       279:                        eup = up + upsize;
                    280:                }
                    281:                *bup++ = '.';
                    282:                *bup++ = '.';
                    283:                *bup = '\0';
                    284:
                    285:                /* Open and stat parent directory. */
                    286:                if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
                    287:                        goto err;
                    288:
                    289:                /* Add trailing slash for next directory. */
                    290:                *bup++ = '/';
                    291:
                    292:                /*
                    293:                 * If it's a mount point, have to stat each element because
                    294:                 * the inode number in the directory is for the entry in the
                    295:                 * parent directory, not the inode number of the mounted file.
                    296:                 */
                    297:                save_errno = 0;
                    298:                if (s.st_dev == dev) {
                    299:                        for (;;) {
                    300:                                if (!(dp = readdir(dir)))
                    301:                                        goto notfound;
1.15    ! christos  302:                                if (dp->d_fileno == ino) {
        !           303: #if defined(__SVR4) || defined(__svr4__)
        !           304:                                        dlen = strlen(dp->d_name);
        !           305: #else
        !           306:                                        dlen = dp->d_namlen;
        !           307: #endif
1.1       cgd       308:                                        break;
1.15    ! christos  309:                                }
1.1       cgd       310:                        }
                    311:                } else
                    312:                        for (;;) {
                    313:                                if (!(dp = readdir(dir)))
                    314:                                        goto notfound;
                    315:                                if (ISDOT(dp))
                    316:                                        continue;
1.15    ! christos  317: #if defined(__SVR4) || defined(__svr4__)
        !           318:                                dlen = strlen(dp->d_name);
        !           319: #else
        !           320:                                dlen = dp->d_namlen;
        !           321: #endif
        !           322:                                memmove(bup, dp->d_name, dlen + 1);
1.1       cgd       323:
                    324:                                /* Save the first error for later. */
                    325:                                if (lstat(up, &s)) {
                    326:                                        if (!save_errno)
                    327:                                                save_errno = errno;
                    328:                                        errno = 0;
                    329:                                        continue;
                    330:                                }
                    331:                                if (s.st_dev == dev && s.st_ino == ino)
                    332:                                        break;
                    333:                        }
                    334:
                    335:                /*
                    336:                 * Check for length of the current name, preceding slash,
                    337:                 * leading slash.
                    338:                 */
1.15    ! christos  339:                if (bpt - pt <= dlen + (first ? 1 : 2)) {
1.1       cgd       340:                        size_t len, off;
                    341:
                    342:                        if (!ptsize) {
                    343:                                errno = ERANGE;
                    344:                                goto err;
                    345:                        }
                    346:                        off = bpt - pt;
                    347:                        len = ept - bpt;
1.4       cgd       348:                        if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1       cgd       349:                                goto err;
                    350:                        bpt = pt + off;
                    351:                        ept = pt + ptsize;
1.14      perry     352:                        memmove(ept - len, bpt, len);
1.1       cgd       353:                        bpt = ept - len;
                    354:                }
                    355:                if (!first)
                    356:                        *--bpt = '/';
1.15    ! christos  357:                bpt -= dlen;
        !           358:                memmove(bpt, dp->d_name, dlen);
1.1       cgd       359:                (void)closedir(dir);
                    360:
                    361:                /* Truncate any file name. */
                    362:                *bup = '\0';
                    363:        }
                    364:
                    365: notfound:
                    366:        /*
                    367:         * If readdir set errno, use it, not any saved error; otherwise,
                    368:         * didn't find the current directory in its parent directory, set
                    369:         * errno to ENOENT.
                    370:         */
                    371:        if (!errno)
                    372:                errno = save_errno ? save_errno : ENOENT;
                    373:        /* FALLTHROUGH */
                    374: err:
                    375:        if (ptsize)
                    376:                free(pt);
                    377:        free(up);
1.4       cgd       378:        return (NULL);
1.1       cgd       379: }

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