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Annotation of src/lib/libc/gen/getcwd.c, Revision 1.51

1.51    ! christos    1: /*     $NetBSD: getcwd.c,v 1.50 2011/02/21 00:40:07 joerg 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.
1.32      agc        18:  * 3. Neither the name of the University nor the names of its contributors
1.1       cgd        19:  *    may be used to endorse or promote products derived from this software
                     20:  *    without specific prior written permission.
                     21:  *
                     22:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     23:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     24:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     25:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     26:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     27:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     28:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     29:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     30:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     31:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     32:  * SUCH DAMAGE.
                     33:  */
                     34:
1.6       christos   35: #include <sys/cdefs.h>
1.1       cgd        36: #if defined(LIBC_SCCS) && !defined(lint)
1.4       cgd        37: #if 0
1.8       perry      38: static char sccsid[] = "@(#)getcwd.c   8.5 (Berkeley) 2/7/95";
1.4       cgd        39: #else
1.51    ! christos   40: __RCSID("$NetBSD: getcwd.c,v 1.50 2011/02/21 00:40:07 joerg Exp $");
1.4       cgd        41: #endif
1.1       cgd        42: #endif /* LIBC_SCCS and not lint */
                     43:
1.7       jtc        44: #include "namespace.h"
1.1       cgd        45: #include <sys/param.h>
                     46: #include <sys/stat.h>
1.8       perry      47:
1.22      lukem      48: #include <assert.h>
1.1       cgd        49: #include <errno.h>
                     50: #include <stdlib.h>
                     51: #include <string.h>
                     52: #include <unistd.h>
1.50      joerg      53: #include <ssp/ssp.h>
1.17      sommerfe   54:
                     55: #include "extern.h"
1.7       jtc        56:
                     57: #ifdef __weak_alias
1.50      joerg      58: __weak_alias(getcwd,_getcwd)
                     59: __weak_alias(_sys_getcwd,_getcwd)
1.24      mycroft    60: __weak_alias(realpath,_realpath)
1.49      tron       61: #endif
1.1       cgd        62:
1.8       perry      63: /*
1.36      enami      64:  * char *realpath(const char *path, char resolved[MAXPATHLEN]);
1.8       perry      65:  *
                     66:  * Find the real name of path, by removing all ".", ".." and symlink
                     67:  * components.  Returns (resolved) on success, or (NULL) on failure,
                     68:  * in which case the path which caused trouble is left in (resolved).
                     69:  */
                     70: char *
1.36      enami      71: realpath(const char *path, char *resolved)
1.8       perry      72: {
                     73:        struct stat sb;
1.51    ! christos   74:        int idx = 0, nlnk = 0;
1.36      enami      75:        const char *q;
                     76:        char *p, wbuf[2][MAXPATHLEN];
                     77:        size_t len;
1.51    ! christos   78:        ssize_t n;
1.22      lukem      79:
                     80:        _DIAGASSERT(resolved != NULL);
1.8       perry      81:
1.46      dholland   82:        /* POSIX sez we must test for this */
                     83:        if (path == NULL) {
                     84:                errno = EINVAL;
                     85:                return NULL;
                     86:        }
                     87:
1.36      enami      88:        /*
                     89:         * Build real path one by one with paying an attention to .,
                     90:         * .. and symbolic link.
                     91:         */
                     92:
                     93:        /*
                     94:         * `p' is where we'll put a new component with prepending
                     95:         * a delimiter.
                     96:         */
                     97:        p = resolved;
                     98:
                     99:        if (*path == 0) {
                    100:                *p = 0;
                    101:                errno = ENOENT;
1.8       perry     102:                return (NULL);
                    103:        }
                    104:
1.36      enami     105:        /* If relative path, start from current working directory. */
                    106:        if (*path != '/') {
1.43      christos  107:                /* check for resolved pointer to appease coverity */
                    108:                if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) {
1.36      enami     109:                        p[0] = '.';
                    110:                        p[1] = 0;
                    111:                        return (NULL);
                    112:                }
                    113:                len = strlen(resolved);
                    114:                if (len > 1)
                    115:                        p += len;
1.31      itojun    116:        }
1.36      enami     117:
1.8       perry     118: loop:
1.36      enami     119:        /* Skip any slash. */
                    120:        while (*path == '/')
                    121:                path++;
                    122:
                    123:        if (*path == 0) {
                    124:                if (p == resolved)
                    125:                        *p++ = '/';
                    126:                *p = 0;
                    127:                return (resolved);
                    128:        }
                    129:
                    130:        /* Find the end of this component. */
                    131:        q = path;
                    132:        do
                    133:                q++;
                    134:        while (*q != '/' && *q != 0);
                    135:
                    136:        /* Test . or .. */
                    137:        if (path[0] == '.') {
                    138:                if (q - path == 1) {
                    139:                        path = q;
1.8       perry     140:                        goto loop;
                    141:                }
1.36      enami     142:                if (path[1] == '.' && q - path == 2) {
                    143:                        /* Trim the last component. */
                    144:                        if (p != resolved)
                    145:                                while (*--p != '/')
                    146:                                        ;
                    147:                        path = q;
                    148:                        goto loop;
1.8       perry     149:                }
                    150:        }
                    151:
1.36      enami     152:        /* Append this component. */
                    153:        if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) {
1.31      itojun    154:                errno = ENAMETOOLONG;
1.36      enami     155:                if (p == resolved)
                    156:                        *p++ = '/';
                    157:                *p = 0;
                    158:                return (NULL);
1.31      itojun    159:        }
1.36      enami     160:        p[0] = '/';
                    161:        memcpy(&p[1], path,
                    162:            /* LINTED We know q > path. */
                    163:            q - path);
                    164:        p[1 + q - path] = 0;
1.8       perry     165:
                    166:        /*
1.36      enami     167:         * If this component is a symlink, toss it and prepend link
                    168:         * target to unresolved path.
                    169:         */
                    170:        if (lstat(resolved, &sb) == -1) {
                    171:                return (NULL);
                    172:        }
                    173:        if (S_ISLNK(sb.st_mode)) {
                    174:                if (nlnk++ >= MAXSYMLINKS) {
                    175:                        errno = ELOOP;
                    176:                        return (NULL);
                    177:                }
                    178:                n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1);
                    179:                if (n < 0)
                    180:                        return (NULL);
                    181:                if (n == 0) {
                    182:                        errno = ENOENT;
                    183:                        return (NULL);
                    184:                }
1.8       perry     185:
1.36      enami     186:                /* Append unresolved path to link target and switch to it. */
                    187:                if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) {
1.8       perry     188:                        errno = ENAMETOOLONG;
1.36      enami     189:                        return (NULL);
1.31      itojun    190:                }
1.36      enami     191:                memcpy(&wbuf[idx][n], q, len + 1);
                    192:                path = wbuf[idx];
                    193:                idx ^= 1;
                    194:
                    195:                /* If absolute symlink, start from root. */
                    196:                if (*path == '/')
                    197:                        p = resolved;
                    198:                goto loop;
1.8       perry     199:        }
1.38      enami     200:        if (*q == '/' && !S_ISDIR(sb.st_mode)) {
                    201:                errno = ENOTDIR;
                    202:                return (NULL);
                    203:        }
1.8       perry     204:
1.36      enami     205:        /* Advance both resolved and unresolved path. */
                    206:        p += 1 + q - path;
                    207:        path = q;
                    208:        goto loop;
1.8       perry     209: }
                    210:
1.16      sommerfe  211: char *
1.50      joerg     212: __ssp_real(getcwd)(char *pt, size_t size)
1.16      sommerfe  213: {
1.35      enami     214:        char *npt;
                    215:
1.16      sommerfe  216:        /*
1.35      enami     217:         * If a buffer is specified, the size has to be non-zero.
1.16      sommerfe  218:         */
1.35      enami     219:        if (pt != NULL) {
                    220:                if (size == 0) {
                    221:                        /* __getcwd(pt, 0) results ERANGE. */
1.16      sommerfe  222:                        errno = EINVAL;
                    223:                        return (NULL);
                    224:                }
1.35      enami     225:                if (__getcwd(pt, size) >= 0)
                    226:                        return (pt);
                    227:                return (NULL);
1.16      sommerfe  228:        }
1.35      enami     229:
                    230:        /*
                    231:         * If no buffer specified by the user, allocate one as necessary.
                    232:         */
                    233:        size = 1024 >> 1;
                    234:        do {
                    235:                if ((npt = realloc(pt, size <<= 1)) == NULL)
                    236:                        break;
                    237:                pt = npt;
                    238:                if (__getcwd(pt, size) >= 0)
                    239:                        return (pt);
                    240:        } while (size <= MAXPATHLEN * 4 && errno == ERANGE);
                    241:
                    242:        free(pt);
                    243:        return (NULL);
1.16      sommerfe  244: }

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