Annotation of embedaddon/sudo/compat/getcwd.c, revision 1.1
1.1 ! misho 1: /*
! 2: * Copyright (c) 1989, 1991, 1993
! 3: * The Regents of the University of California. All rights reserved.
! 4: *
! 5: * Redistribution and use in source and binary forms, with or without
! 6: * modification, are permitted provided that the following conditions
! 7: * are met:
! 8: * 1. Redistributions of source code must retain the above copyright
! 9: * notice, this list of conditions and the following disclaimer.
! 10: * 2. Redistributions in binary form must reproduce the above copyright
! 11: * notice, this list of conditions and the following disclaimer in the
! 12: * documentation and/or other materials provided with the distribution.
! 13: * 3. Neither the name of the University nor the names of its contributors
! 14: * may be used to endorse or promote products derived from this software
! 15: * without specific prior written permission.
! 16: *
! 17: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 20: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 27: * SUCH DAMAGE.
! 28: */
! 29:
! 30: #include <config.h>
! 31:
! 32: #include <sys/param.h>
! 33: #include <sys/stat.h>
! 34:
! 35: #include <errno.h>
! 36: #include <stdio.h>
! 37: #ifdef STDC_HEADERS
! 38: # include <stdlib.h>
! 39: # include <stddef.h>
! 40: #else
! 41: # ifdef HAVE_STDLIB_H
! 42: # include <stdlib.h>
! 43: # endif
! 44: #endif /* STDC_HEADERS */
! 45: #ifdef HAVE_STRING_H
! 46: # include <string.h>
! 47: #endif /* HAVE_STRING_H */
! 48: #ifdef HAVE_STRINGS_H
! 49: # include <strings.h>
! 50: #endif /* HAVE_STRINGS_H */
! 51: #if defined(HAVE_MALLOC_H) && !defined(STDC_HEADERS)
! 52: # include <malloc.h>
! 53: #endif /* HAVE_MALLOC_H && !STDC_HEADERS */
! 54: #ifdef HAVE_UNISTD_H
! 55: # include <unistd.h>
! 56: #endif /* HAVE_UNISTD_H */
! 57: #ifdef HAVE_DIRENT_H
! 58: # include <dirent.h>
! 59: # define NAMLEN(dirent) strlen((dirent)->d_name)
! 60: #else
! 61: # define dirent direct
! 62: # define NAMLEN(dirent) (dirent)->d_namlen
! 63: # ifdef HAVE_SYS_NDIR_H
! 64: # include <sys/ndir.h>
! 65: # endif
! 66: # ifdef HAVE_SYS_DIR_H
! 67: # include <sys/dir.h>
! 68: # endif
! 69: # ifdef HAVE_NDIR_H
! 70: # include <ndir.h>
! 71: # endif
! 72: #endif
! 73:
! 74: #include "missing.h"
! 75:
! 76: #define ISDOT(dp) \
! 77: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
! 78: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
! 79:
! 80: char *
! 81: getcwd(char *pt, size_t size)
! 82: {
! 83: struct dirent *dp;
! 84: DIR *dir = NULL;
! 85: dev_t dev;
! 86: ino_t ino;
! 87: int first;
! 88: char *bpt, *bup;
! 89: struct stat s;
! 90: dev_t root_dev;
! 91: ino_t root_ino;
! 92: size_t ptsize, upsize;
! 93: int save_errno;
! 94: char *ept, *eup, *up;
! 95:
! 96: /*
! 97: * If no buffer specified by the user, allocate one as necessary.
! 98: * If a buffer is specified, the size has to be non-zero. The path
! 99: * is built from the end of the buffer backwards.
! 100: */
! 101: if (pt) {
! 102: ptsize = 0;
! 103: if (!size) {
! 104: errno = EINVAL;
! 105: return NULL;
! 106: }
! 107: ept = pt + size;
! 108: } else {
! 109: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
! 110: return NULL;
! 111: ept = pt + ptsize;
! 112: }
! 113: bpt = ept - 1;
! 114: *bpt = '\0';
! 115:
! 116: /*
! 117: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
! 118: * Should always be enough (it's 340 levels). If it's not, allocate
! 119: * as necessary. Special * case the first stat, it's ".", not "..".
! 120: */
! 121: if ((up = malloc(upsize = 1024 - 4)) == NULL)
! 122: goto err;
! 123: eup = up + PATH_MAX;
! 124: bup = up;
! 125: up[0] = '.';
! 126: up[1] = '\0';
! 127:
! 128: /* Save root values, so know when to stop. */
! 129: if (stat("/", &s))
! 130: goto err;
! 131: root_dev = s.st_dev;
! 132: root_ino = s.st_ino;
! 133:
! 134: errno = 0; /* XXX readdir has no error return. */
! 135:
! 136: for (first = 1;; first = 0) {
! 137: /* Stat the current level. */
! 138: if (lstat(up, &s))
! 139: goto err;
! 140:
! 141: /* Save current node values. */
! 142: ino = s.st_ino;
! 143: dev = s.st_dev;
! 144:
! 145: /* Check for reaching root. */
! 146: if (root_dev == dev && root_ino == ino) {
! 147: *--bpt = '/';
! 148: /*
! 149: * It's unclear that it's a requirement to copy the
! 150: * path to the beginning of the buffer, but it's always
! 151: * been that way and stuff would probably break.
! 152: */
! 153: bcopy(bpt, pt, ept - bpt);
! 154: free(up);
! 155: return pt;
! 156: }
! 157:
! 158: /*
! 159: * Build pointer to the parent directory, allocating memory
! 160: * as necessary. Max length is 3 for "../", the largest
! 161: * possible component name, plus a trailing NULL.
! 162: */
! 163: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
! 164: char *nup;
! 165:
! 166: if ((nup = realloc(up, upsize *= 2)) == NULL)
! 167: goto err;
! 168: up = nup;
! 169: bup = up;
! 170: eup = up + upsize;
! 171: }
! 172: *bup++ = '.';
! 173: *bup++ = '.';
! 174: *bup = '\0';
! 175:
! 176: /* Open and stat parent directory. */
! 177: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
! 178: goto err;
! 179:
! 180: /* Add trailing slash for next directory. */
! 181: *bup++ = '/';
! 182:
! 183: /*
! 184: * If it's a mount point, have to stat each element because
! 185: * the inode number in the directory is for the entry in the
! 186: * parent directory, not the inode number of the mounted file.
! 187: */
! 188: save_errno = 0;
! 189: if (s.st_dev == dev) {
! 190: for (;;) {
! 191: if (!(dp = readdir(dir)))
! 192: goto notfound;
! 193: if (dp->d_fileno == ino)
! 194: break;
! 195: }
! 196: } else
! 197: for (;;) {
! 198: if (!(dp = readdir(dir)))
! 199: goto notfound;
! 200: if (ISDOT(dp))
! 201: continue;
! 202: bcopy(dp->d_name, bup, NAMLEN(dp) + 1);
! 203:
! 204: /* Save the first error for later. */
! 205: if (lstat(up, &s)) {
! 206: if (!save_errno)
! 207: save_errno = errno;
! 208: errno = 0;
! 209: continue;
! 210: }
! 211: if (s.st_dev == dev && s.st_ino == ino)
! 212: break;
! 213: }
! 214:
! 215: /*
! 216: * Check for length of the current name, preceding slash,
! 217: * leading slash.
! 218: */
! 219: if (bpt - pt <= NAMLEN(dp) + (first ? 1 : 2)) {
! 220: size_t len, off;
! 221: char *npt;
! 222:
! 223: if (!ptsize) {
! 224: errno = ERANGE;
! 225: goto err;
! 226: }
! 227: off = bpt - pt;
! 228: len = ept - bpt;
! 229: if ((npt = realloc(pt, ptsize *= 2)) == NULL)
! 230: goto err;
! 231: pt = npt;
! 232: bpt = pt + off;
! 233: ept = pt + ptsize;
! 234: bcopy(bpt, ept - len, len);
! 235: bpt = ept - len;
! 236: }
! 237: if (!first)
! 238: *--bpt = '/';
! 239: bpt -= NAMLEN(dp);
! 240: bcopy(dp->d_name, bpt, NAMLEN(dp));
! 241: (void)closedir(dir);
! 242:
! 243: /* Truncate any file name. */
! 244: *bup = '\0';
! 245: }
! 246:
! 247: notfound:
! 248: /*
! 249: * If readdir set errno, use it, not any saved error; otherwise,
! 250: * didn't find the current directory in its parent directory, set
! 251: * errno to ENOENT.
! 252: */
! 253: if (!errno)
! 254: errno = save_errno ? save_errno : ENOENT;
! 255: /* FALLTHROUGH */
! 256: err:
! 257: if (ptsize)
! 258: free(pt);
! 259: if (up)
! 260: free(up);
! 261: if (dir)
! 262: (void)closedir(dir);
! 263: return NULL;
! 264: }
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