/* $OpenBSD: getcwd.c,v 1.14 2005/08/08 08:05:34 espie Exp */ /* * Copyright (c) 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* OPENBSD ORIGINAL: lib/libc/gen/getcwd.c */ #include "includes.h" #if !defined(HAVE_GETCWD) #include <sys/stat.h> #include <errno.h> #include <dirent.h> #include <sys/dir.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "includes.h" #define ISDOT(dp) \ (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) char * getcwd(char *pt, size_t size) { struct dirent *dp; DIR *dir = NULL; dev_t dev; ino_t ino; int first; char *bpt, *bup; struct stat s; dev_t root_dev; ino_t root_ino; size_t ptsize, upsize; int save_errno; char *ept, *eup, *up; /* * If no buffer specified by the user, allocate one as necessary. * If a buffer is specified, the size has to be non-zero. The path * is built from the end of the buffer backwards. */ if (pt) { ptsize = 0; if (size == 0) { errno = EINVAL; return (NULL); } else if (size == 1) { errno = ERANGE; return (NULL); } ept = pt + size; } else { if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL) return (NULL); ept = pt + ptsize; } bpt = ept - 1; *bpt = '\0'; /* * Allocate bytes for the string of "../"'s. * Should always be enough (it's 340 levels). If it's not, allocate * as necessary. Special * case the first stat, it's ".", not "..". */ if ((up = malloc(upsize = MAXPATHLEN)) == NULL) goto err; eup = up + upsize; bup = up; up[0] = '.'; up[1] = '\0'; /* Save root values, so know when to stop. */ if (stat("/", &s)) goto err; root_dev = s.st_dev; root_ino = s.st_ino; errno = 0; /* XXX readdir has no error return. */ for (first = 1;; first = 0) { /* Stat the current level. */ if (lstat(up, &s)) goto err; /* Save current node values. */ ino = s.st_ino; dev = s.st_dev; /* Check for reaching root. */ if (root_dev == dev && root_ino == ino) { *--bpt = '/'; /* * It's unclear that it's a requirement to copy the * path to the beginning of the buffer, but it's always * been that way and stuff would probably break. */ memmove(pt, bpt, ept - bpt); free(up); return (pt); } /* * Build pointer to the parent directory, allocating memory * as necessary. Max length is 3 for "../", the largest * possible component name, plus a trailing NUL. */ if (bup + 3 + MAXNAMLEN + 1 >= eup) { char *nup; if ((nup = realloc(up, upsize *= 2)) == NULL) goto err; bup = nup + (bup - up); up = nup; eup = up + upsize; } *bup++ = '.'; *bup++ = '.'; *bup = '\0'; /* Open and stat parent directory. */ if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) goto err; /* Add trailing slash for next directory. */ *bup++ = '/'; /* * If it's a mount point, have to stat each element because * the inode number in the directory is for the entry in the * parent directory, not the inode number of the mounted file. */ save_errno = 0; if (s.st_dev == dev) { for (;;) { if (!(dp = readdir(dir))) goto notfound; if (dp->d_fileno == ino) break; } } else for (;;) { if (!(dp = readdir(dir))) goto notfound; if (ISDOT(dp)) continue; memcpy(bup, dp->d_name, dp->d_namlen + 1); /* Save the first error for later. */ if (lstat(up, &s)) { if (!save_errno) save_errno = errno; errno = 0; continue; } if (s.st_dev == dev && s.st_ino == ino) break; } /* * Check for length of the current name, preceding slash, * leading slash. */ if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { size_t len; char *npt; if (!ptsize) { errno = ERANGE; goto err; } len = ept - bpt; if ((npt = realloc(pt, ptsize *= 2)) == NULL) goto err; bpt = npt + (bpt - pt); pt = npt; ept = pt + ptsize; memmove(ept - len, bpt, len); bpt = ept - len; } if (!first) *--bpt = '/'; bpt -= dp->d_namlen; memcpy(bpt, dp->d_name, dp->d_namlen); (void)closedir(dir); /* Truncate any file name. */ *bup = '\0'; } notfound: /* * If readdir set errno, use it, not any saved error; otherwise, * didn't find the current directory in its parent directory, set * errno to ENOENT. */ if (!errno) errno = save_errno ? save_errno : ENOENT; /* FALLTHROUGH */ err: save_errno = errno; if (ptsize) free(pt); free(up); if (dir) (void)closedir(dir); errno = save_errno; return (NULL); } #endif /* !defined(HAVE_GETCWD) */
