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/*
* Copyright (c) 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char *rcsid = "$OpenBSD: realpath.c,v 1.6 2002/01/12 16:24:35 millert Exp $";
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*
* char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
*
* Find the real name of path, by removing all ".", ".." and symlink
* components. Returns (resolved) on success, or (NULL) on failure,
* in which case the path which caused trouble is left in (resolved).
*/
char *
realpath(path, resolved)
const char *path;
char *resolved;
{
struct stat sb;
int fd, n, rootd, serrno;
char *p, *q, wbuf[MAXPATHLEN];
int symlinks = 0;
/* Save the starting point. */
if ((fd = open(".", O_RDONLY)) < 0) {
(void)strcpy(resolved, ".");
return (NULL);
}
/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
if (path[0] == '.' && path[1] == '\0')
path = "";
/*
* Find the dirname and basename from the path to be resolved.
* Change directory to the dirname component.
* lstat the basename part.
* if it is a symlink, read in the value and loop.
* if it is a directory, then change to that directory.
* get the current directory name and append the basename.
*/
strlcpy(resolved, path, MAXPATHLEN);
loop:
q = strrchr(resolved, '/');
if (q != NULL) {
p = q + 1;
if (q == resolved)
q = "/";
else {
do {
--q;
} while (q > resolved && *q == '/');
q[1] = '\0';
q = resolved;
}
if (chdir(q) < 0)
goto err1;
} else
p = resolved;
/* Deal with the last component. */
if (*p != '\0' && lstat(p, &sb) == 0) {
if (S_ISLNK(sb.st_mode)) {
if (++symlinks > MAXSYMLINKS) {
errno = ELOOP;
goto err1;
}
n = readlink(p, resolved, MAXPATHLEN-1);
if (n < 0)
goto err1;
resolved[n] = '\0';
goto loop;
}
if (S_ISDIR(sb.st_mode)) {
if (chdir(p) < 0)
goto err1;
p = "";
}
}
/*
* Save the last component name and get the full pathname of
* the current directory.
*/
(void)strcpy(wbuf, p);
if (getcwd(resolved, MAXPATHLEN) == 0)
goto err1;
/*
* Join the two strings together, ensuring that the right thing
* happens if the last component is empty, or the dirname is root.
*/
if (resolved[0] == '/' && resolved[1] == '\0')
rootd = 1;
else
rootd = 0;
if (*wbuf) {
if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
errno = ENAMETOOLONG;
goto err1;
}
if (rootd == 0)
(void)strcat(resolved, "/");
(void)strcat(resolved, wbuf);
}
/* Go back to where we came from. */
if (fchdir(fd) < 0) {
serrno = errno;
goto err2;
}
/* It's okay if the close fails, what's an fd more or less? */
(void)close(fd);
return (resolved);
err1: serrno = errno;
(void)fchdir(fd);
err2: (void)close(fd);
errno = serrno;
return (NULL);
}
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