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/*
* CU sudo version 1.3.1
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 1, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Please send bugs, changes, problems to sudo-bugs@cs.colorado.edu
*
*******************************************************************
*
* This module contains sudo_realpath(3), a customized version of
* realpath(3). It is necesary to do the final chdir(2) as the
* uid of the invoking user.
*
* sudo_realpath(3) takes a path to qualify and a pointer to a string
* as a copyout parameter. This string should be of size MAXPATHLEN.
*
* Todd C. Miller (millert@colorado.edu) Fri Jun 3 18:32:19 MDT 1994
*/
#ifndef lint
static char rcsid[] = "$Id$";
#endif /* lint */
#include "config.h"
#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */
#ifdef HAVE_STRING_H
#include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif /* HAVE_STRINGS_H */
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <netinet/in.h>
#include "sudo.h"
#include "options.h"
#ifndef STDC_HEADERS
extern char *strcpy __P((char *, const char *));
extern ssize_t readlink __P((const char *, char *, size_t));
extern int lstat __P((const char *, struct stat *));
#endif /* !STDC_HEADERS */
/*
* Posix versions for those without
*/
#ifndef _S_IFMT
#define _S_IFMT S_IFMT
#endif /* _S_IFMT */
#ifndef _S_IFLNK
#define _S_IFLNK S_IFLNK
#endif /* _S_IFLNK */
/*
* Prototypes
*/
static void realpath_restore __P((char *));
/******************************************************************
*
* sudo_realpath()
*
* this function takes a path and makes it fully qualified and resolves
* all symbolic links, returning the fully qualfied path.
*/
char * sudo_realpath(old, new)
const char * old;
char * new;
{
char buf[MAXPATHLEN+1]; /* generic path buffer */
struct stat statbuf; /* for lstat() */
char * temp; /* temporary ptr */
int len; /* length parameter */
int err; /* did we get an error? */
/* check for brain damage */
if (old == NULL || old[0] == '\0')
return(NULL);
new[MAXPATHLEN] = '\0';
(void) strncpy(new, old, MAXPATHLEN);
/* we need to be root for this section */
set_perms(PERM_ROOT);
#ifndef USE_REALPATH
err = stat(new, &statbuf);
set_perms(PERM_USER);
return((err == 0) ? new : NULL);
#endif /* USE_REALPATH */
/*
* Resolve the last component of the path if it is a link
* until it is a non-link.
*/
errno = 0;
while (!lstat(new, &statbuf) && (statbuf.st_mode & _S_IFMT) == _S_IFLNK) {
/* it's a link */
if ((len = readlink(new, buf, sizeof(buf))) <= 0) {
realpath_restore(cwd);
return(NULL);
}
buf[len] = '\0';
/*
* If the link is absolute, copy it in, else remove the last
* component in new and append the link unless the sum is too long.
*/
if (buf[0] == '/') {
(void) strcpy(new, buf);
} else {
if ((temp = strrchr(new, '/')))
*(++temp) = '\0';
if (strlen(new) + strlen(buf) >= MAXPATHLEN ) {
errno = ENAMETOOLONG;
realpath_restore(cwd);
return(NULL);
}
(void) strcat(new, buf);
}
}
/* did an lstat() fail? */
if (errno) {
realpath_restore(cwd);
return(NULL);
}
/*
* separate the last component from the rest of the path
* so we can do a getcwd() safely.
*/
if (!(temp = strrchr(new, '/'))) {
/* this should not happen */
errno = ENOTDIR;
realpath_restore(cwd);
return(NULL);
}
(void) strcpy(buf, ++temp);
*temp = '\0';
/*
* chdir() to new and go a getcwd() to find real path then
* append buf * (last component of the path) and return.
*/
if (chdir(new)) {
realpath_restore(cwd);
return(NULL);
}
if (!(getcwd(new, MAXPATHLEN))) {
realpath_restore(cwd);
return(NULL);
}
/* append "/" and buf to new but watch for double '/' */
len = strlen(new);
if (len) {
temp = new + len - 1;
if (*temp != '/') {
*(++temp) = '/';
*(++temp) = '\0';
}
}
(void) strcat(new, buf);
realpath_restore(cwd);
return(new);
}
/******************************************************************
*
* realpath_ret()
*
* this function cd's to cwd, closes it, and returns path.
*/
static void realpath_restore(cwd)
char * cwd;
{
/* relinquish root privs and chdir to where we started... */
set_perms(PERM_USER);
if (chdir(cwd)) {
fprintf(stderr, "Error: cannot change dir back to %s, sudo aborting!\n",
cwd);
exit(1);
}
}
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