/* Initialize and populate the uids and gids vectors. */
error_t
get_credentials (void)
{
/* Fetch uids... */
uids_len = geteuids (0, 0);
if (uids_len < 0)
return errno;
uids = malloc (uids_len * sizeof (uid_t));
if (! uids)
return ENOMEM;
uids_len = geteuids (uids_len, uids);
if (uids_len < 0)
return errno;
/* ... and gids. */
gids_len = getgroups (0, 0);
if (gids_len < 0)
return errno;
gids = malloc (gids_len * sizeof (gid_t));
if (! uids)
return ENOMEM;
gids_len = getgroups (gids_len, gids);
if (gids_len < 0)
return errno;
return 0;
}
/*Traces the translator stack on the given underlying node until it
finds the first translator called `name` and returns the port
pointing to the translator sitting under this one.*/
error_t
trace_find
(mach_port_t underlying, const char *name, int flags, mach_port_t * port)
{
error_t err = 0;
/*Identity information about the current process */
uid_t *uids;
size_t nuids;
gid_t *gids;
size_t ngids;
/*The name and arguments of the translator being passed now */
char *argz = NULL;
size_t argz_len = 0;
/*The current working directory */
char *cwd = NULL;
/*The port to the directory containing the file pointed to by `underlying` */
file_t dir;
/*The unauthenticated version of `dir` */
file_t unauth_dir;
/*The control port of the current translator */
fsys_t fsys;
/*The port to the translator we are currently looking at */
mach_port_t node = underlying;
/*The port to the previous translator */
mach_port_t prev_node = MACH_PORT_NULL;
/*The retry name and retry type returned by fsys_getroot */
string_t retry_name;
retry_type retry;
/*Finalizes the execution of this function */
void finalize (void)
{
/*If there is a working directory, free it */
if (cwd)
free (cwd);
/*If the ports to the directory exist */
if (dir)
PORT_DEALLOC (dir);
} /*finalize */
/*Obtain the current working directory */
cwd = getcwd (NULL, 0);
if (!cwd)
{
LOG_MSG ("trace_find: Could not obtain cwd.");
return EINVAL;
}
LOG_MSG ("trace_find: cwd: '%s'", cwd);
/*Open a port to this directory */
dir = file_name_lookup (cwd, 0, 0);
if (!dir)
{
finalize ();
return ENOENT;
}
/*Try to get the number of effective UIDs */
nuids = geteuids (0, 0);
if (nuids < 0)
{
finalize ();
return EINVAL;
}
/*Allocate some memory for the UIDs on the stack */
uids = alloca (nuids * sizeof (uid_t));
/*Fetch the UIDs themselves */
nuids = geteuids (nuids, uids);
if (nuids < 0)
{
finalize ();
return EINVAL;
}
/*Try to get the number of effective GIDs */
ngids = getgroups (0, 0);
if (ngids < 0)
{
finalize ();
return EINVAL;
}
/*Allocate some memory for the GIDs on the stack */
gids = alloca (ngids * sizeof (gid_t));
/*Fetch the GIDs themselves */
ngids = getgroups (ngids, gids);
if (ngids < 0)
{
finalize ();
return EINVAL;
}
/*Obtain the unauthenticated version of `dir` */
err = io_restrict_auth (dir, &unauth_dir, 0, 0, 0, 0);
if (err)
{
finalize ();
return err;
}
char buf[256];
char *_buf = buf;
size_t len = 256;
io_read (node, &_buf, &len, 0, len);
LOG_MSG ("trace_find: Read from underlying: '%s'", buf);
/*Go up the translator stack */
for (; !err;)
{
/*retreive the name and options of the current translator */
err = file_get_fs_options (node, &argz, &argz_len);
if (err)
break;
LOG_MSG ("trace_find: Obtained translator '%s'", argz);
if (strcmp (argz, name) == 0)
{
LOG_MSG ("trace_find: Match. Stopping here.");
break;
}
/*try to fetch the control port for this translator */
err = file_get_translator_cntl (node, &fsys);
LOG_MSG ("trace_find: err = %d", (int) err);
if (err)
break;
LOG_MSG ("trace_find: Translator control port: %lu",
(unsigned long) fsys);
prev_node = node;
/*fetch the root of the translator */
err = fsys_getroot
(fsys, unauth_dir, MACH_MSG_TYPE_COPY_SEND,
uids, nuids, gids, ngids,
flags | O_NOTRANS, &retry, retry_name, &node);
LOG_MSG ("trace_find: fsys_getroot returned %d", (int) err);
LOG_MSG ("trace_find: Translator root: %lu", (unsigned long) node);
/*TODO: Remove this debug output. */
/*char buf[256];
char * _buf = buf;
size_t len = 256;
io_read(node, &_buf, &len, 0, len);
LOG_MSG("trace_find: Read: '%s'", buf); */
}
/*If the error occurred (most probably) because of the fact that we
have reached the top of the translator stack */
if ((err == EMACH_SEND_INVALID_DEST) || (err == ENXIO))
/*this is OK */
err = 0;
/*Return the port to read from */
*port = prev_node;
/*Return the result of operations */
finalize ();
return err;
} /*trace_find */
