char *
__realpath (const char *name, char *resolved)
{
char *rpath, *dest, *extra_buf = NULL;
const char *start, *end, *rpath_limit;
long int path_max;
int num_links = 0;
if (name == NULL)
{
/* As per Single Unix Specification V2 we must return an error if
either parameter is a null pointer. We extend this to allow
the RESOLVED parameter to be NULL in case the we are expected to
allocate the room for the return value. */
__set_errno (EINVAL);
return NULL;
}
if (name[0] == '\0')
{
/* As per Single Unix Specification V2 we must return an error if
the name argument points to an empty string. */
__set_errno (ENOENT);
return NULL;
}
#ifdef PATH_MAX
path_max = PATH_MAX;
#else
path_max = pathconf (name, _PC_PATH_MAX);
if (path_max <= 0)
path_max = 1024;
#endif
if (resolved == NULL)
{
rpath = malloc (path_max);
if (rpath == NULL)
return NULL;
}
else
rpath = resolved;
rpath_limit = rpath + path_max;
if (name[0] != '/')
{
if (!__getcwd (rpath, path_max))
{
rpath[0] = '\0';
goto error;
}
dest = __rawmemchr (rpath, '\0');
}
else
{
rpath[0] = '/';
dest = rpath + 1;
}
for (start = end = name; *start; start = end)
{
struct stat64 st;
int n;
/* Skip sequence of multiple path-separators. */
while (*start == '/')
++start;
/* Find end of path component. */
for (end = start; *end && *end != '/'; ++end)
/* Nothing. */;
if (end - start == 0)
break;
else if (end - start == 1 && start[0] == '.')
/* nothing */;
else if (end - start == 2 && start[0] == '.' && start[1] == '.')
{
/* Back up to previous component, ignore if at root already. */
if (dest > rpath + 1)
while ((--dest)[-1] != '/');
}
else
{
size_t new_size;
if (dest[-1] != '/')
*dest++ = '/';
if (dest + (end - start) >= rpath_limit)
{
ptrdiff_t dest_offset = dest - rpath;
char *new_rpath;
if (resolved)
{
__set_errno (ENAMETOOLONG);
if (dest > rpath + 1)
dest--;
*dest = '\0';
goto error;
}
new_size = rpath_limit - rpath;
if (end - start + 1 > path_max)
new_size += end - start + 1;
else
new_size += path_max;
new_rpath = (char *) realloc (rpath, new_size);
if (new_rpath == NULL)
goto error;
rpath = new_rpath;
rpath_limit = rpath + new_size;
dest = rpath + dest_offset;
}
dest = __mempcpy (dest, start, end - start);
*dest = '\0';
if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
goto error;
if (S_ISLNK (st.st_mode))
{
char *buf = __alloca (path_max);
size_t len;
if (++num_links > __eloop_threshold ())
{
__set_errno (ELOOP);
goto error;
}
n = __readlink (rpath, buf, path_max - 1);
if (n < 0)
goto error;
buf[n] = '\0';
if (!extra_buf)
extra_buf = __alloca (path_max);
len = strlen (end);
if ((long int) (n + len) >= path_max)
{
__set_errno (ENAMETOOLONG);
goto error;
}
/* Careful here, end may be a pointer into extra_buf... */
memmove (&extra_buf[n], end, len + 1);
name = end = memcpy (extra_buf, buf, n);
if (buf[0] == '/')
dest = rpath + 1; /* It's an absolute symlink */
else
/* Back up to previous component, ignore if at root already: */
if (dest > rpath + 1)
while ((--dest)[-1] != '/');
}
else if (!S_ISDIR (st.st_mode) && *end != '\0')
{
__set_errno (ENOTDIR);
goto error;
}
}
}
if (dest > rpath + 1 && dest[-1] == '/')
--dest;
*dest = '\0';
assert (resolved == NULL || resolved == rpath);
return rpath;
error:
assert (resolved == NULL || resolved == rpath);
if (resolved == NULL)
free (rpath);
return NULL;
}
char *
chroot_canon (const char *chroot, const char *name)
{
char *rpath;
char *dest;
char *extra_buf = NULL;
char *rpath_root;
const char *start;
const char *end;
const char *rpath_limit;
int num_links = 0;
size_t chroot_len = strlen (chroot);
if (chroot_len < 1)
{
__set_errno (EINVAL);
return NULL;
}
rpath = xmalloc (chroot_len + PATH_MAX);
rpath_limit = rpath + chroot_len + PATH_MAX;
rpath_root = (char *) mempcpy (rpath, chroot, chroot_len) - 1;
if (*rpath_root != '/')
*++rpath_root = '/';
dest = rpath_root + 1;
for (start = end = name; *start; start = end)
{
struct stat64 st;
/* Skip sequence of multiple path-separators. */
while (*start == '/')
++start;
/* Find end of path component. */
for (end = start; *end && *end != '/'; ++end)
/* Nothing. */;
if (end - start == 0)
break;
else if (end - start == 1 && start[0] == '.')
/* nothing */;
else if (end - start == 2 && start[0] == '.' && start[1] == '.')
{
/* Back up to previous component, ignore if at root already. */
if (dest > rpath_root + 1)
while ((--dest)[-1] != '/');
}
else
{
size_t new_size;
if (dest[-1] != '/')
*dest++ = '/';
if (dest + (end - start) >= rpath_limit)
{
ptrdiff_t dest_offset = dest - rpath;
char *new_rpath;
new_size = rpath_limit - rpath;
if (end - start + 1 > PATH_MAX)
new_size += end - start + 1;
else
new_size += PATH_MAX;
new_rpath = (char *) xrealloc (rpath, new_size);
rpath = new_rpath;
rpath_limit = rpath + new_size;
dest = rpath + dest_offset;
}
dest = mempcpy (dest, start, end - start);
*dest = '\0';
if (lstat64 (rpath, &st) < 0)
{
if (*end == '\0')
goto done;
goto error;
}
if (S_ISLNK (st.st_mode))
{
char *buf = alloca (PATH_MAX);
size_t len;
if (++num_links > __eloop_threshold ())
{
__set_errno (ELOOP);
goto error;
}
ssize_t n = readlink (rpath, buf, PATH_MAX - 1);
if (n < 0)
{
if (*end == '\0')
goto done;
goto error;
}
buf[n] = '\0';
if (!extra_buf)
extra_buf = alloca (PATH_MAX);
len = strlen (end);
if (len >= PATH_MAX - n)
{
__set_errno (ENAMETOOLONG);
goto error;
}
/* Careful here, end may be a pointer into extra_buf... */
memmove (&extra_buf[n], end, len + 1);
name = end = memcpy (extra_buf, buf, n);
if (buf[0] == '/')
dest = rpath_root + 1; /* It's an absolute symlink */
else
/* Back up to previous component, ignore if at root already: */
if (dest > rpath_root + 1)
while ((--dest)[-1] != '/');
}
}
}
done:
if (dest > rpath_root + 1 && dest[-1] == '/')
--dest;
*dest = '\0';
return rpath;
error:
free (rpath);
return NULL;
}
