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/*
* Copyright (C) 2009-2010 Junjiro R. Okajima
*
* This program, aufs 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 2 of the License, 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h> /* or <sys/statfs.h> */
#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/aufs_type.h>
#include "libau.h"
static long (*real_pathconf)(const char *path, int name);
LibAuDlFunc(pathconf)
static long (*real_fpathconf)(int fd, int name);
LibAuDlFunc(fpathconf)
static long do_fpathconf(int fd, int name)
{
long err;
int wbr_fd, e;
err = -1;
wbr_fd = ioctl(fd, AUFS_CTL_WBR_FD);
if (wbr_fd >= 0) {
if (!libau_dl_fpathconf())
err = real_fpathconf(wbr_fd, name);
e = errno;
close(wbr_fd);
errno = e;
}
return err;
}
static int open_aufs_fd(const char *path, DIR **rdp)
{
int err, l, e;
struct stat base, st;
char *parent, *p;
*rdp = NULL;
err = open(path, O_RDONLY);
if (err >= 0)
goto out; /* success */
switch (errno) {
case EISDIR:
*rdp = opendir(path);
if (*rdp) {
err = dirfd(*rdp);
goto out; /* success */
}
break;
case EACCES:
/*FALLTHROUGH*/
case EPERM:
/* let's try with the parent dir again */
break;
default:
/* no way */
goto out;
}
/*
* when open(2) for the specified path failed,
* then try opening its ancestor instead in order to get a file
* descriptor in aufs.
*/
err = stat(path, &base);
if (err)
goto out;
parent = malloc(strlen(path) + sizeof("/.."));
if (!parent)
goto out;
l = strlen(path);
while (path[l - 1] == '/')
l--;
memcpy(parent, path, l);
parent[l - 1] = 0;
while (1) {
strcat(parent, "/..");
err = stat(parent, &st);
if (err)
break;
err = -1;
errno = ENOTSUP;
if (st.st_dev != base.st_dev) {
error_at_line(0, errno, __FILE__, __LINE__,
"cannot handle %s\n", path);
break;
}
*rdp = opendir(parent);
if (*rdp) {
err = dirfd(*rdp);
break; /* success */
}
p = realloc(parent, strlen(parent) + sizeof("/.."));
if (p)
parent = p;
else
break;
}
e = errno;
free(parent);
errno = e;
out:
return err;
}
static long libau_pathconf(const char *path, int name)
{
long err;
struct statfs stfs;
int fd, e;
DIR *dp;
err = statfs(path, &stfs);
if (err)
goto out;
err = -1;
if (stfs.f_type == AUFS_SUPER_MAGIC) {
fd = open_aufs_fd(path, &dp);
if (fd >= 0) {
err = do_fpathconf(fd, name);
e = errno;
if (!dp)
close(fd); /* ignore */
else
closedir(dp); /* ignore */
errno = e;
}
} else if (!libau_dl_pathconf())
err = real_pathconf(path, name);
out:
return err;
}
long pathconf(const char *path, int name)
{
long ret;
ret = -1;
if (name == _PC_LINK_MAX
&& (LibAuTestFunc(pathconf) || LibAuTestFunc(fpathconf)))
ret = libau_pathconf(path, name);
else if (!libau_dl_pathconf())
ret = real_pathconf(path, name);
return ret;
}
/* ---------------------------------------------------------------------- */
static long libau_fpathconf(int fd, int name)
{
long err;
struct statfs stfs;
err = fstatfs(fd, &stfs);
if (err)
goto out;
err = -1;
if (stfs.f_type == AUFS_SUPER_MAGIC)
err = do_fpathconf(fd, name);
else if (!libau_dl_fpathconf())
err = real_fpathconf(fd, name);
out:
return err;
}
long fpathconf(int fd, int name)
{
long ret;
ret = -1;
if (name == _PC_LINK_MAX
&& (LibAuTestFunc(pathconf) || LibAuTestFunc(fpathconf)))
ret = libau_fpathconf(fd, name);
else if (!libau_dl_fpathconf())
ret = real_fpathconf(fd, name);
return ret;
}
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