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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *  * Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *  * Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/stat.h>
     30 #include <sys/types.h>
     31 #include <sys/xattr.h>
     32 #include <errno.h>
     33 #include <fcntl.h>
     34 #include <stdio.h>
     35 
     36 #include "private/FdPath.h"
     37 
     38 extern "C" int ___fsetxattr(int, const char*, const void*, size_t, int);
     39 
     40 int fsetxattr(int fd, const char* name, const void* value, size_t size, int flags) {
     41   int saved_errno = errno;
     42   int result = ___fsetxattr(fd, name, value, size, flags);
     43   if (result == 0 || errno != EBADF) {
     44     return result;
     45   }
     46 
     47   // fd could be an O_PATH file descriptor, and the kernel
     48   // may not directly support fsetxattr() on such a file descriptor.
     49   // Use /proc/self/fd instead to emulate this support.
     50   int fd_flag = fcntl(fd, F_GETFL);
     51   if (fd_flag == -1 || (fd_flag & O_PATH) == 0) {
     52     errno = EBADF;
     53     return -1;
     54   }
     55 
     56   errno = saved_errno;
     57   return setxattr(FdPath(fd).c_str(), name, value, size, flags);
     58 }
     59