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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3 
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef __ANDROID_DLEXT_H__
     18 #define __ANDROID_DLEXT_H__
     19 
     20 #include <stddef.h>
     21 #include <sys/cdefs.h>
     22 
     23 __BEGIN_DECLS
     24 
     25 /* bitfield definitions for android_dlextinfo.flags */
     26 enum {
     27   /* When set, the reserved_addr and reserved_size fields must point to an
     28    * already-reserved region of address space which will be used to load the
     29    * library if it fits. If the reserved region is not large enough, the load
     30    * will fail.
     31    */
     32   ANDROID_DLEXT_RESERVED_ADDRESS      = 0x1,
     33 
     34   /* As DLEXT_RESERVED_ADDRESS, but if the reserved region is not large enough,
     35    * the linker will choose an available address instead.
     36    */
     37   ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,
     38 
     39   /* When set, write the GNU RELRO section of the mapped library to relro_fd
     40    * after relocation has been performed, to allow it to be reused by another
     41    * process loading the same library at the same address. This implies
     42    * ANDROID_DLEXT_USE_RELRO.
     43    */
     44   ANDROID_DLEXT_WRITE_RELRO           = 0x4,
     45 
     46   /* When set, compare the GNU RELRO section of the mapped library to relro_fd
     47    * after relocation has been performed, and replace any relocated pages that
     48    * are identical with a version mapped from the file.
     49    */
     50   ANDROID_DLEXT_USE_RELRO             = 0x8,
     51 
     52   /* Instruct dlopen to use library_fd instead of opening file by name.
     53    * The filename parameter is still used to identify the library.
     54    */
     55   ANDROID_DLEXT_USE_LIBRARY_FD        = 0x10,
     56 
     57   /* Mask of valid bits */
     58   ANDROID_DLEXT_VALID_FLAG_BITS       = ANDROID_DLEXT_RESERVED_ADDRESS |
     59                                         ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
     60                                         ANDROID_DLEXT_WRITE_RELRO |
     61                                         ANDROID_DLEXT_USE_RELRO |
     62                                         ANDROID_DLEXT_USE_LIBRARY_FD,
     63 };
     64 
     65 typedef struct {
     66   uint64_t flags;
     67   void*   reserved_addr;
     68   size_t  reserved_size;
     69   int     relro_fd;
     70   int     library_fd;
     71 } android_dlextinfo;
     72 
     73 extern void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo);
     74 
     75 __END_DECLS
     76 
     77 #endif /* __ANDROID_DLEXT_H__ */
     78