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mem.h
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1 /*-------------------------------------------------------------------------
2  *
3  * mem.h
4  * portability definitions for various memory operations
5  *
6  * Copyright (c) 2001-2017, PostgreSQL Global Development Group
7  *
8  * src/include/portability/mem.h
9  *
10  *-------------------------------------------------------------------------
11  */
12 #ifndef MEM_H
13 #define MEM_H
14 
15 #define IPCProtection (0600) /* access/modify by user only */
16 
17 #ifdef SHM_SHARE_MMU /* use intimate shared memory on Solaris */
18 #define PG_SHMAT_FLAGS SHM_SHARE_MMU
19 #else
20 #define PG_SHMAT_FLAGS 0
21 #endif
22 
23 /* Linux prefers MAP_ANONYMOUS, but the flag is called MAP_ANON on other systems. */
24 #ifndef MAP_ANONYMOUS
25 #define MAP_ANONYMOUS MAP_ANON
26 #endif
27 
28 /* BSD-derived systems have MAP_HASSEMAPHORE, but it's not present (or needed) on Linux. */
29 #ifndef MAP_HASSEMAPHORE
30 #define MAP_HASSEMAPHORE 0
31 #endif
32 
33 /*
34  * BSD-derived systems use the MAP_NOSYNC flag to prevent dirty mmap(2)
35  * pages from being gratuitously flushed to disk.
36  */
37 #ifndef MAP_NOSYNC
38 #define MAP_NOSYNC 0
39 #endif
40 
41 #define PG_MMAP_FLAGS (MAP_SHARED|MAP_ANONYMOUS|MAP_HASSEMAPHORE)
42 
43 /* Some really old systems don't define MAP_FAILED. */
44 #ifndef MAP_FAILED
45 #define MAP_FAILED ((void *) -1)
46 #endif
47 
48 #endif /* MEM_H */