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The C and C++ Include Header Files

/usr/include/linux/shm.h


$ cat -n /usr/include/linux/shm.h

     1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
     2	#ifndef _LINUX_SHM_H_
     3	#define _LINUX_SHM_H_
     4	
     5	#include <linux/ipc.h>
     6	#include <linux/errno.h>
     7	#include <asm-generic/hugetlb_encode.h>
     8	#include <unistd.h>
     9	
    10	/*
    11	 * SHMMNI, SHMMAX and SHMALL are default upper limits which can be
    12	 * modified by sysctl. The SHMMAX and SHMALL values have been chosen to
    13	 * be as large possible without facilitating scenarios where userspace
    14	 * causes overflows when adjusting the limits via operations of the form
    15	 * "retrieve current limit; add X; update limit". It is therefore not
    16	 * advised to make SHMMAX and SHMALL any larger. These limits are
    17	 * suitable for both 32 and 64-bit systems.
    18	 */
    19	#define SHMMIN 1			 /* min shared seg size (bytes) */
    20	#define SHMMNI 4096			 /* max num of segs system wide */
    21	#define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */
    22	#define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */
    23	#define SHMSEG SHMMNI			 /* max shared segs per process */
    24	
    25	/* Obsolete, used only for backwards compatibility and libc5 compiles */
    26	struct shmid_ds {
    27		struct ipc_perm		shm_perm;	/* operation perms */
    28		int			shm_segsz;	/* size of segment (bytes) */
    29		__kernel_old_time_t	shm_atime;	/* last attach time */
    30		__kernel_old_time_t	shm_dtime;	/* last detach time */
    31		__kernel_old_time_t	shm_ctime;	/* last change time */
    32		__kernel_ipc_pid_t	shm_cpid;	/* pid of creator */
    33		__kernel_ipc_pid_t	shm_lpid;	/* pid of last operator */
    34		unsigned short		shm_nattch;	/* no. of current attaches */
    35		unsigned short 		shm_unused;	/* compatibility */
    36		void 			*shm_unused2;	/* ditto - used by DIPC */
    37		void			*shm_unused3;	/* unused */
    38	};
    39	
    40	/* Include the definition of shmid64_ds and shminfo64 */
    41	#include <asm/shmbuf.h>
    42	
    43	/*
    44	 * shmget() shmflg values.
    45	 */
    46	/* The bottom nine bits are the same as open(2) mode flags */
    47	#define SHM_R		0400	/* or S_IRUGO from <linux/stat.h> */
    48	#define SHM_W		0200	/* or S_IWUGO from <linux/stat.h> */
    49	/* Bits 9 & 10 are IPC_CREAT and IPC_EXCL */
    50	#define SHM_HUGETLB	04000	/* segment will use huge TLB pages */
    51	#define SHM_NORESERVE	010000	/* don't check for reservations */
    52	
    53	/*
    54	 * Huge page size encoding when SHM_HUGETLB is specified, and a huge page
    55	 * size other than the default is desired.  See hugetlb_encode.h
    56	 */
    57	#define SHM_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
    58	#define SHM_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
    59	
    60	#define SHM_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
    61	#define SHM_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
    62	#define SHM_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
    63	#define SHM_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
    64	#define SHM_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
    65	#define SHM_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
    66	#define SHM_HUGE_32MB	HUGETLB_FLAG_ENCODE_32MB
    67	#define SHM_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
    68	#define SHM_HUGE_512MB	HUGETLB_FLAG_ENCODE_512MB
    69	#define SHM_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
    70	#define SHM_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
    71	#define SHM_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
    72	
    73	/*
    74	 * shmat() shmflg values
    75	 */
    76	#define	SHM_RDONLY	010000	/* read-only access */
    77	#define	SHM_RND		020000	/* round attach address to SHMLBA boundary */
    78	#define	SHM_REMAP	040000	/* take-over region on attach */
    79	#define	SHM_EXEC	0100000	/* execution access */
    80	
    81	/* super user shmctl commands */
    82	#define SHM_LOCK 	11
    83	#define SHM_UNLOCK 	12
    84	
    85	/* ipcs ctl commands */
    86	#define SHM_STAT	13
    87	#define SHM_INFO	14
    88	#define SHM_STAT_ANY    15
    89	
    90	/* Obsolete, used only for backwards compatibility */
    91	struct	shminfo {
    92		int shmmax;
    93		int shmmin;
    94		int shmmni;
    95		int shmseg;
    96		int shmall;
    97	};
    98	
    99	struct shm_info {
   100		int used_ids;
   101		__kernel_ulong_t shm_tot;	/* total allocated shm */
   102		__kernel_ulong_t shm_rss;	/* total resident shm */
   103		__kernel_ulong_t shm_swp;	/* total swapped shm */
   104		__kernel_ulong_t swap_attempts;
   105		__kernel_ulong_t swap_successes;
   106	};
   107	
   108	
   109	#endif /* _LINUX_SHM_H_ */