linux header是啥文件

Posted 2023-05-13

Linux-headers 是 Linux 的开发头文件，编程时要用到。 参考技术A 一般是指Linux C/C++编程中的 .h 文件，即所谓的头文件。里面会写一些宏定义、常量定义等。

在 .c 文件中，通常会在开头申明使用了哪些头文件，例如：include <message.h>本回答被提问者和网友采纳 参考技术B 系统头文件，包含了一些重要的宏，很多软件都会用

linux/msg.h头文件的内容是啥？

参考技术A #ifndef _LINUX_MSG_H
#define _LINUX_MSG_H

#include <linux/ipc.h>

/* ipcs ctl commands */
#define MSG_STAT 11
#define MSG_INFO 12

/* msgrcv options */
#define MSG_NOERROR 010000 /* no error if message is too big */
#define MSG_EXCEPT 020000 /* recv any msg except of specified type.*/

/* Obsolete, used only for backwards compatibility and libc5 compiles */
struct msqid_ds
struct ipc_perm msg_perm;
struct msg *msg_first; /* first message on queue,unused */
struct msg *msg_last; /* last message in queue,unused */
__kernel_time_t msg_stime; /* last msgsnd time */
__kernel_time_t msg_rtime; /* last msgrcv time */
__kernel_time_t msg_ctime; /* last change time */
unsigned long msg_lcbytes; /* Reuse junk fields for 32 bit */
unsigned long msg_lqbytes; /* ditto */
unsigned short msg_cbytes; /* current number of bytes on queue */
unsigned short msg_qnum; /* number of messages in queue */
unsigned short msg_qbytes; /* max number of bytes on queue */
__kernel_ipc_pid_t msg_lspid; /* pid of last msgsnd */
__kernel_ipc_pid_t msg_lrpid; /* last receive pid */
;

/* Include the definition of msqid64_ds */
#include <asm/msgbuf.h>

/* message buffer for msgsnd and msgrcv calls */
struct msgbuf
long mtype; /* type of message */
char mtext[1]; /* message text */
;

/* buffer for msgctl calls IPC_INFO, MSG_INFO */
struct msginfo
int msgpool;
int msgmap;
int msgmax;
int msgmnb;
int msgmni;
int msgssz;
int msgtql;
unsigned short msgseg;
;

/*
* Scaling factor to compute msgmni:
* the memory dedicated to msg queues (msgmni * msgmnb) should occupy
* at most 1/MSG_MEM_SCALE of the lowmem (see the formula in ipc/msg.c):
* up to 8MB : msgmni = 16 (MSGMNI)
* 4 GB : msgmni = 8K
* more than 16 GB : msgmni = 32K (IPCMNI)
*/
#define MSG_MEM_SCALE 32

#define MSGMNI 16 /* <= IPCMNI */ /* max # of msg queue identifiers */
#define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */
#define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */

/* unused */
#define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */
#define MSGTQL MSGMNB /* number of system message headers */
#define MSGMAP MSGMNB /* number of entries in message map */
#define MSGSSZ 16 /* message segment size */
#define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */
#define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff)

#endif /* _LINUX_MSG_H */本回答被提问者和网友采纳