linux 内核发送数据类型,linux内核的数据类型转载

绝地灬酷狼 2023-01-20 02:58 19阅读 0赞

对linux内核的数据类型做一下总结。

当Linux内核在体系结构差异较大的平台之间移植时，会产生与数据类型相关的问题。在编译内核时使用-Wall -Wstrict-prototypes选项，可以避免很多错误的发生。

内核使用的基本数据类型主要有：

ØØint标准C语言整数类型；

ØØu3232位整数类型；

ØØpid\_t特定内核对象pid的类型。

在不同的CPU体系结构上，C语言的数据类型所占空间不一样。下面是在x86下数据类型所占的字节数：

arch

char

short

int

long

ptr

long-long

u16

u32

u64

i686

下面是在其他平台上的数据类型所占的字节数：

arch

char

short

int

long

ptr

long-long

u16

u32

u64

i386

alpha

armv4l

ia64

m68k

mips

ppc

sparc

sparc64

其中基于sparc64平台的Linux用户空间可以运行32位代码，用户空间指针是32位宽的，但内核空间是64位的。

内核中的地址是unsigned long类型，指针大小和long类型相同。

内核提供下列数据类型。所有类型在头文件中声明，这个文件又被头文件所包含。下面是include/asm/types.h文件。这是对ARM体系结构中 /asm/types.h文件中的一些定义： 因为我是对arm体系结构进行了配置

\#ifndef \_\_ASM\_ARM\_TYPES\_H

\#define \_\_ASM\_ARM\_TYPES\_H/\*\* This file is never included by application software unless\* explicitly requested (e.g., via linux/types.h) in which case the\* application is Linux specific so (user-) name space pollution is\* not a major issue. However, for interoperability, libraries still\* need to be careful to avoid a name clashes.\*/

\#ifndef \_\_ASSEMBLY\_\_

typedef unsigned short umode\_t;/\*

\* \_\_xx is ok: it doesn't pollute the POSIX namespace. Use these in the

\* header files exported to user space

\*/

typedef \_\_signed\_\_ char \_\_s8;

typedef unsigned char \_\_u8;

typedef \_\_signed\_\_ short \_\_s16;

typedef unsigned short \_\_u16;

typedef \_\_signed\_\_ int \_\_s32;

typedef unsigned int \_\_u32;

\#if defined(\_\_GNUC\_\_) && !defined(\_\_STRICT\_ANSI\_\_)

typedef \_\_signed\_\_ long long \_\_s64;

typedef unsigned long long \_\_u64;

\#endif

\#endif /\* \_\_ASSEMBLY\_\_ \*//\*

\* These aren't exported outside the kernel to avoid name space clashes

\*/

\#ifdef \_\_KERNEL\_\_

\#define BITS\_PER\_LONG 32

\#ifndef \_\_ASSEMBLY\_\_

typedef signed char s8;

typedef unsigned char u8;

typedef signed short s16;

typedef unsigned short u16;

typedef signed int s32;

typedef unsigned int u32;

typedef signed long long s64;

typedef unsigned long long u64;

/\* Dma addresses are 32-bits wide. \*/

typedef u32 dma\_addr\_t;

typedef u32 dma64\_addr\_t;

\#endif /\* \_\_ASSEMBLY\_\_ \*/

\#endif /\* \_\_KERNEL\_\_ \*/

\#endif

使用有前缀的类型用于将变量显露给用户空间，如\_ \_u8类型。例如：一个驱动程序通过ioctl函数与运行在用户空间的程序交换数据，应该用\_ \_u32来声明32位的数据类型。

有时内核使用C语言的类型，如unsigned int，这通常用于大小独立于体系结构的数据项。内核中许多数据类型由typedef声明，这样方便移植。如使用pid\_t类型作为进程标志符(pid)的类型，而不是int类型，pid\_t屏蔽了在不同平台上的实际数据类型的差异。

如果不容易选择合适的类型，就将其强制转换成最可能的类型(long或unsigned long)。

如上面所说，在中又把你所配置的体系结构中定义的类型的类型定义

包含进去了：下面把这个文件贴出来，我的内核版本是2.6.16.28。

\#ifndef \_LINUX\_TYPES\_H

\#define \_LINUX\_TYPES\_H

\#ifdef    \_\_KERNEL\_\_

\#include

\#define BITS\_TO\_LONGS(bits) \\

(((bits)+BITS\_PER\_LONG-1)/BITS\_PER\_LONG)

\#define DECLARE\_BITMAP(name,bits) \\

unsigned long name\[BITS\_TO\_LONGS(bits)\]

\#define BITS\_PER\_BYTE 8

\#endif

\#include

\#ifndef \_\_KERNEL\_STRICT\_NAMES

typedef \_\_u32 \_\_kernel\_dev\_t;

typedef \_\_kernel\_fd\_set        fd\_set;

typedef \_\_kernel\_dev\_t        dev\_t;

typedef \_\_kernel\_ino\_t        ino\_t;

typedef \_\_kernel\_mode\_t        mode\_t;

typedef \_\_kernel\_nlink\_t    nlink\_t;

typedef \_\_kernel\_off\_t        off\_t;

typedef \_\_kernel\_pid\_t        pid\_t;

typedef \_\_kernel\_daddr\_t    daddr\_t;

typedef \_\_kernel\_key\_t        key\_t;

typedef \_\_kernel\_suseconds\_t    suseconds\_t;

typedef \_\_kernel\_timer\_t    timer\_t;

typedef \_\_kernel\_clockid\_t    clockid\_t;

typedef \_\_kernel\_mqd\_t        mqd\_t;

\#ifdef \_\_KERNEL\_\_

typedef \_\_kernel\_uid32\_t    uid\_t;

typedef \_\_kernel\_gid32\_t    gid\_t;

typedef \_\_kernel\_uid16\_t uid16\_t;

typedef \_\_kernel\_gid16\_t gid16\_t;

\#ifdef CONFIG\_UID16

/\* This is defined by include/asm-\{arch\}/posix\_types.h \*/

typedef \_\_kernel\_old\_uid\_t    old\_uid\_t;

typedef \_\_kernel\_old\_gid\_t    old\_gid\_t;

\#endif /\* CONFIG\_UID16 \*//\* libc5 includes this file to define uid\_t, thus uid\_t can never change

\* when it is included by non-kernel code

\*/

\#else

typedef \_\_kernel\_uid\_t        uid\_t;

typedef \_\_kernel\_gid\_t        gid\_t;

\#endif /\* \_\_KERNEL\_\_ \*/

\#if defined(\_\_GNUC\_\_) && !defined(\_\_STRICT\_ANSI\_\_)

typedef \_\_kernel\_loff\_t        loff\_t;

\#endif/\*

\* The following typedefs are also protected by individual ifdefs for

\* historical reasons:

\*/

\#ifndef \_SIZE\_T

\#define \_SIZE\_T

typedef \_\_kernel\_size\_t        size\_t;

\#endif

\#ifndef \_SSIZE\_T

\#define \_SSIZE\_T

typedef \_\_kernel\_ssize\_t    ssize\_t;

\#endif

\#ifndef \_PTRDIFF\_T

\#define \_PTRDIFF\_T

typedef \_\_kernel\_ptrdiff\_t    ptrdiff\_t;

\#endif

\#ifndef \_TIME\_T

\#define \_TIME\_T

typedef \_\_kernel\_time\_t        time\_t;

\#endif

\#ifndef \_CLOCK\_T

\#define \_CLOCK\_T

typedef \_\_kernel\_clock\_t    clock\_t;

\#endif

\#ifndef \_CADDR\_T

\#define \_CADDR\_T

typedef \_\_kernel\_caddr\_t    caddr\_t;

\#endif

/\* bsd \*/

typedef unsigned char        u\_char;

typedef unsigned short        u\_short;

typedef unsigned int        u\_int;

typedef unsigned long        u\_long;

/\* sysv \*/

typedef unsigned char        unchar;

typedef unsigned short        ushort;

typedef unsigned int        uint;

typedef unsigned long        ulong;

\#ifndef \_\_BIT\_TYPES\_DEFINED\_\_

\#define \_\_BIT\_TYPES\_DEFINED\_\_

typedef        \_\_u8        u\_int8\_t;

typedef        \_\_s8        int8\_t;

typedef        \_\_u16        u\_int16\_t;

typedef        \_\_s16        int16\_t;

typedef        \_\_u32        u\_int32\_t;

typedef        \_\_s32        int32\_t;

\#endif /\* !(\_\_BIT\_TYPES\_DEFINED\_\_) \*/

typedef        \_\_u8        uint8\_t;

typedef        \_\_u16        uint16\_t;

typedef        \_\_u32        uint32\_t;

\#if defined(\_\_GNUC\_\_) && !defined(\_\_STRICT\_ANSI\_\_)

typedef        \_\_u64        uint64\_t;

typedef        \_\_u64        u\_int64\_t;

typedef        \_\_s64        int64\_t;

\#endif

/\* this is a special 64bit data type that is 8-byte aligned \*/

\#define aligned\_u64 unsigned long long \_\_attribute\_\_((aligned(8)))/\*

\* The type used for indexing onto a disc or disc partition.

\* If required, asm/types.h can override it and define

\* HAVE\_SECTOR\_T

\*/

\#ifndef HAVE\_SECTOR\_T

typedef unsigned long sector\_t;

\#endif/\*

\* The type of an index into the pagecache. Use a \#define so asm/types.h

\* can override it.

\*/

\#ifndef pgoff\_t

\#define pgoff\_t unsigned long

\#endif

\#endif /\* \_\_KERNEL\_STRICT\_NAMES \*//\*

\* Below are truly Linux-specific types that should never collide with

\* any application/library that wants linux/types.h.

\*/

\#ifdef \_\_CHECKER\_\_

\#define \_\_bitwise\_\_ \_\_attribute\_\_((bitwise))

\#else

\#define \_\_bitwise\_\_

\#endif

\#ifdef \_\_CHECK\_ENDIAN\_\_

\#define \_\_bitwise \_\_bitwise\_\_

\#else

\#define \_\_bitwise

\#endif

typedef \_\_u16 \_\_bitwise \_\_le16;

typedef \_\_u16 \_\_bitwise \_\_be16;

typedef \_\_u32 \_\_bitwise \_\_le32;

typedef \_\_u32 \_\_bitwise \_\_be32;

\#if defined(\_\_GNUC\_\_) && !defined(\_\_STRICT\_ANSI\_\_)

typedef \_\_u64 \_\_bitwise \_\_le64;

typedef \_\_u64 \_\_bitwise \_\_be64;

\#endif

\#ifdef \_\_KERNEL\_\_

typedef unsigned \_\_bitwise\_\_ gfp\_t;

\#endif

struct ustat \{

\_\_kernel\_daddr\_t    f\_tfree;

\_\_kernel\_ino\_t        f\_tinode;

char            f\_fname\[6\];

char            f\_fpack\[6\];

\};

\#endif /\* \_LINUX\_TYPES\_H \*/

这里面我以可以看到一些自定义类型，如loff\_t,size\_t等。

typedef \_\_kernel\_uid\_t        uid\_t;

typedef \_\_kernel\_gid\_t        gid\_t;

typedef\_\_kernel\_loff\_t        loff\_t;

这样就将loff\_t类型定义为\_\_kernel\_loff\_t这个类型

了,uid\_t类型定义了\_\_kernel\_uid\_t类型了，但是现在\_\_kernel\_loff\_t

\_\_kernel\_uid\_t这种类型是很明显地与体系结构是相关的，对于arm的体系结构，则定义在,代码如下：

/\*

\* linux/include/asm-arm/posix\_types.h

\* This program is free software; you can redistribute it and/or modify

\* it under the terms of the GNU General Public License version 2 as

\* published by the Free Software Foundation.

\* Changelog:

\* 27-06-1996    RMK    Created

\*/

\#ifndef \_\_ARCH\_ARM\_POSIX\_TYPES\_H

\#define \_\_ARCH\_ARM\_POSIX\_TYPES\_H/\*

\* This file is generally used by user-level software, so you need to

\* be a little careful about namespace pollution etc. Also, we cannot

\* assume GCC is being used.

\*/

typedef unsigned long        \_\_kernel\_ino\_t;

typedef unsigned short        \_\_kernel\_mode\_t;

typedef unsigned short        \_\_kernel\_nlink\_t;

typedef long            \_\_kernel\_off\_t;

typedef int            \_\_kernel\_pid\_t;

typedef unsigned short        \_\_kernel\_ipc\_pid\_t;

typedef unsigned short        \_\_kernel\_uid\_t;

typedef unsigned short        \_\_kernel\_gid\_t;

typedef unsigned int        \_\_kernel\_size\_t;

typedef int            \_\_kernel\_ssize\_t;

typedef int            \_\_kernel\_ptrdiff\_t;

typedef long            \_\_kernel\_time\_t;

typedef long            \_\_kernel\_suseconds\_t;

typedef long            \_\_kernel\_clock\_t;

typedef int            \_\_kernel\_timer\_t;

typedef int            \_\_kernel\_clockid\_t;

typedef int            \_\_kernel\_daddr\_t;

typedef char \*            \_\_kernel\_caddr\_t;

typedef unsigned short        \_\_kernel\_uid16\_t;

typedef unsigned short        \_\_kernel\_gid16\_t;

typedef unsigned int        \_\_kernel\_uid32\_t;

typedef unsigned int        \_\_kernel\_gid32\_t;

typedef unsigned short        \_\_kernel\_old\_uid\_t;

typedef unsigned short        \_\_kernel\_old\_gid\_t;

typedef unsigned short        \_\_kernel\_old\_dev\_t;

\#ifdef \_\_GNUC\_\_

typedef long long        \_\_kernel\_loff\_t;

\#endif

typedef struct \{

\#if defined(\_\_KERNEL\_\_) || defined(\_\_USE\_ALL)

int    val\[2\];

\#else /\* !defined(\_\_KERNEL\_\_) && !defined(\_\_USE\_ALL) \*/

int    \_\_val\[2\];

\#endif /\* !defined(\_\_KERNEL\_\_) && !defined(\_\_USE\_ALL) \*/

\} \_\_kernel\_fsid\_t;

\#if defined(\_\_KERNEL\_\_) || !defined(\_\_GLIBC\_\_) || (\_\_GLIBC\_\_ < 2)

\#undef    \_\_FD\_SET

\#define \_\_FD\_SET(fd, fdsetp) \\

(((fd\_set \*)(fdsetp))->fds\_bits\[(fd) >> 5\] |= (1<

\#undef    \_\_FD\_CLR

\#define \_\_FD\_CLR(fd, fdsetp) \\

(((fd\_set \*)(fdsetp))->fds\_bits\[(fd) >> 5\] &= ~(1<

\#undef    \_\_FD\_ISSET

\#define \_\_FD\_ISSET(fd, fdsetp) \\

((((fd\_set \*)(fdsetp))->fds\_bits\[(fd) >> 5\] & (1<

\#undef    \_\_FD\_ZERO

\#define \_\_FD\_ZERO(fdsetp) \\

(memset (fdsetp, 0, sizeof (\*(fd\_set \*)(fdsetp))))

\#endif

现在，你看起内核的一些函数的参数的类型为loff\_t，ssize\_t这些类型就不会发怵了吧！呵呵。

不过我也发现了一个非常不错网站，你可以把linux 的一个参数或者数据类型输入进去，便可查询内部相关数据类型。

linux 内核发送数据类型,linux内核的数据类型转载

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