Linux Kernel 1.0 include/unistd.h

g_hk

include/unistd.h分析
定义标准输入、输出、错误输出
#define STDIN_FILENO    0
#define STDOUT_FILENO    1
#define STDERR_FILENO    2
NULL的定义，注意：NULL一般是用在指针的。
#ifndef NULL
#define NULL    ((void *)0)
#endif
文件操作lseek
/* lseek */
#define SEEK_SET    0
#define SEEK_CUR    1
#define SEEK_END    2
在1.0版本时定义在include/unistd.h中，到后来定义到include/asm/unistd.h中，其中asm为指向具体机型的连接（如：asm-i386,asm-x86_64 ......）
系统调用定义：
#define __NR_setup    0    /* used only by init, to get system going */
#define __NR_exit    1
#define __NR_fork    2
#define __NR_read    3
#define __NR_write    4
#define __NR_open    5
#define __NR_close    6
#define __NR_waitpid    7
#define __NR_creat    8
#define __NR_link    9
#define __NR_unlink    10
#define __NR_execve    11
#define __NR_chdir    12
#define __NR_time    13
#define __NR_mknod    14
#define __NR_chmod    15
#define __NR_chown    16
#define __NR_break    17
#define __NR_stat    18
#define __NR_lseek    19
#define __NR_getpid    20
#define __NR_mount    21
#define __NR_umount    22
#define __NR_setuid    23
#define __NR_getuid    24
#define __NR_stime    25
#define __NR_ptrace    26
#define __NR_alarm    27
#define __NR_fstat    28
#define __NR_pause    29
#define __NR_utime    30
#define __NR_stty    31
#define __NR_gtty    32
#define __NR_access    33
#define __NR_nice    34
#define __NR_ftime    35
#define __NR_sync    36
#define __NR_kill    37
#define __NR_rename    38
#define __NR_mkdir    39
#define __NR_rmdir    40
#define __NR_dup    41
#define __NR_pipe    42
#define __NR_times    43
#define __NR_prof    44
#define __NR_brk    45
#define __NR_setgid    46
#define __NR_getgid    47
#define __NR_signal    48
#define __NR_geteuid    49
#define __NR_getegid    50
#define __NR_acct    51
#define __NR_phys    52
#define __NR_lock    53
#define __NR_ioctl    54
#define __NR_fcntl    55
#define __NR_mpx    56
#define __NR_setpgid    57
#define __NR_ulimit    58
#define __NR_uname    59
#define __NR_umask    60
#define __NR_chroot    61
#define __NR_ustat    62
#define __NR_dup2    63
#define __NR_getppid    64
#define __NR_getpgrp    65
#define __NR_setsid    66
到2.4.32时系统调用已经增加到252个
#define _syscall0(type,name) \
type name(void) \
{ \
type __res; \
__asm__ volatile ("int $0x80" \
    : "=a" (__res) \
    : "0" (__NR_##name)); \
if (__res >= 0) \
    return __res; \
errno = -__res; \
return -1; \
}
#define _syscall1(type,name,atype,a) \
type name(atype a) \
{ \
type __res; \
__asm__ volatile ("int $0x80" \
    : "=a" (__res) \
    : "0" (__NR_##name),"b" (a)); \
if (__res >= 0) \
    return __res; \
errno = -__res; \
return -1; \
}
#define _syscall2(type,name,atype,a,btype,b) \
type name(atype a,btype b) \
{ \
type __res; \
__asm__ volatile ("int $0x80" \
    : "=a" (__res) \
    : "0" (__NR_##name),"b" (a),"c" (b)); \
if (__res >= 0) \
    return __res; \
errno = -__res; \
return -1; \
}
#define _syscall3(type,name,atype,a,btype,b,ctype,c) \
type name(atype a,btype b,ctype c) \
{ \
type __res; \
__asm__ volatile ("int $0x80" \
    : "=a" (__res) \
    : "0" (__NR_##name),"b" (a),"c" (b),"d" (c)); \
if (__res错误号定义：
extern int errno;
我们通常用strerror()来得到更详细的错误信息。
               
               
               

本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u/19782/showart_272434.html