求助，谁来帮我解释一下这段linux下的C程序__include_int_count_char_write_offset_

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求助，谁来帮我解释一下这段linux下的C程序

来源: 互联网发布时间：2017-02-26

本文导语: #include #include #include #include #include #include #include #include #define NEWFILE (O_WRONLY|O_CREAT|O_TRUNC) #define BUFSIZE 1024 #define size 1 int my_read(int fd,char *buf,size_t count); int my_write(int fd,char *bur,size_t count); static char ...

#include
#include
#include
#include
#include
#include
#include
#include
#define NEWFILE (O_WRONLY|O_CREAT|O_TRUNC)
#define BUFSIZE 1024
#define size 1

int my_read(int fd,char *buf,size_t count);
int my_write(int fd,char *bur,size_t count);
static char read_buf[BUFSIZE];
static int read_offset=BUFSIZE;
static int read_max=BUFSIZE;
static char write_buf[BUFSIZE];
static int write_offset=0;

int main(void)
{
    char infile[ ]={"test.dat"};
    char outfile[ ]={"backup.dat"};
    char buf[size];
    int infd,outfd,count;
    if((infd=open(infile,O_RDONLY))==-1)
    {
        printf("ERROR,OPEN READ FILE FAILED: n",sys_errlist[errno]);
        exit(255);
    }
    if((outfd=open(outfile,NEWFILE,0600))==-1)
    {
        printf("ERROR,OPEN WRITE FILE FAILED: n",sys_errlist[errno]);
        exit(255);
    }
    while(count=read(infd,buf,sizeof(buf))>0)
    {
        if(write(outfd,buf,count)!=count)
        {
            printf("ERROR,WRITE FILE FAILED: n",sys_errlist[errno]);
            exit(255);
        }
    }
    if(count==-1)
    {
        printf("ERROR,READ FILE FAILED: n",sys_errlist[errno]);
        exit(255);
    }
    close(infd);
    if(write_offset>0)
    {
        write(outfd,write_buf,write_offset);
        write_offset=0;
    }
    close(outfd);
}

int my_read(int fd,char *buf,size_t count)
{
    int i;
    for(i=0; i