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板凳——————————————————c++(87)

2020年07月13日  | 移动技术网IT编程  | 我要评论

#include <fcntl.h>
#include <stdio.h>
#include <error.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include

int main(int argc, char* argv[]){
//int main(int argc, char ** argv){
struct flock lock;
int res1, fd1 = open(“Test.txt”, O_RDWR|O_CREAT, 0777);
if(fd1 > 0){
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
lock.l_pid = getpid();
res1 = fcntl(fd1, F_SETLK, &lock);
printf(“return value of fcntl = %d\n”, res1);
while(true)
;
}

////Linux C与C++ 一线开发p277
int fd2;
char mapped_mem2, * p2;
int flength2 = 1024;
void * start_addr2 = 0;
fd2 = open(argv[1], O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
flength2 = lseek(fd2, 1, SEEK_END);
write(fd2, “\0”, 1);
lseek(fd2, 0, SEEK_SET);
mapped_mem2 = (char) mmap(start_addr2,
flength2,
PROT_READ,
MAP_PRIVATE,
fd2,
0);
printf("%s\n", mapped_mem2);
close(fd2);
munmap(mapped_mem2, flength2);

////Linux C与C++ 一线开发p278
int fd3;
char *mapped_mem3, *p3;
int flength3 = 1024;
void * start_addr3 = 0;

fd3 = open(argv[1], O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
flength3 = lseek(fd3, 1, SEEK_END);
write(fd3, "\0", 1);
lseek(fd3, 0, SEEK_SET);
start_addr3 = (void*)0x80000;
mapped_mem3 = (char*)mmap(start_addr3, 
                         flength3,
                         PROT_READ|PROT_WRITE, 
			 MAP_SHARED, 
	                 fd3,
		         0);
printf("%s\n", mapped_mem3);
while((p3 = strstr(mapped_mem3, "Hello"))) {
      memcpy(p3, "Linux", 5);
      p3 += 5;
}
close(fd3);
munmap(mapped_mem3, flength3);		
return 0;

}
/*
wannian07@wannian07-PC:~$ g++ -o c13 c13.cpp
wannian07@wannian07-PC:~$ ./c13 output.txt
Hello there!

wannian07@wannian07-PC:~$ g++ -o c13 c13.cpp
wannian07@wannian07-PC:~$ ./c13 output.txt
Hello there!
wannian07@wannian07-PC:~$ cat output.txt
Linux there!
*/

本文地址：https://blog.csdn.net/fengye207161/article/details/107278472

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