linux mmap 驱动

#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>

int fd = open("largefile.dat", O_RDONLY);
if (fd == -1) {
    perror("open");
    return -1;
}

off_t file_size = lseek(fd, 0, SEEK_END);
void *addr = mmap(NULL, file_size, PROT_READ, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
    perror("mmap");
    close(fd);
    return -1;
}

// 使用映射的内存
// ...

munmap(addr, file_size);
close(fd);

#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>

int fd = open("sharedfile.dat", O_RDWR);
if (fd == -1) {
    perror("open");
    return -1;
}

off_t file_size = lseek(fd, 0, SEEK_END);
void *addr = mmap(NULL, file_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
    perror("mmap");
    close(fd);
    return -1;
}

// 获取文件锁
struct flock fl;
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = file_size;
if (fcntl(fd, F_SETLKW, &fl) == -1) {
    perror("fcntl");
    munmap(addr, file_size);
    close(fd);
    return -1;
}

// 修改映射的内存
// ...

// 释放文件锁
fl.l_type = F_UNLCK;
if (fcntl(fd, F_SETLK, &fl) == -1) {
    perror("fcntl");
}

munmap(addr, file_size);
close(fd);