请考虑以下代码段(错误处理故意丢失)：
- void* foo(const char *path,off_t size) {
- int fd;
- void *ret;
- fd = open(path,O_RDWR);
- lockf(fd,F_LOCK,0);
- ret = mmap(NULL,size,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
- close(fd);
- return ret;
- }
所以,想法是打开一个文件,mmap()并返回数据指针.如果文件也可以在mmap时间锁定,那就太好了.
每mmap(3p)：
The mmap() function shall add an extra reference to the file associated with the
file descriptor fildes which is not removed by a subsequent close() on that file
descriptor. This reference shall be removed when there are no more mappings to
the file.
但是对于lockf(3p)：
File locks shall be released on first close by the locking process of any file
descriptor for the file.
因此,使用lockf()我必须保持fd打开并在非常长的时间内携带它的引用.是否有更好的可移植方法来确保文件被锁定,直到调用munmap()？
