进程间文件加锁的问题

lukeden

如果是两个进程的话，用fcntl（）设置锁，参考APUE 14.3:
#include <fcntl.h>

int fcntl(int filedes, int cmd, ... /* struct
flock *flockptr */ );




Returns: depends on cmd if OK (see following), 1 on error


For record locking, cmd is F_GETLK, F_SETLK, or F_SETLKW. The third argument (which we'll call flockptr) is a pointer to an flock structure.

   struct flock {
     short l_type;   /* F_RDLCK, F_WRLCK, or F_UNLCK */
     off_t l_start;  /* offset in bytes, relative to l_whence */
     short l_whence; /* SEEK_SET, SEEK_CUR, or SEEK_END */
     off_t l_len;    /* length, in bytes; 0 means lock to EOF */
     pid_t l_pid;    /* returned with F_GETLK */
   };

This structure describes

The type of lock desired: F_RDLCK (a shared read lock), F_WRLCK (an exclusive write lock), or F_UNLCK (unlocking a region)

The starting byte offset of the region being locked or unlocked (l_start and l_whence)

The size of the region in bytes (l_len)

The ID (l_pid) of the process holding the lock that can block the current process (returned by F_GETLK only)

lanying_wzw

用fcntl()文件锁

net_robber

如果B进程是你自己写的，那么当你不希望B进程对文件进行写操作的时候，为什么会在B进程中加入写文件的代码？？？