進(jìn)程間文件加鎖的問(wèn)題

lukeden

如果是兩個(gè)進(jìn)程的話，用fcntl（）設(shè)置鎖，參考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()文件鎖

net_robber

如果B進(jìn)程是你自己寫(xiě)的，那么當(dāng)你不希望B進(jìn)程對(duì)文件進(jìn)行寫(xiě)操作的時(shí)候，為什么會(huì)在B進(jìn)程中加入寫(xiě)文件的代碼？？？