unlock

Remonter à Io.h - Index

Header File

io.h

Category

Input/output Routines

Prototype

int unlock(int handle, long offset, long length);

Description

Releases file-sharing locks.

unlock provides an interface to the operating system file-sharing mechanism. unlock removes a lock previously placed with a call to lock. To avoid error, all locks must be removed before a file is closed. A program must release all locks before completing.

Return Value

On success, unlock returns 0

O error, it returns -1.

Example

 #include <io.h>
 #include <fcntl.h>
 #include <sys\stat.h>
 #include <process.h>
 #include <share.h>
 #include <stdio.h>
 int main(void)
 {
    int handle, status;
    long length;
    handle = _sopen("c:\\autoexec.bat",O_RDONLY,SH_DENYNO,S_IREAD);
    if (handle < 0)
    {
        printf("_sopen failed\n");
        exit(1);
    }
    length = filelength(handle);
    status = lock(handle,0L,length/2);
    if (status == 0)
       printf("lock succeeded\n");
    else
       printf("lock failed\n");
    status = unlock(handle,0L,length/2);
    if (status == 0)
       printf("unlock succeeded\n");
    else
       printf("unlock failed\n");
    close(handle);
    return 0;
 }

Portability

POSIX	Win32	ANSI C	ANSI C++
	+