llseek()函式 Unix/Linux


llseek - 重新讀取/寫入檔案偏移量

內容簡介

#include <sys/types.h> 
#include <unistd.h> 

int _llseek(unsigned int fd, unsigned long offset_high, unsigned long offset_low, loff_t *result, unsigned int whence);

描述

The _llseek() function repositions the offset of the open file associated with the file descriptor fd to (offset_high<<32) | offset_low bytes relative to the beginning of the file, the current position in the file, or the end of the file, depending on whether whence isSEEK_SETSEEK_CUR, or SEEK_END, respectively. It returns the resulting file position in the argument result.

返回值

Upon successful completion, _llseek() returns 0. Otherwise, a value of -1 is returned and errno is set to indicate the error.

錯誤

標籤 描述
EBADF fd is not an open file descriptor.
EFAULT Problem with copying results to user space.
EINVAL whence is invalid.

遵循於

This function is Linux specific, and should not be used in programs intended to be portable.

注意

Glibc does not provide a wrapper for this system call; call it using syscall(2).

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