llseek (2) - Linux Manuals
llseek: reposition read/write file offset
_llseek - reposition read/write file offset
#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);
DESCRIPTIONNote: for information about the llseek(3) library function, see lseek64(3).
The _llseek() system call repositions the offset of the open file description associated with the file descriptor fd to the value
- (offset_high << 32) | offset_low
This new offset is a byte offset relative to the beginning of the file, the current file offset, or the end of the file, depending on whether whence is SEEK_SET, SEEK_CUR, or SEEK_END, respectively.
The new file offset is returned in the argument result. The type loff_t is a 64-bit signed type.
RETURN VALUEUpon successful completion, _llseek() returns 0. Otherwise, a value of -1 is returned and errno is set to indicate the error.
- fd is not an open file descriptor.
- Problem with copying results to user space.
- whence is invalid.
CONFORMING TOThis function is Linux-specific, and should not be used in programs intended to be portable.
NOTESGlibc does not provide a wrapper for this system call. To invoke it directly, use syscall(2). However, you probably want to use the lseek(2) wrapper function instead.
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