2. System calls (functions provided by the kernel)
LLSEEKSection: Linux Programmer's Manual (2)
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NAME_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);
Note: There is no glibc wrapper for this system call; see NOTES.
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.
This system call exists on various 32-bit platforms to support seeking to large file offsets.
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.
SEE ALSOlseek(2), open(2), lseek64(3)
COLOPHONThis page is part of release 5.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
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