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modify_ldt() - Unix, Linux System Call
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NAME
modify_ldt - get or set ldt
SYNOPSIS
#include <sys/types.h>
int modify_ldt(int func, void *ptr, unsigned long bytecount);
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DESCRIPTION
modify_ldt() reads or writes the local descriptor table (ldt) for a process.
The ldt is a per-process memory management table used by the i386 processor.
For more information on this table, see an Intel 386 processor handbook.
When
func is 0,
modify_ldt() reads the ldt into the memory pointed to by
ptr. The number of bytes read is the smaller of
bytecount and the actual size of the ldt.
When
func is 1,
modify_ldt() modifies one ldt entry.
ptr points to a
modify_ldt_ldt_s structure and
bytecount must equal the size of this structure.
RETURN VALUE
On success,
modify_ldt() returns either the actual number of bytes read (for reading)
or 0 (for writing).
On failure,
modify_ldt() returns -1 and sets
errno. ERRORS
Tag | Description |
EFAULT |
ptr points outside the address space.
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EINVAL |
ptr is 0,
or
func is 1 and
bytecount is not equal to the size of the structure
modify_ldt_ldt_s, or
func is 1 and the new ldt entry has invalid values.
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ENOSYS |
func is neither 0 nor 1.
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CONFORMING TO
This call is Linux specific and should not be used in programs intended
to be portable.
NOTES
Glibc does not provide a wrapper for this system call; call it using
syscall(2).
SEE ALSO
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