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.\" @(#)mprotect.2 8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt MPROTECT 2
.Os
.Sh NAME
.Nm mprotect
.Nd control the protection of pages
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/mman.h>
.Ft int
.Fn mprotect "const void *addr" "size_t len" "int prot"
.Sh DESCRIPTION
The
.Fn mprotect
system call
changes the specified pages to have protection
.Fa prot .
Not all implementations will guarantee protection on a page basis;
the granularity of protection changes may be as large as an entire region.
.Sh RETURN VALUES
Upon successful completion,
.Fn mprotect
returns 0. Otherwise a value of -1 is returned
and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn mprotect
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The virtual address range specified by the
.Fa addr
and
.Fa len
arguments is not valid.
.It Bq Er EACCES
The calling process was not allowed to change
the protection to the value specified by
the
.Fa prot
argument.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mincore 2 ,
.Xr msync 2 ,
.Xr munmap 2
.Sh HISTORY
The
.Fn mprotect
function first appeared in
.Bx 4.4 .
