Manual page for mprotect(2)
mprotect - set protection of memory mapping
SYNOPSIS
#include <sys/types.h>
#include <sys/mman.h>
int mprotect(caddr_t addr,
size_t len,
int prot);
DESCRIPTION
The function
mprotect()
changes the access protections on the mappings specified
by the range
[addr, addr + len)
to be that specified by
prot.
Legitimate values for
prot
are the same as those permitted for
mmap and are defined in
<sys/mman.h> as:
-
PROT_READ /* page can be read */
PROT_WRITE /* page can be written */
PROT_EXEC /* page can be executed */
PROT_NONE /* page can not be accessed */
RETURN VALUES
Upon successful completion, the function
mprotect()
returns a
value of 0; otherwise, it returns a value of -1
and sets errno to indicate an error.
ERRORS
Under the following conditions, the function
mprotect()
fails and sets errno to:
- EACCES
-
prot
specifies a protection that violates the access permission
the process has to the underlying memory object.
- EAGAIN
-
the address range
[addr, addr + len)
includes
one or more pages that have been locked in memory and
that were mapped
MAP_PRIVATE;
prot
includes
PROT_WRITE;
and the system has insufficient resources
to reserve memory for the private pages that may be
created.
These private pages may be created by
store operations into the
now-writable address range.
- EINVAL
-
addr
is not a multiple of the page size as returned by
sysconf.
- EINVAL
-
the
len
argument has a value less than or equal to 0.
- ENOMEM
-
addresses in the range
[addr, addr + len)
are invalid for the address space of a process,
or specify one or more pages which are not mapped.
When
mprotect()
fails for reasons other than
EINVAL,
the protections on some of the pages in the range
[addr, addr + len)
may have been changed.
If the error occurs
on some page at addr2,
then the protections of
all whole pages in the range
[addr, addr2]
will have been modified.
SEE ALSO
mmap.2
plock.3c
mlock.3c
mlockall.3c
sysconf.3c
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
