NAME

mprotect — control the protection of pages

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/mman.h>

int
mprotect(void *addr, size_t len, int prot);

DESCRIPTION

The mprotect() system call changes the specified pages to have protection prot. Not all implementations will guarantee protection on a page basis; the granularity of protection changes may be as large as an entire region. A region is the virtual address space defined by the start and end addresses of a struct vm_map_entry.

Currently these protection bits are known, which can be combined, OR'd together:

PROT_NONE

No permissions at all.

PROT_READ

The pages can be read.

PROT_WRITE

The pages can be written.

PROT_EXEC

The pages can be executed.

RETURN VALUES

The mprotect() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

The mprotect() system call will fail if:

[EACCES]

The calling process was not allowed to change the protection to the value specified by the prot argument.

[EINVAL]

The virtual address range specified by the addr and len arguments is not valid.

SEE ALSO

madvise(2), mincore(2), msync(2), munmap(2)

HISTORY

The mprotect() system call first appeared in 4.4BSD.