MPROTECT(2)

NAME
mprotect - control the protection of pages

LIBRARY
libc

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.

The protections (region accessibility) are specified in the prot argument by OR'ing the following values:

PROT_EXEC
    Pages may be executed.

PROT_READ
    Pages may be read.

PROT_WRITE
    Pages may be written.

PROT_NONE
    Placeholder when requesting no access permission.

RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

[EACCES]
    A memory protection violation occurred.

    The PROT_EXEC flag was attempted on pages which belong to a file system mounted with the NOEXEC flag.

    The new protection is less restrictive than the protection originally set with mmap(2).

    PaX mprotect restrictions prohibit the requested protection.

[EINVAL]
    An invalid memory range, or invalid parameters were provided.

[ENOMEM]
    A resource shortage occurred while internally calling uvm_map_protect(9).

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

HISTORY
The mprotect function first appeared in 4.4BSD.