NAME

     mprotect — control the protection of pages

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/mman.h>

     int
     mprotect(const 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:

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

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

SEE ALSO

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

HISTORY

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