MPROTECT(2)		  FreeBSD System Calls Manual		   MPROTECT(2)

NAME
     mprotect - control the protection of pages

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #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() function 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 pro-
			tection to the value specified by the prot argument.

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

HISTORY
     The mprotect() function first appeared in 4.4BSD.

FreeBSD 4.8			 June 9, 1993			   FreeBSD 4.8