MPROTECT(2)

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 pro-
			tection 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.