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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.