Updated: 2022/Sep/29

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MPROTECT(2)                   System Calls Manual                  MPROTECT(2)

NAME
     mprotect - control the protection of pages

LIBRARY
     Standard C Library (libc, -lc)

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 SunOS 4.0 and subsequently
     4.4BSD.

NetBSD 10.99                   September 8, 2019                  NetBSD 10.99