mprotect(2) [freebsd man page]

MPROTECT(2)						      BSD 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(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 indi-
     cate 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.

BSD
								   June 9, 1993 							       BSD

mprotect(2)							   System Calls 						       mprotect(2)

NAME

       mprotect - set protection of memory mapping

SYNOPSIS

       #include <sys/mman.h>

       int mprotect(void *addr, size_t len, int prot);

DESCRIPTION

       The   mprotect()  function changes the access protections on the mappings specified by the range [addr, addr + len), rounding len up to the
       next multiple of the page size as returned by sysconf(3C), to be that specified by prot. Legitimate values for prot are the same  as  those
       permitted for mmap(2) and are defined in <sys/mman.h> as:

       PROT_READ       /* page can be read */

       PROT_WRITE      /* page can be written */

       PROT_EXEC       /* page can be executed */

       PROT_NONE       /* page can not be accessed */

       When  mprotect()  fails	for  reasons other than EINVAL, the protections on some of the pages in the range [addr, addr + len) may have been
       changed. If the error occurs on some page at addr2, then the protections of all whole pages in the range [addr, addr2] will have been modi-
       fied.

RETURN VALUES

       Upon successful completion, mprotect() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

ERRORS

       The mprotect() function will fail if:

       EACCES	       The  prot  argument  specifies  a  protection  that violates the access permission the process has to the underlying memory
		       object.

       EINVAL	       The len argument has a value equal to 0, or addr is not a multiple of the page size as returned by sysconf(3C).

       ENOMEM	       Addresses in the range [addr, addr + len) are invalid for the address space of a process, or  specify  one  or  more  pages
		       which are not mapped.

       The mprotect() function may fail if:

       EAGAIN	       The  address  range  [addr,  addr  +  len)  includes one or more pages that have been locked in memory and that were mapped
		       MAP_PRIVATE; prot includes PROT_WRITE; and the system has insufficient resources to reserve memory for  the  private  pages
		       that may be created. These private pages may be created by store operations in the now-writable address range.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mmap(2), plock(3C), mlock(3C), mlockall(3C), sysconf(3C), attributes(5), standards(5)

SunOS 5.10							    12 Jan 1998 						       mprotect(2)