posix_mem_offset(3) [linux man page]

POSIX_MEM_OFFSET(P)					     POSIX Programmer's Manual					       POSIX_MEM_OFFSET(P)

NAME

       posix_mem_offset - find offset and length of a mapped typed memory block (ADVANCED REALTIME)

SYNOPSIS

       #include <sys/mman.h>

       int posix_mem_offset(const void *restrict addr, size_t len,
	      off_t *restrict off, size_t *restrict contig_len,
	      int *restrict fildes);

DESCRIPTION

       The  posix_mem_offset()	function shall return in the variable pointed to by off a value that identifies the offset (or location), within a
       memory object, of the memory block currently mapped at addr. The function shall return in the variable pointed to by fildes, the descriptor
       used  (via  mmap())  to	establish  the	mapping  which contains addr. If that descriptor was closed since the mapping was established, the
       returned value of fildes shall be -1. The len argument specifies the length of the block of the memory object the user  wishes  the  offset
       for;  upon  return,  the value pointed to by contig_len shall equal either len, or the length of the largest contiguous block of the memory
       object that is currently mapped to the calling process starting at addr, whichever is smaller.

       If the memory object mapped at addr is a typed memory object, then if the off and contig_len values obtained by calling	posix_mem_offset()
       are  used in a call to mmap() with a file descriptor that refers to the same memory pool as fildes (either through the same port or through
       a different port), and that was opened with neither the POSIX_TYPED_MEM_ALLOCATE nor the POSIX_TYPED_MEM_ALLOCATE_CONTIG  flag,	the  typed
       memory  area  that  is  mapped  shall  be  exactly  the	same  area that was mapped at addr in the address space of the process that called
       posix_mem_offset().

       If the memory object specified by fildes is not a typed memory object, then the behavior of this function is implementation-defined.

RETURN VALUE

       Upon successful completion, the posix_mem_offset() function shall return zero; otherwise, the corresponding error  status  value  shall	be
       returned.

ERRORS

       The posix_mem_offset() function shall fail if:

       EACCES The process has not mapped a memory object supported by this function at the given address addr.

       This function shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mmap() , posix_typed_mem_open() , the Base Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003						       POSIX_MEM_OFFSET(P)

MUNMAP(P)						     POSIX Programmer's Manual							 MUNMAP(P)

NAME

       munmap - unmap pages of memory

SYNOPSIS

       #include <sys/mman.h>

       int munmap(void *addr, size_t len);

DESCRIPTION

       The  munmap() function shall remove any mappings for those entire pages containing any part of the address space of the process starting at
       addr and continuing for len bytes.  Further references to these pages shall result in the generation of a SIGSEGV signal to the process. If
       there are no mappings in the specified address range, then munmap() has no effect.

       The implementation shall require that addr be a multiple of the page size {PAGESIZE}.

       If a mapping to be removed was private, any modifications made in this address range shall be discarded.

       Any  memory  locks  (see  mlock()  and  mlockall()  )  associated with this address range shall be removed, as if by an appropriate call to
       munlock().

       If a mapping removed from a typed memory object causes the corresponding address range of the memory pool to be inaccessible by any process
       in  the	system except through allocatable mappings (that is, mappings of typed memory objects opened with the POSIX_TYPED_MEM_MAP_ALLOCAT-
       ABLE flag), then that range of the memory pool shall become deallocated and may become available to satisfy future typed memory	allocation
       requests.

       A  mapping  removed  from a typed memory object opened with the POSIX_TYPED_MEM_MAP_ALLOCATABLE flag shall not affect in any way the avail-
       ability of that typed memory for allocation.

       The behavior of this function is unspecified if the mapping was not established by a call to mmap().

RETURN VALUE

       Upon successful completion, munmap() shall return 0; otherwise, it shall return -1 and set errno to indicate the error.

ERRORS

       The munmap() function shall fail if:

       EINVAL Addresses in the range [addr,addr+len) are outside the valid range for the address space of a process.

       EINVAL The len argument is 0.

       EINVAL The addr argument is not a multiple of the page size as returned by sysconf().

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The munmap() function is only supported if the Memory Mapped Files option or the Shared Memory Objects option is supported.

RATIONALE

       The munmap() function corresponds to SVR4, just as the mmap() function does.

       It is possible that an application has applied process memory locking to a region that contains shared memory. If this  has  occurred,  the
       munmap() call ignores those locks and, if necessary, causes those locks to be removed.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mlock()	,  mlockall()  ,  mmap()  ,  posix_typed_mem_open() , sysconf() , the Base Definitions volume of IEEE Std 1003.1-2001, <signal.h>,
       <sys/mman.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								 MUNMAP(P)