mirror of https://github.com/mkerrisk/man-pages
98 lines
3.5 KiB
Plaintext
98 lines
3.5 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
|
|
.TH "POSIX_MEM_OFFSET" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
|
|
.\" posix_mem_offset
|
|
.SH NAME
|
|
posix_mem_offset \- find offset and length of a mapped typed memory
|
|
block (\fBADVANCED REALTIME\fP)
|
|
.SH SYNOPSIS
|
|
.LP
|
|
\fB#include <sys/mman.h>
|
|
.br
|
|
.sp
|
|
int posix_mem_offset(const void *restrict\fP \fIaddr\fP\fB, size_t\fP
|
|
\fIlen\fP\fB,
|
|
.br
|
|
\ \ \ \ \ \ off_t *restrict\fP \fIoff\fP\fB, size_t *restrict\fP
|
|
\fIcontig_len\fP\fB,
|
|
.br
|
|
\ \ \ \ \ \ int *restrict\fP \fIfildes\fP\fB); \fP
|
|
\fB
|
|
.br
|
|
\fP
|
|
.SH DESCRIPTION
|
|
.LP
|
|
The \fIposix_mem_offset\fP() function shall return in the variable
|
|
pointed to by \fIoff\fP a value that identifies the offset
|
|
(or location), within a memory object, of the memory block currently
|
|
mapped at \fIaddr\fP. The function shall return in the
|
|
variable pointed to by \fIfildes\fP, the descriptor used (via \fImmap\fP())
|
|
to establish the
|
|
mapping which contains \fIaddr\fP. If that descriptor was closed since
|
|
the mapping was established, the returned value of
|
|
\fIfildes\fP shall be -1. The \fIlen\fP argument specifies the length
|
|
of the block of the memory object the user wishes the
|
|
offset for; upon return, the value pointed to by \fIcontig_len\fP
|
|
shall equal either \fIlen\fP, or the length of the largest
|
|
contiguous block of the memory object that is currently mapped to
|
|
the calling process starting at \fIaddr\fP, whichever is
|
|
smaller.
|
|
.LP
|
|
If the memory object mapped at \fIaddr\fP is a typed memory object,
|
|
then if the \fIoff\fP and \fIcontig_len\fP values
|
|
obtained by calling \fIposix_mem_offset\fP() are used in a call to
|
|
\fImmap\fP() with a file
|
|
descriptor that refers to the same memory pool as \fIfildes\fP (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 \fIaddr\fP
|
|
in the address space of the process that called
|
|
\fIposix_mem_offset\fP().
|
|
.LP
|
|
If the memory object specified by \fIfildes\fP is not a typed memory
|
|
object, then the behavior of this function is
|
|
implementation-defined.
|
|
.SH RETURN VALUE
|
|
.LP
|
|
Upon successful completion, the \fIposix_mem_offset\fP() function
|
|
shall return zero; otherwise, the corresponding error status
|
|
value shall be returned.
|
|
.SH ERRORS
|
|
.LP
|
|
The \fIposix_mem_offset\fP() function shall fail if:
|
|
.TP 7
|
|
.B EACCES
|
|
The process has not mapped a memory object supported by this function
|
|
at the given address \fIaddr\fP.
|
|
.sp
|
|
.LP
|
|
This function shall not return an error code of [EINTR].
|
|
.LP
|
|
\fIThe following sections are informative.\fP
|
|
.SH EXAMPLES
|
|
.LP
|
|
None.
|
|
.SH APPLICATION USAGE
|
|
.LP
|
|
None.
|
|
.SH RATIONALE
|
|
.LP
|
|
None.
|
|
.SH FUTURE DIRECTIONS
|
|
.LP
|
|
None.
|
|
.SH SEE ALSO
|
|
.LP
|
|
\fImmap\fP() , \fIposix_typed_mem_open\fP() , the Base
|
|
Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<sys/mman.h>\fP
|
|
.SH COPYRIGHT
|
|
Portions of this text are reprinted and reproduced in electronic form
|
|
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
|
|
-- 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 .
|