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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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POSIX_MEMALIGN(3P) POSIX Programmer's Manual POSIX_MEMALIGN(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
posix_memalign — aligned memory allocation (ADVANCED REALTIME)
#include <stdlib.h>
int posix_memalign(void **memptr, size_t alignment, size_t size);
The posix_memalign() function shall allocate size bytes aligned
on a boundary specified by alignment, and shall return a pointer
to the allocated memory in memptr. The value of alignment shall
be a power of two multiple of sizeof(void *).
Upon successful completion, the value pointed to by memptr shall
be a multiple of alignment.
If the size of the space requested is 0, the behavior is
implementation-defined: either a null pointer shall be returned
in memptr, or the behavior shall be as if the size were some non-
zero value, except that the behavior is undefined if the the
value returned in memptr is used to access an object.
The free() function shall deallocate memory that has previously
been allocated by posix_memalign().
Upon successful completion, posix_memalign() shall return zero;
otherwise, an error number shall be returned to indicate the
error and the contents of memptr shall either be left unmodified
or be set to a null pointer.
If size is 0, either:
* posix_memalign() shall not attempt to allocate any space, in
which case either an implementation-defined error number
shall be returned, or zero shall be returned with a null
pointer returned in memptr, or
* posix_memalign() shall attempt to allocate some space and, if
the allocation succeeds, zero shall be returned and a pointer
to the allocated space shall be returned in memptr. The
application shall ensure that the pointer is not used to
access an object.
The posix_memalign() function shall fail if:
EINVAL The value of the alignment parameter is not a power of two
multiple of sizeof(void *).
ENOMEM There is insufficient memory available with the requested
alignment.
The following sections are informative.
The following example shows how applications can obtain
consistent behavior on error by setting *memptr to be a null
pointer before calling posix_memalign().
void *ptr = NULL;
...
//do some work, which might goto error
if (posix_memalign(&ptr, align, size))
goto error;
//do some more work, which might goto error
...
error:
free(ptr);
//more cleanup;
The posix_memalign() function is part of the Advisory Information
option and need not be provided on all implementations.
None.
None.
free(3p), malloc(3p)
The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 POSIX_MEMALIGN(3P)
Pages that refer to this page: stdlib.h(0p), free(3p), malloc(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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