posix_memalign(3p) — Linux manual page

POSIX_MEMALIGN(3P)      POSIX Programmer's Manual     POSIX_MEMALIGN(3P)

PROLOG

       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.

NAME

       posix_memalign — aligned memory allocation (ADVANCED REALTIME)

SYNOPSIS

       #include <stdlib.h>

       int posix_memalign(void **memptr, size_t alignment, size_t size);

DESCRIPTION

       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().

RETURN VALUE

       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.

ERRORS

       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.

EXAMPLES

       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;

APPLICATION USAGE

       The posix_memalign() function is part of the Advisory Information
       option and need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       free(3p), malloc(3p)

       The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)

COPYRIGHT

       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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