oracular (3) posix_memalign.3posix.gz

Provided by: manpages-posix-dev_2017a-2_all bug

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(), malloc()

       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>


       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 .