1POSIX_MEMALIGN(3P) POSIX Programmer's Manual POSIX_MEMALIGN(3P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 posix_memalign — aligned memory allocation (ADVANCED REALTIME)
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15 #include <stdlib.h>
16 int posix_memalign(void **memptr, size_t alignment, size_t size);
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20 The posix_memalign() function shall allocate size bytes aligned on a
21 boundary specified by alignment, and shall return a pointer to the
22 allocated memory in memptr. The value of alignment shall be a power of
23 two multiple of sizeof(void *).
24 Upon successful completion, the value pointed to by memptr shall be a
26 multiple of alignment.
27 If the size of the space requested is 0, the behavior is implementa‐
29 tion-defined: either a null pointer shall be returned in memptr, or the
30 behavior shall be as if the size were some non-zero value, except that
31 the behavior is undefined if the the value returned in memptr is used
32 to access an object.
33 The free() function shall deallocate memory that has previously been
35 allocated by posix_memalign().
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38 Upon successful completion, posix_memalign() shall return zero; other‐
39 wise, an error number shall be returned to indicate the error and the
40 contents of memptr shall either be left unmodified or be set to a null
41 pointer.
42 If size is 0, either:
44 * posix_memalign() shall not attempt to allocate any space, in which
46 case either an implementation-defined error number shall be
47 returned, or zero shall be returned with a null pointer returned in
48 memptr, or
49 * posix_memalign() shall attempt to allocate some space and, if the
51 allocation succeeds, zero shall be returned and a pointer to the
52 allocated space shall be returned in memptr. The application shall
53 ensure that the pointer is not used to access an object.
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56 The posix_memalign() function shall fail if:
57 EINVAL The value of the alignment parameter is not a power of two mul‐
59 tiple of sizeof(void *).
60 ENOMEM There is insufficient memory available with the requested align‐
62 ment.
63 The following sections are informative.
65
67 The following example shows how applications can obtain consistent
68 behavior on error by setting *memptr to be a null pointer before call‐
69 ing posix_memalign().
70 void *ptr = NULL;
73 ...
74 //do some work, which might goto error
75 if (posix_memalign(&ptr, align, size))
76 goto error;
77 //do some more work, which might goto error
79 ...
80 error:
81 free(ptr);
82 //more cleanup;
83
85 The posix_memalign() function is part of the Advisory Information
86 option and need not be provided on all implementations.
87
89 None.
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92 None.
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95 free(), malloc()
96 The Base Definitions volume of POSIX.1‐2017, <stdlib.h>
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100 Portions of this text are reprinted and reproduced in electronic form
101 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
102 table Operating System Interface (POSIX), The Open Group Base Specifi‐
103 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
104 Electrical and Electronics Engineers, Inc and The Open Group. In the
105 event of any discrepancy between this version and the original IEEE and
106 The Open Group Standard, the original IEEE and The Open Group Standard
107 is the referee document. The original Standard can be obtained online
108 at http://www.opengroup.org/unix/online.html .
109 Any typographical or formatting errors that appear in this page are
111 most likely to have been introduced during the conversion of the source
112 files to man page format. To report such errors, see https://www.ker‐
113 nel.org/doc/man-pages/reporting_bugs.html .
114IEEE/The Open Group 2017 POSIX_MEMALIGN(3P)