121 lines
3.1 KiB
HTML
121 lines
3.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of MALLOC_USABLE_SIZE</TITLE>
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<H1>MALLOC_USABLE_SIZE</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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malloc_usable_size - obtain size of block of memory allocated from heap
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/malloc.h">malloc.h</A>></B>
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<P>
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<B>size_t malloc_usable_size (void *</B><I>ptr</I><B>);</B>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>malloc_usable_size</B>()
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function returns the number of usable bytes in the block pointed to by
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<I>ptr</I>,
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a pointer to a block of memory allocated by
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<B><A HREF="/cgi-bin/man/man2html?3+malloc">malloc</A></B>(3)
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or a related function.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<B>malloc_usable_size</B>()
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returns the number of usable bytes in
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the block of allocated memory pointed to by
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<I>ptr</I>.
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If
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<I>ptr</I>
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is NULL, 0 is returned.
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<A NAME="lbAF"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>malloc_usable_size</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAG"> </A>
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<H2>CONFORMING TO</H2>
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This function is a GNU extension.
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<A NAME="lbAH"> </A>
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<H2>NOTES</H2>
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The value returned by
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<B>malloc_usable_size</B>()
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may be greater than the requested size of the allocation because
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of alignment and minimum size constraints.
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Although the excess bytes can be overwritten by the application
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without ill effects,
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this is not good programming practice:
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the number of excess bytes in an allocation depends on
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the underlying implementation.
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<P>
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The main use of this function is for debugging and introspection.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+malloc">malloc</A></B>(3)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="5"><A HREF="#lbAF">ATTRIBUTES</A><DD>
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<DT id="6"><A HREF="#lbAG">CONFORMING TO</A><DD>
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<DT id="7"><A HREF="#lbAH">NOTES</A><DD>
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<DT id="8"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="9"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:47 GMT, March 31, 2021
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</BODY>
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</HTML>
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