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118 lines
5.0 KiB
HTML
118 lines
5.0 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Value Sizes (Debugging with GDB)</title>
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<meta name="description" content="Value Sizes (Debugging with GDB)">
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<meta name="keywords" content="Value Sizes (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Data.html#Data" rel="up" title="Data">
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<link href="Optimized-Code.html#Optimized-Code" rel="next" title="Optimized Code">
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<link href="Searching-Memory.html#Searching-Memory" rel="prev" title="Searching Memory">
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</style>
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</head>
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<body lang="en">
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<a name="Value-Sizes"></a>
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<div class="header">
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<p>
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Previous: <a href="Searching-Memory.html#Searching-Memory" accesskey="p" rel="prev">Searching Memory</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Value-Sizes-1"></a>
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<h3 class="section">10.23 Value Sizes</h3>
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<p>Whenever <small>GDB</small> prints a value memory will be allocated within
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<small>GDB</small> to hold the contents of the value. It is possible in
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some languages with dynamic typing systems, that an invalid program
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may indicate a value that is incorrectly large, this in turn may cause
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<small>GDB</small> to try and allocate an overly large ammount of memory.
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</p>
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<dl compact="compact">
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<dd><a name="index-set-max_002dvalue_002dsize"></a>
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</dd>
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<dt><code>set max-value-size <var>bytes</var></code></dt>
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<dt><code>set max-value-size unlimited</code></dt>
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<dd><p>Set the maximum size of memory that <small>GDB</small> will allocate for the
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contents of a value to <var>bytes</var>, trying to display a value that
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requires more memory than that will result in an error.
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</p>
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<p>Setting this variable does not effect values that have already been
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allocated within <small>GDB</small>, only future allocations.
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</p>
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<p>There’s a minimum size that <code>max-value-size</code> can be set to in
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order that <small>GDB</small> can still operate correctly, this minimum is
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currently 16 bytes.
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</p>
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<p>The limit applies to the results of some subexpressions as well as to
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complete expressions. For example, an expression denoting a simple
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integer component, such as <code>x.y.z</code>, may fail if the size of
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<var>x.y</var> is dynamic and exceeds <var>bytes</var>. On the other hand,
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<small>GDB</small> is sometimes clever; the expression <code>A[i]</code>, where
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<var>A</var> is an array variable with non-constant size, will generally
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succeed regardless of the bounds on <var>A</var>, as long as the component
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size is less than <var>bytes</var>.
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</p>
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<p>The default value of <code>max-value-size</code> is currently 64k.
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</p>
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<a name="index-show-max_002dvalue_002dsize"></a>
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</dd>
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<dt><code>show max-value-size</code></dt>
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<dd><p>Show the maximum size of memory, in bytes, that <small>GDB</small> will
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allocate for the contents of a value.
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</p></dd>
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</dl>
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</body>
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</html>
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