85 lines
3.9 KiB
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85 lines
3.9 KiB
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<title>Value Sizes - Debugging with GDB</title>
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<a name="Value-Sizes"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Searching-Memory.html#Searching-Memory">Searching Memory</a>,
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Up: <a rel="up" accesskey="u" href="Data.html#Data">Data</a>
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<hr>
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</div>
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<h3 class="section">10.23 Value Sizes</h3>
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<p>Whenever <span class="sc">gdb</span> prints a value memory will be allocated within
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<span class="sc">gdb</span> 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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<span class="sc">gdb</span> to try and allocate an overly large ammount of memory.
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<a name="index-set-max_002dvalue_002dsize-832"></a>
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<dl><dt><code>set max-value-size </code><var>bytes</var><dt><code>set max-value-size unlimited</code><dd>Set the maximum size of memory that <span class="sc">gdb</span> 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>Setting this variable does not effect values that have already been
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allocated within <span class="sc">gdb</span>, only future allocations.
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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 <span class="sc">gdb</span> can still operate correctly, this minimum is
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currently 16 bytes.
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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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<span class="sc">gdb</span> 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>The default value of <code>max-value-size</code> is currently 64k.
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<p><a name="index-show-max_002dvalue_002dsize-833"></a><br><dt><code>show max-value-size</code><dd>Show the maximum size of memory, in bytes, that <span class="sc">gdb</span> will
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allocate for the contents of a value.
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</dl>
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</body></html>
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