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| <h5 class="subsubsection">24.4.7.2 Atomic Types</h5> |
| |
| <p>To avoid uncertainty about interrupting access to a variable, you can |
| use a particular data type for which access is always atomic: |
| <code>sig_atomic_t</code>. Reading and writing this data type is guaranteed |
| to happen in a single instruction, so there's no way for a handler to |
| run “in the middle” of an access. |
| |
| <p>The type <code>sig_atomic_t</code> is always an integer data type, but which |
| one it is, and how many bits it contains, may vary from machine to |
| machine. |
| |
| <!-- signal.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Data Type: <b>sig_atomic_t</b><var><a name="index-sig_005fatomic_005ft-2939"></a></var><br> |
| <blockquote><p>This is an integer data type. Objects of this type are always accessed |
| atomically. |
| </p></blockquote></div> |
| |
| <p>In practice, you can assume that <code>int</code> is atomic. |
| You can also assume that pointer |
| types are atomic; that is very convenient. Both of these assumptions |
| are true on all of the machines that the GNU C library supports and on |
| all POSIX systems we know of. |
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