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- <a name="gets_002d_002d_002dget-character-string-_0028obsolete_002c-use-fgets-instead_0029"></a>
- <h3 class="section">4.39 <code>gets</code>—get character string (obsolete, use <code>fgets</code> instead)</h3>
- <a name="index-gets"></a>
- <a name="index-_005fgets_005fr"></a>
- <p><strong>Synopsis</strong>
- </p><div class="example">
- <pre class="example">#include <stdio.h>
-
- char *gets(char *<var>buf</var>);
-
- char *_gets_r(struct _reent *<var>reent</var>, char *<var>buf</var>);
-
- </pre></div>
- <p><strong>Description</strong><br>
- Reads characters from standard input until a newline is found.
- The characters up to the newline are stored in <var>buf</var>. The
- newline is discarded, and the buffer is terminated with a 0.
- </p>
- <p>This is a <em>dangerous</em> function, as it has no way of checking
- the amount of space available in <var>buf</var>. One of the attacks
- used by the Internet Worm of 1988 used this to overrun a
- buffer allocated on the stack of the finger daemon and
- overwrite the return address, causing the daemon to execute
- code downloaded into it over the connection.
- </p>
- <p>The alternate function <code>_gets_r</code> is a reentrant version. The extra
- argument <var>reent</var> is a pointer to a reentrancy structure.
- </p>
- <br>
- <p><strong>Returns</strong><br>
- <code>gets</code> returns the buffer passed to it, with the data filled
- in. If end of file occurs with some data already accumulated,
- the data is returned with no other indication. If end of file
- occurs with no data in the buffer, NULL is returned.
- </p>
- <p>Supporting OS subroutines required: <code>close</code>, <code>fstat</code>, <code>isatty</code>,
- <code>lseek</code>, <code>read</code>, <code>sbrk</code>, <code>write</code>.
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