88 lines
4.4 KiB
HTML
88 lines
4.4 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>The Ctrl-C Message - Debugging with GDB</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Debugging with GDB">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="File_002dI_002fO-Remote-Protocol-Extension.html#File_002dI_002fO-Remote-Protocol-Extension" title="File-I/O Remote Protocol Extension">
|
|
<link rel="prev" href="The-F-Reply-Packet.html#The-F-Reply-Packet" title="The F Reply Packet">
|
|
<link rel="next" href="Console-I_002fO.html#Console-I_002fO" title="Console I/O">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
Copyright (C) 1988-2019 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with the
|
|
Invariant Sections being ``Free Software'' and ``Free Software Needs
|
|
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
|
|
and with the Back-Cover Texts as in (a) below.
|
|
|
|
(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
|
developing GNU and promoting software freedom.''
|
|
-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<a name="The-Ctrl-C-Message"></a>
|
|
<a name="The-Ctrl_002dC-Message"></a>
|
|
<p>
|
|
Next: <a rel="next" accesskey="n" href="Console-I_002fO.html#Console-I_002fO">Console I/O</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="The-F-Reply-Packet.html#The-F-Reply-Packet">The F Reply Packet</a>,
|
|
Up: <a rel="up" accesskey="u" href="File_002dI_002fO-Remote-Protocol-Extension.html#File_002dI_002fO-Remote-Protocol-Extension">File-I/O Remote Protocol Extension</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h4 class="subsection">E.13.5 The ‘<samp><span class="samp">Ctrl-C</span></samp>’ Message</h4>
|
|
|
|
<p><a name="index-ctrl_002dc-message_002c-in-file_002di_002fo-protocol-3601"></a>
|
|
If the ‘<samp><span class="samp">Ctrl-C</span></samp>’ flag is set in the <span class="sc">gdb</span>
|
|
reply packet (see <a href="The-F-Reply-Packet.html#The-F-Reply-Packet">The F Reply Packet</a>),
|
|
the target should behave as if it had
|
|
gotten a break message. The meaning for the target is “system call
|
|
interrupted by <code>SIGINT</code>”. Consequentially, the target should actually stop
|
|
(as with a break message) and return to <span class="sc">gdb</span> with a <code>T02</code>
|
|
packet.
|
|
|
|
<p>It's important for the target to know in which
|
|
state the system call was interrupted. There are two possible cases:
|
|
|
|
<ul>
|
|
<li>The system call hasn't been performed on the host yet.
|
|
|
|
<li>The system call on the host has been finished.
|
|
|
|
</ul>
|
|
|
|
<p>These two states can be distinguished by the target by the value of the
|
|
returned <code>errno</code>. If it's the protocol representation of <code>EINTR</code>, the system
|
|
call hasn't been performed. This is equivalent to the <code>EINTR</code> handling
|
|
on POSIX systems. In any other case, the target may presume that the
|
|
system call has been finished — successfully or not — and should behave
|
|
as if the break message arrived right after the system call.
|
|
|
|
<p><span class="sc">gdb</span> must behave reliably. If the system call has not been called
|
|
yet, <span class="sc">gdb</span> may send the <code>F</code> reply immediately, setting <code>EINTR</code> as
|
|
<code>errno</code> in the packet. If the system call on the host has been finished
|
|
before the user requests a break, the full action must be finished by
|
|
<span class="sc">gdb</span>. This requires sending <code>M</code> or <code>X</code> packets as necessary.
|
|
The <code>F</code> packet may only be sent when either nothing has happened
|
|
or the full action has been completed.
|
|
|
|
</body></html>
|
|
|