<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
<html>
|
<!-- Copyright (C) 1992-2021 Free Software Foundation, Inc.
|
Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon,
|
and David MacKenzie.
|
|
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 no
|
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
|
Texts. A copy of the license is included in the section entitled "GNU
|
Free Documentation License". -->
|
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
|
<head>
|
<title>STABS: Protections</title>
|
|
<meta name="description" content="STABS: Protections">
|
<meta name="keywords" content="STABS: Protections">
|
<meta name="resource-type" content="document">
|
<meta name="distribution" content="global">
|
<meta name="Generator" content="makeinfo">
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
<link href="index.html#Top" rel="start" title="Top">
|
<link href="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index">
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
<link href="Cplusplus.html#Cplusplus" rel="up" title="Cplusplus">
|
<link href="Method-Modifiers.html#Method-Modifiers" rel="next" title="Method Modifiers">
|
<link href="Member-Type-Descriptor.html#Member-Type-Descriptor" rel="previous" title="Member Type Descriptor">
|
<style type="text/css">
|
<!--
|
a.summary-letter {text-decoration: none}
|
blockquote.smallquotation {font-size: smaller}
|
div.display {margin-left: 3.2em}
|
div.example {margin-left: 3.2em}
|
div.indentedblock {margin-left: 3.2em}
|
div.lisp {margin-left: 3.2em}
|
div.smalldisplay {margin-left: 3.2em}
|
div.smallexample {margin-left: 3.2em}
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
div.smalllisp {margin-left: 3.2em}
|
kbd {font-style:oblique}
|
pre.display {font-family: inherit}
|
pre.format {font-family: inherit}
|
pre.menu-comment {font-family: serif}
|
pre.menu-preformatted {font-family: serif}
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
pre.smallexample {font-size: smaller}
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
pre.smalllisp {font-size: smaller}
|
span.nocodebreak {white-space:nowrap}
|
span.nolinebreak {white-space:nowrap}
|
span.roman {font-family:serif; font-weight:normal}
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
ul.no-bullet {list-style: none}
|
-->
|
</style>
|
|
|
</head>
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
<a name="Protections"></a>
|
<div class="header">
|
<p>
|
Next: <a href="Method-Modifiers.html#Method-Modifiers" accesskey="n" rel="next">Method Modifiers</a>, Previous: <a href="Member-Type-Descriptor.html#Member-Type-Descriptor" accesskey="p" rel="previous">Member Type Descriptor</a>, Up: <a href="Cplusplus.html#Cplusplus" accesskey="u" rel="up">Cplusplus</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
<hr>
|
<a name="Protections-1"></a>
|
<h3 class="section">8.9 Protections</h3>
|
|
<p>In the simple class definition shown above all member data and
|
functions were publicly accessible. The example that follows
|
contrasts public, protected and privately accessible fields and shows
|
how these protections are encoded in C<tt>++</tt> stabs.
|
</p>
|
<p>If the character following the ‘<samp><var>field-name</var>:</samp>’ part of the
|
string is ‘<samp>/</samp>’, then the next character is the visibility. ‘<samp>0</samp>’
|
means private, ‘<samp>1</samp>’ means protected, and ‘<samp>2</samp>’ means public.
|
Debuggers should ignore visibility characters they do not recognize, and
|
assume a reasonable default (such as public) (GDB 4.11 does not, but
|
this should be fixed in the next GDB release). If no visibility is
|
specified the field is public. The visibility ‘<samp>9</samp>’ means that the
|
field has been optimized out and is public (there is no way to specify
|
an optimized out field with a private or protected visibility).
|
Visibility ‘<samp>9</samp>’ is not supported by GDB 4.11; this should be fixed
|
in the next GDB release.
|
</p>
|
<p>The following C<tt>++</tt> source:
|
</p>
|
<div class="example">
|
<pre class="example">class vis {
|
private:
|
int priv;
|
protected:
|
char prot;
|
public:
|
float pub;
|
};
|
</pre></div>
|
|
<p>generates the following stab:
|
</p>
|
<div class="example">
|
<pre class="example"># <span class="roman">128 is N_LSYM</span>
|
.stabs "vis:T19=s12priv:/01,0,32;prot:/12,32,8;pub:12,64,32;;",128,0,0,0
|
</pre></div>
|
|
<p>‘<samp>vis:T19=s12</samp>’ indicates that type number 19 is a 12 byte structure
|
named <code>vis</code> The <code>priv</code> field has public visibility
|
(‘<samp>/0</samp>’), type int (‘<samp>1</samp>’), and offset and size ‘<samp>,0,32;</samp>’.
|
The <code>prot</code> field has protected visibility (‘<samp>/1</samp>’), type char
|
(‘<samp>2</samp>’) and offset and size ‘<samp>,32,8;</samp>’. The <code>pub</code> field has
|
type float (‘<samp>12</samp>’), and offset and size ‘<samp>,64,32;</samp>’.
|
</p>
|
<p>Protections for member functions are signified by one digit embedded in
|
the field part of the stab describing the method. The digit is 0 if
|
private, 1 if protected and 2 if public. Consider the C<tt>++</tt> class
|
definition below:
|
</p>
|
<div class="example">
|
<pre class="example">class all_methods {
|
private:
|
int priv_meth(int in){return in;};
|
protected:
|
char protMeth(char in){return in;};
|
public:
|
float pubMeth(float in){return in;};
|
};
|
</pre></div>
|
|
<p>It generates the following stab. The digit in question is to the left
|
of an ‘<samp>A</samp>’ in each case. Notice also that in this case two symbol
|
descriptors apply to the class name struct tag and struct type.
|
</p>
|
<div class="display">
|
<pre class="display">.stabs "class_name:sym_desc(struct tag&type)type_def(21)=
|
sym_desc(struct)struct_bytes(1)
|
meth_name::type_def(22)=sym_desc(method)returning(int);
|
:args(int);protection(private)modifier(normal)virtual(no);
|
meth_name::type_def(23)=sym_desc(method)returning(char);
|
:args(char);protection(protected)modifier(normal)virtual(no);
|
meth_name::type_def(24)=sym_desc(method)returning(float);
|
:args(float);protection(public)modifier(normal)virtual(no);;",
|
N_LSYM,NIL,NIL,NIL
|
</pre></div>
|
|
<div class="smallexample">
|
<pre class="smallexample">.stabs "all_methods:Tt21=s1priv_meth::22=##1;:i;0A.;protMeth::23=##2;:c;1A.;
|
pubMeth::24=##12;:f;2A.;;",128,0,0,0
|
</pre></div>
|
|
<hr>
|
<div class="header">
|
<p>
|
Next: <a href="Method-Modifiers.html#Method-Modifiers" accesskey="n" rel="next">Method Modifiers</a>, Previous: <a href="Member-Type-Descriptor.html#Member-Type-Descriptor" accesskey="p" rel="previous">Member Type Descriptor</a>, Up: <a href="Cplusplus.html#Cplusplus" accesskey="u" rel="up">Cplusplus</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
|
|
|
</body>
|
</html>
|
