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| 1 | <?xml version="1.0" encoding="UTF-8" standalone="no"?> | 1 | <?xml version="1.0" encoding="UTF-8" standalone="no"?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title xmlns:d="http://docbook.org/ns/docbook">4.2. Accessing User-Space Target Variables</title><link rel="stylesheet" type="text/css" href="Common_Content/css/default.css" /><link rel="stylesheet" media="print" href="Common_Content/css/print.css" type="text/css" /><meta xmlns:d="http://docbook.org/ns/docbook" name="generator" content="publican v4.1.3" /><meta xmlns:d="http://docbook.org/ns/docbook" name="package" content="SystemTap-SystemTap_Beginners_Guide-2.7-en-US-2.0-1" /><link rel="home" href="index.html" title="SystemTap Beginners Guide" /><link rel="up" href="userspace-probing.html" title="Chapter 4. User-space Probing" /><link rel="prev" href="userspace-probing.html" title="Chapter 4. User-space Probing" /><link rel="next" href="ustack.html" title="4.3. User-Space Stack Backtraces" /></head><body><p id="title"><a class="left" href="https://fedorahosted.org/publican"><img alt="Product Site" src="Common_Content/images//image_left.png" /></a><a class="right" href="https://fedorahosted.org/publican"><img alt="Documentation Site" src="Common_Content/images//image_right.png" /></a></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="userspace-probing.html"><strong>Prev</strong></a></li><li class="home">SystemTap Beginners Guide</li><li class="next"><a accesskey="n" href="ustack.html"><strong>Next</strong></a></li></ul><div class="section"><div class="titlepage"><div><div><h2 class="title"><a id="utargetvariable"> | 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title xmlns:d="http://docbook.org/ns/docbook">4.2. Accessing User-Space Target Variables</title><link rel="stylesheet" type="text/css" href="Common_Content/css/default.css" /><link rel="stylesheet" media="print" href="Common_Content/css/print.css" type="text/css" /><meta xmlns:d="http://docbook.org/ns/docbook" name="generator" content="not publican" /><meta xmlns:d="http://docbook.org/ns/docbook" name="package" content="" /><link rel="home" href="index.html" title="SystemTap Beginners Guide" /><link rel="up" href="userspace-probing.html" title="Chapter 4. User-space Probing" /><link rel="prev" href="userspace-probing.html" title="Chapter 4. User-space Probing" /><link rel="next" href="ustack.html" title="4.3. User-Space Stack Backtraces" /></head><body><p id="title"></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="userspace-probing.html"><strong>Prev</strong></a></li><li class="home">SystemTap Beginners Guide</li><li class="next"><a accesskey="n" href="ustack.html"><strong>Next</strong></a></li></ul><div class="section"><div class="titlepage"><div><div><h2 class="title"><a id="utargetvariable"> |
| 3 | </a>4.2. Accessing User-Space Target Variables</h2></div></div></div><a id="idm47748233418640" class="indexterm"></a><div class="para"> | 3 | </a>4.2. Accessing User-Space Target Variables</h2></div></div></div><a id="idm140174739361616" class="indexterm"></a><div class="para"> |
| 4 | You can access user-space target variables in the same manner as described in <a class="xref" href="targetvariables.html">Section 3.3.2, “Target Variables”</a>. In Linux, however, there are separate address spaces for the user and kernel code. When using the <code class="literal">-></code> operator, SystemTap accesses the appropriate address space. | 4 | You can access user-space target variables in the same manner as described in |
| 5 | </div><div class="para"> | 5 | <a class="xref" href="targetvariables.html">Section 3.3.2, “Target Variables”</a>. |
| 6 | For pointers to base types such as integers and strings, there are a number of functions listed below to access user-space data. The first argument for each functions is the pointer to the data item. | 6 | In Linux, however, there are separate address spaces for the user and |
| 7 | </div><div class="variablelist"><dl class="variablelist"><dt><span class="term">user_char(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | 7 | kernel code. |
| 8 | Obtains the character at <em class="replaceable">address</em> for the current user process. | 8 | When using the <code class="literal">-></code> operator, SystemTap accesses the appropriate address space. |
| 9 | </div></dd><dt><span class="term">user_short(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | 9 | </div><div class="para"> |
| 10 | Obtains the short integer at <em class="replaceable">address</em> for the current user process. | 10 | For pointers to base types such as integers and strings, |
| 11 | </div></dd><dt><span class="term">user_int(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | 11 | there are a number of functions listed below to access user-space data. |
| 12 | Obtains the integer at <em class="replaceable">address</em> for the current user process. | 12 | The first argument for each functions is the pointer to the data item. |
| 13 | </div></dd><dt><span class="term">user_long(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | 13 | </div><div class="variablelist"><dl class="variablelist"><dt><span class="term">user_char(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> |
| 14 | Obtains the long integer at <em class="replaceable">address</em> for the current user process. | 14 | Obtains the character at <em class="replaceable">address</em> for the current |
| 15 | </div></dd><dt><span class="term">user_string(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | 15 | user process. |
| 16 | Obtains the string at <em class="replaceable">address</em> for the current user process. | 16 | </div></dd><dt><span class="term">user_short(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> |
| 17 | </div></dd><dt><span class="term">user_string_n(<em class="replaceable">address</em>, <em class="replaceable">n</em>)</span></dt><dd><div class="para"> | 17 | Obtains the short integer at <em class="replaceable">address</em> for the current |
| 18 | Obtains the string at <em class="replaceable">address</em> for the current user process and limits the string to <em class="replaceable">n</em> bytes. | 18 | user process. |
| 19 | </div></dd></dl></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="userspace-probing.html"><strong>Prev</strong>Chapter 4. User-space Probing</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="ustack.html"><strong>Next</strong>4.3. User-Space Stack Backtraces</a></li></ul></body></html> \ No newline at end of file | 19 | </div></dd><dt><span class="term">user_int(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> |
| 20 | Obtains the integer at <em class="replaceable">address</em> for the current | ||
| 21 | user process. | ||
| 22 | </div></dd><dt><span class="term">user_long(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | ||
| 23 | Obtains the long integer at <em class="replaceable">address</em> for the current | ||
| 24 | user process. | ||
| 25 | </div></dd><dt><span class="term">user_string(<em class="replaceable">address</em>)</span></dt><dd><div class="para"> | ||
| 26 | Obtains the string at <em class="replaceable">address</em> for the current | ||
| 27 | user process. | ||
| 28 | </div></dd><dt><span class="term">user_string_n(<em class="replaceable">address</em>, <em class="replaceable">n</em>)</span></dt><dd><div class="para"> | ||
| 29 | Obtains the string at <em class="replaceable">address</em> for the current | ||
| 30 | user process and limits the string to <em class="replaceable">n</em> bytes. | ||
| 31 | </div></dd></dl></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="userspace-probing.html"><strong>Prev</strong>Chapter 4. User-space Probing</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="ustack.html"><strong>Next</strong>4.3. User-Space Stack Backtraces</a></li></ul></body></html> \ No newline at end of file | ||