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diff --git a/docs/htmldocs/Samba3-Developers-Guide/tracing.html b/docs/htmldocs/Samba3-Developers-Guide/tracing.html deleted file mode 100644 index 711429155d..0000000000 --- a/docs/htmldocs/Samba3-Developers-Guide/tracing.html +++ /dev/null @@ -1,77 +0,0 @@ -<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 14. Tracing samba system calls</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="SAMBA Developers Guide"><link rel="up" href="pt04.html" title="Part IV. Debugging and tracing"><link rel="prev" href="pt04.html" title="Part IV. Debugging and tracing"><link rel="next" href="devprinting.html" title="Chapter 15. Samba Printing Internals"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 14. Tracing samba system calls</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pt04.html">Prev</a> </td><th width="60%" align="center">Part IV. Debugging and tracing</th><td width="20%" align="right"> <a accesskey="n" href="devprinting.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 14. Tracing samba system calls"><div class="titlepage"><div><div><h2 class="title"><a name="tracing"></a>Chapter 14. Tracing samba system calls</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Andrew</span> <span class="surname">Tridgell</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span></div></div></div></div></div><p> -This file describes how to do a system call trace on Samba to work out -what its doing wrong. This is not for the faint of heart, but if you -are reading this then you are probably desperate. -</p><p> -Actually its not as bad as the the above makes it sound, just don't -expect the output to be very pretty :-) -</p><p> -Ok, down to business. One of the big advantages of unix systems is -that they nearly all come with a system trace utility that allows you -to monitor all system calls that a program is making. This is -extremely using for debugging and also helps when trying to work out -why something is slower than you expect. You can use system tracing -without any special compilation options. -</p><p> -The system trace utility is called different things on different -systems. On Linux systems its called strace. Under SunOS 4 its called -trace. Under SVR4 style systems (including solaris) its called -truss. Under many BSD systems its called ktrace. -</p><p> -The first thing you should do is read the man page for your native -system call tracer. In the discussion below I'll assume its called -strace as strace is the only portable system tracer (its available for -free for many unix types) and its also got some of the nicest -features. -</p><p> -Next, try using strace on some simple commands. For example, <code class="literal">strace -ls</code> or <code class="literal">strace echo hello</code>. -</p><p> -You'll notice that it produces a LOT of output. It is showing you the -arguments to every system call that the program makes and the -result. Very little happens in a program without a system call so you -get lots of output. You'll also find that it produces a lot of -"preamble" stuff showing the loading of shared libraries etc. Ignore -this (unless its going wrong!) -</p><p> -For example, the only line that really matters in the <code class="literal">strace echo -hello</code> output is: -</p><pre class="programlisting"> -write(1, "hello\n", 6) = 6 -</pre><p>all the rest is just setting up to run the program.</p><p> -Ok, now you're familiar with strace. To use it on Samba you need to -strace the running smbd daemon. The way I tend ot use it is to first -login from my Windows PC to the Samba server, then use smbstatus to -find which process ID that client is attached to, then as root I do -<code class="literal">strace -p PID</code> to attach to that process. I normally redirect the -stderr output from this command to a file for later perusal. For -example, if I'm using a csh style shell: -</p><p><code class="literal">strace -f -p 3872 >& strace.out</code></p><p>or with a sh style shell:</p><p><code class="literal">strace -f -p 3872 > strace.out 2>&1</code></p><p> -Note the "-f" option. This is only available on some systems, and -allows you to trace not just the current process, but any children it -forks. This is great for finding printing problems caused by the -"print command" being wrong. -</p><p> -Once you are attached you then can do whatever it is on the client -that is causing problems and you will capture all the system calls -that smbd makes. -</p><p> -So how do you interpret the results? Generally I search through the -output for strings that I know will appear when the problem -happens. For example, if I am having touble with permissions on a file -I would search for that files name in the strace output and look at -the surrounding lines. Another trick is to match up file descriptor -numbers and "follow" what happens to an open file until it is closed. -</p><p> -Beyond this you will have to use your initiative. To give you an idea -of what you are looking for here is a piece of strace output that -shows that <code class="filename">/dev/null</code> is not world writeable, which -causes printing to fail with Samba: -</p><pre class="programlisting"> -[pid 28268] open("/dev/null", O_RDWR) = -1 EACCES (Permission denied) -[pid 28268] open("/dev/null", O_WRONLY) = -1 EACCES (Permission denied) -</pre><p> -The process is trying to first open <code class="filename">/dev/null</code> read-write -then read-only. Both fail. This means <code class="filename">/dev/null</code> has -incorrect permissions. -</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pt04.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pt04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="devprinting.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Part IV. Debugging and tracing </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 15. Samba Printing Internals</td></tr></table></div></body></html> |