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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML LANG="en-us">
<HEAD>
<META name="Author" content="Carlo Wood">
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<TITLE>libcwd: The C++ Debugging Support Library - Features</TITLE>
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<table border=0 cellspacing=15 cellpadding=0 width=100%>
<!-- *** Page Header *** -->
<tr>
<td class="tag-cw-main-header" colspan=4 align=middle><B><SPAN class="H1code">libcw<FONT color=red>d</FONT></SPAN></B></td>
</tr>
<tr>
<td colspan=2><H2>Features</H2></td>
</tr>
<tr>
<td width=50% valign=top>
<table border=0 cellspacing=5 cellpadding=0 width=100%>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
End-users of an application don't need to install libcwd.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
The use of namespaces prevents name collisions between debug channels of different libraries.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Debug channels and devices can be turned on or off on a per thread basis.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
All debug code can be omitted from the executable by not defining a single <SPAN class=code>CWDEBUG</SPAN> macro.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
<SPAN class="features">Code using libcwd looks clean and is surveyable as a result of using a few well-defined macros, avoiding the need
of disturbing <SPAN class=code>#ifdef CWDEBUG</SPAN> ... <SPAN class=code>#endif</SPAN> constructs.</SPAN>
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Debug output is written to an ostream and as such type-safe and customizable as is usual for C++ ostreams.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
An arbitrary number of debug channels and debug devices can be created without any penalty in terms of cpu usage.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Full support for all forms of iterative and recursive calls.
</td>
</tr>
</table>
</td>
<td width=50% valign=top>
<table border=0 cellspacing=5 cellpadding=0 width=100%>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Debug output is surveyable as a result of several possibilities to format the output, like
a margin string, a marker string, indentation and fixed-width channel labels.
All formatting is thread specific.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Printing the type of arbitrary variables in demangled form.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Printing addresses in <I>source file</I><SPAN class=code>:</SPAN><I>line number</I> presentation.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Deallocation pointer validation.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Magic numbers around allocated memory blocks in order to detect buffer overruns.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Printing an overview of current memory allocations, including
start address, size, type of allocated object, source file and line number of allocation and a user definable description.
</td>
</tr>
<tr>
<td width=16 valign=top><img width=16 height=16 src="../images/ball_neon_gimp.gif"></td>
<td width=100%>
Finding allocation information with only a pointer that points <EM>inside</EM> an allocated memory block,
in logarithmic time.
</td>
</tr>
</table>
</td>
</tr>
</table>
<A NAME="screenshot"></A>
<div class="screenshot">
<H2>"Screen shot"</H2>
<h5>code example</h5>
<pre class="code" STYLE="margin-left: 0">Dout(dc::notice|error_cf, "Hello World");</pre>
<table border=0 cellspacing=0 cellpadding=0>
<tr>
<td width=10% class="margin" valign=middle align=middle>
<- margin ->
</td>
<td width=10% class="label" valign=top align=left>
<span class="output"><B>NOTICE</B></span>
</td>
<td width=10 class="marker" valign=top align=middle>
<- marker ->
</td>
<td width=10% class="indentation" valign=top align=middle>
<- indentation ->
</td>
<td width=60% class="text" valign=top align=left>
<span class="output"> <B>Hello World : </B></span><I>error string</I> <new-line>
</td>
</tr>
</table>
<h5>output example</h5>
<pre class="output" STYLE="margin-left: 0">
NOTICE : Entering exec_prog()
SYSTEM : pipe([3, 4]) = 0
SYSTEM : pipe([5, 6]) = 0
child MALLOC : operator new (size = 24) = <unfinished>
child BFD : Loading debug symbols from /home/carlo/c++/bfd/bfd... done
SYSTEM : fork() = 13078 [parent process]
SYSTEM : close(4) = 0
SYSTEM : close(6) = 0
child BFD : Loading debug symbols from /home/carlo/c++/libcw/lib/libcwd.so.0 (40013000) ... done
child BFD : Loading debug symbols from /usr/lib/libstdc++-libc6.1-2.so.3 (40057000) ... done
child BFD : Loading debug symbols from /lib/libm.so.6 (4009e000) ... done
child BFD : Loading debug symbols from /lib/libc.so.6 (400ba000) ... done
child BFD : Loading debug symbols from /usr/lib/libbfd-2.9.5.0.14.so (401ad000) ... done
child BFD : Loading debug symbols from /lib/ld-linux.so.2 (40000000) ... done
child BFD : 0x40082003 is at (streambuf.cc:211)
child MALLOC : <continued> 0x8053a68
SYSTEM : poll( [ { 3, POLLIN, 0 }, { 5, POLLIN, 0 }, { 7, POLLIN, POLLIN } ], 3, -1) = 1
child SYSTEM : fork() = 0 [child process]
child SYSTEM : close(3) = 0
child SYSTEM : close(5) = 0
child SYSTEM : close(1) = 0
child SYSTEM : close(2) = 0
child SYSTEM : dup2(4, 1) = 1
child SYSTEM : dup2(6, 2) = 2
child SYSTEM : close(4) = 0
SYSTEM : poll( [ { 3, POLLIN, POLLIN }, { 5, POLLIN, 0 }, { 7, POLLIN, 0 } ], 3, -1) = 1
SYSTEM : read(3, "\t", 128) = 1
SYSTEM : read(3, "libcwd.so.0", 128) = 11
SYSTEM : read(3, " => ", 128) = 4
SYSTEM : read(3, "/usr/lib/libcwd.so.0", 128) = 20
SYSTEM : read(3, " (0x", 128) = 4
SYSTEM : read(3, "40018000", 128) = 8
SYSTEM : read(3, ")\n", 128) = 2
NOTICE : child process stdout: "\tlibcwd.so.0 => /usr/lib/libcwd.so.0 (0x40018000)\n"
</pre>
<h5>code example</h5>
<pre class="code" STYLE="margin-left: 0">
template<typename T>
B<T>::~B(void)
{
Dout(dc::notice, "Calling the destructor of " <<
libcwd::type_info_of(*this).demangled_name() << " (this == " << this << ")");
libcwd::alloc_ct const* alloc = libcwd::find_alloc(this);
if (sizeof(*this) != alloc->size())
{
Debug(dc::malloc.off());
Debug(libcw_do.push_marker());
Debug(libcw_do.marker().assign(": | "));
Dout(dc::notice, "This is a base class of an object starting at " << alloc->start());
Dout(dc::notice, "The type of the pointer to the allocated object is " <<
alloc->type_info().demangled_name());
Debug(libcw_do.marker().assign(": ` "));
Dout(dc::notice, "The destructor was called from " << location_ct(builtin_return_address(0)));
Debug(dc::malloc.on());
Debug(libcw_do.pop_marker());
}
}
</pre>
<P>(<FONT size=-1>Click <A HREF="screenshot.cc">here</A> to download/view the complete program.</FONT>)</P>
<h5>output</h5>
<pre class="output" STYLE="margin-left: 0">
MALLOC : operator new (size = 4) = 0x80584d0 [screenshot.cc:56]
NOTICE : b is 0x80584d0
MALLOC : operator new (size = 12) = 0x8100fa0 [screenshot.cc:60]
NOTICE : c is 0x8100fa0
NOTICE : Calling the destructor of B<int> (this == 0x80584d0)
MALLOC : delete 0x80584d0 screenshot.cc:56 B<int>; (sz = 4) object `b'
NOTICE : Calling the destructor of B<B<char> > (this == 0x8100fa4)
NOTICE : | This is a base class of an object starting at 0x8100fa0
NOTICE : | The type of the pointer to the allocated object is C<double, B<char> >*
NOTICE : ` The destructor was called from screenshot.cc:65
MALLOC : delete 0x8100fa0 screenshot.cc:60 C<double, B<char> >; (sz = 12) object `c'
</pre>
<h5>Another output example</h5>
<pre class="output" STYLE="margin-left: 0">
MALLOC : malloc(10) = <unfinished>
WARNING : Object file /lib/ld-linux.so.2 does not have debug info. Address lookups inside this object file will result in a function name only, not a source file location.
MALLOC : <continued> 0x8125978 [ld-linux.so.2:open_path]
MALLOC : calloc(586, 1) = 0x8124f10 [ld-linux.so.2:_dl_new_object]
MALLOC : realloc(0x0, 138) = 0x8125170 [ld-linux.so.2:_dl_new_object]
MALLOC : malloc(52) = 0x8110fa0 [ld-linux.so.2:_dl_map_object_deps]
MALLOC : calloc(8, 16) = 0x8052c98 [ld-linux.so.2:_dl_check_map_versions]
MALLOC : malloc(68) = <unfinished>
WARNING : Object file /lib/tls/libc.so.6 does not have debug info. Address lookups inside this object file will result in a function name only, not a source file location.
MALLOC : <continued> 0x80569e0 [libc.so.6:dl_open_worker]
BFD : Loading debug symbols from module.so (0x40424000) ... done (179 symbols)
MALLOC : malloc(310) = <unfinished>
BFD : Loading debug info from module.so... done
BFD : address 0x4042bc90 corresponds to module.cc:24
MALLOC : <continued> 0x81ab7b0 [module.cc:24]
MALLOC : malloc(300) = <unfinished>
BFD : address 0x4042ba86 corresponds to module.cc:13
MALLOC : <continued> 0x81ab8f8 [module.cc:13]
MALLOC : Allocated memory: 1592 bytes in 8 blocks.
malloc 0x81ab8f8 module.cc:13 void*; (sz = 300) Allocated inside static_test_symbol
malloc 0x81ab7b0 module.cc:24 void*; (sz = 310) Allocated inside global_test_symbol
malloc 0x80569e0 dl_open_worker <unknown type>; (sz = 68)
malloc 0x8052c98 _dl_check_map_versions <unknown type>; (sz = 128)
malloc 0x8110fa0 _dl_map_object_deps <unknown type>; (sz = 52)
realloc 0x8125170 _dl_new_object <unknown type>; (sz = 138)
malloc 0x8124f10 _dl_new_object <unknown type>; (sz = 586)
malloc 0x8125978 open_path <unknown type>; (sz = 10)
MALLOC : free(0x81ab7b0) module.cc:24 void*; (sz = 310) Allocated inside global_test_symbol
MALLOC : free(0x81ab8f8) module.cc:13 void*; (sz = 300) Allocated inside static_test_symbol
MALLOC : free(0x8052c98) _dl_check_map_versions <unknown type>; (sz = 128)
MALLOC : free(0x8125170) _dl_new_object <unknown type>; (sz = 138)
MALLOC : free(0x8125978) open_path <unknown type>; (sz = 10)
MALLOC : Trying to free NULL - ignored.
MALLOC : Trying to free NULL - ignored.
MALLOC : free(0x8124f10) _dl_new_object <unknown type>; (sz = 586)
MALLOC : free(0x8110fa0) _dl_map_object_deps <unknown type>; (sz = 52)
NOTICE : Finished
</pre>
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