HOWTO use gdb to debug program errors - Revision history

Gabriel at 17:40, 27 October 2023

2023-10-27T17:40:55Z

← Older revision		Revision as of 17:40, 27 October 2023
Line 3:		Line 3:
	[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.		[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

	One example of such tutorials is part of the [https://access.redhat.com/documentation/en-us/red_hat_developer_toolset/9/html/user_guide/chap-gdb ~~RedHat~~ user guide].		One example of such tutorials is part of the [https://access.redhat.com/documentation/en-us/red_hat_developer_toolset/9/html/user_guide/chap-gdb Red Hat user guide].

	This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.		This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.

Gabriel at 17:40, 27 October 2023

2023-10-27T17:40:40Z

← Older revision		Revision as of 17:40, 27 October 2023
Line 3:		Line 3:
	[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.		[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

	One example of such tutorials is part of the [https://access.redhat.com/documentation/en-us/red_hat_developer_toolset/9/html/user_guide/chap-gdb RedHat user ~~guides~~].		One example of such tutorials is part of the [https://access.redhat.com/documentation/en-us/red_hat_developer_toolset/9/html/user_guide/chap-gdb RedHat user guide].

	This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.		This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.

Gabriel: Add link to RedHat GDB guide

2023-10-27T17:39:45Z

Add link to RedHat GDB guide

← Older revision		Revision as of 17:39, 27 October 2023
Line 2:		Line 2:

	[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.		[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

			One example of such tutorials is part of the [https://access.redhat.com/documentation/en-us/red_hat_developer_toolset/9/html/user_guide/chap-gdb RedHat user guides].

	This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.		This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.

Tomh: /* running gdb with ns3 script */

2023-10-19T12:54:47Z

running gdb with ns3 script

@@ Line 50: / Line 50: @@
    ...
    Program received signal SIGSEGV, Segmentation fault.
-x0000000000413ac9 in ns3::PeekPointer<ns3::Node> (p=...) at ./ns3/ptr.h:282
+   ns3::NodeContainer::Get (this=this@entry=0x7fffffffd980, i=4294967295)
-	  return p.m_ptr;
+     at ../src/network/helper/node-container.cc:95
-   (gdb)
+	  return m_nodes[i];
-To debug an individual test suite, use the ''test-runner'' program:
+The program execution is now stopped at the point of the segmentation fault.  For a segmentation fault, this often means that the program is trying to access an object from a pointer, but the pointer is not valid.  You can check here on the value of 'i' and 'm_nodes[i]' by using the gdb print (abbreviated as 'p'):
    ./ns3 run --gdb test-runner

Tomh: update from Waf to ns3 script

2022-07-16T16:51:53Z

update from Waf to ns3 script

← Older revision		Revision as of 16:51, 16 July 2022
Line 1:		Line 1:
	{{TOC}}		{{TOC}}

	[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 ~~and Waf~~ to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.		[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

	This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.		This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.
Line 9:		Line 9:
	== running gdb directly ==		== running gdb directly ==

	gdb can be invoked on a program executable in the normal way (''gdb <program-name>''), and to do this with ns-3, it is easiest to use the ~~Waf~~ shell (to set the library paths correctly). We demonstrate with an example of the ''third'' tutorial example.		gdb can be invoked on a program executable in the normal way (''gdb <program-name>''), and to do this with ns-3, it is easiest to use the ns3 shell (to set the library paths correctly). We demonstrate with an example of the ''third'' tutorial example.

	./~~waf~~ shell		./ns3 shell
	cd build/examples/tutorial		cd build/examples/tutorial
	gdb ns3-dev-third-debug		gdb ns3-dev-third-debug
Line 31:		Line 31:
	To run a test-suite through gdb, use the ''test-runner'' program, such as:		To run a test-suite through gdb, use the ''test-runner'' program, such as:

	./~~waf~~ shell		./ns3 shell
	cd build/utils/		cd build/utils/
	gdb ns3-dev-test-runner-debug		gdb ns3-dev-test-runner-debug
Line 37:		Line 37:
	(gdb) quit		(gdb) quit

	== running gdb with ~~Waf~~ ==		== running gdb with ns3 script ==

	~~Waf~~ supports a ''--~~command-template~~'' argument that allows users to launch gdb and run the programs from there.		ns3 supports a ''--gdb'' argument that allows users to launch gdb and run the programs from there.

	./~~waf~~ --~~command-template="~~gdb ~~%s" --run~~ <program-name>		./ns3 run --gdb <program-name>

	An example using the ''third'' tutorial example, running it first to ask that the help message be printed out, and then running it with an illegal argument:		An example using the ''third'' tutorial example, running it first to ask that the help message be printed out, and then running it with an illegal argument:

	./~~waf~~ --~~command-template="~~gdb ~~%s" --run~~ third		./ns3 run --gdb third
	(gdb) r --help		(gdb) r --help
	(gdb) run --nWifi=0		(gdb) run --nWifi=0
Line 56:		Line 56:
	To debug an individual test suite, use the ''test-runner'' program:		To debug an individual test suite, use the ''test-runner'' program:

	./~~waf~~ --~~command-template="~~gdb ~~%s" --run~~ test-runner		./ns3 run --gdb test-runner
	(gdb) run --suite=csma-system		(gdb) run --suite=csma-system

	== running gdb with ~~Waf~~, redirecting all output to a file ==		== running gdb with ns3, redirecting all output to a file ==

	Sometimes a program will generate a lot of output to stdout and stderr, which may get in the way of interactively using the gdb prompt. It is possible to redirect program output to a file, while interacting with the gdb prompt. Here is a trivial example.		Sometimes a program will generate a lot of output to stdout and stderr, which may get in the way of interactively using the gdb prompt. It is possible to redirect program output to a file, while interacting with the gdb prompt. Here is a trivial example.

	./~~waf~~ --~~command-template="~~gdb ~~%s" --run~~ third		./ns3 run --gdb third
	(gdb) run --help > output.txt 2>&1		(gdb) run --help > output.txt 2>&1

	An example of how to run an individual test suite this way, launching gdb from the command line:		An example of how to run an individual test suite this way, launching gdb from the command line:

	./~~waf --~~run test-runner --command-template="gdb -ex 'run --suite=csma-system > csma-output.txt 2>&1' --args %s"		./ns3 run test-runner --command-template="gdb -ex 'run --suite=csma-system > csma-output.txt 2>&1' --args %s"

	== saving breakpoints across sessions ==		== saving breakpoints across sessions ==

Tomh: /* saving breakpoints across sessions */

2015-02-10T15:18:33Z

saving breakpoints across sessions

← Older revision		Revision as of 15:18, 10 February 2015
Line 83:		Line 83:
	to save them to a file called 'breaks':		to save them to a file called 'breaks':

	(gdb) save breakpoints ~~break~~		(gdb) save breakpoints breaks

	Later, one can retrieve them as follows.		Later, one can retrieve them as follows.

Tomh: gdb saving breakpoints

2015-02-10T15:18:19Z

gdb saving breakpoints

← Older revision		Revision as of 15:18, 10 February 2015
Line 69:		Line 69:

	./waf --run test-runner --command-template="gdb -ex 'run --suite=csma-system > csma-output.txt 2>&1' --args %s"		./waf --run test-runner --command-template="gdb -ex 'run --suite=csma-system > csma-output.txt 2>&1' --args %s"

			== saving breakpoints across sessions ==

			As of gdb 7.2, breakpoints can be saved to a file and reloaded for a separate session.

			For example:

			(gdb) info break
			Num Type Disp Enb Address What
			1 breakpoint keep y <PENDING> random-variable-stream.cc:175
			2 breakpoint keep y <PENDING> random-variable-stream.cc:186

			to save them to a file called 'breaks':

			(gdb) save breakpoints break

			Later, one can retrieve them as follows.

			(gdb) source breaks

			In ns-3 with shared libraries, one may get this error:

			(gdb) source breaks
			No source file named random-variable-stream.cc.
			Make breakpoint pending on future shared library load? (y or [n]) [answered N; input not from terminal]
			No source file named random-variable-stream.cc.
			Make breakpoint pending on future shared library load? (y or [n]) [answered N; input not from terminal]

			to work around this, use the command 'set breakpoints pending on' before sourcing the file:

			(gdb) set breakpoint pending on
			(gdb) source breaks
			No source file named random-variable-stream.cc.
			Breakpoint 1 (random-variable-stream.cc:175) pending.
			No source file named random-variable-stream.cc.
			Breakpoint 2 (random-variable-stream.cc:186) pending.
			(gdb) info break
			Num Type Disp Enb Address What
			1 breakpoint keep y <PENDING> random-variable-stream.cc:175
			2 breakpoint keep y <PENDING> random-variable-stream.cc:186

Tomh: typo

2014-11-27T16:11:51Z

typo

← Older revision		Revision as of 16:11, 27 November 2014
Line 3:		Line 3:
	[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 and Waf to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.		[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 and Waf to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

	This HOWTO is related to [[[[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.		This HOWTO is related to [[HOWTO understand and find cause of terminated with signal errors \| another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.

	This HOWTO is also related to [[HOWTO use Valgrind to debug memory problems \| another HOWTO]] that describes how to invoke the [http://www.valgrind.org valgrind tool] to find memory leaks.		This HOWTO is also related to [[HOWTO use Valgrind to debug memory problems \| another HOWTO]] that describes how to invoke the [http://www.valgrind.org valgrind tool] to find memory leaks.

Tomh: more gdb examples

2014-11-27T16:11:35Z

more gdb examples

@@ Line 3: / Line 3: @@
 [http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 and Waf to debug program errors.  There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.
-This HOWTO is related to another HOWTO that describes how to invoke the [[HOWTO_use_Valgrind_to_debug_memory_problems | valgrind]] tool to find memory leaks.
+This HOWTO is related to [[[[HOWTO understand and find cause of terminated with signal errors | another HOWTO]] that explains how to use the [https://www.sourceware.org/insight/ insight tool] (a graphical front-end for gdb) to debug segmentation faults.
 == running gdb directly ==
 == running gdb with Waf ==

Tomh: gdb HOWTO

2014-11-27T15:51:38Z

gdb HOWTO

New page

{{TOC}}

[http://www.gnu.org/software/gdb/ The GNU Debugger (gdb)] can be used with ns-3 and Waf to debug program errors. There are several tutorials online (search for 'gdb tutorial' in a search engine) that explain how to use gdb in general.

This HOWTO is related to another HOWTO that describes how to invoke the [[HOWTO_use_Valgrind_to_debug_memory_problems | valgrind]] tool to find memory leaks.

== running gdb directly ==

== running gdb with Waf ==

Waf supports a ''--command-template'' argument that allows users to launch gdb and run the programs from there.

./waf --command-template="gdb %s" --run <program-name>

An example using the ''third'' tutorial example, running it first to ask that the help message be printed out, and then running it with an illegal argument:

./waf --command-template="gdb %s" --run third
(gdb) r --help
(gdb) run --nWifi=0
...
Program received signal SIGSEGV, Segmentation fault.
0x0000000000413ac9 in ns3::PeekPointer<ns3::Node> (p=...) at ./ns3/ptr.h:282
282 return p.m_ptr;
(gdb)

To debug an individual test suite, use the ''test-runner'' program:

./waf --command-template="gdb %s" --run test-runner
(gdb) run --suite=csma-system

== running gdb with Waf, redirecting all output to a file ==

Sometimes a program will generate a lot of output to stdout and stderr, which may get in the way of interactively using the gdb prompt. It is possible to redirect program output to a file, while interacting with the gdb prompt. Here is a trivial example.

./waf --command-template="gdb %s" --run third
(gdb) run --help > output.txt 2>&1

An example of how to run an individual test suite this way, launching gdb from the command line:

./waf --run test-runner --command-template="gdb -ex 'run --suite=csma-system > csma-output.txt 2>&1' --args %s"