When running my program, I am getting Gtk-CRITICAL error on the Terminal, which I'd like to fix.
I found this link through Google, but turns out there is no such option in gdb:
igor#IgorReinCloud ~/dbhandler/Debug/dbhandler $ gdb --g-fatal-warnings dbhandler
gdb: unrecognized option '--g-fatal-warnings'
Use `gdb --help' for a complete list of options.
I also tried to set a breakpoint on the g_log() function, but the execution didn't stop there.
What am I missing?
Thank you.
you can use G_DEBUG=fatal-criticals, so that the application execution breaks at the first location where a critical is emitted.
To run inside gdb, run G_DEBUG=fatal-criticals gdb my-app, and as usual, do run inside gdb to run your application.
You may also set the G_DEBUG environment variable with export (if in bash). Thus you could do export G_DEBUG=fatal-criticals, and then run your app as gdb my-app, which will have the same effect.
See https://docs.gtk.org/glib/running.html for more details
What am I missing?
Looks like that after reading the link, you were confused that gdb should have --g-fatal-warnings option for debugging Gtk applications. This is not the case because gdb is not Gtk application, but your program is. So you should run your program with --g-fatal-warnings option inside gdb like this:
gdb --args dbhandler --g-fatal-warnings
See also related question How do I run a program with commandline args using gdb within a bash script?.
Related
I'm receiving this gdb error on any code I try to debug any program with gdb. Here's the simplest process that reproduces the error
Create a main.cpp file with this content:
int main(){
return 0;
}
Run g++ -g main.cpp
Run gdb a.out
Inside gdb set a break point at line 2 with break 2
In gdb run the program with run
Output:
Starting program: /tmp/test/a.out
During startup program exited normally.
This is all done with gdb on the command line. I've tried using g++ and gcc with the same result. I'm not really sure where to go from here.
gdb version = 9.2
g++ version = 9.3.0
EDIT: I figured out what is causing the issue, but not how to fix it. The issue seems to be something related to my SHELL variable. I'm currently using xonsh as my shell but when I set my SHELL environment variable back to /bin/bash everything works as expected. Is there anything I can do to fix this while using xonsh? Should I report this to xonsh, gdb, both or neither?
I'm currently using xonsh as my shell but when I set my SHELL environment variable back to /bin/bash everything works as expected. Is there anything I can do to fix this while using xonsh? Should I report this to xonsh, gdb, both or neither?
This might be your xonsh startup problem, or it might be xonsh problem, or it could be that xonsh doesn't do what GDB expects it to do.
Normally, GDB forks / execs $SHELL -c "/path/to/your/exe $args" and expects the $SHELL to exec your program (this is done so shell redirection still works under GDB).
Only after that exec will GDB start setting breakpoints, etc.
If you have some xonsh init-file, which e.g. causes xonsh to exec something else, things could go bad. So I suggest trying to remove any such ~/.xonshrc or whatever it's called file, and seeing whether that fixes the problem.
If it doesn't, it could be that xonsh e.g. forks and execs your binary in a child (grandchild of GDB) instead of doing it directly, or it could be that xonsh doesn't understand the -c ... syntax.
If you don't care about redirection, you could also ask GDB to not use $SHELL at all: set startup-with-shell off. Documentation.
How do I give commands to run before starting gdb debugging in Eclipse ?
Actually I want to execute few scripts that set environment variables (export vars) and execute a bunch of other programs before gdb process is launched from eclipse to debug my program.
I tried doing the following in debugger tab option:
<command> && <path-to-gdb-executable>
But I got the error that eclipse cannot execute gdb as given in above statement.
Please help - I actually want to execute a script called "before-launch-commands.sh" before debugging is started by gdb. I am trying to execute a cpp program under eclipse kepler.
Thanks.
The Eclipse Debug Configurations can already setup environment variables for you. I'm going to assume that that isn't sufficient, or you'd have already done it.
The first thing to do is create a new script, wrapped-gdb.sh:
#!/bin/sh
# Export any variables we need.
# Note that '.' (dot) is like an "include" statement.
. /path/to/before-launch-commands.sh
# Run GDB using the parameters passed in
exec /path/to/gdb "$#"
Next, set that script executable:
chmod +x /path/to/wrapped-gdb.sh
Finally, go to the Debugger tab in the debug configuration dialog, and in the box marked "GDB Debugger" enter /path/to/wrapped-gdb.sh.
When you launch your debug session it should now Do The Right Thing.
I am a beginner and got some trouble in RE.
I have an ELF 'bomb' and an unknown file 'model.abc'.
The correct way to run bomb is:
bomb model.abc
Now I want to use gdb to see the value of some addresses when running it. Can any one help me?
First start gdb from a shell prompt:
$ gdb bomb
Then run your program from the (gdb) prompt with the command line you want:
(gdb) run model.abc
You need to launch your program this way because gdb doesn't allow you to specify command line arguments for your program on the gdb command line.
Another, more convenient way of debugging a program with arguments:
gdb --args program <arguments>
If you don't have symbols, you'll have to start from the entry point. To figure our where it is, use:
(gdb) info file
Symbols from "/.../tesprog".
Local exec file:
`/.../tesprog', file type elf32-i386.
Entry point: 0x804abc0
Then you can set breakpoint on it before running:
break *0x804abc0
Note that the entry will be most often the library startup code (ctr0.s), it might take a while to get to the actual code written by the programmer.
I'm trying to debug a server I wrote with gdb as it segfaults under very specific and rare conditions.
Is there any way I can make gdb run in the background (via quiet or batch mode?), follow children (as my server is a daemon and detaches from the main PID) and automatically dump the core and the backtrace (to a designated file) once the program crashes?
Assuming you have appropriate permissions, you can have gdb attach to any process. You can do it on the command line with:
gdb /path/to/binary _pid_
or from within gdb with the attach command:
attach _pid_
So, once your daemon has started, you can use either of these techniques to attach to the final PID your daemon is running as. Attaching gdb stops the process which you are tracing so you will need to issue a "continue" to restart it.
I don't know a direct way to get gdb to run arbitrary commands when the program crashes. Here is one workaround I can think of:
Create and register a signal handlers for SIGSEGV.
Tell gdb not to stop on that signal (handle SIGSEGV nostop)
Set a breakpoint at the first line of your signal handler.
Assign commands to the breakpoint from step 3
Why not just run the process interactively in a persistent screen session? Why must it be a daemon when debugging? Or just run gdb in the screen session and attach it to the running process (e.g. gdb /path/to/binary -p PID_of_binary) after it forks.
First, I'd setup your shell / environment to give you a core dump. In bash:
ulimit -c unlimited
Once you have the core dump, you can use gdb to examine the stack trace:
gdb /path/to/app /path/to/core/file
I'm not really a gdb expert but two things come to mind
Tracepoints which might give you the necessary information as your program runs or
Use gdb's remote debugging facility to debug your program while it's running as a daemon.
How to generate a stacktrace when my gcc C++ app crashes answer for this question should do what you want. (assuming you can make changes in your code)
You might want to take a look at how Samba facilitates debugging; it has a configurable "panic action" that can suspend the application, notify the developer, spawn gdb, etc., and is run as part of its signal handler. See lib/util/fault.c in the Samba source tree.
My practice: comment out daemon function call, rebuild binary, then use gdb to run.
I'd like to have gdb immediately run the executable, as if I'd typed "run"
(motivation: I dislike typing "run").
One way is to pipe the command to gdb like this:
$ echo run | gdb myApp
But the problem with this approach is that you lose interactivity with gdb,
eg. if a breakpoint triggers or myApp crashes, gdb quits.
This method is discussed here.
Looking at the options in --help, I don't see a way to do this, but perhaps I'm missing something.
gdb -ex run ./a.out
If you need to pass arguments to a.out:
gdb -ex run --args ./a.out arg1 arg2 ...
EDIT:
Orion says this doesn't work on Mac OSX.
The -ex flag has been available since GDB-6.4 (released in 2005), but OSX uses Apple's fork of GDB, and the latest XCode for Leopard contains GDB 6.3.50-20050815 (Apple version gdb-967), so you are out of luck.
Building current GDB-7.0.1 release is one possible solution. Just be sure to read this.
I would use a gdb-script:
gdb -x your-script
where your-script contains something like:
file a.out
b main
r
afterwards you have the normal interactive gdb prompt
EDIT:
here is an optimization for the truly lazy:
save the script as .gdbinit in the working directory.
Afterwards you simply run gdb as
gdb
... and gdb automatically loads and executes the content of .gdbinit.
(echo r ; cat) | gdb a.out
The cat allows you keep typing after gdb breaks.
start command
This command is another good option:
gdb -ex start --args ./a.out arg1 arg2
It is like run, but also sets a temporary breakpoint at main and stops there.
This temporary breakpoint is deactivated once it is hit.
starti
There is also a related starti which starts the program and stops at the very first instruction instead, see also: Stopping at the first machine code instruction in GDB
Great when you are doing some low level stuff.
gdb -x <(echo run) --args $program $args