gtk+ seg fault

[swappo1]

Hello,

I am getting a segmentation fault from the open_file function and I can't figure out what the problem is. I put a printf statement in and determined that the seg fault is just above it. Any ideas?


#include "menu.h"
#include <stdio.h>

#define NUM_ENTRIES 11
#define RAD_ENTRIES 3



static GtkActionEntry entries[] =
{
{"File", NULL, "_File", NULL, NULL, NULL},
{"New", GTK_STOCK_NEW, NULL, NULL,
"Create a new file", NULL},
{"Open", GTK_STOCK_OPEN, NULL, NULL,
"Open an existing file", G_CALLBACK(open_file)},
{"Save", GTK_STOCK_SAVE, NULL, NULL,
"Save the current file", NULL},
{"Edit", NULL, "_Edit", NULL, NULL, NULL},
{"Undo", GTK_STOCK_UNDO, NULL, NULL,
"Undo the last change", NULL},
{"Cut", GTK_STOCK_CUT, NULL, NULL,
"Cut the selection to the clipboard", NULL},
{"Copy", GTK_STOCK_COPY, NULL, NULL,
"Copy the selection to the clipboard", NULL},
{"Paste", GTK_STOCK_PASTE, NULL, NULL,
"Paste from the clipboard", NULL},
{"View", NULL, "_View", NULL, NULL, NULL},
{"Highlight Mode", NULL, "_Highlight Mode", NULL, NULL, NULL}
};

/*for radio submenu on highlight mode drop down menu*/
static GtkRadioActionEntry radio_entries[] =
{
{"Plain Text", NULL, "Plain Text", NULL, NULL, 1},
{"C Text", NULL, "C", NULL, NULL, 2},
{"C++ Text", NULL, "C++", NULL, NULL, 3},
};

/*this will create the menu and tool bar*/
void create_menu_bar(MainWin *mw)
{
GtkActionGroup *group;
GtkUIManager *ui_manager;

group = gtk_action_group_new("MainActionGroup");
gtk_action_group_add_actions(group, entries, NUM_ENTRIES, NULL);
/*add a radio submenu onto Highlight Mode*/
gtk_action_group_add_radio_actions(group, radio_entries,
RAD_ENTRIES, 1, NULL, NULL);

ui_manager = gtk_ui_manager_new();
gtk_ui_manager_insert_action_group(ui_manager, group, 0);

/*add the menu from the xml file to the ui*/
gtk_ui_manager_add_ui_from_file(ui_manager, "menu.ui", NULL);
/*return the widget found by path /MenuBar*/
mw->menu_bar = gtk_ui_manager_get_widget(ui_manager, "/MenuBar");

gtk_ui_manager_add_ui_from_file(ui_manager, "toolbar.ui", NULL);
/* return the widget found by the path /ToolBar*/
mw->tool_bar = gtk_ui_manager_get_widget(ui_manager, "/ToolBar");

gtk_window_add_accel_group(GTK_WINDOW(mw->window),
gtk_ui_manager_get_accel_group(ui_manager));
}

GtkWidget *create_find()
{
GtkWidget *entry, *hbox, *button;

entry = gtk_entry_new();
button = gtk_button_new_from_stock(GTK_STOCK_FIND);
hbox = gtk_hbox_new(FALSE, 0);
gtk_box_pack_start(GTK_BOX(hbox), button, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(hbox), entry, FALSE, FALSE, 0);

return hbox;
}

static void open_file(GtkButton *open, MainWin *mw)
{
GtkWidget *dialog;
gchar *filename, *content;
gint result;

dialog = gtk_file_chooser_dialog_new("Open File", NULL,
GTK_FILE_CHOOSER_ACTION_OPEN, GTK_STOCK_OK,
GTK_RESPONSE_ACCEPT, GTK_STOCK_CANCEL,
GTK_RESPONSE_CANCEL, NULL);

result = gtk_dialog_run(GTK_DIALOG(dialog));

if(result == GTK_RESPONSE_ACCEPT)
{

filename = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dia log));

if(g_file_get_contents(filename, &content, NULL, NULL))
{

mw->buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(mw->text_view));
printf("ok\n");
gtk_text_buffer_set_text(mw->buffer, content, -1);

g_free(filename);
g_free(content);
}
}

gtk_widget_destroy(dialog);
}

[dwhitney67]

Compile your source code file(s) with the -g option.

Then run your app in the debugger.

[swappo1]

Compile your source code file(s) with the -g option.

Then run your app in the debugger.
Can you explain this in more detail? Where should I put -g option? I'm assuming this goes in my Makefile. Sorry for my ignorance, but I've never used the debugger and am not at all familiar with it.

[Zugzwang]

Can you explain this in more detail? Where should I put -g option? I'm assuming this goes in my Makefile. Sorry for my ignorance, but I've never used the debugger and am not at all familiar with it.

Here's a small introduction: http://www.ibm.com/developerworks/library/l-gdb/

There are also alternatives to the command-line debugger "gdb" (i.e., graphical front-ends), but for the time being, that article should tell you a little bit about the basics.

[dwhitney67]

And if you are into GUIs, you may want to consider installing/using "ddd", which is a front-end to "gdb".

Once you have compiled your code with the -g option, you can launch gdb or ddd in a similar fashion.


gdb myprogram

# or

ddd myprogram &

[swappo1]

Here's a small introduction: http://www.ibm.com/developerworks/library/l-gdb/
I am having a problem running the example program in gdb. Here is my output.


hopchewer@hopchewer:~/Programming/C_programs$ gcc -g gdb_ex.c -o gdb_ex
hopchewer@hopchewer:~/Programming/C_programs$ gdb gdb_ex
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
---Type <return> to continue, or q <return> to quit---
This GDB was configured as "x86_64-linux-gnu"...
(gdb) print no1
No symbol "no1" in current context.
(gdb)


It seems that the program is not being run in gdb when I type gdb gdb_ex. According to the example, when I type gdb filename I should get the following.

Program received signal SIGFPE, Arithmetic exception.
0x80483ea in wib (no1=8, no2=8) at eg1.c:7
7 result = no1 / diff;
(gdb)

Is there anything I need to do to gdb in addition to installing it to set it up?

[dwhitney67]

I believe your issue occurred because you have yet to run the program. Simply running gdb is not sufficient. Do the following after launching gdb...

Set a breakpoint, at main()


b main

Then run the program:


r

Then single-step until you find the line of interest:


n

If you need to traverse into a function:


s

All this would be much easier if you were to use "ddd", which is a GUI front-end to "gdb".

[MadCow108]

you still need to run it in gdb
type run into the gdb prompt
it also takes arguments like the command line

a very useful command is: backtrace
it will show you a call stack where you can exactly see where the segfault occurs without having to set breakpoints