From: Darren Eisenzimmer <deisenzimmer AT operamail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Allegro GUI routines produces a General Protection Fault
Date: Wed, 03 May 2000 01:34:54 -0500
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

If there's a more appropriate place to ask allegro questions please let
me know.  I'm having
trouble with the GUI routines.  Following is the source I'm having
problems with.  Specifically,
the get_csv_files() function of mine seems to cause the problem.
However, it alone is not the
problem.  Somehow it's not compatible with allegro.  I compile with the
-Wall -O3 -g switches.
The code that I'm posting produces a General Protection Fault on my
computer.  However,
commenting out the get_csv_files() call and it works OK.  Any help would
be appreciated.
Darren

-------------  my_gui.c ------------------

#include "allegro.h"
#include <dirent.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* linked list of strings */
struct CSV_LIST {
  char *file_name;
  struct CSV_LIST *next;
} CSV_LIST;

/* recursively destroys linked list */
void destroy_list(struct CSV_LIST *csv_list )
{
  if( csv_list == NULL ) return;
  else if( csv_list->next )
    destroy_list( csv_list->next );
  else {
    free( csv_list->file_name );
    free( csv_list );
  }
}

int num_csv_files;
struct CSV_LIST *csv_list;

/* Get all .csv files in the current directory and put them in the
 * linked list structure.  Ultimately, these will be displayed to
 * the user through the GUI dialog procedure list
 */
void get_csv_files()
{
  DIR *current_dir = opendir(".");
  struct dirent *dir_entry;
  char filename[10];
  char *token = NULL;
  struct CSV_LIST *list_trav = NULL;

  while( (dir_entry = readdir(current_dir)) ) {
    strcpy(filename, dir_entry->d_name);
    token = strtok(filename,".");
    token = strtok(NULL,".");
    if( token ) {
      if( strcmp(token, "csv") == 0 || strcmp(token, "CSV") == 0 ) {
        if( csv_list == NULL ) {
          csv_list = malloc( sizeof(void *) );
          list_trav = csv_list;
        }
        else {
          list_trav->next = malloc( sizeof(void *) );
          list_trav = list_trav->next;
        }
        list_trav->file_name = malloc( sizeof(dir_entry->d_name) );
        strcpy( list_trav->file_name, dir_entry->d_name);
        list_trav->next = NULL;
        num_csv_files++;
        }
      }
    }
  closedir(current_dir);
}


/* Dialog procedure to display all .csv files.  Currently the filenames
 * are hard coded, eventually they will be read from the csv_list
structure.
 */
char *csv_listbox(int index, int *list_size)
{
  char *csv_files[] = { "test1.csv", "test2.csv", "test3.csv" };

  if (index < 0) {
    *list_size = 3;
    return NULL;
  }
  else {
    return csv_files[index];
  }
}


int main( int argc, char *argv[] )
{
  struct CSV_LIST *list_trav;
  DIALOG my_dialog[] =
  {
    /* PROCEDURE          x     y     w     h    fg   bg    key
flags      d1       d2     dp                dp2              dp3 */
    { d_list_proc,       200,  100,  200,  200,  255,  0,    0,
0,          0,       0,    csv_listbox,      NULL,            NULL  },
    { d_button_proc,     250,  350,  100,   50,  255,  0,    0,
D_EXIT,     0,       0,    "Exit",           NULL,            NULL  },
    { NULL,                0,    0,    0,    0,    0,  0,    0,
0,          0,       0,    NULL,             NULL,            NULL  }
  };

  /* Initialize global variables */
  num_csv_files = 0;
  csv_list = NULL;

  get_csv_files();
  printf("num_csv_files = %d\n", num_csv_files);
  for( list_trav = csv_list ; list_trav ; list_trav = list_trav->next )
    puts( list_trav->file_name );
  getchar();
  allegro_init();
  install_keyboard();
  install_mouse();
  install_timer();
  set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0);
  set_pallete(desktop_pallete);

  do_dialog(my_dialog, -1);

  allegro_exit();
  destroy_list( csv_list );

  return 1;
}