Curses keyname() giving me segmentation fault when i send it an int counter variable greater than 256

Question

The following code gives me a segmentation fault when I change the keys variable to > 256. The issue seems to be with the strcpy(str[i], keyname(i)); statement. I can get output if I swap out the i with a value like 300 but if I use the counter it gives me the fault.

#include <curses.h>
#include <string.h>

int main(){

  initscr();
  noecho();
  nonl();
  keypad(stdscr, TRUE);
  int length = 300;
  int keys = 255;
  char buf[length];
  int i=0;
  char str[keys+1][length];

  strcpy(str[0], "keyname()\thas_key()\tinteger\n");

    for(i=1;i<keys;i++){

            strcpy(str[i], keyname(i));

            if(has_key(i))
              strcat(str[i], "\t\tTRUE");
            else
              strcat(str[i], "\t\tFALSE");

            sprintf(buf, "\t\t%i", i);
            strcat(str[i], buf);
            strcat(str[i], "\n");
    }
    endwin();
    echo();

    for(i=0;i<keys-1;i++){
            printf("%s", str[i]);
    }
    return 0;
}

Answer 1

The curses keyname function returns a null pointer if there is no name for that key. (Which happens when you pass 256 and so on).

Trying to strcpy out of a null pointer causes your segmentation fault.

To fix this you will need to take different action when keyname returns a null pointer, e.g.

char const *name = keyname(i);
if ( name )
    strcpy( str[i], name );
else
    strcpy( str[i], "unknown key" );