4.6  Déverminage 1/4

• Outil gdb : GNU Debugger.
• Une interface graphique à gdb : ddd.
• Prendre soin de compiler avec gcc -g.
• Exemple de session gdb :

  $ gcc -Wall -g segfault.c -o segfault
  $ gdb ./segfault
  GNU gdb 6.8-debian
  ...
  (gdb) run
  Starting program: ./segfault 
  
  Program received signal SIGSEGV, Segmentation fault.
  0xb77ee9b7 in memcpy () from /lib/libc.so.6
  (gdb) backtrace
  #0  0xb77ee9b7 in memcpy () from /lib/libc.so.6
  #1  0x08048400 in main () at segfault.c:6
  (gdb) list
  1 #include <stdio.h>
  2 #include <string.h>
  3 
  4 int main(void){
  5 char *chaine;
  6 strcpy(chaine,"Bouuuuuuuum !!!!!!!");
  7 printf("%s\n",chaine);
  8 return 0;
  9 }
  (gdb) break 6
  Breakpoint 1 at 0x80483e5: file segfault.c, line 6.
  (gdb) run
  The program being debugged has been started already.
  Start it from the beginning? (y or n) y
  Starting program: ./segfault 
  
  Breakpoint 1, main () at segfault.c:6
  6 strcpy(chaine,"Bouuuuuuuum !!!!!!!");
  
  (gdb) (gdb) print/x chaine
  $4 = 0xb7717775
  (gdb) quit
  The program is running.  Exit anyway? (y or n) y