Question

I’ve disassemble in GDB and in inside of the sscanf function I get:

    at vfscanf.c:603
_IO_vsscanf (string=string@entry=0x804b760 "1 \\233 200", 
    format=format@entry=0x804a21e "%d %c %d", 
    args=args@entry=0xbffff0a8 "\304\360\377\277\277\360\377\277\300\360\377\277\224\361\377\277\310\360\377\277\201\222\004\\\351") at iovsscanf.c:47

I’m trying to get the information in args but I’m not sure how to translate that string to something readable. What I’m really trying to get is the addresses that sscanf is saving to. I assume these addresses are represented in this string. This is what I got when looking up the charset:

(gdb) show charset
The host character set is "auto; currently ANSI_X3.4-1968".
The target character set is "auto; currently ANSI_X3.4-1968".
The target wide character set is "auto; currently UTF-32".

I’m using Linux, IA-32.

Answer 1

echo $'\304\360\377\277\277\360\377\277\300\360\377\277\224\361\377\277\310\360\377\277\201\222\004\\\351'|od -t x4  

0000000 bffff0c4 bffff0bf bffff0c0 bffff194
0000020 bffff0c8 5c049281 00000ae9
0000032

Then you can inspect the contents by:

print *(int*)(0xbffff0c4)

or with gdb’s internal printf command

printf "%s\n", 0xbffff0bf

or even by calling printf in your program under debug (if linked)

call printf("%8.3f\n",*(float*)(0xbffff194))

Likewise, using directly the string (I’ll use argv[0]):

print argv[0]
"/home/asu..."
// assuming "/hom" was a proper address...
print **(int**)(argv[0]+0)
// assuming "e/as" was a proper address...
print **(int**)(argv[0]+4)