Script started on Thu Sep 11 10:22:09 2003
linux2% nasm -f elf toupper.asm
linux2% ld toupper.o
linux2% a.out
Enter string: aBcdEF
Original: aBcdEF
Convert:  ABCDEF
linux2% 
linux2% a.out
Enter string: 
Read error
linux2% more ~/.gdbinit
set disassembly-flavor intel
linux2% 
linux2% gdb a.out
GNU gdb Red Hat Linux (5.2-2)
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux"...
(no debugging symbols found)...
(gdb) 
(gdb) run
Starting program: /afs/umbc.edu/users/c/h/chang/home/asm/a.out 
Enter string: abcDEF
Original: abcDEF
Convert:  ABCDEF

Program exited normally.
(gdb) break *start
Breakpoint 1 at 0x8048081
(gdb) run
Starting program: /afs/umbc.edu/users/c/h/chang/home/asm/a.out 

Breakpoint 1, 0x08048081 in start ()
(gdb) disas
Dump of assembler code for function start:
0x8048081 <start>:      mov    eax,0x4
0x8048086 <start+5>:    mov    ebx,0x1
0x804808b <start+10>:   mov    ecx,0x804915c
0x8048090 <start+15>:   mov    edx,0xe
0x8048095 <start+20>:   int    0x80
0x8048097 <start+22>:   mov    eax,0x3
0x804809c <start+27>:   mov    ebx,0x0
0x80480a1 <start+32>:   mov    ecx,0x804918c
0x80480a6 <start+37>:   mov    edx,0x100
0x80480ab <start+42>:   int    0x80
0x80480ad <start+44>:   mov    ds:0x804938c,eax
0x80480b2 <start+49>:   cmp    eax,0x0
0x80480b5 <start+52>:   jg     0x80480d2 <read_OK>
0x80480b7 <start+54>:   mov    eax,0x4
0x80480bc <start+59>:   mov    ebx,0x1
0x80480c1 <start+64>:   mov    ecx,0x804917e
0x80480c6 <start+69>:   mov    edx,0xc
0x80480cb <start+74>:   int    0x80
0x80480cd <start+76>:   jmp    0x804814f <exit>
End of assembler dump.
(gdb) stepi
0x08048086 in start ()
(gdb) info registers
eax            0x4      4
ecx            0x0      0
edx            0x0      0
ebx            0x0      0
esp            0xbffffb50       0xbffffb50
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x8048086        0x8048086
eflags         0x346    838
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
fctrl          0x37f    895
fstat          0x0      0
ftag           0xffff   65535
fiseg          0x0      0
fioff          0x0      0
foseg          0x0      0
fooff          0x0      0
fop            0x0      0
xmm0           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm1           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm2           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm3           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm4           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm5           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm6           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
xmm7           {f = {0x0, 0x0, 0x0, 0x0}}       {f = {0, 0, 0, 0}}
mxcsr          0x1f80   8064
orig_eax       0xffffffff       -1
(gdb) print $eax
$1 = 4
(gdb) stepi
0x0804808b in start ()
(gdb) print $ebs
$2 = void
(gdb) print $ebx
$3 = 1
(gdb) display/i $eip
1: x/i $eip  0x804808b <start+10>:      mov    ecx,0x804915c
(gdb) print $ecx
$4 = 0
(gdb) stepi
0x08048090 in start ()
1: x/i $eip  0x8048090 <start+15>:      mov    edx,0xe
(gdb) print $ecx
$5 = 134517084
(gdb) print/x $ecx
$6 = 0x804915c
(gdb) x &msg1
0x804915c <msg1>:       0x65746e45
(gdb) x/c &msg1
0x804915c <msg1>:       69 'E'
(gdb) x/12c &msg1
0x804915c <msg1>:       69 'E'  110 'n' 116 't' 101 'e' 114 'r' 32 ' '  115 's' 116 't'
0x8049164 <msg1+8>:     114 'r' 105 'i' 110 'n' 103 'g'
(gdb) x/16c &msg1
0x804915c <msg1>:       69 'E'  110 'n' 116 't' 101 'e' 114 'r' 32 ' '  115 's' 116 't'
0x8049164 <msg1+8>:     114 'r' 105 'i' 110 'n' 103 'g' 58 ':'  32 ' '  79 'O'  114 'r'
(gdb) disas start read_OK
Dump of assembler code from 0x8048081 to 0x80480d2:
0x8048081 <start>:      mov    eax,0x4
0x8048086 <start+5>:    mov    ebx,0x1
0x804808b <start+10>:   mov    ecx,0x804915c
0x8048090 <start+15>:   mov    edx,0xe
0x8048095 <start+20>:   int    0x80
0x8048097 <start+22>:   mov    eax,0x3
0x804809c <start+27>:   mov    ebx,0x0
0x80480a1 <start+32>:   mov    ecx,0x804918c
0x80480a6 <start+37>:   mov    edx,0x100
0x80480ab <start+42>:   int    0x80
0x80480ad <start+44>:   mov    ds:0x804938c,eax
0x80480b2 <start+49>:   cmp    eax,0x0
0x80480b5 <start+52>:   jg     0x80480d2 <read_OK>
0x80480b7 <start+54>:   mov    eax,0x4
0x80480bc <start+59>:   mov    ebx,0x1
0x80480c1 <start+64>:   mov    ecx,0x804917e
0x80480c6 <start+69>:   mov    edx,0xc
0x80480cb <start+74>:   int    0x80
0x80480cd <start+76>:   jmp    0x804814f <exit>
End of assembler dump.
(gdb) break *start+44
Breakpoint 2 at 0x80480ad
(gdb) cont
Continuing.
Enter string: abC

Breakpoint 2, 0x080480ad in start ()
1: x/i $eip  0x80480ad <start+44>:      mov    ds:0x804938c,eax
(gdb) print $eax
$7 = 4
(gdb) x/4c &buf
0x804918c <buf>:        97 'a'  98 'b'  67 'C'  10 '\n'
(gdb) stepi
0x080480b2 in start ()
1: x/i $eip  0x80480b2 <start+49>:      cmp    eax,0x0
(gdb) x &rlen
0x804938c <rlen>:       4 '\004'
(gdb) x/x &rlen
0x804938c <rlen>:       0x04
(gdb) x/t &rlen
0x804938c <rlen>:       00000100
(gdb) x/d &rlen
0x804938c <rlen>:       4
(gdb) break *L1_init
Breakpoint 3 at 0x80480d2
(gdb) break *L1_top
Breakpoint 4 at 0x80480e2
(gdb) display $ecx
2: $ecx = 134517132
(gdb) display/x $esi
3: /x $esi = 0x0
(gdb) display/x $edi
4: /x $edi = 0x0
(gdb) display/c $eax
5: /c $eax = 4 '\004'
(gdb) cont
Continuing.

Breakpoint 3, 0x080480d2 in read_OK ()
5: /c $eax = 4 '\004'
4: /x $edi = 0x0
3: /x $esi = 0x0
2: $ecx = 134517132
1: x/i $eip  0x80480d2 <read_OK>:       mov    ecx,ds:0x804938c
(gdb) si
0x080480d8 in read_OK ()
5: /c $eax = 4 '\004'
4: /x $edi = 0x0
3: /x $esi = 0x0
2: $ecx = 4
1: x/i $eip  0x80480d8 <read_OK+6>:     mov    esi,0x804918c
(gdb) si
0x080480dd in read_OK ()
5: /c $eax = 4 '\004'
4: /x $edi = 0x0
3: /x $esi = 0x804918c
2: $ecx = 4
1: x/i $eip  0x80480dd <read_OK+11>:    mov    edi,0x804928c
(gdb) si

Breakpoint 4, 0x080480e2 in L1_top ()
5: /c $eax = 4 '\004'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918c
2: $ecx = 4
1: x/i $eip  0x80480e2 <L1_top>:        mov    al,BYTE PTR [esi]
(gdb) si
0x080480e4 in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918c
2: $ecx = 4
1: x/i $eip  0x80480e4 <L1_top+2>:      inc    esi
(gdb) si
0x080480e5 in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480e5 <L1_top+3>:      cmp    al,0x61
(gdb) si
0x080480e7 in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480e7 <L1_top+5>:      jb     0x80480ef <L1_cont>
(gdb) si
0x080480e9 in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480e9 <L1_top+7>:      cmp    al,0x7a
(gdb) si
0x080480eb in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480eb <L1_top+9>:      ja     0x80480ef <L1_cont>
(gdb) si
0x080480ed in L1_top ()
5: /c $eax = 97 'a'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480ed <L1_top+11>:     and    al,0xdf
(gdb) si
0x080480ef in L1_cont ()
5: /c $eax = 65 'A'
4: /x $edi = 0x804928c
3: /x $esi = 0x804918d
2: $ecx = 4
1: x/i $eip  0x80480ef <L1_cont>:       mov    BYTE PTR [edi],al
(gdb) cont
Continuing.

Breakpoint 4, 0x080480e2 in L1_top ()
5: /c $eax = 65 'A'
4: /x $edi = 0x804928d
3: /x $esi = 0x804918d
2: $ecx = 3
1: x/i $eip  0x80480e2 <L1_top>:        mov    al,BYTE PTR [esi]
(gdb) cont
Continuing.

Breakpoint 4, 0x080480e2 in L1_top ()
5: /c $eax = 66 'B'
4: /x $edi = 0x804928e
3: /x $esi = 0x804918e
2: $ecx = 2
1: x/i $eip  0x80480e2 <L1_top>:        mov    al,BYTE PTR [esi]
(gdb) undisplay 4
(gdb) undisplay 3
(gdb) si
0x080480e4 in L1_top ()
5: /c $eax = 67 'C'
2: $ecx = 2
1: x/i $eip  0x80480e4 <L1_top+2>:      inc    esi
(gdb) cont
Continuing.

Breakpoint 4, 0x080480e2 in L1_top ()
5: /c $eax = 67 'C'
2: $ecx = 1
1: x/i $eip  0x80480e2 <L1_top>:        mov    al,BYTE PTR [esi]
(gdb) cont
Continuing.
Original: abC
Convert:  ABC

Program exited normally.
(gdb) run
Starting program: /afs/umbc.edu/users/c/h/chang/home/asm/a.out 

Breakpoint 1, 0x08048081 in start ()
5: /c $eax = 0 '\0'
2: $ecx = 0
1: x/i $eip  0x8048081 <start>: mov    eax,0x4
(gdb) cont
Continuing.
Enter string: ABC^D
Breakpoint 2, 0x080480ad in start ()
5: /c $eax = 3 '\003'
2: $ecx = 134517132
1: x/i $eip  0x80480ad <start+44>:      mov    ds:0x804938c,eax
(gdb) x/5c &buf
0x804918c <buf>:        65 'A'  66 'B'  67 'C'  0 '\0'  0 '\0'
(gdb) quit
The program is running.  Exit anyway? (y or n) y
linux2% exit
exit

Script done on Thu Sep 11 10:45:57 2003