Using SCODB

User input

Enter a <Space> to execute the displayed instruction, or a quit character to return to the debugger; an r can be given to cause SCODB to finish executing the current function, stopping after a return:

   debug0:1> s
   read+3                inc    sysinfo+5C <Space>
   read+9                pushb  1 r
   systrap+207           cmpl   &aud_cont+1,0 q

If the next instruction is a call, the user is prompted for input:

   debug0:2> s
   read+B                call   rdwr [ejr]? q

The call can be ``jumped over'' by inputting a j:

   debug0:3> s
   read+B                call   rdwr [ejr]? j
   read+10               leave <Space>
   read+11               ret q

The function called can be entered by inputting a e:

   debug0:4> s
   read+B                call   rdwr [ejr]? e
   rdwr                  pushl  %ebp <Space>
   rdwr+1                movl   %ebp,%esp <Space>
   rdwr+3                subl   %esp,1C <Space>
   rdwr+6                pushl  %ebx r
   read+10               leave q

Other instructions are executed by inputting a <Space>. The e and j keys are aliases to <Space> and also cause the displayed instruction to be executed. When held down and used in a repeat fashion, these keys allow continuous single-stepping without interruptions for call instructions.

The C key causes instructions to be single-stepped until the next control transfer instruction is encountered (that is, up until the next jmp/call/ret instruction).

No breakpoints are in effect while single-stepping.