LLDB Automatic Stepping Through Program With Python Returning Steps/Lines That Don't Appear Manually - lldb

Question

Following LLDB - automatically step, and print list of lines, until a breakpoint, I was able to successfully write a csv file of the line numbers and file names of each step when stepping through my program. However, I find my output very strange. My CSV file contains lines that dun appear when I step through manually. For example:
431,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
435,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
132,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
132,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
452,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
462,/Users/user/Documents/zDEVELOP/bash-3.2.57/lib/readline/input.c
For eg., if you look at input.c:
int
rl_getc (stream)
FILE *stream;
{
int result;
unsigned char c;
while (1)
{
#if defined (__MINGW32__)
...
Line 462 is actually this line:
{
Which is not a line that is usually stopped at.
This is my Python code:
import lldb
import csv
lldb.debugger.SetAsync(False)
i = 1
while i:
with open('Z.csv', mode='a') as employee_file:
employee_writer = csv.writer(employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
l = lldb.thread.frames[0].addr.GetLineEntry().line
fn = str(lldb.thread.frames[0].addr.GetLineEntry().GetFileSpec())
employee_writer.writerow([l, fn])
lldb.thread.StepInto()
i=i+1
In lldb, I ran the script command, and then pasted the above code in the embedded Python interpreter.
This is how it would be like if I had manually step through the code:
Process 14194 launched: '/Users/user/Documents/zDEVELOP/bash-3.2.57/bash' (x86_64)
bash-3.2$ bash was compiled with optimization - stepping may behave oddly; variables may not be available.
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
frame #0: 0x000000010007c9a4 bash`rl_read_key at input.c:421 [opt]
418 {
419 int c;
420
-> 421 rl_key_sequence_length++;
422
423 if (rl_pending_input)
424 {
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c9bd bash`rl_read_key at input.c:423 [opt]
420
421 rl_key_sequence_length++;
422
-> 423 if (rl_pending_input)
424 {
425 c = rl_pending_input;
426 rl_clear_pending_input ();
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c9df bash`rl_read_key at input.c:431 [opt]
428 else
429 {
430 /* If input is coming from a macro, then use that. */
-> 431 if (c = _rl_next_macro_key ())
432 return (c);
433
434 /* If the user has an event function, then call it periodically. */
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007bf94 bash`_rl_next_macro_key at macro.c:105 [opt]
102 {
103 int c;
104
-> 105 if (rl_executing_macro == 0)
106 return (0);
107
108 if (rl_executing_macro[executing_macro_index] == 0)
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c0a0 bash`_rl_next_macro_key at macro.c:122 [opt]
119 #else
120 return (rl_executing_macro[executing_macro_index++]);
121 #endif
-> 122 }
123
124 /* Save the currently executing macro on a stack of saved macros. */
125 void
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c9e4 bash`rl_read_key at input.c:431 [opt]
428 else
429 {
430 /* If input is coming from a macro, then use that. */
-> 431 if (c = _rl_next_macro_key ())
432 return (c);
433
434 /* If the user has an event function, then call it periodically. */
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007ca01 bash`rl_read_key at input.c:435 [opt]
432 return (c);
433
434 /* If the user has an event function, then call it periodically. */
-> 435 if (rl_event_hook)
436 {
437 while (rl_event_hook && rl_get_char (&c) == 0)
438 {
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007cdd8 bash`rl_read_key at input.c:451 [opt]
448 }
449 else
450 {
-> 451 if (rl_get_char (&c) == 0)
452 c = (*rl_getc_function) (rl_instream);
453 }
454 }
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007cdd8 bash`rl_read_key [inlined] rl_get_char at input.c:132 [opt]
129 rl_get_char (key)
130 int *key;
131 {
-> 132 if (push_index == pop_index)
133 return (0);
134
135 *key = ibuffer[pop_index++];
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007cde7 bash`rl_read_key at input.c:452 [opt]
449 else
450 {
451 if (rl_get_char (&c) == 0)
-> 452 c = (*rl_getc_function) (rl_instream);
453 }
454 }
455
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c4a0 bash`rl_getc(stream=0x00007fff8abf8110) at input.c:462 [opt]
459 int
460 rl_getc (stream)
461 FILE *stream;
-> 462 {
463 int result;
464 unsigned char c;
465
Target 0: (bash) stopped.
(lldb) s
Process 14194 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x000000010007c4ad bash`rl_getc(stream=0x00007fff8abf8110) at input.c:472 [opt]
469 if (isatty (fileno (stream)))
470 return (getch ());
471 #endif
-> 472 result = read (fileno (stream), &c, sizeof (unsigned char));
473
474 if (result == sizeof (unsigned char))
475 return (c);
Target 0: (bash) stopped.
What could be the reason why this happens? And is there a way to solve this problem?
EDIT:
After trying the following new code, I still have the same problematic output:
import lldb
import csv
lldb.debugger.SetAsync(False)
i = 1
while i:
with open('Z.csv', mode='a') as employee_file:
employee_writer = csv.writer(employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
l = lldb.thread.frames[0].line_entry.line
fn = str(lldb.thread.frames[0].line_entry.GetFileSpec())
employee_writer.writerow([l, fn])
lldb.thread.StepInto()
i=I+1
EDIT 2:
This is how I obtained the executable that I ran lldb on:
First, downloaded this:
http://ftp.gnu.org/gnu/bash/bash-3.2.57.tar.gz
Then followed the instructions on:
https://www.gnu.org/software/bash/manual/bash.html#Basic-Installation
That's how I got the file:
/Users/user/Documents/zDEVELOP/bash-3.2.57/bas
Which I executed lldb on.
These is the sequence of lldb commands I used from start to finish:
user$ lldb
(lldb) file /Users/user/Documents/zDEVELOP/bash-3.2.57/bash
Traceback (most recent call last):
File "<input>", line 1, in <module>
File "/Users/user/miniconda3/lib/python2.7/copy.py", line 52, in <module>
import weakref
File "/Users/user/miniconda3/lib/python2.7/weakref.py", line 14, in <module>
from _weakref import (
ImportError: cannot import name _remove_dead_weakref
Current executable set to '/Users/user/Documents/zDEVELOP/bash-3.2.57/bash' (x86_64).
(lldb) breakpoint set -n main
Breakpoint 1: where = bash`main + 30 at shell.c:354, address = 0x000000010000152e
(lldb) run
Process 3118 launched: '/Users/user/Documents/zDEVELOP/bash-3.2.57/bash' (x86_64)
bash was compiled with optimization - stepping may behave oddly; variables may not be available.
Process 3118 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
frame #0: 0x000000010000152e bash`main(argc=1, argv=0x00007ffeefbffa70, env=0x00007ffeefbffa80) at shell.c:354 [opt]
351 #endif
352
353 /* Catch early SIGINTs. */
-> 354 code = setjmp (top_level);
355 if (code)
356 exit (2);
357
Target 0: (bash) stopped.
(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
And then I executed the following code in the Python interpreter:
import lldb
import csv
lldb.debugger.SetAsync(False)
i = 1
while i:
with open('Z.csv', mode='a') as employee_file:
employee_writer = csv.writer(employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
l = lldb.thread.frames[0].line_entry.line
fn = str(lldb.thread.frames[0].line_entry.GetFileSpec())
employee_writer.writerow([l, fn])
lldb.thread.StepInto()
i=I+1