How to debug ruby source code using gdb?, can't print array content

I tried something like this in array.c

rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
{
  long len;
  int ln;
  int *ar;
  VALUE size, val;
  switch (TYPE(ary)) {
    case T_FIXNUM:
      break;
    case T_STRING:
      break;
    case T_ARRAY:
      ar=RARRAY(ary);
      ln=RARRAY_LEN(ary);
      printf("ln: %d\n",ln);
      ar=RARRAY_PTR(ary);
      break;
    default:
      rb_raise(rb_eTypeError, "not valid value");
      break;
  }

gdb ./ruby
(gdb)run
ctrl+c
(gdb)break array.c:rb_ary_initialize
(gdb)continue
arr=Array.new(3)
arr[0]=5
arr[1]=7
ctrl+d
(gdb)next

But i can't understand how to print the value using printf(); in
array.c:rb_ary_initialize function doing some casting.

Can anyone post reply with example to do it?

Thanks.

···

--
Posted via http://www.ruby-forum.com/.

Ruby has GDB helpers. Take a look at https://github.com/ruby/ruby/blob/trunk/.gdbinit
Fo instance rp prints any ruby value. There are other handy helpers as well.

···

On Jun 22, 2012, at 7:55 AM, gmspro gmspro wrote:

I tried something like this in array.c

rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
{
long len;
int ln;
int *ar;
VALUE size, val;
switch (TYPE(ary)) {
   case T_FIXNUM:
     break;
   case T_STRING:
     break;
   case T_ARRAY:
     ar=RARRAY(ary);
     ln=RARRAY_LEN(ary);
     printf("ln: %d\n",ln);
     ar=RARRAY_PTR(ary);
     break;
   default:
     rb_raise(rb_eTypeError, "not valid value");
     break;
}

gdb ./ruby
(gdb)run
ctrl+c
(gdb)break array.c:rb_ary_initialize
(gdb)continue
arr=Array.new(3)
arr[0]=5
arr[1]=7
ctrl+d
(gdb)next

But i can't understand how to print the value using printf(); in
array.c:rb_ary_initialize function doing some casting.

Can anyone post reply with example to do it?

https://github.com/ruby/ruby/blob/0b0dea752c0ef35d1a964b812a1a7fd033ab9e2e/README.EXT#L125

https://github.com/ruby/ruby/blob/0b0dea752c0ef35d1a964b812a1a7fd033ab9e2e/array.c#L569

Thanks.

--
Posted via http://www.ruby-forum.com/.

Alex Newone wrote in post #1065644:

Ruby has GDB helpers. Take a look at
https://github.com/ruby/ruby/blob/trunk/.gdbinit
Fo instance rp prints any ruby value. There are other handy helpers as
well.

How to use that .gdbinit?

···

--
Posted via http://www.ruby-forum.com/.

FYI, this is a help vampire that we recently banned on IRC. He has a long history of this.

···

On Jun 22, 2012, at 00:35 , Sigurd wrote:

Ruby has GDB helpers. Take a look at https://github.com/ruby/ruby/blob/trunk/.gdbinit
Fo instance rp prints any ruby value. There are other handy helpers as well.

Copy it to the home folder and it'll be automatically loaded by gdb.

···

On Jun 22, 2012, at 11:49 AM, gmspro gmspro wrote:

Alex Newone wrote in post #1065644:

Ruby has GDB helpers. Take a look at
https://github.com/ruby/ruby/blob/trunk/.gdbinit
Fo instance rp prints any ruby value. There are other handy helpers as
well.

How to use that .gdbinit?
https://github.com/ruby/ruby/blob/trunk/.gdbinit

--
Posted via http://www.ruby-forum.com/.

Ryan Davis wrote in post #1065745:

Ruby has GDB helpers. Take a look at

https://github.com/ruby/ruby/blob/trunk/.gdbinit

Fo instance rp prints any ruby value. There are other handy helpers as well.

FYI, this is a help vampire that we recently banned on IRC. He has a
long history of this.

No, i have tried this,

arr=Array.new(3)
arr[0]=5
arr[1]=3
arr[2]=2

These lines should call this function,
https://github.com/ruby/ruby/blob/trunk/array.c#L568 according to this,
http://www.ruby-doc.org/core-1.9.3/Array.html

So I have added couple of lines there to display the values of array.
But i didn't get the expected result.

else {
    memfill(RARRAY_PTR(ary), len, val);
    ARY_SET_LEN(ary, len);
    int i;
    int result;
    result = 0;
    VALUE *s_arr = RARRAY_PTR(ary);
    for(i = 0; i < len; i++) {
        result = LONG2NUM(s_arr[i]);
        printf("r: %d\n",result);
    }
}

I got the result like this:

arr=Array.new(3)
arr[0]=5
arr[1]=3
arr[2]=2
r: 9
r: 9
r: 9

Why is this result? Why 9?

I have followed these to solve it:

How to convert ruby array to C array with RubyInline?

Also tried this, result = NUM2LONG(s_arr[i]); result =
FIX2NUM(s_arr[i]); result = rb_long2int(s_arr[i]); nothing gets the
expected result.

Can anyone please help to display/printf the value of ruby array in C?

Any reply/answer will be highly appreciated.

Thanks in advanced.

···

On Jun 22, 2012, at 00:35 , Sigurd wrote:

--
Posted via http://www.ruby-forum.com/.

Alex Newone wrote in post #1065660:

Copy it to the home folder and it'll be automatically loaded by gdb.

I did this. But it looks, it doesn't help or do anything from (gdb).

···

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