GDB script improvements

[arnaud-lb]

Improve the Python GDB script in the following ways:

• Support IS_INDIRECT, IS_PTR, IS_ALIAS_PTR when printing zvals:

(gdb) p $z1
$3 = (zval *) 0x7ffff7a5f040
(gdb) p *$z1
$4 = ((zval *) 0x7ffff7a5f040) indirect: ((zval*) 0x7ffff7a58628) "foo" = {
  ... (zval fields)
}

(gdb) p $z2
$6 = (zval *) 0x1356580
(gdb) p *$z2
$7 = ((zval *) 0x1356580) ptr: ((void*) 0x7ffff7a02018) = {
  ... (zval fields)
}

• Pretty print the ce_flags field when pretty printing a zend_class_entry

(gdb) p Z_CE_P($z2)
$9 = ((zend_class_entry *) 0x7ffff7a02220) "C" = {
  type = 2 '\002',
  name = "C",
  <anonymous> = {
    parent = 0x0,
    parent_name = 0x0
  },
  refcount = 1,
  ce_flags = 4872 (ZEND_ACC_LINKED | ZEND_ACC_HAS_TYPE_HINTS | ZEND_ACC_TOP_LEVEL | ZEND_ACC_CONSTANTS_UPDATED),
  ... (other zend_class_entry fields)

• Pretty print the const flags when pretty printing a zend_class_constant

(gdb) p $c
$4 = (zend_class_constant *) 0x7ffff7a02220
(gdb) p *$c
$5 = ((zend_class_constant *) 0x7ffff7a02220) {
  value.u2.constant_flags = 1 (ZEND_ACC_PUBLIC),
  ... (other zend_class_constant fields)
}

• Added a minimal zend_property_info pretty printer to pretty print the flags field

(gdb) p $p
$10 = (struct _zend_property_info *) 0x7ffff7a02258
(gdb) p *$p
$11 = {
  offset = 40,
  flags = 1 (ZEND_ACC_PUBLIC),
  name = "foo",
  ... (other zend_property_info fields)
}

• Added minimal zend_function, zend_op_array, and zend_internal_function pretty printers:
  • The the string value is the function/method name, function type (user/internal), and location (when application)
  • Pretty print fn_flags field

(gdb) p $f
$13 = (zend_function *) 0x7ffff7a022a0
(gdb) p *$f
$14 = ((zend_function *) 0x7ffff7a022a0) user method "C"::"foo" "Command line code":1 = {
  type = 2 '\002',
  quick_arg_flags = 2,
  op_array = ((zend_op_array *) 0x7ffff7a022a0) method "C"::"foo" "Command line code":1 = {
    type = 2 '\002',
    arg_flags = "\000\000",
    fn_flags = 33554466 (ZEND_ACC_PROTECTED | ZEND_ACC_FINAL | ZEND_ACC_DONE_PASS_TWO),
  ... (other fields)
}

• Added a minimal zend_op pretty printer to pretty print the opcode

(gdb) p $f.op_array.opcodes[0]
$15 = {
  opcode = 62 (ZEND_RETURN),
  ... (other zend_op fields)
}

• Added a zend_refcounted_h pretty printer to pretty print the type_info

(gdb) p struc.value.obj.gc
$76 = {
  refcount = 3,
  u.type_info = 3221226632 (IS_OBJECT | IS_OBJ_WEAKLY_REFERENCED(GC_PERSISTENT) | GC_PURPLE | GC_ADDRESS(1))
}

• Added minimal pretty printers for zend_object and zend_array:

(gdb) p *$obj
$77 = object("stdClass") = {
  ...
}

(gdb) p *$arr
$79 = array(2) = {
  ...
}

(This doesn't print members yet, but the print_ht commands from .gdbinit can be used for that)

• Print the type and address of pretty-printed structs:

Before:

(gdb) p *zv
$15 = "foo" = {
  value = "foo" = {

After:

(gdb) p *zv
$15 = ((zval*) 0x7ffff7a130d0) "foo" = {
  value = ((zend_string*) 0x7ffff7a01cc0) "foo" = {

• Added a few gdb commands:
  • print_fn_flags, print_ce_flags, print_prop_flags, print_const_flags
  • print_opcode
  • print_ref_type_info

(gdb) print_fn_flags 33554466
ZEND_ACC_PROTECTED | ZEND_ACC_FINAL | ZEND_ACC_DONE_PASS_TWO
(gdb) print_ce_flags 4872
ZEND_ACC_LINKED | ZEND_ACC_HAS_TYPE_HINTS | ZEND_ACC_TOP_LEVEL | ZEND_ACC_CONSTANTS_UPDATED
(gdb) print_prop_flags 1
ZEND_ACC_PUBLIC
(gdb) print_const_flags 1
ZEND_ACC_PUBLIC

(gdb) print_opcode 1
ZEND_ADD

(gdb) print_ref_type_info 71
IS_ARRAY | IS_ARRAY_IMMUTABLE(GC_IMMUTABLE) | GC_BLACK

• Fields of type zend_string, zend_class_entry, zend_array are printed by default in all our pretty printers, using short representation
• Increased the maximum length of printed strings (before truncation) to 200 chars (from 50)
• Small refactors

[iluuu1994]

Very nice improvements! It would also be nice to have direct pretty printing support of zend_object, HashTable, and zend_refcounted, when not working with zval directly.

[arnaud-lb]

@iluuu1994 I've added a pretty printer for zend_refcounted_h and a command to pretty print a zend_refcounted_h.u.type_info value. Also, minimal printers for objects and arrays. I plan to add support for printing array elements at some point, but the print_ht command from .gdbinit works well already.