Gecko:Debugging Tools
From MozillaWiki
Contents
.gdbinit
GDB pretty printers
Printing arrays
define ptarray if $argc == 0 help ptarray else set $size = $arg0.mHdr->mLength set $capacity = $arg0.mHdr->mCapacity set $size_max = $size - 1 set $elts = $arg0.Elements() end if $argc == 1 set $i = 0 while $i < $size printf "elem[%u]: ", $i p *($elts + $i) set $i++ end end if $argc == 2 set $idx = $arg1 if $idx < 0 || $idx > $size_max printf "idx1, idx2 are not in acceptable range: [0..%u].\n", $size_max else printf "elem[%u]: ", $idx p *($elts + $idx) end end if $argc == 3 set $start_idx = $arg1 set $stop_idx = $arg2 if $start_idx > $stop_idx set $tmp_idx = $start_idx set $start_idx = $stop_idx set $stop_idx = $tmp_idx end if $start_idx < 0 || $stop_idx < 0 || $start_idx > $size_max || $stop_idx > $size_max printf "idx1, idx2 are not in acceptable range: [0..%u].\n", $size_max else set $i = $start_idx while $i <= $stop_idx printf "elem[%u]: ", $i p *($elts + $i) set $i++ end end end if $argc > 0 printf "nsTArray length = %u\n", $size printf "nsTArray capacity = %u\n", $capacity printf "Element " whatis *$elts end end
Chris Jones' handy ptarray command
Frame Tree Dump
<bz> for a frame dump, you can use the layout debugger, or... if you're in a debugger and want to examine the tree, you can do
def frametree call nsFrame::DumpFrameTree($arg0) end
<bz> That should work when called on any nsIFrame to dump the tree it belongs to
Printing nsIAtoms
def pa set $atom = $arg0 if (sizeof(*((&*$atom)->mString)) == 2) pu (&*$atom)->mString end end
Reflow Logs
See [Debugging Frame Reflow]
Printing strings
# Define a "ps" command to display subclasses of nsAC?String. Note that # this assumes strings as of Gecko 1.9 (well, and probably a few # releases before that as well); going back far enough will get you # to string classes that this function doesn't work for. def ps set $str = $arg0 if (sizeof(*$str.mData) == 1 && ($str.mFlags & 1) != 0) print $str.mData else pu $str.mData $str.mLength end end
# Define a "pu" command to display PRUnichar * strings (100 chars max) # Also allows an optional argument for how many chars to print as long as # it's less than 100. def pu set $uni = $arg0 if $argc == 2 set $limit = $arg1 if $limit > 100 set $limit = 100 end else set $limit = 100 end # scratch array with space for 100 chars plus null terminator. Make # sure to not use ' ' as the char so this copy/pastes well. set $scratch = "____________________________________________________________________________________________________" set $i = 0 set $scratch_idx = 0 while (*$uni && $i++ < $limit) if (*$uni < 0x80) set $scratch[$scratch_idx++] = *(char*)$uni++ else if ($scratch_idx > 0)
set $scratch[$scratch_idx] = '\0' print $scratch set $scratch_idx = 0
end print /x *(short*)$uni++ end end if ($scratch_idx > 0) set $scratch[$scratch_idx] = '\0' print $scratch end end
Dumping the JS Stack
def js call DumpJSStack() end