[lldb-dev] GetSymbolContext(lldb.eSymbolContextEverything)

[Greg Clayton via lldb-dev]

We currently don't expose this information through the API, though we could. You could add a new method to SBValue:

namespace lldb
{
  class SBValue
  {
    SBData GetDWARFLocation();
  }
};

This could return the DWARF location as a SBData object. Then you could consume the data by parsing the DWARF DW_OP enumerations. Otherwise you can parse the textual output of the "image lookup -va 0x123" command:

result = lldb.SBCommandReturnObject()
ci = debugger.GetCommandInterpreter()
ci.HandleCommand("image lookup -va %#x" % (frame.GetPC()), result, False)

# Now all output from the above command is in "result"
output = result.GetOutput()

# Parse "output" for variable locations




> On Jun 21, 2016, at 9:07 AM, Kamenee Arumugam <kamenee at seas.upenn.edu> wrote:
> 
> Hi Greg,
> 
> Thanks for your reply. I did try the method you mention above but variable.GetLocation() only provide me the memory address of the variable. What exactly I am looking for was  the register offset that stores variable i here. Example, I am looking for method able to output the one highlighted in yellow:
> 
> Variable: id = {0x000000a2}, name = "i", type= "int", location = DW_OP_fbreg(-564), decl = ivm_demo.c:6
> 
> 
> Basically, I am working on  a binary instrumentation research tool, that will inject code to check changes on selected variable. Therefore, using register offset, I am able to inject check for instruction using this register with this offset.
> Please let me know if you have any better method to grab register offset for particular variable.
> 
> Thanks,
> Kamenee
> 
> On Mon, Jun 20, 2016 at 7:15 PM, Greg Clayton <gclayton at apple.com> wrote:
> The variables are available through the frame in your symbol context. You have a line of code commented out in your script:
> 
>                     #variable = frame.GetVariables(target,True,True,True)
> 
> Change it to:
> 
> get_arguments = True # Get argument variables
> get_locals = True # Get local variables
> get_statics = True # Get globals and static variables
> get_in_scope_only = True # only get variables that are in scope
> use_dynamic = lldb.eDynamicDontRunTarget # Get dynamic types for variables
> variables = frame.GetVariables (get_arguments, get_locals, get_statics, get_in_scope_only, use_dynamic)
> print variables
> 
> This output will look different from the output in "image lookup --address 0x... --verbose" because we have an actual frame here so we can dump the variable value itself because we have a stack frame that allows us to have variable values. If you want the location of the variable you can also print that in a for loop using "variables" from above:
> 
> for variable in variables:
>     print str(variable)
>     print "Location = %s" % (variable.GetLocation())
> 
> 
> Each "variable" object is a lldb.SBValue type. There are many API calls on these that you can call manually depending on what you want. Let me know if you have any questions.
> 
> Greg Clayton
> 
> 
> 
> 
> > On Jun 17, 2016, at 11:34 AM, Kamenee Arumugam via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> >
> > Hi,
> >
> > I am trying program using Lldb Python API to get an output exactly same when I run this command "image lookup --address 0x0000000405a6 --verbose". But when I print return value of GetSymbolContext(lldb.eSymbolContextEverything), it doesnt contain the decoding of local variables which the above commands can print out local variables.
> >
> > I have attached a simple script.py that I have developed. It is not possible to print out local variables using the APIs or I am missing something out?
> >
> > I am looking forward to hear from you soon.
> >
> > Thanks,
> > kmn
> > <script.txt>_______________________________________________
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> > lldb-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
> 
>