How to convert a gdb Value to a python numeral obj

问题:

I'm using python2.6's gdb module while debugging a C program, and would like to convert a gdb.Value instance into a python numeral object (variable) based off the instance's '.Type'.

E.g. turn my C program's SomeStruct->some_float_val = 1./6; to a Python gdb.Value via sfv=gdb.parse_and_eval('SomeStruct->some_double_val'), but THEN turn this into a double precision floating point python variable -- knowing that str(sfv.type.strip_typedefs())=='double' and its size is 8B -- WITHOUT just converting through a string using dbl=float(str(sfv)) or Value.string() but rather something like unpacking the bytes using struct to get the correct double value.

Every link returned from my searches points https://sourceware.org/gdb/onlinedocs/gdb/Values-From-Inferior.html#Values-From-Inferior, but I can't see how to convert a Value instance into a python variable cleanly, say the Value wasn't even in C memory but represented a gdb.Value.address (so can't use Inferior.read_memory()), how would one turn this into a Python int without casting string values?

回答1:

You can convert it directly from the Value using int or float:

(gdb) python print int(gdb.Value(0))
0
(gdb) python print float(gdb.Value(0.0))
0.0

There seems to be at least one glitch in the system, though, as float(gdb.Value(0)) does not work.