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Re: [RFC] convert a host address to a string
2009/1/10 Joel Brobecker <brobecker@adacore.com>:
>> I think it is a sub-optimal solution to have just support for Vista64, but
>> not for XP.
>
> To me, the question is not about whether to support XP64 or not.
> I agree it would be nice to support XP64 as well. It's about who
> has the time and energy to drive the discussion to find an accepted
> solution. I decided to drop XP64, because it's not in the list of
> things I'm interested in while I'm sensing that it's going to take
> a bit of effort to reach a consensus. You already made a very nice
> contribution in the coff/pe reader, why not send another patch to
> further improve host_address_to_string for XP64?
>
>> On a second thought, I remembered, that bfd does things right ;) There
>> is the macro sprintf_vma in bfd.h, which handles things pretty well
>> and can be used here in utils.c, too.
>
> The problem with that routine is that it is designed to print target
> addresses, not host addresses.
>
> --
> Joel
>
ok, so I sugget the following patch instead. It is able to generate
addresses for XP64 without the use of any vendor specific printf
formatters, and uses for targets where sizeof(long) == sizeof(void*)
the long variant.
Cheers,
Kai
--
| (\_/) This is Bunny. Copy and paste
| (='.'=) Bunny into your signature to help
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Index: src/gdb/utils.c
===================================================================
--- src.orig/gdb/utils.c
+++ src/gdb/utils.c
@@ -3071,11 +3071,54 @@ host_address_to_string (const void *addr
{
char *str = get_cell ();
- /* We could use the %p conversion specifier to sprintf if we had any
- way of knowing whether this host supports it. But the following
- should work on the Alpha and on 32 bit machines. */
- sprintf (str, "0x%lx", (unsigned long) addr);
+ /* We do not use the %p conversion specifier, because the resulting
+ image can vary from implementation to implementation. For instance,
+ some implementations format the pointer value with a leading "0x"
+ whereas others don't (Solaris, for instance). Also, it is unspecified
+ whether the alphabetical digits are printed using uppercase letters
+ or not (in GDB, we want lowercase).
+
+ So we use the %x type instead. This, however, introduces
+ a couple of issues:
+
+ 1. The %x type expects an integer value, not a pointer.
+ So we first need to cast our pointer to an integer type
+ whose size is identical to the size of our pointer.
+ We use uintptr_t for that.
+
+ 2. The %x type alone expects and int, which is not always
+ large enough to hold an address. Usually, type "long"
+ has the same size as pointers, but certain ABIs define
+ the size of pointers to be larger than the size of long
+ (64bit Windows is one such example).
+
+ So, to be certain to have a type that's large enough
+ to hold an address, we need to use "long long". But
+ the trick is that not all printf implementations support
+ the "ll" modifier. On those platforms where the "ll"
+ modifier is not available, we'll assume that type "long"
+ can be used to print an address.
+
+ To make sure that the type we pass to sprintf matches
+ the type we specified in our expression, we perform
+ a second cast to "unsigned long long" if we used "%llx",
+ or "unsigned long" if we used "%lx". */
+
+#if defined(PRINTF_HAS_LONG_LONG) && BITSIZEOF_SIZE_T == 64 && \
+ SIZEOF_LONG == 4
+ sprintf (str, "0x%llx", (unsigned long long) (uintptr_t) addr);
+#elif BITSIZEOF_SIZE_T == 64 && SIZEOF_LONG == 4
+ unsigned long long val = (unsigned long) (uintptr_t) addr;
+ if ((val & ~0xffffffffull) != 0)
+ sprintf (str, "0x%lx%08lx",
+ (unsigned long) (val >> 32), (unsigned long) val);
+ else
+ sprintf (str, "0x%lx", (unsigned long) (uintptr_t) val);
+#else
+ sprintf (str, "0x%lx", (unsigned long) (uintptr_t) addr);
+#endif
return str;
+ BITSIZEOF_SIZE_T SIZEOF_LONG
}
char *