Re: [RFC] convert a host address to a string

Kai Tietz
2009-01-10T13:34:24Z

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2009/1/10 Kai Tietz <ktietz70@googlemail.com>:
> 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.

Sorry, I just detected a wrong type cast.

Cheers,
Kai
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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 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 *