At present, libfdt functions returning a structure offset return a
zero-or-positive offset on success, and return a negative error code
on failure. Functions which only return an error code return a
positive version of the error code, or 0 on success.
This patch improves consistency by always returning negative error
codes on failure, for both types of function. With this change, we do
away with the special fdt_offset_error() macro for checking whether a
returned offset value is an error and extracting the encoded error
value within. Instead an explicit (ret_value < 0) is now the
preferred way of checking return values for both offset-returning and
error-code-returning functions.
The fdt_strerror() function in the test code is updated
correspondingly to make more sense with the new conventions.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This patch abolishes the non-standard and confusing encoding of errors
into pointer return values. The only functions still returning such a
potentially encoded pointer are fdt_get_property() and fdt_getprop().
Those functions also return a length via an (int *). With this patch
those functions instead now return NULL on any error, and return the
code indicating the type of error in the length paramater.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The libfdt functions are supposed to behave tolerably well when practical,
even if given a corrupted device tree as input. A silly mistake in
fdt_get_property() means we're bounds checking against the size of a pointer
instead of the size of a property header, meaning we can get bogus
behaviour in a corrupted device tree where the structure block ends in
what's supposed to be the middle of a property.
This patch corrects the problem (fdt_get_property() will now return
BADSTRUCTURE in this case), and also adds a testcase to catch the bug.
