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>
At present, the blob containing a device tree is passed to the various
fdt_*() functions as a (struct fdt_header *) i.e. a pointer to the
header structure at the beginning of the blob.
This patch changes all the functions so that they instead take a (void
*) pointing to the blob. Under some circumstances can avoid the need
for the caller to cast a blob pointer into a (struct fdt_header *)
before passing it to the fdt_*() functions.
Using a (void *) also reduce the temptation for users of the library
to directly dereference toe (struct fdt_header *) to access header
fields. Instead they must use the fdt_get_header() or
fdt_set_header() macros, or the fdt_magic(), fdt_totalsize()
etc. wrappers around them which are safer, since they will always
handle endian conversion.
With this change, the whole-tree moving, or manipulating functions:
fdt_move(), fdt_open_into() and fdt_pack() no longer need to return a
pointer to the "new" tree. The given (void *) buffer pointer they
take can instead be used directly by the caller as the new tree.
Those functions are thus changed to instead return an error code
(which in turn reduces the number of functions using the ugly encoding
of error values into pointers).
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.
fdt_property_offset() is the only function in the library returning a
direct offset to a property, and no function takes such an offset
(they only take offsets to nodes, not properties). Furthermore the
only client uses for this function I can think of involve immediately
translating the offset into a pointer, effectively duplicating the
internal function _fdt_getprop()
This function abolishes fdt_property_offset(), replacing it with
fdt_get_property(), a renamed and now externally visible version of
_fdt_getprop().
This patch adds exported accessor macros for the various flat device
tree header fields to libfdt.h. This necessitates moving some of the
byte-swapping functions.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The range sanity checking on the fdt_string_cmp() function causes problems
for the sequential write code (or at least for using RO functions on an
incomplete SW tree). Plus they didn't really fit with the philosphy for
the RO code of working as widely as possible on weirdly constructed trees.
