libfdt: More thorough use of constification

As a read-only functions, which take a const pointer to the fdt, treat
fdt_get_property() and fdt_getprop() as returning const pointers to
within the blob.  fdt_get_property_w() and fdt_getprop_w() versions
are supplied which take a non-const fdt pointer and return a non-const
pointer for the benefit of callers wishing to alter the device tree
contents.

Likewise the lower-level fdt_offset_ptr() and _fdt_offset_ptr()
functions are changed to return const pointers, with *_w() versions
supplied.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

fdt.c

@@ -42,9 +42,9 @@ int _fdt_check_header(const void *fdt)
 	return 0;
 }
 
-void *fdt_offset_ptr(const void *fdt, int offset, int len)
+const void *fdt_offset_ptr(const void *fdt, int offset, int len)
 {
-	void *p;
+	const void *p;
 
 	if (fdt_version(fdt) >= 0x11)
 		if (((offset + len) < offset)

fdt_ro.c

@@ -137,13 +137,13 @@ int fdt_path_offset(const void *fdt, const char *path)
 	return offset;	
 }
 
-struct fdt_property *fdt_get_property(const void *fdt,
-				      int nodeoffset,
-				      const char *name, int *lenp)
+const struct fdt_property *fdt_get_property(const void *fdt,
+					    int nodeoffset,
+					    const char *name, int *lenp)
 {
 	int level = 0;
 	uint32_t tag;
-	struct fdt_property *prop;
+	const struct fdt_property *prop;
 	int namestroff;
 	int offset, nextoffset;
 	int err;
@@ -216,7 +216,7 @@ struct fdt_property *fdt_get_property(const void *fdt,
 	return NULL;
 }
 
-void *fdt_getprop(const void *fdt, int nodeoffset,
+const void *fdt_getprop(const void *fdt, int nodeoffset,
 		  const char *name, int *lenp)
 {
 	const struct fdt_property *prop;

fdt_rw.c

@@ -123,7 +123,7 @@ static int _resize_property(void *fdt, int nodeoffset, const char *name, int len
 	int oldlen;
 	int err;
 
-	*prop = fdt_get_property(fdt, nodeoffset, name, &oldlen);
+	*prop = fdt_get_property_w(fdt, nodeoffset, name, &oldlen);
 	if (! (*prop))
 		return oldlen;
 
@@ -153,7 +153,7 @@ static int _add_property(void *fdt, int nodeoffset, const char *name, int len,
 	if (namestroff < 0)
 		return namestroff;
 
-	*prop = _fdt_offset_ptr(fdt, nextoffset);
+	*prop = _fdt_offset_ptr_w(fdt, nextoffset);
 	proplen = sizeof(**prop) + ALIGN(len, FDT_TAGSIZE);
 
 	err = _blob_splice_struct(fdt, *prop, 0, proplen);
@@ -192,7 +192,7 @@ int fdt_delprop(void *fdt, int nodeoffset, const char *name)
 
 	RW_CHECK_HEADER(fdt);
 
-	prop = fdt_get_property(fdt, nodeoffset, name, &len);
+	prop = fdt_get_property_w(fdt, nodeoffset, name, &len);
 	if (! prop)
 		return len;
 
@@ -225,7 +225,7 @@ int fdt_add_subnode_namelen(void *fdt, int parentoffset,
 		tag = _fdt_next_tag(fdt, offset, &nextoffset);
 	} while (tag == FDT_PROP);
 
-	nh = _fdt_offset_ptr(fdt, offset);
+	nh = _fdt_offset_ptr_w(fdt, offset);
 	nodelen = sizeof(*nh) + ALIGN(namelen+1, FDT_TAGSIZE) + FDT_TAGSIZE;
 
 	err = _blob_splice_struct(fdt, nh, 0, nodelen);
@@ -254,7 +254,7 @@ int fdt_del_node(void *fdt, int nodeoffset)
 	if (endoffset < 0)
 		return endoffset;
 
-	return _blob_splice_struct(fdt, _fdt_offset_ptr(fdt, nodeoffset),
+	return _blob_splice_struct(fdt, _fdt_offset_ptr_w(fdt, nodeoffset),
 				   endoffset - nodeoffset, 0);
 }
 

fdt_sw.c

@@ -42,7 +42,7 @@ static void *grab_space(void *fdt, int len)
 		return NULL;
 
 	fdt_set_header(fdt, size_dt_struct, offset + len);
-	return fdt_offset_ptr(fdt, offset, len);
+	return fdt_offset_ptr_w(fdt, offset, len);
 }
 
 int fdt_create(void *buf, int bufsize)
@@ -82,7 +82,7 @@ int fdt_add_reservemap_entry(void *fdt, uint64_t addr, uint64_t size)
 	if ((offset + sizeof(*re)) > fdt_totalsize(fdt))
 		return -FDT_ERR_NOSPACE;
 
-	re = (struct fdt_reserve_entry *)((void *)fdt + offset);
+	re = (struct fdt_reserve_entry *)(fdt + offset);
 	re->address = cpu_to_fdt64(addr);
 	re->size = cpu_to_fdt64(size);
 
@@ -205,8 +205,8 @@ int fdt_finish(void *fdt)
 	offset = 0;
 	while ((tag = _fdt_next_tag(fdt, offset, &nextoffset)) != FDT_END) {
 		if (tag == FDT_PROP) {
-			struct fdt_property *prop = fdt_offset_ptr(fdt, offset,
-								   sizeof(*prop));
+			struct fdt_property *prop =
+				fdt_offset_ptr_w(fdt, offset, sizeof(*prop));
 			int nameoff;
 
 			if (! prop)

fdt_wip.c

@@ -29,7 +29,7 @@ int fdt_setprop_inplace(void *fdt, int nodeoffset, const char *name,
 	void *propval;
 	int proplen;
 
-	propval = fdt_getprop(fdt, nodeoffset, name, &proplen);
+	propval = fdt_getprop_w(fdt, nodeoffset, name, &proplen);
 	if (! propval)
 		return proplen;
 
@@ -53,7 +53,7 @@ int fdt_nop_property(void *fdt, int nodeoffset, const char *name)
 	struct fdt_property *prop;
 	int len;
 
-	prop = fdt_get_property(fdt, nodeoffset, name, &len);
+	prop = fdt_get_property_w(fdt, nodeoffset, name, &len);
 	if (! prop)
 		return len;
 
@@ -107,6 +107,6 @@ int fdt_nop_node(void *fdt, int nodeoffset)
 	if (endoffset < 0)
 		return endoffset;
 
-	nop_region(fdt_offset_ptr(fdt, nodeoffset, 0), endoffset - nodeoffset);
+	nop_region(fdt_offset_ptr_w(fdt, nodeoffset, 0), endoffset - nodeoffset);
 	return 0;
 }

libfdt.h

@@ -45,7 +45,7 @@
 #define FDT_ERR_MAX		11
 
 #define fdt_get_header(fdt, field) \
-	(fdt32_to_cpu(((struct fdt_header *)(fdt))->field))
+	(fdt32_to_cpu(((const struct fdt_header *)(fdt))->field))
 #define fdt_magic(fdt) 			(fdt_get_header(fdt, magic))
 #define fdt_totalsize(fdt)		(fdt_get_header(fdt, totalsize))
 #define fdt_off_dt_struct(fdt)		(fdt_get_header(fdt, off_dt_struct))
@@ -60,10 +60,17 @@
 #define fdt_set_header(fdt, field, val) \
 	((struct fdt_header *)(fdt))->field = cpu_to_fdt32(val)
 
-void *fdt_offset_ptr(const void *fdt, int offset, int checklen);
+const void *fdt_offset_ptr(const void *fdt, int offset, int checklen);
+static inline void *fdt_offset_ptr_w(void *fdt, int offset, int checklen)
+{
+	return (void *)fdt_offset_ptr(fdt, offset, checklen);
+}
+
 
 #define fdt_offset_ptr_typed(fdt, offset, var) \
 	((typeof(var))(fdt_offset_ptr((fdt), (offset), sizeof(*(var)))))
+#define fdt_offset_ptr_typed_w(fdt, offset, var) \
+	((typeof(var))(fdt_offset_ptr_w((fdt), (offset), sizeof(*(var)))))
 
 int fdt_move(const void *fdt, void *buf, int bufsize);
 
@@ -76,10 +83,24 @@ int fdt_subnode_offset(const void *fdt, int parentoffset, const char *name);
 
 int fdt_path_offset(const void *fdt, const char *path);
 
-struct fdt_property *fdt_get_property(const void *fdt, int nodeoffset,
-				      const char *name, int *lenp);
-void *fdt_getprop(const void *fdt, int nodeoffset,
-		  const char *name, int *lenp);
+const struct fdt_property *fdt_get_property(const void *fdt, int nodeoffset,
+					    const char *name, int *lenp);
+
+static inline struct fdt_property *fdt_get_property_w(void *fdt, int nodeoffset,
+						      const char *name,
+						      int *lenp)
+{
+	return (struct fdt_property *)fdt_get_property(fdt, nodeoffset,
+						       name, lenp);
+}
+
+const void *fdt_getprop(const void *fdt, int nodeoffset,
+			const char *name, int *lenp);
+static inline void *fdt_getprop_w(void *fdt, int nodeoffset,
+				  const char *name, int *lenp)
+{
+	return (void *)fdt_getprop(fdt, nodeoffset, name, lenp);
+}
 
 /* Write-in-place functions */
 int fdt_setprop_inplace(void *fdt, int nodeoffset, const char *name,

libfdt_internal.h

@@ -31,9 +31,14 @@ uint32_t _fdt_next_tag(const void *fdt, int startoffset, int *nextoffset);
 const char *_fdt_find_string(const char *strtab, int tabsize, const char *s);
 int _fdt_node_end_offset(void *fdt, int nodeoffset);
 
-static inline void *_fdt_offset_ptr(const struct fdt_header *fdt, int offset)
+static inline const void *_fdt_offset_ptr(const void *fdt, int offset)
 {
-	return (void *)fdt + fdt_off_dt_struct(fdt) + offset;
+	return fdt + fdt_off_dt_struct(fdt) + offset;
+}
+
+static inline void *_fdt_offset_ptr_w(void *fdt, int offset)
+{
+	return (void *)_fdt_offset_ptr(fdt, offset);
 }
 
 #define SW_MAGIC		(~FDT_MAGIC)

tests/del_property.c

@@ -33,8 +33,8 @@
 int main(int argc, char *argv[])
 {
 	void *fdt;
-	uint32_t *intp;
-	char *strp;
+	const uint32_t *intp;
+	const char *strp;
 	int err, lenerr;
 	int oldsize, delsize, newsize;
 

tests/nop_property.c

@@ -33,8 +33,8 @@
 int main(int argc, char *argv[])
 {
 	void *fdt;
-	uint32_t *intp;
-	char *strp;
+	const uint32_t *intp;
+	const char *strp;
 	int err;
 	int lenerr;
 

tests/notfound.c

@@ -37,11 +37,11 @@ void check_error(const char *s, int err)
 
 int main(int argc, char *argv[])
 {
-	struct fdt_property *prop;
+	const struct fdt_property *prop;
 	void *fdt;
 	int offset;
 	int subnode1_offset;
-	void *val;
+	const void *val;
 	int lenerr;
 
 	test_init(argc, argv);

tests/setprop.c

@@ -37,8 +37,8 @@ int main(int argc, char *argv[])
 {
 	void *fdt;
 	void *buf;
-	uint32_t *intp;
-	char *strp;
+	const uint32_t *intp;
+	const char *strp;
 	int err;
 
 	test_init(argc, argv);

tests/setprop_inplace.c

@@ -33,8 +33,9 @@
 int main(int argc, char *argv[])
 {
 	void *fdt;
-	uint32_t *intp;
-	char *strp, *xstr;
+	const uint32_t *intp;
+	const char *strp;
+	char *xstr;
 	int xlen, i;
 	int err;
 

tests/tests.h

@@ -117,8 +117,8 @@ void check_property(void *fdt, int nodeoffset, const char *name,
 	})
 
 
-void *check_getprop(void *fdt, int nodeoffset, const char *name,
-		    int len, const void *val);
+const void *check_getprop(void *fdt, int nodeoffset, const char *name,
+			  int len, const void *val);
 #define check_getprop_typed(fdt, nodeoffset, name, val) \
 	({ \
 		typeof(val) x = val; \

tests/testutils.c

@@ -107,10 +107,10 @@ void check_property(void *fdt, int nodeoffset, const char *name,
 	
 }
 
-void *check_getprop(void *fdt, int nodeoffset, const char *name,
-		    int len, const void *val)
+const void *check_getprop(void *fdt, int nodeoffset, const char *name,
+			  int len, const void *val)
 {
-	void *propval;
+	const void *propval;
 	int proplen;
 
 	propval = fdt_getprop(fdt, nodeoffset, name, &proplen);

tests/truncated_property.c

@@ -32,7 +32,7 @@
 int main(int argc, char *argv[])
 {
 	void *fdt = &_truncated_property;
-	void *prop;
+	const void *prop;
 	int err;
 	int len;