libfdt: Several cleanups to parameter checking

This patch makes a couple of small cleanups to parameter checking of
libfdt functions.

	- In several functions which take a node offset, we use an
idiom involving fdt_next_tag() first to check that we have indeed been
given a node offset.  This patch adds a helper function
_fdt_check_node_offset() to encapsulate this usage of fdt_next_tag().

	- In fdt_rw.c in several places we have the expanded version
of the RW_CHECK_HEADER() macro for no particular reason.  This patch
replaces those instances with an invocation of the macro; that's what
it's for.

	- In fdt_sw.c we rename the check_header_sw() function to
sw_check_header() to match the analgous function in fdt_rw.c, and we
provide an SW_CHECK_HEADER() wrapper macro as RW_CHECK_HEADER()
functions in fdt_rw.c

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

5 files changed, 44 insertions, 55 deletions

diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index cfa1989..cb08ba0 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -133,16 +133,23 @@ uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset)
 	return tag;
 }
 
+int _fdt_check_node_offset(const void *fdt, int offset)
+{
+	if ((offset < 0) || (offset % FDT_TAGSIZE)
+	    || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
+		return -FDT_ERR_BADOFFSET;
+
+	return offset;
+}
+
 int fdt_next_node(const void *fdt, int offset, int *depth)
 {
 	int nextoffset = 0;
 	uint32_t tag;
 
-	if (offset >= 0) {
-		tag = fdt_next_tag(fdt, offset, &nextoffset);
-		if (tag != FDT_BEGIN_NODE)
-			return -FDT_ERR_BADOFFSET;
-	}
+	if (offset >= 0)
+		if ((nextoffset = _fdt_check_node_offset(fdt, offset)) < 0)
+			return nextoffset;
 
 	do {
 		offset = nextoffset;
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 11d80d2..69af7bb 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -161,16 +161,12 @@ int fdt_path_offset(const void *fdt, const char *path)
 
 const char *fdt_get_name(const void *fdt, int nodeoffset, int *len)
 {
-	const struct fdt_node_header *nh;
+	const struct fdt_node_header *nh = _fdt_offset_ptr(fdt, nodeoffset);
 	int err;
 
-	if ((err = fdt_check_header(fdt)) != 0)
-		goto fail;
-
-	err = -FDT_ERR_BADOFFSET;
-	nh = fdt_offset_ptr(fdt, nodeoffset, sizeof(*nh));
-	if (!nh || (fdt32_to_cpu(nh->tag) != FDT_BEGIN_NODE))
-		goto fail;
+	if (((err = fdt_check_header(fdt)) != 0)
+	    || ((err = _fdt_check_node_offset(fdt, nodeoffset)) < 0))
+			goto fail;
 
 	if (len)
 		*len = strlen(nh->name);
@@ -193,17 +189,11 @@ const struct fdt_property *fdt_get_property(const void *fdt,
 	int offset, nextoffset;
 	int err;
 
-	if ((err = fdt_check_header(fdt)) != 0)
-		goto fail;
-
-	err = -FDT_ERR_BADOFFSET;
-	if (nodeoffset % FDT_TAGSIZE)
-		goto fail;
-
-	tag = fdt_next_tag(fdt, nodeoffset, &nextoffset);
-	if (tag != FDT_BEGIN_NODE)
-		goto fail;
+	if (((err = fdt_check_header(fdt)) != 0)
+	    || ((err = _fdt_check_node_offset(fdt, nodeoffset)) < 0))
+			goto fail;
 
+	nextoffset = err;
 	do {
 		offset = nextoffset;
 
diff --git a/libfdt/fdt_rw.c b/libfdt/fdt_rw.c
index 8609fa7..95a5c2c 100644
--- a/libfdt/fdt_rw.c
+++ b/libfdt/fdt_rw.c
@@ -176,8 +176,7 @@ int fdt_add_mem_rsv(void *fdt, uint64_t address, uint64_t size)
 	struct fdt_reserve_entry *re;
 	int err;
 
-	if ((err = rw_check_header(fdt)))
-		return err;
+	RW_CHECK_HEADER(fdt);
 
 	re = _fdt_mem_rsv_w(fdt, fdt_num_mem_rsv(fdt));
 	err = _blob_splice_mem_rsv(fdt, re, 0, 1);
@@ -194,8 +193,8 @@ int fdt_del_mem_rsv(void *fdt, int n)
 	struct fdt_reserve_entry *re = _fdt_mem_rsv_w(fdt, n);
 	int err;
 
-	if ((err = rw_check_header(fdt)))
-		return err;
+	RW_CHECK_HEADER(fdt);
+
 	if (n >= fdt_num_mem_rsv(fdt))
 		return -FDT_ERR_NOTFOUND;
 
@@ -227,15 +226,13 @@ static int _resize_property(void *fdt, int nodeoffset, const char *name, int len
 static int _add_property(void *fdt, int nodeoffset, const char *name, int len,
 			 struct fdt_property **prop)
 {
-	uint32_t tag;
 	int proplen;
 	int nextoffset;
 	int namestroff;
 	int err;
 
-	tag = fdt_next_tag(fdt, nodeoffset, &nextoffset);
-	if (tag != FDT_BEGIN_NODE)
-		return -FDT_ERR_BADOFFSET;
+	if ((nextoffset = _fdt_check_node_offset(fdt, nodeoffset)) < 0)
+		return nextoffset;
 
 	namestroff = _find_add_string(fdt, name);
 	if (namestroff < 0)
@@ -260,8 +257,7 @@ int fdt_set_name(void *fdt, int nodeoffset, const char *name)
 	int oldlen, newlen;
 	int err;
 
-	if ((err = rw_check_header(fdt)))
-		return err;
+	RW_CHECK_HEADER(fdt);
 
 	namep = (char *)fdt_get_name(fdt, nodeoffset, &oldlen);
 	if (!namep)
@@ -284,8 +280,7 @@ int fdt_setprop(void *fdt, int nodeoffset, const char *name,
 	struct fdt_property *prop;
 	int err;
 
-	if ((err = rw_check_header(fdt)))
-		return err;
+	RW_CHECK_HEADER(fdt);
 
 	err = _resize_property(fdt, nodeoffset, name, len, &prop);
 	if (err == -FDT_ERR_NOTFOUND)
@@ -456,11 +451,8 @@ int fdt_open_into(const void *fdt, void *buf, int bufsize)
 int fdt_pack(void *fdt)
 {
 	int mem_rsv_size;
-	int err;
 
-	err = rw_check_header(fdt);
-	if (err)
-		return err;
+	RW_CHECK_HEADER(fdt);
 
 	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
 		* sizeof(struct fdt_reserve_entry);
diff --git a/libfdt/fdt_sw.c b/libfdt/fdt_sw.c
index dda2de3..df09876 100644
--- a/libfdt/fdt_sw.c
+++ b/libfdt/fdt_sw.c
@@ -55,13 +55,21 @@
 
 #include "libfdt_internal.h"
 
-static int check_header_sw(void *fdt)
+static int sw_check_header(void *fdt)
 {
 	if (fdt_magic(fdt) != SW_MAGIC)
 		return -FDT_ERR_BADMAGIC;
+	/* FIXME: should check more details about the header state */
 	return 0;
 }
 
+#define SW_CHECK_HEADER(fdt) \
+	{ \
+		int err; \
+		if ((err = sw_check_header(fdt)) != 0) \
+			return err; \
+	}
+
 static void *grab_space(void *fdt, int len)
 {
 	int offset = fdt_size_dt_struct(fdt);
@@ -102,11 +110,10 @@ int fdt_create(void *buf, int bufsize)
 int fdt_add_reservemap_entry(void *fdt, uint64_t addr, uint64_t size)
 {
 	struct fdt_reserve_entry *re;
-	int err = check_header_sw(fdt);
 	int offset;
 
-	if (err)
-		return err;
+	SW_CHECK_HEADER(fdt);
+
 	if (fdt_size_dt_struct(fdt))
 		return -FDT_ERR_BADSTATE;
 
@@ -131,11 +138,9 @@ int fdt_finish_reservemap(void *fdt)
 int fdt_begin_node(void *fdt, const char *name)
 {
 	struct fdt_node_header *nh;
-	int err = check_header_sw(fdt);
 	int namelen = strlen(name) + 1;
 
-	if (err)
-		return err;
+	SW_CHECK_HEADER(fdt);
 
 	nh = grab_space(fdt, sizeof(*nh) + ALIGN(namelen, FDT_TAGSIZE));
 	if (! nh)
@@ -149,10 +154,8 @@ int fdt_begin_node(void *fdt, const char *name)
 int fdt_end_node(void *fdt)
 {
 	uint32_t *en;
-	int err = check_header_sw(fdt);
 
-	if (err)
-		return err;
+	SW_CHECK_HEADER(fdt);
 
 	en = grab_space(fdt, FDT_TAGSIZE);
 	if (! en)
@@ -188,11 +191,9 @@ static int find_add_string(void *fdt, const char *s)
 int fdt_property(void *fdt, const char *name, const void *val, int len)
 {
 	struct fdt_property *prop;
-	int err = check_header_sw(fdt);
 	int nameoff;
 
-	if (err)
-		return err;
+	SW_CHECK_HEADER(fdt);
 
 	nameoff = find_add_string(fdt, name);
 	if (nameoff == 0)
@@ -211,15 +212,13 @@ int fdt_property(void *fdt, const char *name, const void *val, int len)
 
 int fdt_finish(void *fdt)
 {
-	int err = check_header_sw(fdt);
 	char *p = (char *)fdt;
 	uint32_t *end;
 	int oldstroffset, newstroffset;
 	uint32_t tag;
 	int offset, nextoffset;
 
-	if (err)
-		return err;
+	SW_CHECK_HEADER(fdt);
 
 	/* Add terminator */
 	end = grab_space(fdt, sizeof(*end));
diff --git a/libfdt/libfdt_internal.h b/libfdt/libfdt_internal.h
index 52e1b8d..f72e70d 100644
--- a/libfdt/libfdt_internal.h
+++ b/libfdt/libfdt_internal.h
@@ -66,6 +66,7 @@
 	}
 
 uint32_t _fdt_next_tag(const void *fdt, int startoffset, int *nextoffset);
+int _fdt_check_node_offset(const void *fdt, int offset);
 const char *_fdt_find_string(const char *strtab, int tabsize, const char *s);
 int _fdt_node_end_offset(void *fdt, int nodeoffset);