[flashrom-gerrit] Change in flashrom[master]: cbtable.c: Factor out lb_header_validation logic

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/37238 )

Change subject: cbtable.c: Factor out lb_header_validation logic
......................................................................

cbtable.c: Factor out lb_header_validation logic

Write a pure function for the header validation logic, it is
easier to unit-test.

Change-Id: Ia288bcbc5c371329952a6efba30ccf0e18965a3d
Signed-off-by: Edward O'Callaghan 
---
M cbtable.c
1 file changed, 20 insertions(+), 12 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/38/37238/1

diff --git a/cbtable.c b/cbtable.c
index bdf53ce..cd0cf15 100644
--- a/cbtable.c
+++ b/cbtable.c
@@ -131,6 +131,25 @@
    return (~chksum.word) & 0xFFFF;
 }

+static int lb_header_valid(struct lb_header *head, unsigned long addr)
+{
+	if (memcmp(head->signature, "LBIO", 4) != 0)
+		return 0;
+	msg_pdbg("Found candidate at: %08lx-%08lx\n",
+		     addr, addr + sizeof(*head) + head->table_bytes);
+	if (head->header_bytes != sizeof(*head)) {
+		msg_perr("Header bytes of %d are incorrect.\n",
+			head->header_bytes);
+		return 0;
+	}
+	if (compute_checksum((uint8_t *) head, sizeof(*head)) != 0) {
+		msg_perr("Bad header checksum.\n");
+		return 0;
+	}
+
+	return 1;
+}
+
 #define for_each_lbrec(head, rec) \
    for(rec = (struct lb_record *)(((char *)head) + sizeof(*head)); \
    	(((char *)rec) < (((char *)head) + sizeof(*head) + head->table_bytes))  && \
@@ -162,24 +181,13 @@
    	    (struct lb_header *)(((char *)base) + addr);
    	struct lb_record *recs =
    	    (struct lb_record *)(((char *)base) + addr + sizeof(*head));
-		if (memcmp(head->signature, "LBIO", 4) != 0)
+		if (!lb_header_valid(head, addr))
    		continue;
-		msg_pdbg("Found candidate at: %08lx-%08lx\n",
-			     addr, addr + head->table_bytes);
-		if (head->header_bytes != sizeof(*head)) {
-			msg_perr("Header bytes of %d are incorrect.\n",
-				head->header_bytes);
-			continue;
-		}
    	if (count_lb_records(head) != head->table_entries) {
    		msg_perr("Bad record count: %d.\n",
    			head->table_entries);
    		continue;
    	}
-		if (compute_checksum((uint8_t *) head, sizeof(*head)) != 0) {
-			msg_perr("Bad header checksum.\n");
-			continue;
-		}
    	if (compute_checksum(recs, head->table_bytes)
    	    != head->table_checksum) {
    		msg_perr("Bad table checksum: %04x.\n",