blk: update checksum calculation algorithm

- Update the checksum handling to handle BE systems.
- Improve the way the chk-sums are calculated.
- Adjust the checksum unittest to be endianess aware.

Initial version by @mdalecki

src/blk.c

@@ -346,7 +346,6 @@ pmemblk_pool_open_common(const char *path, size_t bsize, int rdonly)
 		uuid_generate(hdrp->uuid);
 		hdrp->crtime = htole64((uint64_t)time(NULL));
 		util_checksum(hdrp, sizeof (*hdrp), &hdrp->checksum, 1);
-		hdrp->checksum = htole64(hdrp->checksum);
 
 		/* store pool's header */
 		pmem_msync(hdrp, sizeof (*hdrp));

src/btt.c

@@ -318,7 +318,6 @@ read_info(struct btt_info *infop)
 	infop->mapoff = le64toh(infop->mapoff);
 	infop->flogoff = le64toh(infop->flogoff);
 	infop->infooff = le64toh(infop->infooff);
-	infop->checksum = le64toh(infop->checksum);
 
 	/* and to be valid, the fields must checksum correctly */
 	if (!util_checksum(infop, sizeof (*infop), &infop->checksum, 0)) {

src/log.c

@@ -173,7 +173,6 @@ pmemlog_pool_open_common(const char *path, int rdonly)
 		uuid_generate(hdrp->uuid);
 		hdrp->crtime = htole64((uint64_t)time(NULL));
 		util_checksum(hdrp, sizeof (*hdrp), &hdrp->checksum, 1);
-		hdrp->checksum = htole64(hdrp->checksum);
 
 		/* store pool's header */
 		pmem_msync(hdrp, sizeof (*hdrp));

src/test/checksum/checksum.c

@@ -36,6 +36,7 @@
  * usage: checksum files...
  */
 
+#include <endian.h>
 #include "unittest.h"
 
 #include "util.h"
@@ -55,11 +56,12 @@ fletcher64(void *addr, size_t len)
 	uint32_t hi32 = 0;
 
 	while (p32 < p32end) {
-		lo32 += *p32++;
+		lo32 += le32toh(*p32);
+		p32++;
 		hi32 += lo32;
 	}
 
-	return (uint64_t)hi32 << 32 | lo32;
+	return htole64((uint64_t)hi32 << 32 | lo32);
 }
 
 int
@@ -96,7 +98,7 @@ main(int argc, char *argv[])
 			uint64_t oldval = *ptr;
 
 			/* mess with it */
-			*ptr = 0x123;
+			*ptr = htole64(0x123);
 
 			/*
 			 * calc a checksum and have it installed

src/util.c

@@ -218,8 +218,9 @@ util_unmap(void *addr, size_t len)
  * util_checksum -- compute Fletcher64 checksum
  *
  * csump points to where the checksum lives, so that location
- * is treated as zeros while calculating the checksum.  If
- * insert is true, the calculated checksum is inserted into
+ * is treated as zeros while calculating the checksum. The
+ * checksummed data is assumed to be in little endian order.
+ * If insert is true, the calculated checksum is inserted into
  * the range at *csump.  Otherwise the calculated checksum is
  * checked against *csump and the result returned (true means
  * the range checksummed correctly).
@@ -242,18 +243,19 @@ util_checksum(void *addr, size_t len, uint64_t *csump, int insert)
 			p32++;
 			hi32 += lo32;
 		} else {
-			lo32 += *p32++;
+			lo32 += le32toh(*p32);
+			++p32;
 			hi32 += lo32;
 		}
 
 	csum = (uint64_t)hi32 << 32 | lo32;
 
 	if (insert) {
-		*csump = csum;
+		*csump = htole64(csum);
 		return 1;
 	}
 
-	return *csump == csum;
+	return *csump == htole64(csum);
 }
 
 /*