dedup

commit 9eb852d729dd0e58a51d453beb76b3fb3d420084
parent e45da8785b9e8436fb747f023743c910b06f36b5
Author: sin <sin@2f30.org>
Date:   Mon, 18 Feb 2019 19:24:24 +0000

Encode file format version in the bottom 16 bits of flags

Diffstat:
M
TODO
 | 
1
-
M
dedup.c
 | 
19
++++++++++++++++++-

2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/TODO b/TODO
@@ -1,4 +1,3 @@
 endianness agnostic
-version field in entry header
 file locking
 overflow checks
diff --git a/dedup.c b/dedup.c
@@ -23,6 +23,10 @@
 #define MSGSIZE 256
 #define MDSIZE SHA256_DIGEST_LENGTH
 
+/* file format version */
+#define VER_MIN 0
+#define VER_MAJ 0
+
 #define ROTL(x, y) (((x) << (y)) | ((x) >> (32 - (y))))
 
 enum {
@@ -676,8 +680,21 @@ init(void)
 
 	if (fstat(ifd, &sb) < 0)
 		err(1, "fstat %s", INDEXF);
-	if (sb.st_size != 0)
+	if (sb.st_size != 0) {
+		uint8_t maj, min;
+
 		xread(ifd, &enthdr, sizeof(enthdr));
+		min = enthdr.flags & 0xff;
+		maj = (enthdr.flags >> 8) & 0xff;
+
+		if (maj != VER_MAJ || min != VER_MIN)
+			errx(1, "expected index format version %u.%u but got %u.%u",
+			     VER_MAJ, VER_MIN, maj, min);
+	} else {
+		enthdr.flags = (VER_MAJ << 8) | VER_MIN;
+		xwrite(ifd, &enthdr, sizeof(enthdr));
+	}
+
 	if (verbose) {
 		fprintf(stderr, "original size: %llu bytes\n",
 		        (unsigned long long)enthdr.st.orig_size);