dedup

commit 514871477eab5d433ff6e942f1438d321e2e2dd0
parent 346aca7c9992b325ea9683adf7327c55613a1c54
Author: sin <sin@2f30.org>
Date:   Sat,  2 Mar 2019 12:30:15 +0000

Implement repo init operation

Diffstat:
M
README
 | 
11
+++++------
M
dedup.1
 | 
6
++++--
M
dedup.c
 | 
81
+++++++++++++++++++++++++++++++++++++++++++++----------------------------------

3 files changed, 55 insertions(+), 43 deletions(-)
diff --git a/README b/README
@@ -1,5 +1,9 @@
 dedup is a simple data deduplication program.
 
+To use dedup you have to first initialize the repository.
+
+    dedup -r ~/bak -i
+
 dedup only handles a single file at a time, so using tar is advised.
 For example, to dedup a tar file you can invoke dedup as follows:
 
@@ -22,9 +26,4 @@ To extract a file from the deduplicated store run:
 
     dedup -r ~/bak -e <hash> > dir.tar
 
-Cheers,
-sin
-
-Requirements:
-dedup uses LZ4 compression algorithm.
-You'll need a library for handling this, for example http://www.lz4.org
+Dedup depends on liblz4 and openssl.
diff --git a/dedup.1 b/dedup.1
@@ -1,4 +1,4 @@
-.Dd Feb 22, 2019
+.Dd March 02, 2019
 .Dt DEDUP 1
 .Os
 .Sh NAME
@@ -6,7 +6,7 @@
 .Nd data deduplication program
 .Sh SYNOPSIS
 .Nm dedup
-.Op Fl clv
+.Op Fl cilv
 .Op Fl e Ar id
 .Op Fl r Ar root
 .Op Fl m Ar message
@@ -20,6 +20,8 @@ only handles a single file at a time, so using tar is advised.
 .Bl -tag -width "-r root"
 .It Fl c
 Perform a consistency check on the deduplication storage.
+.It Fl i
+Initialize the repository.
 .It Fl l
 List snapshots by hash.
 .It Fl v
diff --git a/dedup.c b/dedup.c
@@ -485,19 +485,15 @@ save_cache(void)
 }
 
 static void
-load_blk_hdr(void)
+init_blk_hdr(void)
 {
-	struct stat sb;
-
-	if (fstat(sfd, &sb) < 0)
-		err(1, "fstat %s", STOREF);
-	if (sb.st_size == 0) {
-		blk_hdr.flags = (VER_MAJ << 8) | VER_MIN;
-		blk_hdr.size = BLK_HDR_LEN;
-		write_blk_hdr(sfd, &blk_hdr);
-		return;
-	}
+	blk_hdr.flags = (VER_MAJ << 8) | VER_MIN;
+	blk_hdr.size = BLK_HDR_LEN;
+}
 
+static void
+load_blk_hdr(void)
+{
 	read_blk_hdr(sfd, &blk_hdr);
 	match_ver(blk_hdr.flags);
 }
@@ -510,20 +506,16 @@ save_blk_hdr(void)
 }
 
 static void
-load_snap_hdr(void)
+init_snap_hdr(void)
 {
-	struct stat sb;
-
-	if (fstat(ifd, &sb) < 0)
-		err(1, "fstat %s", SNAPSF);
-	if (sb.st_size == 0) {
-		snap_hdr.flags = (VER_MAJ << 8) | VER_MIN;
-		snap_hdr.size = SNAP_HDR_LEN;
-		snap_hdr.st.min_blk_size = comp_size(BLKSIZE_MAX);
-		write_snap_hdr(ifd, &snap_hdr);
-		return;
-	}
+	snap_hdr.flags = (VER_MAJ << 8) | VER_MIN;
+	snap_hdr.size = SNAP_HDR_LEN;
+	snap_hdr.st.min_blk_size = comp_size(BLKSIZE_MAX);
+}
 
+static void
+load_snap_hdr(void)
+{
 	read_snap_hdr(ifd, &snap_hdr);
 	match_ver(snap_hdr.flags);
 }
@@ -536,19 +528,25 @@ save_snap_hdr(void)
 }
 
 static void
-init(void)
+init(int iflag)
 {
+	int flags;
+
 	cache = alloc_cache();
 
-	ifd = open(SNAPSF, O_RDWR | O_CREAT, 0600);
+	flags = O_RDWR;
+	if (iflag)
+		flags |= O_CREAT | O_EXCL;
+
+	ifd = open(SNAPSF, flags, 0600);
 	if (ifd < 0)
 		err(1, "open %s", SNAPSF);
 
-	sfd = open(STOREF, O_RDWR | O_CREAT, 0600);
+	sfd = open(STOREF, flags, 0600);
 	if (sfd < 0)
 		err(1, "open %s", STOREF);
 
-	cfd = open(CACHEF, O_RDWR | O_CREAT, 0600);
+	cfd = open(CACHEF, flags, 0600);
 	if (cfd < 0)
 		err(1, "open %s", CACHEF);
 
@@ -557,9 +555,14 @@ init(void)
 	    flock(cfd, LOCK_NB | LOCK_EX) < 0)
 		errx(1, "busy lock");
 
-	load_snap_hdr();
-	load_blk_hdr();
-	load_cache();
+	if (iflag) {
+		init_snap_hdr();
+		init_blk_hdr();
+	} else {
+		load_snap_hdr();
+		load_blk_hdr();
+		load_cache();
+	}
 }
 
 static void
@@ -568,9 +571,9 @@ term(void)
 	if (verbose > 0)
 		print_stats(&snap_hdr.st);
 
-	save_snap_hdr();
-	save_blk_hdr();
 	save_cache();
+	save_blk_hdr();
+	save_snap_hdr();
 
 	fsync(ifd);
 	fsync(sfd);
@@ -586,7 +589,7 @@ term(void)
 static void
 usage(void)
 {
-	fprintf(stderr, "usage: %s [-clv] [-e id] [-r root] [-m message] [file]\n", argv0);
+	fprintf(stderr, "usage: %s [-cilv] [-e id] [-r root] [-m message] [file]\n", argv0);
 	exit(1);
 }
 
@@ -595,7 +598,7 @@ main(int argc, char *argv[])
 {
 	uint8_t md[MDSIZE];
 	char *id = NULL, *root = NULL, *msg = NULL;
-	int fd = -1, lflag = 0, cflag = 0;
+	int fd = -1, iflag = 0, lflag = 0, cflag = 0;
 
 	ARGBEGIN {
 	case 'c':
@@ -604,6 +607,9 @@ main(int argc, char *argv[])
 	case 'e':
 		id = EARGF(usage());
 		break;
+	case 'i':
+		iflag = 1;
+		break;
 	case 'l':
 		lflag = 1;
 		break;
@@ -645,7 +651,12 @@ main(int argc, char *argv[])
 			err(1, "chdir: %s", root);
 	}
 
-	init();
+	init(iflag);
+
+	if (iflag) {
+		term();
+		return 0;
+	}
 
 	if (cflag) {
 		xlseek(ifd, SNAP_HDR_LEN, SEEK_SET);