Fix alignment bug. Add security FIXME. Add SCHEMA describing db layout.

6 files changed, 86 insertions, 17 deletions

diff --git a/Makefile.am b/Makefile.am
index cf1db27..cbc139d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,5 +16,5 @@ dbfs_LDADD	= @GLIB_LIBS@ @FUSE_LIBS@ @DB_LIBS@ libdbfs.a
 mkdbfs_SOURCES	= mkdbfs.c
 mkdbfs_LDADD	= @GLIB_LIBS@ @DB_LIBS@ libdbfs.a
 
-EXTRA_DIST	= autogen.sh
+EXTRA_DIST	= autogen.sh SCHEMA
 
diff --git a/SCHEMA b/SCHEMA
new file mode 100644
index 0000000..aa8ca0e
--- /dev/null
+++ b/SCHEMA
@@ -0,0 +1,67 @@
+
+		Berkeley DB database schema for filesystem
+		------------------------------------------
+
+
+
+system environment variables:
+DB_HOME:	database home dir, for transaction database + logs
+DB_PASSWORD:	if present, AES-encrypt database with this password
+
+db4 environment
+---------------
+	"metadata": metadata database
+		page size 512
+		little endian byte order
+	optionally encrypted w/ DB4 AES encryption
+
+inode
+-----
+key:	/inode/%Lu	(%Lu == inode number)
+
+value record's fields (all little endian):
+
+struct dbfs_raw_inode:
+guint64         ino:		inode number (identity)
+guint64         version:	linear sequence number, starts @ 1
+guint32         mode:		unix mode_t
+guint32         nlink:		number of hard links
+guint32         uid:		unix user id
+guint32         gid:		unix group id
+guint64         rdev:		unix dev_t
+guint64         size:		inode data size, in bytes
+guint64         ctime:		file creation time
+guint64         atime:		file last-accessed time
+guint64         mtime:		file last-modified time
+struct dbfs_extent blocks[0]:	array of extents, describing inode data
+
+struct dbfs_extent:
+dbfs_blk_id_t   id:		20-byte sha1 hash of data
+guint64         size:		size of data block
+
+
+directories
+-----------
+An array of struct dbfs_dirent, aligned on DBFS_DIRENT_ALIGN bounds.
+
+key:	/dir/%Lu		inode number associated with this dir
+
+struct dbfs_dirent:
+guint32         magic:		magic number (0xd4d4d4d4U)
+guint16         res2:		reserved for future use
+guint16         namelen:	length of final filename component
+guint64         ino:		inode number of referenced inode
+char            name[0]:	UTF8 final filename component (namelen bytes)
+0-7 bytes			alignment padding
+
+The array of struct dbfs_direct is terminated by a final dbfs_dirent
+containing a zero-length name (namelen==0).
+
+
+symbolic links
+--------------
+key:	/symlink/%Lu		inode number associated with this symlink
+
+value:	UTF8 string, containing link text (variable length)
+
+
diff --git a/dbfs-backend.c b/dbfs-backend.c
index bee74f1..b4d7c44 100644
--- a/dbfs-backend.c
+++ b/dbfs-backend.c
@@ -237,8 +237,7 @@ int dbfs_dir_foreach(void *dir, dbfs_dir_actor_t func, void *userdata)
 		 * do not wind up misaligned.
 		 */
 		namelen = GUINT16_FROM_LE(de->namelen);
-		p += sizeof(struct dbfs_dirent) + namelen +
-		     (4 - (namelen & 0x3));
+		p += dbfs_dirent_next(namelen);
 	}
 
 	return rc;
@@ -374,8 +373,7 @@ static int dbfs_dir_append(guint64 parent, guint64 ino_n, const char *name)
 	/* adjust pointer 'p' to point to terminator entry */
 	de = p = di.end_ent;
 	namelen = GUINT16_FROM_LE(de->namelen);
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	/* increase directory data area size */
 	dir_size = p - val.data;
@@ -391,8 +389,7 @@ static int dbfs_dir_append(guint64 parent, guint64 ino_n, const char *name)
 	memcpy(de->name, name, di.namelen);
 
 	namelen = di.namelen;
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	/* append terminator entry */
 	de = p;
@@ -400,8 +397,7 @@ static int dbfs_dir_append(guint64 parent, guint64 ino_n, const char *name)
 	de->magic = GUINT32_TO_LE(DBFS_DE_MAGIC);
 
 	namelen = 0;
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	val.size = p - val.data;
 
diff --git a/dbfs.h b/dbfs.h
index 02f7342..0803156 100644
--- a/dbfs.h
+++ b/dbfs.h
@@ -3,12 +3,16 @@
 
 #include <glib.h>
 
+#define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
+
 enum {
 	DBFS_BLK_ID_LEN		= 20,
 
 	DBFS_UNLINK_DIR		= (1 << 0),
 
 	DBFS_ROOT_INO		= 1,
+
+	DBFS_DIRENT_ALIGN	= 8,
 };
 
 enum {
@@ -102,4 +106,9 @@ extern int dbfs_dir_new(guint64 parent, guint64 ino_n, const struct dbfs_inode *
 extern int dbfs_dir_write(guint64 ino, DBT *val);
 extern void dbfs_inode_free(struct dbfs_inode *ino);
 
+static inline size_t dbfs_dirent_next(guint16 namelen)
+{
+	return ALIGN(sizeof(struct dbfs_dirent) + namelen, DBFS_DIRENT_ALIGN);
+}
+
 #endif /* __DBFS_H__ */
diff --git a/libdbfs.c b/libdbfs.c
index 1c28f03..9b4d878 100644
--- a/libdbfs.c
+++ b/libdbfs.c
@@ -132,7 +132,7 @@ struct dbfs *dbfs_new(void)
 	if (passwd) {
 		fs->passwd = strdup(passwd);
 
-		/* this isn't a very good way to shroud the password */
+		/* FIXME: this isn't a very good way to shroud the password */
 		if (putenv("DB_PASSWORD=X"))
 			perror("putenv DB_PASSWORD (SECURITY WARNING)");
 	}
@@ -202,8 +202,7 @@ int dbfs_dir_new(guint64 parent, guint64 ino_n, const struct dbfs_inode *ino)
 	memcpy(q, ".", 1);
 
 	namelen = GUINT16_FROM_LE(de->namelen);
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	/*
 	 * add entry for ".."
@@ -217,8 +216,7 @@ int dbfs_dir_new(guint64 parent, guint64 ino_n, const struct dbfs_inode *ino)
 	memcpy(q, "..", 2);
 
 	namelen = GUINT16_FROM_LE(de->namelen);
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	/*
 	 * add terminating entry
@@ -227,8 +225,7 @@ int dbfs_dir_new(guint64 parent, guint64 ino_n, const struct dbfs_inode *ino)
 	de->magic = GUINT32_TO_LE(DBFS_DE_MAGIC);
 
 	namelen = GUINT16_FROM_LE(de->namelen);
-	p += sizeof(struct dbfs_dirent) + namelen +
-	     (4 - (namelen & 0x3));
+	p += dbfs_dirent_next(namelen);
 
 	/*
 	 * store dir in database
diff --git a/mkdbfs.c b/mkdbfs.c
index 524fb1d..8670c2a 100644
--- a/mkdbfs.c
+++ b/mkdbfs.c
@@ -48,7 +48,7 @@ void create_db(void)
 			goto err_out;
 		}
 
-		/* this isn't a very good way to shroud the password */
+		/* FIXME: this isn't a very good way to shroud the password */
 		if (putenv("DB_PASSWORD=X"))
 			perror("putenv (SECURITY WARNING)");
 	}