Make xenstored use tdb, transactions can soft-fail (EAGAIN)

Transactions no longer take root dir, no longer lock & block: commit can fail spuriously with EAGAIN, not ETIMEDOUT.
Speeds up transactions by over 1000 times, should be NFS safe.
New program: xs_tdb_dump to dump raw TDB contents.
Don't do failure testing: we are no longer robust against all ENOMEM 8(
Introduce "struct node" which contains perms, children and data.
Make struct xs_permissions unpadded, so we can write to tdb w/o valgrind complaints.
Gently modify TDB to use talloc, not do alloc on tdb_delete.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 157 insertions, 0 deletions

diff --git a/tools/xenstore/tdb.h b/tools/xenstore/tdb.h
new file mode 100644
index 0000000000..d0e782de50
--- /dev/null
+++ b/tools/xenstore/tdb.h
@@ -0,0 +1,157 @@
+#ifndef __TDB_H__
+#define __TDB_H__
+
+/* 
+   Unix SMB/CIFS implementation.
+
+   trivial database library
+
+   Copyright (C) Andrew Tridgell 1999-2004
+   
+     ** NOTE! The following LGPL license applies to the tdb
+     ** library. This does NOT imply that all of Samba is released
+     ** under the LGPL
+   
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+
+/* flags to tdb_store() */
+#define TDB_REPLACE 1
+#define TDB_INSERT 2
+#define TDB_MODIFY 3
+
+/* flags for tdb_open() */
+#define TDB_DEFAULT 0 /* just a readability place holder */
+#define TDB_CLEAR_IF_FIRST 1
+#define TDB_INTERNAL 2 /* don't store on disk */
+#define TDB_NOLOCK   4 /* don't do any locking */
+#define TDB_NOMMAP   8 /* don't use mmap */
+#define TDB_CONVERT 16 /* convert endian (internal use) */
+#define TDB_BIGENDIAN 32 /* header is big-endian (internal use) */
+
+#define TDB_ERRCODE(code, ret) ((tdb->ecode = (code)), ret)
+
+/* error codes */
+enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK, 
+		TDB_ERR_OOM, TDB_ERR_EXISTS, TDB_ERR_NOLOCK, TDB_ERR_LOCK_TIMEOUT,
+		TDB_ERR_NOEXIST};
+
+#ifndef u32
+#define u32 unsigned
+#endif
+
+typedef struct TDB_DATA {
+	char *dptr;
+	size_t dsize;
+} TDB_DATA;
+
+typedef u32 tdb_len;
+typedef u32 tdb_off;
+
+/* this is stored at the front of every database */
+struct tdb_header {
+	char magic_food[32]; /* for /etc/magic */
+	u32 version; /* version of the code */
+	u32 hash_size; /* number of hash entries */
+	tdb_off rwlocks;
+	tdb_off reserved[31];
+};
+
+struct tdb_lock_type {
+	u32 count;
+	u32 ltype;
+};
+
+struct tdb_traverse_lock {
+	struct tdb_traverse_lock *next;
+	u32 off;
+	u32 hash;
+};
+
+#ifndef PRINTF_ATTRIBUTE
+#define PRINTF_ATTRIBUTE(a,b)
+#endif
+
+/* this is the context structure that is returned from a db open */
+typedef struct tdb_context {
+	char *name; /* the name of the database */
+	void *map_ptr; /* where it is currently mapped */
+	int fd; /* open file descriptor for the database */
+	tdb_len map_size; /* how much space has been mapped */
+	int read_only; /* opened read-only */
+	struct tdb_lock_type *locked; /* array of chain locks */
+	enum TDB_ERROR ecode; /* error code for last tdb error */
+	struct tdb_header header; /* a cached copy of the header */
+	u32 flags; /* the flags passed to tdb_open */
+	struct tdb_traverse_lock travlocks; /* current traversal locks */
+	struct tdb_context *next; /* all tdbs to avoid multiple opens */
+	dev_t device;	/* uniquely identifies this tdb */
+	ino_t inode;	/* uniquely identifies this tdb */
+	void (*log_fn)(struct tdb_context *tdb, int level, const char *, ...) PRINTF_ATTRIBUTE(3,4); /* logging function */
+	u32 (*hash_fn)(TDB_DATA *key);
+	int open_flags; /* flags used in the open - needed by reopen */
+} TDB_CONTEXT;
+
+typedef int (*tdb_traverse_func)(TDB_CONTEXT *, TDB_DATA, TDB_DATA, void *);
+typedef void (*tdb_log_func)(TDB_CONTEXT *, int , const char *, ...);
+typedef u32 (*tdb_hash_func)(TDB_DATA *key);
+
+TDB_CONTEXT *tdb_open(const char *name, int hash_size, int tdb_flags,
+		      int open_flags, mode_t mode);
+TDB_CONTEXT *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
+			 int open_flags, mode_t mode,
+			 tdb_log_func log_fn,
+			 tdb_hash_func hash_fn);
+
+int tdb_reopen(TDB_CONTEXT *tdb);
+int tdb_reopen_all(void);
+void tdb_logging_function(TDB_CONTEXT *tdb, tdb_log_func);
+enum TDB_ERROR tdb_error(TDB_CONTEXT *tdb);
+const char *tdb_errorstr(TDB_CONTEXT *tdb);
+TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_delete(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_store(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, int flag);
+int tdb_append(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA new_dbuf);
+int tdb_close(TDB_CONTEXT *tdb);
+TDB_DATA tdb_firstkey(TDB_CONTEXT *tdb);
+TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_traverse(TDB_CONTEXT *tdb, tdb_traverse_func fn, void *);
+int tdb_exists(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_lockall(TDB_CONTEXT *tdb);
+void tdb_unlockall(TDB_CONTEXT *tdb);
+
+/* Low level locking functions: use with care */
+int tdb_chainlock(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_chainunlock(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_chainlock_read(TDB_CONTEXT *tdb, TDB_DATA key);
+int tdb_chainunlock_read(TDB_CONTEXT *tdb, TDB_DATA key);
+TDB_CONTEXT *tdb_copy(TDB_CONTEXT *tdb, const char *outfile);
+
+/* Debug functions. Not used in production. */
+void tdb_dump_all(TDB_CONTEXT *tdb);
+int tdb_printfreelist(TDB_CONTEXT *tdb);
+
+extern TDB_DATA tdb_null;
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif /* tdb.h */