read_write_all: avoid arithmetic on void pointers.

[ccan] / ccan / tdb2 / tdb2.h

diff --git a/ccan/tdb2/tdb2.h b/ccan/tdb2/tdb2.h
index f934a7bf3baa70cb9fe27aa1731fe7dae771ba73..fa5787c3779acd424e7f3cbde6a4c5e6746eb45d 100644 (file)
--- a/ccan/tdb2/tdb2.h
+++ b/ccan/tdb2/tdb2.h
@@ -45,6 +45,7 @@ extern "C" {
 #endif
 #include <ccan/compiler/compiler.h>
 #include <ccan/typesafe_cb/typesafe_cb.h>
+#include <ccan/cast/cast.h>
 
 union tdb_attribute;
 struct tdb_context;
@@ -78,6 +79,7 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
 #define TDB_NOMMAP   8 /* don't use mmap */
 #define TDB_CONVERT 16 /* convert endian */
 #define TDB_NOSYNC   64 /* don't use synchronous transactions */
+#define TDB_SEQNUM   128 /* maintain a sequence number */
 
 /**
  * tdb_close - close and free a tdb.
@@ -220,6 +222,24 @@ static inline bool tdb_deq(struct tdb_data a, struct tdb_data b)
        return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0;
 }
 
+/**
+ * tdb_mkdata - make a struct tdb_data from const data
+ * @p: the constant pointer
+ * @len: the length
+ *
+ * As the dptr member of struct tdb_data is not constant, you need to
+ * cast it.  This function keeps thost casts in one place, as well as
+ * suppressing the warning some compilers give when casting away a
+ * qualifier (eg. gcc with -Wcast-qual)
+ */
+static inline struct tdb_data tdb_mkdata(const void *p, size_t len)
+{
+       struct tdb_data d;
+       d.dptr = cast_const(void *, p);
+       d.dsize = len;
+       return d;
+}
+
 /**
  * tdb_transaction_start - start a transaction
  * @tdb: the tdb context returned from tdb_open()
@@ -323,6 +343,25 @@ enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
                                                         TDB_DATA data,
                                                         void *p),
                                 void *p);
+
+/**
+ * tdb_get_seqnum - get a database sequence number
+ * @tdb: the tdb context returned from tdb_open()
+ *
+ * This returns a sequence number: any change to the database from a
+ * tdb context opened with the TDB_SEQNUM flag will cause that number
+ * to increment.  Note that the incrementing is unreliable (it is done
+ * without locking), so this is only useful as an optimization.
+ *
+ * For example, you may have a regular database backup routine which
+ * does not operate if the sequence number is unchanged.  In the
+ * unlikely event of a failed increment, it will be backed up next
+ * time any way.
+ *
+ * Returns an enum TDB_ERROR (ie. negative) on error.
+ */
+int64_t tdb_get_seqnum(struct tdb_context *tdb);
+
 /**
  * tdb_firstkey - get the "first" key in a TDB
  * @tdb: the tdb context returned from tdb_open()
@@ -410,6 +449,17 @@ enum TDB_ERROR tdb_check_(struct tdb_context *tdb,
                                                  void *private),
                          void *private);
 
+/**
+ * tdb_error - get the last error (not threadsafe)
+ * @tdb: the tdb context returned from tdb_open()
+ *
+ * Returns the last error returned by a TDB function.
+ *
+ * This makes porting from TDB1 easier, but note that the last error is not
+ * reliable in threaded programs.
+ */
+enum TDB_ERROR tdb_error(struct tdb_context *tdb);
+
 /**
  * enum tdb_summary_flags - flags for tdb_summary.
  */