tdb2: use 64 bit file offsets on 32 bit systems if available.

And testing reveals a latent bug on 32 bit systems.

ccan/tdb2/io.c

@@ -48,8 +48,13 @@ void tdb_mmap(struct tdb_context *tdb)
 	if (tdb->flags & TDB_NOMMAP)
 		return;
 
-	tdb->file->map_ptr = mmap(NULL, tdb->file->map_size, tdb->mmap_flags,
-				  MAP_SHARED, tdb->file->fd, 0);
+	/* size_t can be smaller than off_t. */
+	if ((size_t)tdb->file->map_size == tdb->file->map_size) {
+		tdb->file->map_ptr = mmap(NULL, tdb->file->map_size,
+					  tdb->mmap_flags,
+					  MAP_SHARED, tdb->file->fd, 0);
+	} else
+		tdb->file->map_ptr = MAP_FAILED;
 
 	/*
 	 * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!

ccan/tdb2/private.h

@@ -19,6 +19,9 @@
 */
 
 #include "config.h"
+#if HAVE_FILE_OFFSET_BITS
+#define _FILE_OFFSET_BITS 64
+#endif
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>

ccan/tdb2/test/run-64-bit-tdb.c

@@ -0,0 +1,80 @@
+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/open.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tdb2/traverse.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	int flags[] = { TDB_DEFAULT, TDB_NOMMAP,
+			TDB_CONVERT, 
+			TDB_NOMMAP|TDB_CONVERT };
+
+	if (sizeof(off_t) <= 4) {
+		plan_tests(1);
+		pass("No 64 bit off_t");
+		return exit_status();
+	}
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 14);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		off_t old_size;
+		TDB_DATA k, d;
+		struct hash_info h;
+		struct tdb_used_record rec;
+		tdb_off_t off;
+
+		tdb = tdb_open("run-64-bit-tdb.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		ok1(tdb);
+		if (!tdb)
+			continue;
+
+		old_size = tdb->file->map_size;
+
+		/* This makes a sparse file */
+		ok1(ftruncate(tdb->file->fd, 0xFFFFFFF0) == 0);
+		ok1(add_free_record(tdb, old_size, 0xFFFFFFF0 - old_size,
+				    TDB_LOCK_WAIT) == TDB_SUCCESS);
+
+		/* Now add a little record past the 4G barrier. */
+		ok1(tdb_expand_file(tdb, 100) == TDB_SUCCESS);
+		ok1(add_free_record(tdb, 0xFFFFFFF0, 100, TDB_LOCK_WAIT)
+		    == TDB_SUCCESS);
+
+		ok1(tdb_check(tdb, NULL, NULL) == TDB_SUCCESS);
+
+		/* Test allocation path. */
+		k = tdb_mkdata("key", 4);
+		d = tdb_mkdata("data", 5);
+		ok1(tdb_store(tdb, k, d, TDB_INSERT) == 0);
+		ok1(tdb_check(tdb, NULL, NULL) == TDB_SUCCESS);
+
+		/* Make sure it put it at end as we expected. */
+		off = find_and_lock(tdb, k, F_RDLCK, &h, &rec, NULL);
+		ok1(off >= 0xFFFFFFF0);
+		tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
+
+		ok1(tdb_fetch(tdb, k, &d) == 0);
+		ok1(d.dsize == 5);
+		ok1(strcmp((char *)d.dptr, "data") == 0);
+		free(d.dptr);
+
+		ok1(tdb_delete(tdb, k) == 0);
+		ok1(tdb_check(tdb, NULL, NULL) == TDB_SUCCESS);
+
+		tdb_close(tdb);
+	}
+
+	/* We might get messages about mmap failing, so don't test
+	 * tap_log_messages */
+	return exit_status();
+}