1 files changed, 98 insertions, 0 deletions
diff --git a/db-4.8.30/os_windows/os_truncate.c b/db-4.8.30/os_windows/os_truncate.c
new file mode 100644
index 0000000..b35233b
--- /dev/null
+++ b/db-4.8.30/os_windows/os_truncate.c
@@ -0,0 +1,98 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2004-2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#include "db_config.h"
+
+#include "db_int.h"
+
+/*
+ * __os_truncate --
+ *	Truncate the file.
+ */
+int
+__os_truncate(env, fhp, pgno, pgsize)
+	ENV *env;
+	DB_FH *fhp;
+	db_pgno_t pgno;
+	u_int32_t pgsize;
+{
+	/* Yes, this really is how Microsoft have designed their API */
+	union {
+		__int64 bigint;
+		struct {
+			unsigned long low;
+			long high;
+		};
+	} off;
+	DB_ENV *dbenv;
+	off_t offset;
+	int ret;
+
+	dbenv = env == NULL ? NULL : env->dbenv;
+	offset = (off_t)pgsize * pgno;
+	ret = 0;
+
+	if (dbenv != NULL &&
+	    FLD_ISSET(dbenv->verbose, DB_VERB_FILEOPS | DB_VERB_FILEOPS_ALL))
+		__db_msg(env,
+		    "fileops: truncate %s to %lu", fhp->name, (u_long)offset);
+
+#ifdef HAVE_FILESYSTEM_NOTZERO
+	/*
+	 * If the filesystem doesn't zero fill, it isn't safe to extend the
+	 * file, or we end up with junk blocks.  Just return in that case.
+	 */
+	if (__os_fs_notzero()) {
+		off_t stat_offset;
+		u_int32_t mbytes, bytes;
+
+		/* Stat the file. */
+		if ((ret =
+		    __os_ioinfo(env, NULL, fhp, &mbytes, &bytes, NULL)) != 0)
+			return (ret);
+		stat_offset = (off_t)mbytes * MEGABYTE + bytes;
+
+		if (offset > stat_offset)
+			return (0);
+	}
+#endif
+
+	LAST_PANIC_CHECK_BEFORE_IO(env);
+
+	/*
+	 * Windows doesn't provide truncate directly.  Instead, it has
+	 * SetEndOfFile, which truncates to the current position.  To
+	 * deal with that, we open a duplicate file handle for truncating.
+	 *
+	 * We want to retry the truncate call, which involves a SetFilePointer
+	 * and a SetEndOfFile, but there are several complications:
+	 *
+	 * 1) since the Windows API deals in 32-bit values, it's possible that
+	 *    the return from SetFilePointer (the low 32-bits) is
+	 *    INVALID_SET_FILE_POINTER even when the call has succeeded.  So we
+	 *    have to also check whether GetLastError() returns NO_ERROR.
+	 *
+	 * 2) when it returns, SetFilePointer overwrites the high bits of the
+	 *    offset, so if we need to retry, we have to reset the offset each
+	 *    time.
+	 *
+	 * We can't switch to SetFilePointerEx, which knows about 64-bit
+	 * offsets, because it isn't supported on Win9x/ME.
+	 */
+	RETRY_CHK((off.bigint = (__int64)pgsize * pgno,
+	    (SetFilePointer(fhp->trunc_handle, off.low, &off.high, FILE_BEGIN)
+	    == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR) ||
+	    !SetEndOfFile(fhp->trunc_handle)), ret);
+
+	if (ret != 0) {
+		__db_syserr(env, ret, "SetFilePointer: %lu", pgno * pgsize);
+		ret = __os_posix_err(ret);
+	}
+
+	return (ret);
+}