Add fetch.c/fetch.h, a module for fetching function arguments

- this is now a thin wrapper over gimme_arg, ideally the backends will
  eventually use this right interface

- in display_args.c, strip one layer of pointer wrapping, which is now
  done in output.c

1 files changed, 64 insertions, 0 deletions

diff --git a/fetch.h b/fetch.h
new file mode 100644
index 0000000..6a5385c
--- /dev/null
+++ b/fetch.h
@@ -0,0 +1,64 @@
+/*
+ * This file is part of ltrace.
+ * Copyright (C) 2011,2012 Petr Machata, Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef FETCH_H
+#define FETCH_H
+
+#include "forward.h"
+
+/* XXX isn't SYSCALL TOF just a different ABI?  Maybe we needed to
+ * support variant ABIs all along.  */
+enum tof {
+	LT_TOF_FUNCTION,	/* A real library function */
+	LT_TOF_FUNCTIONR,	/* Return from a real library function */
+	LT_TOF_SYSCALL,		/* A syscall */
+	LT_TOF_SYSCALLR,	/* Return from a syscall */
+};
+
+/* The contents of the structure is defined by the back end.  */
+struct fetch_context;
+
+/* Initialize argument fetching.  Returns NULL on failure.  RET_INFO
+ * is the return type of the function.  */
+struct fetch_context *fetch_arg_init(enum tof type, struct Process *proc,
+				     struct arg_type_info *ret_info);
+
+/* Make a clone of context.  */
+struct fetch_context *fetch_arg_clone(struct Process *proc,
+				      struct fetch_context *context);
+
+/* Load next argument.  The function returns 0 on success or a
+ * negative value on failure.  The extracted value is stored in
+ * *VALUEP.  */
+int fetch_arg_next(struct fetch_context *context, enum tof type,
+		   struct Process *proc,
+		   struct arg_type_info *info, struct value *valuep);
+
+/* Load return value.  The function returns 0 on success or a negative
+ * value on failure.  The extracted value is stored in *VALUEP.  */
+int fetch_retval(struct fetch_context *context, enum tof type,
+		 struct Process *proc,
+		 struct arg_type_info *info, struct value *valuep);
+
+/* Destroy fetch context.  CONTEXT shall be the same memory location
+ * that was passed to fetch_arg_next.  */
+void fetch_arg_done(struct fetch_context *context);
+
+#endif /* FETCH_H */