rust: c header generator

diff --git a/rust/gen-c-headers.py b/rust/gen-c-headers.py
new file mode 100755 (executable)
index 0000000..391c51c
--- /dev/null
+++ b/rust/gen-c-headers.py
@@ -0,0 +1,194 @@
+#! /usr/bin/env python2
+
+# This script will scan Rust source files looking for extern "C"
+# functions and generate C header files from them with a filename
+# based on the Rust filename.
+#
+# Usage: From the top suricata source directory:
+#
+#    ./rust/gen-c-headers.py
+#
+
+from __future__ import print_function
+
+import sys
+import os
+import re
+from io import StringIO
+
+template = """/* Copyright (C) 2017 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * 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
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/*
+ * DO NOT EDIT. This file is automatically generated.
+ */
+
+#ifndef __%(name)s__
+#define __%(name)s__
+
+%(prototypes)s
+#endif /* ! __%(name)s__ */
+"""
+
+# Map of Rust types to C types.
+type_map = {
+    "i8": "int8_t",
+    "i32" :"int32_t",
+
+    "u8": "uint8_t",
+
+    "libc::c_void": "void",
+
+    "libc::c_int": "int",
+    "c_int": "int",
+    "libc::int8_t": "int8_t",
+
+    "libc::uint8_t": "uint8_t",
+    "libc::uint16_t": "uint16_t",
+    "libc::uint32_t": "uint32_t",
+    "libc::uint64_t": "uint64_t",
+
+    "SuricataContext": "SuricataContext",
+    "core::Flow": "Flow",
+    "DNSState": "RSDNSState",
+    "DNSTransaction": "RSDNSTransaction",
+    "JsonT": "json_t",
+    "DetectEngineState": "DetectEngineState",
+    "core::DetectEngineState": "DetectEngineState",
+    "core::AppLayerDecoderEvents": "AppLayerDecoderEvents",
+    "CLuaState": "lua_State",
+}
+
+def convert_type(rs_type):
+    m = re.match("^[^\s]+$", rs_type)
+    if m:
+        if rs_type in type_map:
+            return type_map[rs_type]
+
+    m = re.match("^(.*)(\s[^\s]+)$", rs_type)
+    if m:
+        mod = m.group(1).strip()
+        rtype = m.group(2).strip()
+        if rtype in type_map:
+            if mod in [
+                    "*mut",
+                    "*const",
+                    "&mut",
+                    "&'static mut",
+                    ]:
+                return "%s *" % (type_map[rtype])
+            elif mod in [
+                    "*mut *const"]:
+                return "%s **" % (type_map[rtype])
+            else:
+                raise Exception("Unknown modifier '%s' in '%s'." % (
+                    mod, rs_type))
+        else:
+            raise Exception("Unknown type: %s" % (rtype))
+
+    raise Exception("Failed to parse Rust type: %s" % (rs_type))
+
+def make_output_filename(filename):
+    parts = filename.split(os.path.sep)[2:]
+    last = os.path.splitext(parts.pop())[0]
+    outpath = "../src/rust-%s-%s.h" % (
+        "-".join(parts), last)
+    return outpath.replace("--", "-")
+
+def write_header(fileobj, filename):
+    filename = os.path.basename(filename).replace(
+        "-", "_").replace(".", "_").upper()
+    fileobj.write(file_header % {"name": filename})
+
+def should_regen(input_filename, output_filename):
+    """Check if a file should be regenerated. If the output doesn't exist,
+    or the input is newer than the output return True. Otherwise
+    return False.
+
+    """
+    if not os.path.exists(output_filename):
+        return True
+    if os.stat(input_filename).st_mtime > os.stat(output_filename).st_mtime:
+        return True
+    return False
+
+def gen_headers(filename):
+
+    output_filename = make_output_filename(filename)
+
+    if not should_regen(filename, output_filename):
+        return
+
+    buf = open(filename).read()
+    writer = StringIO()
+
+    for fn in re.findall(
+            r"^pub extern \"C\" fn ([A_Za-z0-9_]+)\(([^{]+)?\)"
+            r"(\s+-> ([^{]+))?",
+            buf,
+            re.M | re.DOTALL):
+
+        args = []
+
+        fnName = fn[0]
+
+        for arg in fn[1].split(","):
+            if not arg:
+                continue
+            arg_name, rs_type = arg.split(":", 1)
+            arg_name = arg_name.strip()
+            rs_type = rs_type.strip()
+            c_type = convert_type(rs_type)
+
+            if arg_name != "_":
+                args.append("%s %s" % (c_type, arg_name))
+            else:
+                args.append(c_type)
+
+        if not args:
+            args.append("void")
+
+        retType = fn[3].strip()
+        if retType == "":
+            returns = "void"
+        else:
+            returns = convert_type(retType)
+
+        writer.write(u"%s %s(%s);\n" % (returns, fnName, ", ".join(args)))
+
+    if writer.tell() > 0:
+        print("Writing %s" % (output_filename))
+        with open(output_filename, "w") as output:
+            output.write(template % {
+                "prototypes": writer.getvalue(),
+                "name": os.path.basename(output_filename).replace(
+                    "-", "_").replace(".", "_").upper()
+            })
+
+def main():
+
+    rust_top = os.path.dirname(sys.argv[0])
+    os.chdir(rust_top)
+
+    for dirpath, dirnames, filenames in os.walk("./src"):
+        for filename in filenames:
+            if filename.endswith(".rs"):
+                path = os.path.join(dirpath, filename)
+                gen_headers(path)
+
+if __name__ == "__main__":
+    sys.exit(main())