blockdev: Add dynamic generation of module_block.h

To simplify the addition of new block modules, add a script that generates
module_block.h automatically from the modules' source code.

This script assumes that the QEMU coding style rules are followed.

Signed-off-by: Marc Marí <markmb@redhat.com>
Signed-off-by: Colin Lord <clord@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1471008424-16465-3-git-send-email-clord@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Makefile

@@ -76,6 +76,8 @@ GENERATED_HEADERS += trace/generated-ust-provider.h
 GENERATED_SOURCES += trace/generated-ust.c
 endif
 
+GENERATED_HEADERS += module_block.h
+
 # Don't try to regenerate Makefile or configure
 # We don't generate any of them
 Makefile: ;
@@ -352,6 +354,11 @@ ivshmem-client$(EXESUF): $(ivshmem-client-obj-y) libqemuutil.a libqemustub.a
 ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) libqemuutil.a libqemustub.a
 	$(call LINK, $^)
 
+module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak
+	$(call quiet-command,$(PYTHON) $< $@ \
+	$(addprefix $(SRC_PATH)/,$(patsubst %.mo,%.c,$(block-obj-m))), \
+	"  GEN   $@")
+
 clean:
 # avoid old build problems by removing potentially incorrect old files
 	rm -f config.mak op-i386.h opc-i386.h gen-op-i386.h op-arm.h opc-arm.h gen-op-arm.h

scripts/modules/module_block.py

@@ -0,0 +1,108 @@
+#!/usr/bin/python
+#
+# Module information generator
+#
+# Copyright Red Hat, Inc. 2015 - 2016
+#
+# Authors:
+#  Marc Mari <markmb@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.
+# See the COPYING file in the top-level directory.
+
+from __future__ import print_function
+import sys
+import os
+
+def get_string_struct(line):
+    data = line.split()
+
+    # data[0] -> struct element name
+    # data[1] -> =
+    # data[2] -> value
+
+    return data[2].replace('"', '')[:-1]
+
+def add_module(fheader, library, format_name, protocol_name):
+    lines = []
+    lines.append('.library_name = "' + library + '",')
+    if format_name != "":
+        lines.append('.format_name = "' + format_name + '",')
+    if protocol_name != "":
+        lines.append('.protocol_name = "' + protocol_name + '",')
+
+    text = '\n        '.join(lines)
+    fheader.write('\n    {\n        ' + text + '\n    },')
+
+def process_file(fheader, filename):
+    # This parser assumes the coding style rules are being followed
+    with open(filename, "r") as cfile:
+        found_something = False
+        found_start = False
+        library, _ = os.path.splitext(os.path.basename(filename))
+        for line in cfile:
+            if found_start:
+                line = line.replace('\n', '')
+                if line.find(".format_name") != -1:
+                    format_name = get_string_struct(line)
+                elif line.find(".protocol_name") != -1:
+                    protocol_name = get_string_struct(line)
+                elif line == "};":
+                    add_module(fheader, library, format_name, protocol_name)
+                    found_start = False
+            elif line.find("static BlockDriver") != -1:
+                found_something = True
+                found_start = True
+                format_name = ""
+                protocol_name = ""
+
+        if not found_something:
+            print("No BlockDriver struct found in " + filename + ". \
+                    Is this really a module?", file=sys.stderr)
+            sys.exit(1)
+
+def print_top(fheader):
+    fheader.write('''/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
+/*
+ * QEMU Block Module Infrastructure
+ *
+ * Authors:
+ *  Marc Mari       <markmb@redhat.com>
+ */
+
+''')
+
+    fheader.write('''#ifndef QEMU_MODULE_BLOCK_H
+#define QEMU_MODULE_BLOCK_H
+
+#include "qemu-common.h"
+
+static const struct {
+    const char *format_name;
+    const char *protocol_name;
+    const char *library_name;
+} block_driver_modules[] = {''')
+
+def print_bottom(fheader):
+    fheader.write('''
+};
+
+#endif
+''')
+
+# First argument: output file
+# All other arguments: modules source files (.c)
+output_file = sys.argv[1]
+with open(output_file, 'w') as fheader:
+    print_top(fheader)
+
+    for filename in sys.argv[2:]:
+        if os.path.isfile(filename):
+            process_file(fheader, filename)
+        else:
+            print("File " + filename + " does not exist.", file=sys.stderr)
+            sys.exit(1)
+
+    print_bottom(fheader)
+
+sys.exit(0)