Re: [Qemu-devel] [PATCH v2 2/2] Add dynamic generation of module_block.h

[Fam Zheng <famz@redhat.com>]

On Tue, 09/08 15:53, Marc Marí wrote:
> diff --git a/include/qemu/module_block.h b/include/qemu/module_block.h
> deleted file mode 100644
> index d725db8..0000000
> --- a/include/qemu/module_block.h
> +++ /dev/null
> @@ -1,90 +0,0 @@
> -/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
> -/*
> - * QEMU Block Module Infrastructure
> - *
> - * Copyright Red Hat, Inc. 2015
> - *
> - * 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.
> - *
> - */
> -

Could you reorder the patches so you don't need to add them remove the
generated header?

> diff --git a/scripts/modules/module_block.py b/scripts/modules/module_block.py
> new file mode 100755
> index 0000000..0846362
> --- /dev/null
> +++ b/scripts/modules/module_block.py
> @@ -0,0 +1,134 @@
> +#!/usr/bin/python
> +#
> +# Module information generator
> +#
> +# Copyright Red Hat, Inc. 2015
> +#
> +# 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(fhader, library, format_name, protocol_name,
> +                probe, probe_device):
> +    lines = []
> +    lines.append('.library_name = "' + library + '",')
> +    if format_name != "":
> +        lines.append('.format_name = "' + format_name + '",')
> +    if protocol_name != "":
> +        lines.append('.protocol_name = "' + protocol_name + '",')
> +    if probe:
> +        lines.append('.has_probe = true,')
> +    if probe_device:
> +        lines.append('.has_probe_device = true,')
> +
> +    text = '\n\t'.join(lines)
> +    fheader.write('\n\t{\n\t' + text + '\n\t},')
> +
> +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.find(".bdrv_probe") != -1:
> +                    probe = True
> +                elif line.find(".bdrv_probe_device") != -1:
> +                    probe_device = True
> +                elif line == "};":
> +                    add_module(fheader, library, format_name, protocol_name,
> +                                probe, probe_device)
> +                    found_start = False
> +            elif line.find("static BlockDriver") != -1:
> +                found_something = True
> +                found_start = True
> +                format_name = ""
> +                protocol_name = ""
> +                probe = False
> +                probe_device = False
> +
> +        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
> + *
> + * Copyright Red Hat, Inc. 2015
> + *
> + * 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.
> + *
> + */
> +
> +''')
> +
> +    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;
> +    bool has_probe;
> +    bool has_probe_device;
> +} block_driver_modules[] = {''')
> +
> +def print_bottom(fheader):
> +    fheader.write('''
> +};
> +
> +#endif
> +''')
> +
> +# First argument: output folder
> +# All other arguments: modules source files (.c)
> +output_dir = sys.argv[1]
> +if not os.path.isdir(output_dir):
> +    print("Folder " + output_dir + " does not exist", file=sys.stderr)
> +    sys.exit(1)
> +
> +path = output_dir + 'module_block.h'
> +
> +with open(path, '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)

If we decide to parse c sources, I really want the parser as simple as
possible, while keeping the syntax explicit:

in block_int.h:

    /* In order to allow dynamical loading, block modules should specify which
     * protocols and formats are supported with one or more of following
     * macros, which are parsed by code generator to create mappings from
     * format or protocol name to module name.
     */
    #define BLOCK_PROTOCOL_MODULE(protocol, has_probe)
    #define BLOCK_FORMAT_MODULE(format, has_probe)

in curl.c:
    BLOCK_PROTOCOL_MODULE(http, false)
    BLOCK_PROTOCOL_MODULE(https, false)
    BLOCK_PROTOCOL_MODULE(ftp, false)
    BLOCK_PROTOCOL_MODULE(ftps, false)
    BLOCK_PROTOCOL_MODULE(tftp, false)

in dmg.c:
    BLOCK_FORMAT_MODULE(dmg, true)

In generator.py, you can grep for "BLOCK_PROTOCOL_MODULE(*)" and
"BLOCK_FORMAT_MODULE(*)".

Fam