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

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Aug 17, 2015 at 10:09:35AM +0200, Marc Marí wrote:
> To simplify the addition of new block modules, add a script that generates
> include/qemu/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>
> ---
>  .gitignore                      |   1 +
>  Makefile                        |  10 ++-
>  scripts/modules/module_block.py | 132 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 140 insertions(+), 3 deletions(-)
>  create mode 100755 scripts/modules/module_block.py

I'd expect to see module_block.h deleted in this commit, otherwise
you're re-generating a file stored in git each time someone runs
make.

> diff --git a/scripts/modules/module_block.py b/scripts/modules/module_block.py
> new file mode 100755
> index 0000000..a9a9412
> --- /dev/null
> +++ b/scripts/modules/module_block.py
> @@ -0,0 +1,132 @@
> +#!/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.
> +
> +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?")
> +            sys.exit(1)


Errors ought to go to sys.stderr rather than stdout.



> +
> +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>

When the file is auto-generated, I'm not sure it is right to claim
copyright / authorship on it - if anything the copyright comes from
the files that you're using as the source for auto-generation.

> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.  See
> + * the COPYING file in the top-level directory.
> + *
> + */

> +# 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")

Again about 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.")

Again here.

> +            sys.exit(1)
> +
> +    print_bottom(fheader)
> +
> +sys.exit(0)

Regards,
Daniel
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