New upstream version 1.0upstream/1.0

20 files changed, 1155 insertions, 0 deletions

diff --git a/src/hydrilla/__init__.py b/src/hydrilla/__init__.py
new file mode 100644
index 0000000..6aeb276
--- /dev/null
+++ b/src/hydrilla/__init__.py
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: 0BSD
+
+# Copyright (C) 2013-2020, PyPA
+
+# https://packaging.python.org/en/latest/guides/packaging-namespace-packages/#pkgutil-style-namespace-packages
+
+__path__ = __import__('pkgutil').extend_path(__path__, __name__)
diff --git a/src/hydrilla/builder/__init__.py b/src/hydrilla/builder/__init__.py
new file mode 100644
index 0000000..73dc579
--- /dev/null
+++ b/src/hydrilla/builder/__init__.py
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: CC0-1.0
+
+# Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+#
+# Available under the terms of Creative Commons Zero v1.0 Universal.
+
+from .build import Build
diff --git a/src/hydrilla/builder/__main__.py b/src/hydrilla/builder/__main__.py
new file mode 100644
index 0000000..87dc9e2
--- /dev/null
+++ b/src/hydrilla/builder/__main__.py
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: CC0-1.0
+
+# Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+#
+# Available under the terms of Creative Commons Zero v1.0 Universal.
+
+from . import build
+
+build.perform()
diff --git a/src/hydrilla/builder/_version.py b/src/hydrilla/builder/_version.py
new file mode 100644
index 0000000..d953eef
--- /dev/null
+++ b/src/hydrilla/builder/_version.py
@@ -0,0 +1,5 @@
+# coding: utf-8
+# file generated by setuptools_scm
+# don't change, don't track in version control
+version = '1.0'
+version_tuple = (1, 0)
diff --git a/src/hydrilla/builder/build.py b/src/hydrilla/builder/build.py
new file mode 100644
index 0000000..8eec4a4
--- /dev/null
+++ b/src/hydrilla/builder/build.py
@@ -0,0 +1,417 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# Building Hydrilla packages.
+#
+# This file is part of Hydrilla
+#
+# Copyright (C) 2022 Wojtek Kosior
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+#
+# I, Wojtek Kosior, thereby promise not to sue for violation of this
+# file's license. Although I request that you do not make use this code
+# in a proprietary program, I am not going to enforce this in court.
+
+# Enable using with Python 3.7.
+from __future__ import annotations
+
+import json
+import re
+import zipfile
+from pathlib import Path
+from hashlib import sha256
+from sys import stderr
+
+import jsonschema
+import click
+
+from .. import util
+from . import _version
+
+here = Path(__file__).resolve().parent
+
+_ = util.translation(here / 'locales').gettext
+
+index_validator = util.validator_for('package_source-1.0.1.schema.json')
+
+schemas_root = 'https://hydrilla.koszko.org/schemas'
+
+generated_by = {
+    'name': 'hydrilla.builder',
+    'version': _version.version
+}
+
+class FileReferenceError(Exception):
+    """
+    Exception used to report various problems concerning files referenced from
+    source package's index.json.
+    """
+
+class ReuseError(Exception):
+    """
+    Exception used to report various problems when calling the REUSE tool.
+    """
+
+class FileBuffer:
+    """
+    Implement a file-like object that buffers data written to it.
+    """
+    def __init__(self):
+        """
+        Initialize FileBuffer.
+        """
+        self.chunks = []
+
+    def write(self, b):
+        """
+        Buffer 'b', return number of bytes buffered.
+
+        'b' is expected to be an instance of 'bytes' or 'str', in which case it
+        gets encoded as UTF-8.
+        """
+        if type(b) is str:
+            b = b.encode()
+        self.chunks.append(b)
+        return len(b)
+
+    def flush(self):
+        """
+        A no-op mock of file-like object's flush() method.
+        """
+        pass
+
+    def get_bytes(self):
+        """
+        Return all data written so far concatenated into a single 'bytes'
+        object.
+        """
+        return b''.join(self.chunks)
+
+def generate_spdx_report(root):
+    """
+    Use REUSE tool to generate an SPDX report for sources under 'root' and
+    return the report's contents as 'bytes'.
+
+    'root' shall be an instance of pathlib.Path.
+
+    In case the directory tree under 'root' does not constitute a
+    REUSE-compliant package, linting report is printed to standard output and
+    an exception is raised.
+
+    In case the reuse package is not installed, an exception is also raised.
+    """
+    try:
+        from reuse._main import main as reuse_main
+    except ModuleNotFoundError:
+        raise ReuseError(_('couldnt_import_reuse_is_it_installed'))
+
+    mocked_output = FileBuffer()
+    if reuse_main(args=['--root', str(root), 'lint'], out=mocked_output) != 0:
+        stderr.write(mocked_output.get_bytes().decode())
+        raise ReuseError(_('spdx_report_from_reuse_incompliant'))
+
+    mocked_output = FileBuffer()
+    if reuse_main(args=['--root', str(root), 'spdx'], out=mocked_output) != 0:
+        stderr.write(mocked_output.get_bytes().decode())
+        raise ReuseError("Couldn't generate an SPDX report for package.")
+
+    return mocked_output.get_bytes()
+
+class FileRef:
+    """Represent reference to a file in the package."""
+    def __init__(self, path: Path, contents: bytes):
+        """Initialize FileRef."""
+        self.include_in_distribution = False
+        self.include_in_zipfile      = True
+        self.path                    = path
+        self.contents                = contents
+
+        self.contents_hash = sha256(contents).digest().hex()
+
+    def make_ref_dict(self, filename: str):
+        """
+        Represent the file reference through a dict that can be included in JSON
+        defintions.
+        """
+        return {
+            'file':   filename,
+            'sha256': self.contents_hash
+        }
+
+class Build:
+    """
+    Build a Hydrilla package.
+    """
+    def __init__(self, srcdir, index_json_path):
+        """
+        Initialize a build. All files to be included in a distribution package
+        are loaded into memory, all data gets validated and all necessary
+        computations (e.g. preparing of hashes) are performed.
+
+        'srcdir' and 'index_json' are expected to be pathlib.Path objects.
+        """
+        self.srcdir          = srcdir.resolve()
+        self.index_json_path = index_json_path
+        self.files_by_path   = {}
+        self.resource_list   = []
+        self.mapping_list    = []
+
+        if not index_json_path.is_absolute():
+            self.index_json_path = (self.srcdir / self.index_json_path)
+
+        self.index_json_path = self.index_json_path.resolve()
+
+        with open(self.index_json_path, 'rt') as index_file:
+            index_json_text = index_file.read()
+
+        index_obj = json.loads(util.strip_json_comments(index_json_text))
+
+        self.files_by_path[self.srcdir / 'index.json'] = \
+            FileRef(self.srcdir / 'index.json', index_json_text.encode())
+
+        self._process_index_json(index_obj)
+
+    def _process_file(self, filename: str, include_in_distribution: bool=True):
+        """
+        Resolve 'filename' relative to srcdir, load it to memory (if not loaded
+        before), compute its hash and store its information in
+        'self.files_by_path'.
+
+        'filename' shall represent a relative path using '/' as a separator.
+
+        if 'include_in_distribution' is True it shall cause the file to not only
+        be included in the source package's zipfile, but also written as one of
+        built package's files.
+
+        Return file's reference object that can be included in JSON defintions
+        of various kinds.
+        """
+        path = self.srcdir
+        for segment in filename.split('/'):
+            path /= segment
+
+        path = path.resolve()
+        if not path.is_relative_to(self.srcdir):
+            raise FileReferenceError(_('loading_{}_outside_package_dir')
+                                     .format(filename))
+
+        if str(path.relative_to(self.srcdir)) == 'index.json':
+            raise FileReferenceError(_('loading_reserved_index_json'))
+
+        file_ref = self.files_by_path.get(path)
+        if file_ref is None:
+            with open(path, 'rb') as file_handle:
+                contents = file_handle.read()
+
+            file_ref = FileRef(path, contents)
+            self.files_by_path[path] = file_ref
+
+        if include_in_distribution:
+            file_ref.include_in_distribution = True
+
+        return file_ref.make_ref_dict(filename)
+
+    def _prepare_source_package_zip(self, root_dir_name: str):
+        """
+        Create and store in memory a .zip archive containing files needed to
+        build this source package.
+
+        'root_dir_name' shall not contain any slashes ('/').
+
+        Return zipfile's sha256 sum's hexstring.
+        """
+        fb = FileBuffer()
+        root_dir_path = Path(root_dir_name)
+
+        def zippath(file_path):
+            file_path = root_dir_path / file_path.relative_to(self.srcdir)
+            return file_path.as_posix()
+
+        with zipfile.ZipFile(fb, 'w') as xpi:
+            for file_ref in self.files_by_path.values():
+                if file_ref.include_in_zipfile:
+                    xpi.writestr(zippath(file_ref.path), file_ref.contents)
+
+        self.source_zip_contents = fb.get_bytes()
+
+        return sha256(self.source_zip_contents).digest().hex()
+
+    def _process_item(self, item_def: dict):
+        """
+        Process 'item_def' as definition of a resource/mapping and store in
+        memory its processed form and files used by it.
+
+        Return a minimal item reference suitable for using in source
+        description.
+        """
+        copy_props = ['type', 'identifier', 'long_name', 'description']
+        for prop in ('comment', 'uuid'):
+            if prop in item_def:
+                copy_props.append(prop)
+
+        if item_def['type'] == 'resource':
+            item_list = self.resource_list
+
+            copy_props.append('revision')
+
+            script_file_refs = [self._process_file(f['file'])
+                                for f in item_def.get('scripts', [])]
+
+            deps = [{'identifier': res_ref['identifier']}
+                    for res_ref in item_def.get('dependencies', [])]
+
+            new_item_obj = {
+                'dependencies': deps,
+                'scripts':      script_file_refs
+            }
+        else:
+            item_list = self.mapping_list
+
+            payloads = {}
+            for pat, res_ref in item_def.get('payloads', {}).items():
+                payloads[pat] = {'identifier': res_ref['identifier']}
+
+            new_item_obj = {
+                'payloads': payloads
+            }
+
+        new_item_obj.update([(p, item_def[p]) for p in copy_props])
+
+        new_item_obj['version'] = util.normalize_version(item_def['version'])
+        new_item_obj['$schema'] = f'{schemas_root}/api_{item_def["type"]}_description-1.schema.json'
+        new_item_obj['source_copyright'] = self.copyright_file_refs
+        new_item_obj['source_name'] = self.source_name
+        new_item_obj['generated_by'] = generated_by
+
+        item_list.append(new_item_obj)
+
+        props_in_ref = ('type', 'identifier', 'version', 'long_name')
+        return dict([(prop, new_item_obj[prop]) for prop in props_in_ref])
+
+    def _process_index_json(self, index_obj: dict):
+        """
+        Process 'index_obj' as contents of source package's index.json and store
+        in memory this source package's zipfile as well as package's individual
+        files and computed definitions of the source package and items defined
+        in it.
+        """
+        index_validator.validate(index_obj)
+
+        schema = f'{schemas_root}/api_source_description-1.schema.json'
+
+        self.source_name = index_obj['source_name']
+
+        generate_spdx = index_obj.get('reuse_generate_spdx_report', False)
+        if generate_spdx:
+            contents  = generate_spdx_report(self.srcdir)
+            spdx_path = (self.srcdir / 'report.spdx').resolve()
+            spdx_ref  = FileRef(spdx_path, contents)
+
+            spdx_ref.include_in_zipfile = False
+            self.files_by_path[spdx_path] = spdx_ref
+
+        self.copyright_file_refs = \
+            [self._process_file(f['file']) for f in index_obj['copyright']]
+
+        if generate_spdx and not spdx_ref.include_in_distribution:
+            raise FileReferenceError(_('report_spdx_not_in_copyright_list'))
+
+        item_refs = [self._process_item(d) for d in index_obj['definitions']]
+
+        for file_ref in index_obj.get('additional_files', []):
+            self._process_file(file_ref['file'], include_in_distribution=False)
+
+        root_dir_path = Path(self.source_name)
+
+        source_archives_obj = {
+            'zip' : {
+                'sha256': self._prepare_source_package_zip(root_dir_path)
+            }
+        }
+
+        self.source_description = {
+            '$schema':            schema,
+            'source_name':        self.source_name,
+            'source_copyright':   self.copyright_file_refs,
+            'upstream_url':       index_obj['upstream_url'],
+            'definitions':        item_refs,
+            'source_archives':    source_archives_obj,
+            'generated_by':       generated_by
+        }
+
+        if 'comment' in index_obj:
+            self.source_description['comment'] = index_obj['comment']
+
+    def write_source_package_zip(self, dstpath: Path):
+        """
+        Create a .zip archive containing files needed to build this source
+        package and write it at 'dstpath'.
+        """
+        with open(dstpath, 'wb') as output:
+            output.write(self.source_zip_contents)
+
+    def write_package_files(self, dstpath: Path):
+        """Write package files under 'dstpath' for distribution."""
+        file_dir_path = (dstpath / 'file' / 'sha256').resolve()
+        file_dir_path.mkdir(parents=True, exist_ok=True)
+
+        for file_ref in self.files_by_path.values():
+            if file_ref.include_in_distribution:
+                file_path = file_dir_path / file_ref.contents_hash
+                file_path.write_bytes(file_ref.contents)
+
+        source_dir_path = (dstpath / 'source').resolve()
+        source_dir_path.mkdir(parents=True, exist_ok=True)
+        source_name = self.source_description["source_name"]
+
+        with open(source_dir_path / f'{source_name}.json', 'wt') as output:
+            json.dump(self.source_description, output)
+
+        with open(source_dir_path / f'{source_name}.zip', 'wb') as output:
+            output.write(self.source_zip_contents)
+
+        for item_type, item_list in [
+                ('resource', self.resource_list),
+                ('mapping', self.mapping_list)
+        ]:
+            item_type_dir_path = (dstpath / item_type).resolve()
+
+            for item_def in item_list:
+                item_dir_path = item_type_dir_path / item_def['identifier']
+                item_dir_path.mkdir(parents=True, exist_ok=True)
+
+                version = '.'.join([str(n) for n in item_def['version']])
+                with open(item_dir_path / version, 'wt') as output:
+                    json.dump(item_def, output)
+
+dir_type = click.Path(exists=True, file_okay=False, resolve_path=True)
+
+@click.option('-s', '--srcdir', default='./', type=dir_type, show_default=True,
+              help=_('source_directory_to_build_from'))
+@click.option('-i', '--index-json', default='index.json', type=click.Path(),
+              help=_('path_instead_of_index_json'))
+@click.option('-d', '--dstdir', type=dir_type, required=True,
+              help=_('built_package_files_destination'))
+@click.version_option(version=_version.version, prog_name='Hydrilla builder',
+                      message=_('%(prog)s_%(version)s_license'),
+                      help=_('version_printing'))
+def perform(srcdir, index_json, dstdir):
+    """<this will be replaced by a localized docstring for Click to pick up>"""
+    build = Build(Path(srcdir), Path(index_json))
+    build.write_package_files(Path(dstdir))
+
+perform.__doc__ = _('build_package_from_srcdir_to_dstdir')
+
+perform = click.command()(perform)
diff --git a/src/hydrilla/builder/locales/en_US/LC_MESSAGES/hydrilla-messages.po b/src/hydrilla/builder/locales/en_US/LC_MESSAGES/hydrilla-messages.po
new file mode 100644
index 0000000..e3ab525
--- /dev/null
+++ b/src/hydrilla/builder/locales/en_US/LC_MESSAGES/hydrilla-messages.po
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: CC0-1.0
+#
+# English (United States) translations for hydrilla.builder.
+# Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+# Available under the terms of Creative Commons Zero v1.0 Universal.
+msgid ""
+msgstr ""
+"Project-Id-Version: hydrilla.builder 0.1.dev16+g4e46d7f.d20220211\n"
+"Report-Msgid-Bugs-To: koszko@koszko.org\n"
+"POT-Creation-Date: 2022-04-19 13:51+0200\n"
+"PO-Revision-Date: 2022-02-12 00:00+0000\n"
+"Last-Translator: Wojtek Kosior <koszko@koszko.org>\n"
+"Language: en_US\n"
+"Language-Team: en_US <koszko@koszko.org>\n"
+"Plural-Forms: nplurals=2; plural=(n != 1)\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=utf-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Generated-By: Babel 2.8.0\n"
+
+#: src/hydrilla/builder/build.py:118
+msgid "couldnt_import_reuse_is_it_installed"
+msgstr ""
+"Could not import 'reuse'. Is the tool installed and visible to this "
+"Python instance?"
+
+#: src/hydrilla/builder/build.py:123
+msgid "spdx_report_from_reuse_incompliant"
+msgstr "Attempt to generate an SPDX report for a REUSE-incompliant package."
+
+#: src/hydrilla/builder/build.py:207
+msgid "loading_{}_outside_package_dir"
+msgstr "Attempt to load '{}' which lies outside package source directory."
+
+#: src/hydrilla/builder/build.py:211
+msgid "loading_reserved_index_json"
+msgstr "Attempt to load 'index.json' which is a reserved filename."
+
+#: src/hydrilla/builder/build.py:329
+msgid "report_spdx_not_in_copyright_list"
+msgstr ""
+"Told to generate 'report.spdx' but 'report.spdx' is not listed among "
+"copyright files. Refusing to proceed."
+
+#: src/hydrilla/builder/build.py:402
+msgid "source_directory_to_build_from"
+msgstr "Source directory to build from."
+
+#: src/hydrilla/builder/build.py:404
+msgid "path_instead_of_index_json"
+msgstr ""
+"Path to file to be processed instead of index.json (if not absolute, "
+"resolved relative to srcdir)."
+
+#: src/hydrilla/builder/build.py:406
+msgid "built_package_files_destination"
+msgstr "Destination directory to write built package files to."
+
+#: src/hydrilla/builder/build.py:408
+#, python-format
+msgid "%(prog)s_%(version)s_license"
+msgstr ""
+"%(prog)s %(version)s\n"
+"Copyright (C) 2021,2022 Wojtek Kosior and contributors.\n"
+"License GPLv3+: GNU AGPL version 3 or later "
+"<https://gnu.org/licenses/gpl.html>\n"
+"This is free software: you are free to change and redistribute it.\n"
+"There is NO WARRANTY, to the extent permitted by law."
+
+#: src/hydrilla/builder/build.py:409
+msgid "version_printing"
+msgstr "Print version information and exit."
+
+#: src/hydrilla/builder/build.py:415
+msgid "build_package_from_srcdir_to_dstdir"
+msgstr ""
+"Build Hydrilla package from `scrdir` and write the resulting files under "
+"`dstdir`."
+
+#: src/hydrilla/util/_util.py:79
+msgid "bad_comment"
+msgstr "bad comment"
+
diff --git a/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json b/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json
new file mode 100644
index 0000000..880a5c4
--- /dev/null
+++ b/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json
@@ -0,0 +1,21 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/api_mapping_description-1.0.1.schema.json",
+    "title": "Mapping description",
+    "description": "Definition of a Hydrilla mapping, as served through HTTP API",
+    "allOf": [{
+	"$ref": "./common_definitions-1.0.1.schema.json#/definitions/mapping_definition_base"
+    }, {
+	"$ref": "./common_definitions-1.0.1.schema.json#/definitions/item_definition"
+    }, {
+	"type": "object",
+	"required": ["$schema"],
+	"properties": {
+	    "$schema": {
+		"description": "Mark this instance as conforming to mapping description schema 1.x",
+		"type": "string",
+		"pattern": "^https://hydrilla\\.koszko\\.org/schemas/api_mapping_description-1\\.(([1-9][0-9]*|0)\\.)*schema\\.json$"
+	    }
+	}
+    }]
+}
diff --git a/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json.license b/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/api_mapping_description-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/schemas/api_query_result-1.0.1.schema.json b/src/hydrilla/schemas/api_query_result-1.0.1.schema.json
new file mode 100644
index 0000000..89c5428
--- /dev/null
+++ b/src/hydrilla/schemas/api_query_result-1.0.1.schema.json
@@ -0,0 +1,25 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/api_query_result-1.0.1.schema.json",
+    "title": "Query result",
+    "description": "Object with a list of references to mappings that contain payloads for requested URL",
+    "type": "object",
+    "required": ["$schema", "mappings"],
+    "properties": {
+	"$schema": {
+	    "description": "Mark this instance as conforming to query result schema 1.x",
+	    "type": "string",
+	    "pattern": "^https://hydrilla\\.koszko\\.org/schemas/api_query_result-1\\.(([1-9][0-9]*|0)\\.)*schema\\.json$"
+	},
+	"mappings": {
+	    "description": "References to mappings using at least one pattern that matches the requested URL",
+	    "type": "array",
+	    "items": {
+		"$ref": "./common_definitions-1.0.1.schema.json#/definitions/item_ref"
+	    }
+	},
+	"generated_by": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/generated_by"
+	}
+    }
+}
diff --git a/src/hydrilla/schemas/api_query_result-1.0.1.schema.json.license b/src/hydrilla/schemas/api_query_result-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/api_query_result-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json b/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json
new file mode 100644
index 0000000..7459394
--- /dev/null
+++ b/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json
@@ -0,0 +1,26 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/api_resource_description-1.0.1.schema.json",
+    "title": "Resource description",
+    "description": "Definition of a Hydrilla resource, as served through HTTP API",
+    "allOf": [{
+	"$ref": "./common_definitions-1.0.1.schema.json#/definitions/resource_definition_base"
+    }, {
+	"$ref": "./common_definitions-1.0.1.schema.json#/definitions/item_definition"
+    }, {
+	"type": "object",
+	"required": ["$schema"],
+	"properties": {
+	    "$schema": {
+		"description": "Mark this instance as conforming to resource description schema 1.x",
+		"type": "string",
+		"pattern": "^https://hydrilla\\.koszko\\.org/schemas/api_resource_description-1\\.(([1-9][0-9]*|0)\\.)*schema\\.json$"
+	    },
+	    "scripts": {
+		"description": "Which files are resource's scripts and need to be installed",
+		"$ref": "./common_definitions-1.0.1.schema.json#/definitions/file_ref_list_sha256",
+		"default": []
+	    }
+	}
+    }]
+}
diff --git a/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json.license b/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/api_resource_description-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/schemas/api_source_description-1.0.1.schema.json b/src/hydrilla/schemas/api_source_description-1.0.1.schema.json
new file mode 100644
index 0000000..0744d1a
--- /dev/null
+++ b/src/hydrilla/schemas/api_source_description-1.0.1.schema.json
@@ -0,0 +1,66 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/api_source_description-1.0.1.schema.json",
+    "title": "Source description",
+    "description": "Built description of a Hydrilla source package",
+    "type": "object",
+    "required": [
+	"$schema",
+	"source_name",
+	"source_copyright",
+	"source_archives",
+	"upstream_url",
+	"definitions"
+    ],
+    "properties": {
+	"$schema": {
+	    "description": "Mark this instance as conforming to source description schema 1.x",
+	    "type": "string",
+	    "pattern": "^https://hydrilla\\.koszko\\.org/schemas/api_source_description-1\\.(([1-9][0-9]*|0)\\.)*schema\\.json$"
+	},
+	"source_name": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/source_name"
+	},
+	"source_copyright":  {
+	    "description": "Which files indicate license terms of the source package",
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/file_ref_list_sha256"
+	},
+	"source_archives": {
+	    "description": "What archive extensions are available for this package's sources",
+	    "type": "object",
+	    "required": ["zip"],
+	    "additionalProperties": {
+		"description": "What is the SHA256 sum of given source archive",
+		"type": "object",
+		"required": ["sha256"],
+		"properties": {
+		    "sha256": {
+			"$ref": "./common_definitions-1.0.1.schema.json#/definitions/sha256"
+		    }
+		}
+	    },
+	    "examples": [{
+		"zip": {
+		    "sha256": "688461da362ffe2fc8e85db73e709a5356d41c8aeb7d1eee7170c64ee21dd2a2"
+		}
+	    }]
+	},
+	"upstream_url": {
+	    "description": "Where this software/work initially comes from",
+	    "type": "string"
+	},
+	"comment": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/comment"
+	},
+	"definitions": {
+	    "description": "References to site resources and pattern->payload mappings",
+	    "type": "array",
+	    "items": {
+		"$ref": "./common_definitions-1.0.1.schema.json#/definitions/typed_item_ref"
+	    }
+	},
+	"generated_by": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/generated_by"
+	}
+    }
+}
diff --git a/src/hydrilla/schemas/api_source_description-1.0.1.schema.json.license b/src/hydrilla/schemas/api_source_description-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/api_source_description-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/schemas/common_definitions-1.0.1.schema.json b/src/hydrilla/schemas/common_definitions-1.0.1.schema.json
new file mode 100644
index 0000000..b803188
--- /dev/null
+++ b/src/hydrilla/schemas/common_definitions-1.0.1.schema.json
@@ -0,0 +1,233 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/common_definitions-1.0.1.schema.json",
+    "title": "Common definitions",
+    "description": "Definitions used by other Hydrilla schemas",
+    "definitions": {
+	"version": {
+	    "description": "Version expressed as an array of integers",
+	    "type": "array",
+	    "minItems": 1,
+	    "items": {
+		"type": "integer",
+		"minimum": 0
+	    },
+	    "contains": {
+		"type": "integer",
+		"minimum": 1
+	    },
+	    "minItems": 1
+	},
+	"source_name": {
+	    "description": "Unique identifier of this source package",
+	    "type": "string",
+	    "pattern": "^[-0-9a-z.]+$"
+	},
+	"comment": {
+	    "description": "An optional comment",
+	    "type": "string"
+	},
+        "file_ref_list": {
+	    "description": "List of simple file references",
+	    "type": "array",
+	    "items": {
+		"type": "object",
+		"required": ["file"],
+		"properties": {
+		    "file": {
+			"description": "Filename relative to source package main directory; separator is '/'",
+			"type": "string",
+			"pattern": "^[^/]"
+		    }
+		}
+	    }
+        },
+	"sha256": {
+	    "description": "An SHA256 sum, in hexadecimal",
+	    "type": "string",
+	    "pattern": "^[0-9a-f]{64}$"
+	},
+        "file_ref_list_sha256": {
+	    "description": "List of file references with files' SHA256 sums included",
+	    "allOf": [{
+		"$ref": "#/definitions/file_ref_list"
+	    }, {
+		"type": "array",
+		"items": {
+		    "type": "object",
+		    "required": ["sha256"],
+		    "properties": {
+			"sha256": {
+			    "$ref": "#/definitions/sha256"
+			}
+		    }
+		}
+	    }]
+        },
+	"item_identifier": {
+	    "description": "Identifier of an item (shared with other versions of the item, otherwise unique)",
+	    "type": "string",
+	    "pattern": "^[-0-9a-z]+$"
+	},
+	"item_dep_specifier": {
+	    "description": "Simple reference to an item as a dependency",
+	    "type": "object",
+	    "required": ["identifier"],
+	    "properties": {
+		"identifier": {
+		    "$ref": "#/definitions/item_identifier"
+		}
+	    }
+	},
+	"item_ref": {
+	    "description": "An object containing a subset of fields from full item definition",
+	    "type": "object",
+	    "required": ["identifier", "long_name", "version"],
+	    "properties": {
+		"identifier": {
+		    "$ref": "#/definitions/item_identifier"
+		},
+		"long_name": {
+		    "description": "User-friendly alternative to the identifier",
+		    "type": "string"
+		},
+		"version": {
+		    "$ref": "#/definitions/version"
+		}
+	    }
+	},
+	"typed_item_ref": {
+	    "description": "An object containing a subset of fields from full item definition, including type",
+	    "allOf": [{
+		"$ref": "#/definitions/item_ref"
+	    }, {
+		"type": "object",
+		"required": ["type"],
+		"properties": {
+		    "type": {
+			"description": "What kind of item is it (resource or mapping)",
+			"enum": ["resource", "mapping"]
+		    }
+		}
+	    }]
+	},
+	"item_definition_base": {
+	    "description": "Definition of a resource/mapping (fields common to source definitions and built definitions)",
+	    "allOf": [{
+		"$ref": "#/definitions/typed_item_ref"
+	    }, {
+		"type": "object",
+		"required": ["description"],
+		"properties": {
+		    "uuid": {
+			"description": "UUIDv4 of this item (shared with other versions of this item, otherwise unique)",
+			"type": "string",
+			"pattern": "^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$"
+		    },
+		    "description": {
+			"description": "Item's description",
+			"type": "string"
+		    },
+		    "comment": {
+			"$ref": "#/definitions/comment"
+		    }
+		}
+	    }]
+	},
+	"resource_definition_base": {
+	    "description": "Definition of a resource (fields common to source definitions and built definitions)",
+	    "allOf": [{
+		"$ref": "#/definitions/item_definition_base"
+	    }, {
+		"type": "object",
+		"required": ["type", "revision"],
+		"properties": {
+		    "type": {
+			"description": "Identify this item as a resource",
+			"const": "resource"
+		    },
+		    "revision": {
+			"description": "Which revision of a packaging of given version of an upstream resource is this",
+			"type": "integer",
+			"minimum": 1
+		    },
+		    "scripts": {
+			"description": "What scripts are included in the resource",
+			"$ref": "#/definitions/file_ref_list",
+			"default": []
+		    },
+		    "dependencies": {
+			"description": "Which other resources this resource depends on",
+			"type": "array",
+			"items": {
+			    "$ref": "#/definitions/item_dep_specifier"
+			},
+			"default": []
+		    }
+		}
+	    }]
+	},
+	"mapping_definition_base": {
+	    "description": "Definition of a mapping (fields common to source definitions and built definitions)",
+	    "allOf": [{
+		"$ref": "#/definitions/item_definition_base"
+	    }, {
+		"type": "object",
+		"required": ["type"],
+		"properties": {
+		    "type": {
+			"description": "Identify this item as a mapping",
+			"const": "mapping"
+		    },
+		    "payloads": {
+			"description": "Which payloads are to be applied to which URLs",
+			"additionalProperties": {
+			    "$ref": "#/definitions/item_dep_specifier"
+			},
+			"default": {},
+			"examples": [{
+			    "https://hydrillabugs.koszko.org/***": {
+				"identifier": "helloapple"
+			    },
+			    "https://*.koszko.org/***": {
+				"identifier": "hello-potato"
+			    }
+			}]
+		    }
+		}
+	    }]
+	},
+	"generated_by": {
+	    "description": "Describe what software generated this instance",
+	    "type": "object",
+	    "required": ["name"],
+	    "properties": {
+		"name": {
+		    "type": "string",
+		    "description": "Instance generator software name, without version"
+		},
+		"version": {
+		    "type": "string",
+		    "description": "Instance generator software version, in arbitrary format"
+		}
+	    }
+	},
+	"item_definition": {
+	    "description": "Definition of a resource/mapping (fields specific to built definitions)",
+	    "type": "object",
+	    "required": ["source_name", "source_copyright"],
+	    "properties": {
+		"source_name": {
+		    "$ref": "#/definitions/source_name"
+		},
+		"source_copyright": {
+		    "description": "Which files indicate license terms of the source package and should be installed",
+		    "$ref": "#/definitions/file_ref_list_sha256"
+		},
+		"generated_by": {
+		    "$ref": "#/definitions/generated_by"
+		}
+	    }
+	}
+    }
+}
diff --git a/src/hydrilla/schemas/common_definitions-1.0.1.schema.json.license b/src/hydrilla/schemas/common_definitions-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/common_definitions-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/schemas/package_source-1.0.1.schema.json b/src/hydrilla/schemas/package_source-1.0.1.schema.json
new file mode 100644
index 0000000..2f9482e
--- /dev/null
+++ b/src/hydrilla/schemas/package_source-1.0.1.schema.json
@@ -0,0 +1,56 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://hydrilla.koszko.org/schemas/package_source-1.0.1.schema.json",
+    "title": "Package source",
+    "description": "Definition of a Hydrilla source package",
+    "type": "object",
+    "required": [
+	"$schema",
+	"source_name",
+	"copyright",
+	"upstream_url",
+	"definitions"
+    ],
+    "properties": {
+	"$schema": {
+	    "description": "Mark this instance as conforming to package source schema 1.x",
+	    "type": "string",
+	    "pattern": "^https://hydrilla\\.koszko\\.org/schemas/package_source-1\\.(([1-9][0-9]*|0)\\.)*schema\\.json$"
+	},
+	"source_name": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/source_name"
+	},
+	"copyright":  {
+	    "description": "Which files from the source package indicate its license terms and should be included in the distribution packages",
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/file_ref_list"
+	},
+	"upstream_url": {
+	    "description": "Where this software/work initially comes from",
+	    "type": "string"
+	},
+	"comment": {
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/comment"
+	},
+	"definitions": {
+	    "description": "Definitions of site resources and pattern->payload mappings",
+	    "type": "array",
+	    "items": {
+		"anyOf": [{
+		    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/resource_definition_base"
+		}, {
+		    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/mapping_definition_base"
+		}]
+	    }
+	},
+	"additional_files": {
+	    "description": "Files which should be included in the source archive produced by Hydrilla builder in addition to script and copyright files",
+	    "$ref": "./common_definitions-1.0.1.schema.json#/definitions/file_ref_list",
+	    "default": []
+	},
+	"reuse_generate_spdx_report": {
+	    "description": "Should report.spdx be automatically generated for the package using REUSE tool",
+	    "type": "boolean",
+	    "default": false
+	}
+    }
+}
diff --git a/src/hydrilla/schemas/package_source-1.0.1.schema.json.license b/src/hydrilla/schemas/package_source-1.0.1.schema.json.license
new file mode 100644
index 0000000..f41d511
--- /dev/null
+++ b/src/hydrilla/schemas/package_source-1.0.1.schema.json.license
@@ -0,0 +1,5 @@
+SPDX-License-Identifier: CC0-1.0
+
+Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+Available under the terms of Creative Commons Zero v1.0 Universal.
diff --git a/src/hydrilla/util/__init__.py b/src/hydrilla/util/__init__.py
new file mode 100644
index 0000000..fadb81c
--- /dev/null
+++ b/src/hydrilla/util/__init__.py
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: CC0-1.0
+
+# Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+#
+# Available under the terms of Creative Commons Zero v1.0 Universal.
+
+from ._util import strip_json_comments, normalize_version, parse_version, \
+    version_string, validator_for, translation
diff --git a/src/hydrilla/util/_util.py b/src/hydrilla/util/_util.py
new file mode 100644
index 0000000..778e78f
--- /dev/null
+++ b/src/hydrilla/util/_util.py
@@ -0,0 +1,162 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# Building Hydrilla packages.
+#
+# This file is part of Hydrilla
+#
+# Copyright (C) 2021, 2022 Wojtek Kosior
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+#
+# I, Wojtek Kosior, thereby promise not to sue for violation of this
+# file's license. Although I request that you do not make use this code
+# in a proprietary program, I am not going to enforce this in court.
+
+# Enable using with Python 3.7.
+from __future__ import annotations
+
+import re
+import json
+import locale
+import gettext
+
+from pathlib import Path
+from typing import Optional, Union
+
+from jsonschema import RefResolver, Draft7Validator
+
+here = Path(__file__).resolve().parent
+
+_strip_comment_re = re.compile(r'''
+^ # match from the beginning of each line
+( # catch the part before '//' comment
+  (?: # this group matches either a string or a single out-of-string character
+    [^"/] |
+    "
+    (?: # this group matches any in-a-string character
+      [^"\\] |          # match any normal character
+      \\[^u] |          # match any escaped character like '\f' or '\n'
+      \\u[a-fA-F0-9]{4} # match an escape
+    )*
+    "
+  )*
+)
+# expect either end-of-line or a comment:
+# * unterminated strings will cause matching to fail
+# * bad comment (with '/' instead of '//') will be indicated by second group
+#   having length 1 instead of 2 or 0
+(//?|$)
+''', re.VERBOSE)
+
+def strip_json_comments(text: str) -> str:
+    """
+    Accept JSON text with optional C++-style ('//') comments and return the text
+    with comments removed. Consecutive slashes inside strings are handled
+    properly. A spurious single slash ('/') shall generate an error. Errors in
+    JSON itself shall be ignored.
+    """
+    processed = 0
+    stripped_text = []
+    for line in text.split('\n'):
+        match = _strip_comment_re.match(line)
+
+        if match is None: # unterminated string
+            # ignore this error, let json module report it
+            stripped = line
+        elif len(match[2]) == 1:
+            raise json.JSONDecodeError(_('bad_comment'), text,
+                                       processed + len(match[1]))
+        else:
+            stripped = match[1]
+
+        stripped_text.append(stripped)
+        processed += len(line) + 1
+
+    return '\n'.join(stripped_text)
+
+def normalize_version(ver: list[int]) -> list[int]:
+    """Strip right-most zeroes from 'ver'. The original list is not modified."""
+    new_len = 0
+    for i, num in enumerate(ver):
+        if num != 0:
+            new_len = i + 1
+
+    return ver[:new_len]
+
+def parse_version(ver_str: str) -> list[int]:
+    """
+    Convert 'ver_str' into an array representation, e.g. for ver_str="4.6.13.0"
+    return [4, 6, 13, 0].
+    """
+    return [int(num) for num in ver_str.split('.')]
+
+def version_string(ver: list[int], rev: Optional[int]=None) -> str:
+    """
+    Produce version's string representation (optionally with revision), like:
+        1.2.3-5
+    No version normalization is performed.
+    """
+    return '.'.join([str(n) for n in ver]) + ('' if rev is None else f'-{rev}')
+
+schemas = {}
+for path in (here.parent / 'schemas').glob('*-1.0.1.schema.json'):
+    schema = json.loads(path.read_text())
+    schemas[schema['$id']] = schema
+
+common_schema_filename = 'common_definitions-1.schema.json'
+common_schema_path = here.parent / "schemas" / common_schema_filename
+
+resolver = RefResolver(
+    base_uri=f'file://{str(common_schema_path)}',
+    referrer=f'https://hydrilla.koszko.org/{common_schema_filename}',
+    store=schemas
+)
+
+def validator_for(schema_filename: str) -> Draft7Validator:
+    """
+    Prepare a validator for one of the schemas in '../schemas'.
+
+    This function is not thread-safe.
+    """
+    return Draft7Validator(resolver.resolve(schema_filename)[1],
+                           resolver=resolver)
+
+def translation(localedir: Union[Path, str], lang: Optional[str]=None) \
+    -> gettext.GNUTranslations:
+    """
+    Configure translations for domain 'hydrilla-messages' and return the object
+    that represents them.
+
+    If `lang` is set, look for translations for `lang`. Otherwise, try to
+    determine system's default language and use that.
+    """
+    # https://stackoverflow.com/questions/3425294/how-to-detect-the-os-default-language-in-python
+    # But I am not going to surrender to Microbugs' nonfree, crappy OS to test
+    # it, to the lines inside try: may fail.
+    if lang is None:
+        try:
+            from ctypes.windll import kernel32 as windll
+            lang = locale.windows_locale[windll.GetUserDefaultUILanguage()]
+        except:
+            lang = locale.getdefaultlocale()[0] or 'en_US'
+
+    localedir = Path(localedir)
+    if not (localedir / lang).is_dir():
+        lang = 'en_US'
+
+    return gettext.translation('hydrilla-messages', localedir=localedir,
+                               languages=[lang])
+
+_ = translation(here.parent / 'builder' / 'locales').gettext