[v2,6/9] classes/go-mod-update-modules: add class to generate module list

diff --git a/meta/classes-recipe/go-mod-update-modules.bbclass b/meta/classes-recipe/go-mod-update-modules.bbclass
new file mode 100644
index 00000000000..6ef7ab553b0
--- /dev/null
+++ b/meta/classes-recipe/go-mod-update-modules.bbclass
@@ -0,0 +1,152 @@ 
+addtask do_update_modules after do_configure
+do_update_modules[nostamp] = "1"
+do_update_modules[network] = "1"
+
+# This class maintains two files, BPN-go-mods.inc and BPN-licenses.inc.
+#
+# -go-mods.inc will append SRC_URI with all of the Go modules that are
+# dependencies of this recipe.
+#
+# -licenses.inc will append LICENSE and LIC_FILES_CHKSUM with the found licenses
+# in the modules.
+#
+# These files are machine-generated and should not be modified.
+
+python do_update_modules() {
+    import subprocess, tempfile, json, re, urllib.parse
+    from oe.license import tidy_licenses
+    from oe.license_finder import find_licenses
+
+    def unescape_path(path):
+        """Unescape capital letters using exclamation points."""
+        return re.sub(r'!([a-z])', lambda m: m.group(1).upper(), path)
+
+    def fold_uri(uri):
+        """Fold URI for sorting shorter module paths before longer."""
+        return uri.replace(';', ' ').replace('/', '!')
+
+    def parse_existing_licenses():
+        hashes = {}
+        for url in d.getVar("LIC_FILES_CHKSUM").split():
+            (method, host, path, user, pswd, parm) = bb.fetch.decodeurl(url)
+            if "spdx" in parm and parm["spdx"] != "Unknown":
+                hashes[parm["md5"]] = urllib.parse.unquote_plus(parm["spdx"])
+        return hashes
+
+    bpn = d.getVar("BPN")
+    thisdir = d.getVar("THISDIR")
+    s_dir = d.getVar("S")
+
+    with tempfile.TemporaryDirectory(prefix='go-mod-') as mod_cache_dir:
+        notice = """
+# This file has been generated by go-mod-update-modules.bbclass
+#
+# Do not modify it by hand, as the contents will be replaced when
+# running the update-modules task.
+
+"""
+
+        env = dict(os.environ, GOMODCACHE=mod_cache_dir)
+
+        source = d.expand("${WORKDIR}/${GO_SRCURI_DESTSUFFIX}")
+        output = subprocess.check_output(("go", "mod", "edit", "-json"), cwd=source, env=env, text=True)
+        go_mod = json.loads(output)
+
+        output = subprocess.check_output(("go", "list", "-json=Dir,Module", "-deps", f"{go_mod['Module']['Path']}/..."), cwd=source, env=env, text=True)
+
+        #
+        # Licenses
+        #
+
+        # load hashes from the existing licenses.inc
+        extra_hashes = parse_existing_licenses()
+
+        # The output of this isn't actually valid JSON, but a series of dicts.
+        # Wrap in [] and join the dicts with ,
+        # Very frustrating that the json parser in python can't repeatedly
+        # parse from a stream.
+        pkgs = json.loads('[' + output.replace('}\n{', '},\n{') + ']')
+        # Collect licenses for the dependencies.
+        licenses = set()
+        lic_files_chksum = []
+        lic_files = {}
+
+        for pkg in pkgs:
+            mod = pkg.get('Module', None)
+            if not mod or mod.get('Main', False):
+                continue
+
+            mod_dir = mod['Dir']
+
+            if mod_dir.startswith(s_dir):
+                continue
+
+            path = os.path.relpath(mod_dir, mod_cache_dir)
+
+            for license_name, license_file, license_md5 in find_licenses(mod['Dir'], d, first_only=True, extra_hashes=extra_hashes):
+                lic_files[os.path.join(path, license_file)] = (license_name, license_md5)
+
+        for lic_file in lic_files:
+            license_name, license_md5 = lic_files[lic_file]
+            if license_name == "Unknown":
+                bb.warn(f"Unknown license: {lic_file} {license_md5}")
+
+            licenses.add(lic_files[lic_file][0])
+            lic_files_chksum.append(
+                f'file://pkg/mod/{lic_file};md5={license_md5};spdx={urllib.parse.quote_plus(license_name)}')
+
+        licenses_filename = os.path.join(thisdir, f"{bpn}-licenses.inc")
+        with open(licenses_filename, "w") as f:
+            f.write(notice)
+            f.write(f'LICENSE += "& {" & ".join(tidy_licenses(licenses))}"\n\n')
+            f.write('LIC_FILES_CHKSUM += "\\\n')
+            for lic in sorted(lic_files_chksum, key=fold_uri):
+                f.write('    ' + lic + ' \\\n')
+            f.write('"\n')
+
+        #
+        # Sources
+        #
+
+        # Collect the module cache files downloaded by the go list command as
+        # the go list command knows best what the go list command needs and it
+        # needs more files in the module cache than the go install command as
+        # it doesn't do the dependency pruning mentioned in the Go module
+        # reference, https://go.dev/ref/mod, for go 1.17 or higher.
+        src_uris = []
+        downloaddir = os.path.join(mod_cache_dir, 'cache', 'download')
+        for dirpath, _, filenames in os.walk(downloaddir):
+            # We want to process files under @v directories
+            path, base = os.path.split(os.path.relpath(dirpath, downloaddir))
+            if base != '@v':
+                continue
+
+            path = unescape_path(path)
+            zipver = None
+            for name in filenames:
+                ver, ext = os.path.splitext(name)
+                if ext == '.zip':
+                    chksum = bb.utils.sha256_file(os.path.join(dirpath, name))
+                    src_uris.append(f'gomod://{path};version={ver};sha256sum={chksum}')
+                    zipver = ver
+                    break
+            for name in filenames:
+                ver, ext = os.path.splitext(name)
+                if ext == '.mod' and ver != zipver:
+                    chksum = bb.utils.sha256_file(os.path.join(dirpath, name))
+                    src_uris.append(f'gomod://{path};version={ver};mod=1;sha256sum={chksum}')
+
+
+        go_mods_filename = os.path.join(thisdir, f"{bpn}-go-mods.inc")
+        with open(go_mods_filename, "w") as f:
+            f.write(notice)
+            f.write('SRC_URI += "\\\n')
+            for uri in sorted(src_uris, key=fold_uri):
+                f.write('    ' + uri + ' \\\n')
+            f.write('"\n')
+
+        subprocess.check_output(("go", "clean", "-modcache"), cwd=source, env=env, text=True)
+}
+
+# This doesn't work as we need to wipe the inc files first so we don't try looking for LICENSE files that don't yet exist
+# RECIPE_UPGRADE_EXTRA_TASKS += "do_update_modules"