utils/checkpackagelib: add check for CPE variables set to default values

Now that we can specify that the default values for the CPE_ID variables
are valid, without having to actually set one (or more) to their
default, add a check-package check that validates that the CPE_ID
variables are indeed not set to their default.

It also validates that CPE_ID_VALID is not set when another CPE_ID
variable is set to a non-default value.

Add an anchor in the manual so that we can easily point to it.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

docs/manual/adding-packages-generic.adoc

@@ -511,7 +511,7 @@ LIBFOO_IGNORE_CVES += CVE-2020-12345
 LIBFOO_IGNORE_CVES += CVE-2020-54321
 ----------------------
 
-* +LIBFOO_CPE_ID_*+ variables is a set of variables that allows the
+* [[cpe-id]] +LIBFOO_CPE_ID_*+ variables is a set of variables that allows the
   package to define its https://nvd.nist.gov/products/cpe[CPE
   identifier]. The available variables are:
 +

utils/checkpackagelib/lib_mk.py

@@ -366,3 +366,76 @@ class VariableWithBraces(_CheckFunction):
             return ["{}:{}: use $() to delimit variables, not ${{}}"
                     .format(self.filename, lineno),
                     text]
+
+
+class CPEVariables(_CheckFunction):
+    """
+    Check that the values for the CPE variables are not the default.
+      - CPE_ID_* variables must not be set to their default
+      - CPE_ID_VALID must not be set if a non-default CPE_ID variable is set
+    """
+    def before(self):
+        pkg, _ = os.path.splitext(os.path.basename(self.filename))
+        self.CPE_fields_defaults = {
+            "VALID": "NO",
+            "PREFIX": "cpe:2.3:a",
+            "VENDOR": f"{pkg}_project",
+            "PRODUCT": pkg,
+            "VERSION": None,
+            "UPDATE": "*",
+        }
+        self.valid = None
+        self.non_defaults = 0
+        self.CPE_FIELDS_RE = re.compile(
+            r"^\s*(.+_CPE_ID_({}))\s*=\s*(.+)$"
+            .format("|".join(self.CPE_fields_defaults)),
+        )
+        self.VERSION_RE = re.compile(
+            rf"^(HOST_)?{pkg.upper().replace('-', '_')}_VERSION\s*=\s*(.+)$",
+        )
+        self.COMMENT_RE = re.compile(r"^\s*#.*")
+
+    def check_line(self, lineno, text):
+        text = self.COMMENT_RE.sub('', text.rstrip())
+
+        # WARNING! The VERSION_RE can _also_ match the same lines as CPE_FIELDS_RE,
+        # but not the other way around. So we must first check for CPE_FIELDS_RE,
+        # and if not matched, then and only then check for VERSION_RE.
+        match = self.CPE_FIELDS_RE.match(text)
+        if match:
+            var, field, val = match.groups()
+            return self._check_field(lineno, text, field, var, val)
+
+        match = self.VERSION_RE.match(text)
+        if match:
+            self.CPE_fields_defaults["VERSION"] = match.groups()[1]
+
+    def after(self):
+        # "VALID" counts in the non-defaults; so when "VALID" is present,
+        # 1 non-default means only "VALID" is present, so that's OK.
+        if self.valid and self.non_defaults > 1:
+            return ["{}:{}: 'YES' is implied when a non-default CPE_ID field is specified: {} ({}#cpe-id)".format(
+                        self.filename,
+                        self.valid["lineno"],
+                        self.valid["text"],
+                        self.url_to_manual,
+            )]
+
+    def _check_field(self, lineno, text, field, var, val):
+        if field == "VERSION" and self.CPE_fields_defaults[field] is None:
+            return ["{}:{}: expecting package version to be set before CPE_ID_VERSION".format(
+                self.filename,
+                lineno,
+            )]
+        if val == self.CPE_fields_defaults[field]:
+            return ["{}:{}: '{}' is the default value for {} ({}#cpe-id)".format(
+                self.filename,
+                lineno,
+                val,
+                var,
+                self.url_to_manual,
+            )]
+        else:
+            if field == "VALID":
+                self.valid = {"lineno": lineno, "text": text}
+            self.non_defaults += 1