check-package: check *.mk for typo in variable

Warn when a variable is defined in a .mk file and it don't start with
the package name.

This function generates false warnings and the maintenance of the
whitelist can be an extra burden, but it catches some typos really hard
to see:
- POPLER_CONF_OPTS [1]
- BALELD_LICENSE [2]
- DRDB_UTILS_DEPENDENCIES [3]
- PERL_LIBWWW_LICENSE_FILES [4]
- AVRDUDR_LICENSE_FILES [5]
- GST1_PLUGINS_ULGY_HAS_GPL_LICENSE [6]
- ON2_8170_LICENSE [7]
- LIBFDTI_CONF_OPTS [8][9]
- IPSEC_DEPENDENCIES [10]

[1] http://patchwork.ozlabs.org/patch/681533
[2] http://patchwork.ozlabs.org/patch/643293
[3] http://patchwork.ozlabs.org/patch/449589
[4] http://patchwork.ozlabs.org/patch/464545
[5] http://patchwork.ozlabs.org/patch/305060
[6] http://patchwork.ozlabs.org/patch/253089
[7] http://patchwork.ozlabs.org/patch/250523
[8] http://patchwork.ozlabs.org/patch/394125
[9] https://github.com/buildroot/buildroot/commit/fe7a4b524b72bcb448f7e723873d8244620cb2f1
[10] https://github.com/buildroot/buildroot/commit/dff1d590b2a0fadf58b6eed60029b2ecbab7c710

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/scripts/checkpackagelib_mk.py

@@ -131,6 +131,58 @@ class TrailingBackslash(_CheckFunction):
                     self.lastline]
 
 
+class TypoInPackageVariable(_CheckFunction):
+    ALLOWED = re.compile("|".join([
+        "ACLOCAL_DIR",
+        "ACLOCAL_HOST_DIR",
+        "BR_CCACHE_INITIAL_SETUP",
+        "BR_NO_CHECK_HASH_FOR",
+        "LINUX_POST_PATCH_HOOKS",
+        "LINUX_TOOLS",
+        "LUA_RUN",
+        "MKFS_JFFS2",
+        "MKIMAGE_ARCH",
+        "PKG_CONFIG_HOST_BINARY",
+        "TARGET_FINALIZE_HOOKS",
+        "XTENSA_CORE_NAME"]))
+    PACKAGE_NAME = re.compile("/([^/]+)\.mk")
+    VARIABLE = re.compile("^([A-Z0-9_]+_[A-Z0-9_]+)\s*(\+|)=")
+
+    def before(self):
+        package = self.PACKAGE_NAME.search(self.filename).group(1)
+        package = package.replace("-", "_").upper()
+        # linux tools do not use LINUX_TOOL_ prefix for variables
+        package = package.replace("LINUX_TOOL_", "")
+        self.package = package
+        self.REGEX = re.compile("^(HOST_)?({}_[A-Z0-9_]+)".format(package))
+        self.FIND_VIRTUAL = re.compile(
+            "^{}_PROVIDES\s*(\+|)=\s*(.*)".format(package))
+        self.virtual = []
+
+    def check_line(self, lineno, text):
+        m = self.VARIABLE.search(text)
+        if m is None:
+            return
+
+        variable = m.group(1)
+
+        # allow to set variables for virtual package this package provides
+        v = self.FIND_VIRTUAL.search(text)
+        if v:
+            self.virtual += v.group(2).upper().split()
+            return
+        for virtual in self.virtual:
+            if variable.startswith("{}_".format(virtual)):
+                return
+
+        if self.ALLOWED.match(variable):
+            return
+        if self.REGEX.search(text) is None:
+            return ["{}:{}: possible typo: {} -> *{}*"
+                    .format(self.filename, lineno, variable, self.package),
+                    text]
+
+
 class UselessFlag(_CheckFunction):
     DEFAULT_AUTOTOOLS_FLAG = re.compile("^.*{}".format("|".join([
         "_AUTORECONF\s*=\s*NO",