bitbake/fetch: Spell out which fetcher backends support and recommend checksums

There were some hardcoded behaviours in the system for which backends
support checksums verses which backends recommend them verses which
don't recommend them.

This moves the functionality into specific fetchers and then makes the
general code generic. This cleans up the codebase and fixes some corner
cases such as trying to checksum directories returned by the git fetcher.

(Bitbake rev: ef6d268f7b8527541a7fb044cf95a973be4097f4)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/__init__.py

@@ -271,10 +271,13 @@ def verify_checksum(u, ud, d):
     matched
     """
 
+    if not ud.method.supports_checksum(ud):
+        return
+
     md5data = bb.utils.md5_file(ud.localpath)
     sha256data = bb.utils.sha256_file(ud.localpath)
 
-    if ud.type in ["http", "https", "ftp", "ftps"]:
+    if ud.method.recommends_checksum(ud):
         # If strict checking enabled and neither sum defined, raise error
         strict = d.getVar("BB_STRICT_CHECKSUM", True) or None
         if (strict and ud.md5_expected == None and ud.sha256_expected == None):
@@ -578,10 +581,14 @@ class FetchData(object):
             self.sha256_name = "sha256sum"
         if self.md5_name in self.parm:
             self.md5_expected = self.parm[self.md5_name]
+        elif self.type not in ["http", "https", "ftp", "ftps"]:
+            self.md5_expected = None
         else:
             self.md5_expected = d.getVarFlag("SRC_URI", self.md5_name)
         if self.sha256_name in self.parm:
             self.sha256_expected = self.parm[self.sha256_name]
+        elif self.type not in ["http", "https", "ftp", "ftps"]:
+            self.sha256_expected = None
         else:
             self.sha256_expected = d.getVarFlag("SRC_URI", self.sha256_name)
 
@@ -660,6 +667,19 @@ class FetchMethod(object):
         """
         return os.path.join(data.getVar("DL_DIR", d, True), urldata.localfile)
 
+    def supports_checksum(self, urldata):
+        """
+        Is localpath something that can be represented by a checksum?
+        """
+        return True
+
+    def recommends_checksum(self, urldata):
+        """
+        Is the backend on where checksumming is recommended (should warnings 
+        by displayed if there is no checksum)?
+        """
+        return False
+
     def _strip_leading_slashes(self, relpath):
         """
         Remove leading slash as os.path.join can't cope

bitbake/lib/bb/fetch2/git.py

@@ -82,6 +82,9 @@ class Git(FetchMethod):
         """
         return ud.type in ['git']
 
+    def supports_checksum(self, urldata):
+        return False
+
     def urldata_init(self, ud, d):
         """
         init git specific variable within url data

bitbake/lib/bb/fetch2/ssh.py

@@ -69,6 +69,9 @@ class SSH(FetchMethod):
     def supports(self, url, urldata, d):
         return __pattern__.match(url) != None
 
+    def supports_checksum(self, urldata):
+        return False
+
     def localpath(self, url, urldata, d):
         m = __pattern__.match(urldata.url)
         path = m.group('path')

bitbake/lib/bb/fetch2/wget.py

@@ -45,6 +45,9 @@ class Wget(FetchMethod):
         """
         return ud.type in ['http', 'https', 'ftp']
 
+    def recommends_checksum(self, urldata):
+        return True
+
     def urldata_init(self, ud, d):
 
         ud.basename = os.path.basename(ud.path)