bitbake: wget: Avoid bad checksum race issues

If two recipes have conflicting checksums for a file, the code will currently
remove the existing file when a mismatch is downloaded, even if another task
successfully fetched it.

This changes the code to verify the checksum (if possible) before replacing
the file. This removes a potential race window and stops builds failing
everywhere from one incorrect checksum.

To make this work, we need to be able to override localpath and avoid
NoChecksum errors being logged.

(Bitbake rev: 4b8de2e7d12667d69d86ffe6e9f85a7932c4c9a5)

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

bitbake/lib/bb/fetch2/__init__.py

@@ -545,7 +545,7 @@ def mirror_from_string(data):
         bb.warn('Invalid mirror data %s, should have paired members.' % data)
     return list(zip(*[iter(mirrors)]*2))
 
-def verify_checksum(ud, d, precomputed={}):
+def verify_checksum(ud, d, precomputed={}, localpath=None, fatal_nochecksum=True):
     """
     verify the MD5 and SHA256 checksum for downloaded src
 
@@ -563,13 +563,16 @@ def verify_checksum(ud, d, precomputed={}):
     if ud.ignore_checksums or not ud.method.supports_checksum(ud):
         return {}
 
+    if localpath is None:
+        localpath = ud.localpath
+
     def compute_checksum_info(checksum_id):
         checksum_name = getattr(ud, "%s_name" % checksum_id)
 
         if checksum_id in precomputed:
             checksum_data = precomputed[checksum_id]
         else:
-            checksum_data = getattr(bb.utils, "%s_file" % checksum_id)(ud.localpath)
+            checksum_data = getattr(bb.utils, "%s_file" % checksum_id)(localpath)
 
         checksum_expected = getattr(ud, "%s_expected" % checksum_id)
 
@@ -595,7 +598,7 @@ def verify_checksum(ud, d, precomputed={}):
             checksum_lines = ["SRC_URI[%s] = \"%s\"" % (ci["name"], ci["data"])]
 
     # If no checksum has been provided
-    if ud.method.recommends_checksum(ud) and all(ci["expected"] is None for ci in checksum_infos):
+    if fatal_nochecksum and ud.method.recommends_checksum(ud) and all(ci["expected"] is None for ci in checksum_infos):
         messages = []
         strict = d.getVar("BB_STRICT_CHECKSUM") or "0"
 
@@ -627,7 +630,7 @@ def verify_checksum(ud, d, precomputed={}):
     for ci in checksum_infos:
         if ci["expected"] and ci["expected"] != ci["data"]:
             messages.append("File: '%s' has %s checksum '%s' when '%s' was " \
-                            "expected" % (ud.localpath, ci["id"], ci["data"], ci["expected"]))
+                            "expected" % (localpath, ci["id"], ci["data"], ci["expected"]))
             bad_checksum = ci["data"]
 
     if bad_checksum:

bitbake/lib/bb/fetch2/wget.py

@@ -132,6 +132,11 @@ class Wget(FetchMethod):
 
         self._runwget(ud, d, fetchcmd, False)
 
+        # Try and verify any checksum now, meaning if it isn't correct, we don't remove the
+        # original file, which might be a race (imagine two recipes referencing the same
+        # source, one with an incorrect checksum)
+        bb.fetch2.verify_checksum(ud, d, localpath=localpath, fatal_nochecksum=False)
+
         # Remove the ".tmp" and move the file into position atomically
         # Our lock prevents multiple writers but mirroring code may grab incomplete files
         os.rename(localpath, localpath[:-4])