bitbake: ensure -f causes dependent tasks to be re-run

If -f is specified, force dependent tasks to be re-run next time. This
works by changing the force behaviour so that instead of deleting the
task's stamp, we write a "taint" file into the stamps directory, which
will alter the taskhash randomly and thus trigger the task to re-run
next time we evaluate whether or not that should be done as well as
influencing the taskhashes of any dependent tasks so that they are
similarly re-triggered. As a bonus because we write this file as
<stamp file name>.taskname.taint, the existing code which deletes the
stamp files in OE's do_clean will already handle removing it.

This means you can now do the following:

bitbake somepackage
[ change the source code in the package's WORKDIR ]
bitbake -c compile -f somepackage
bitbake somepackage

and the result will be that all of the tasks that depend on do_compile
(do_install, do_package, etc.) will be re-run in the last step.

Note that to operate in the manner described above you need full hashing
enabled (i.e. BB_SIGNATURE_HANDLER must be set to a signature handler
that inherits from BasicHash). If this is not the case, -f will just
delete the stamp for the specified task as it did before.

This fix is required for [YOCTO #2615] and [YOCTO #2256].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/bb/build.py b/lib/bb/build.py
index a9ba02d34..a0a7dd4e1 100644
--- a/lib/bb/build.py
+++ b/lib/bb/build.py
@@ -494,6 +494,24 @@ def del_stamp(task, d, file_name = None):
     stamp = stamp_internal(task, d, file_name)
     bb.utils.remove(stamp)
 
+def write_taint(task, d, file_name = None):
+    """
+    Creates a "taint" file which will force the specified task and its
+    dependents to be re-run the next time by influencing the value of its
+    taskhash.
+    (d can be a data dict or dataCache)
+    """
+    import uuid
+    if file_name:
+        taintfn = d.stamp[file_name] + '.' + task + '.taint'
+    else:
+        taintfn = d.getVar('STAMP', True) + '.' + task + '.taint'
+    bb.utils.mkdirhier(os.path.dirname(taintfn))
+    # The specific content of the taint file is not really important,
+    # we just need it to be random, so a random UUID is used
+    with open(taintfn, 'w') as taintf:
+        taintf.write(str(uuid.uuid4()))
+
 def stampfile(taskname, d, file_name = None):
     """
     Return the stamp for a given task