summaryrefslogtreecommitdiffstats
path: root/bitbake/lib/bb/build.py
blob: 65cc851df453e390dd8c4f2fa99b0a6a71d338ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
# ex:ts=4:sw=4:sts=4:et
# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
#
# BitBake 'Build' implementation
#
# Core code for function execution and task handling in the
# BitBake build tools.
#
# Copyright (C) 2003, 2004  Chris Larson
#
# Based on Gentoo's portage.py.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# Based on functions from the base bb module, Copyright 2003 Holger Schurig

import os
import sys
import logging
import shlex
import glob
import time
import bb
import bb.msg
import bb.process
from contextlib import nested
from bb import event, utils

bblogger = logging.getLogger('BitBake')
logger = logging.getLogger('BitBake.Build')

NULL = open(os.devnull, 'r+')

# When we execute a Python function, we'd like certain things
# in all namespaces, hence we add them to __builtins__.
# If we do not do this and use the exec globals, they will
# not be available to subfunctions.
__builtins__['bb'] = bb
__builtins__['os'] = os

class FuncFailed(Exception):
    def __init__(self, name = None, logfile = None):
        self.logfile = logfile
        self.name = name
        if name:
            self.msg = 'Function failed: %s' % name
        else:
            self.msg = "Function failed"

    def __str__(self):
        if self.logfile and os.path.exists(self.logfile):
            msg = ("%s (log file is located at %s)" %
                   (self.msg, self.logfile))
        else:
            msg = self.msg
        return msg

class TaskBase(event.Event):
    """Base class for task events"""

    def __init__(self, t, logfile, d):
        self._task = t
        self._package = d.getVar("PF", True)
        self.taskfile = d.getVar("FILE", True)
        self.taskname = self._task
        self.logfile = logfile
        self.time = time.time()
        event.Event.__init__(self)
        self._message = "recipe %s: task %s: %s" % (d.getVar("PF", True), t, self.getDisplayName())

    def getTask(self):
        return self._task

    def setTask(self, task):
        self._task = task

    def getDisplayName(self):
        return bb.event.getName(self)[4:]

    task = property(getTask, setTask, None, "task property")

class TaskStarted(TaskBase):
    """Task execution started"""
    def __init__(self, t, logfile, taskflags, d):
        super(TaskStarted, self).__init__(t, logfile, d)
        self.taskflags = taskflags

class TaskSucceeded(TaskBase):
    """Task execution completed"""

class TaskFailed(TaskBase):
    """Task execution failed"""

    def __init__(self, task, logfile, metadata, errprinted = False):
        self.errprinted = errprinted
        super(TaskFailed, self).__init__(task, logfile, metadata)

class TaskFailedSilent(TaskBase):
    """Task execution failed (silently)"""
    def getDisplayName(self):
        # Don't need to tell the user it was silent
        return "Failed"

class TaskInvalid(TaskBase):

    def __init__(self, task, metadata):
        super(TaskInvalid, self).__init__(task, None, metadata)
        self._message = "No such task '%s'" % task


class LogTee(object):
    def __init__(self, logger, outfile):
        self.outfile = outfile
        self.logger = logger
        self.name = self.outfile.name

    def write(self, string):
        self.logger.plain(string)
        self.outfile.write(string)

    def __enter__(self):
        self.outfile.__enter__()
        return self

    def __exit__(self, *excinfo):
        self.outfile.__exit__(*excinfo)

    def __repr__(self):
        return '<LogTee {0}>'.format(self.name)
    def flush(self):
        self.outfile.flush()

def exec_func(func, d, dirs = None):
    """Execute a BB 'function'"""

    body = d.getVar(func)
    if not body:
        if body is None:
            logger.warn("Function %s doesn't exist", func)
        return

    flags = d.getVarFlags(func)
    cleandirs = flags.get('cleandirs')
    if cleandirs:
        for cdir in d.expand(cleandirs).split():
            bb.utils.remove(cdir, True)
            bb.utils.mkdirhier(cdir)

    if dirs is None:
        dirs = flags.get('dirs')
        if dirs:
            dirs = d.expand(dirs).split()

    if dirs:
        for adir in dirs:
            bb.utils.mkdirhier(adir)
        adir = dirs[-1]
    else:
        adir = d.getVar('B', True)
        bb.utils.mkdirhier(adir)

    ispython = flags.get('python')

    lockflag = flags.get('lockfiles')
    if lockflag:
        lockfiles = [f for f in d.expand(lockflag).split()]
    else:
        lockfiles = None

    tempdir = d.getVar('T', True)

    # or func allows items to be executed outside of the normal
    # task set, such as buildhistory
    task = d.getVar('BB_RUNTASK', True) or func
    if task == func:
        taskfunc = task
    else:
        taskfunc = "%s.%s" % (task, func)

    runfmt = d.getVar('BB_RUNFMT', True) or "run.{func}.{pid}"
    runfn = runfmt.format(taskfunc=taskfunc, task=task, func=func, pid=os.getpid())
    runfile = os.path.join(tempdir, runfn)
    bb.utils.mkdirhier(os.path.dirname(runfile))

    # Setup the courtesy link to the runfn, only for tasks
    # we create the link 'just' before the run script is created
    # if we create it after, and if the run script fails, then the
    # link won't be created as an exception would be fired.
    if task == func:
        runlink = os.path.join(tempdir, 'run.{0}'.format(task))
        if runlink:
            bb.utils.remove(runlink)

            try:
                os.symlink(runfn, runlink)
            except OSError:
                pass

    with bb.utils.fileslocked(lockfiles):
        if ispython:
            exec_func_python(func, d, runfile, cwd=adir)
        else:
            exec_func_shell(func, d, runfile, cwd=adir)

_functionfmt = """
def {function}(d):
{body}

{function}(d)
"""
logformatter = bb.msg.BBLogFormatter("%(levelname)s: %(message)s")
def exec_func_python(func, d, runfile, cwd=None):
    """Execute a python BB 'function'"""

    bbfile = d.getVar('FILE', True)
    code = _functionfmt.format(function=func, body=d.getVar(func, True))
    bb.utils.mkdirhier(os.path.dirname(runfile))
    with open(runfile, 'w') as script:
        bb.data.emit_func_python(func, script, d)

    if cwd:
        try:
            olddir = os.getcwd()
        except OSError:
            olddir = None
        os.chdir(cwd)

    bb.debug(2, "Executing python function %s" % func)

    try:
        comp = utils.better_compile(code, func, bbfile)
        utils.better_exec(comp, {"d": d}, code, bbfile)
    except (bb.parse.SkipRecipe, bb.build.FuncFailed):
        raise
    except:
        raise FuncFailed(func, None)
    finally:
        bb.debug(2, "Python function %s finished" % func)

        if cwd and olddir:
            try:
                os.chdir(olddir)
            except OSError:
                pass

def shell_trap_code():
    return '''#!/bin/sh\n
# Emit a useful diagnostic if something fails:
bb_exit_handler() {
    ret=$?
    case $ret in
    0)  ;;
    *)  case $BASH_VERSION in
        "")   echo "WARNING: exit code $ret from a shell command.";;
        *)    echo "WARNING: ${BASH_SOURCE[0]}:${BASH_LINENO[0]} exit $ret from
  \"$BASH_COMMAND\"";;
        esac
        exit $ret
    esac
}
trap 'bb_exit_handler' 0
set -e
'''

def exec_func_shell(func, d, runfile, cwd=None):
    """Execute a shell function from the metadata

    Note on directory behavior.  The 'dirs' varflag should contain a list
    of the directories you need created prior to execution.  The last
    item in the list is where we will chdir/cd to.
    """

    # Don't let the emitted shell script override PWD
    d.delVarFlag('PWD', 'export')

    with open(runfile, 'w') as script:
        script.write(shell_trap_code())

        bb.data.emit_func(func, script, d)

        if bb.msg.loggerVerboseLogs:
            script.write("set -x\n")
        if cwd:
            script.write("cd '%s'\n" % cwd)
        script.write("%s\n" % func)
        script.write('''
# cleanup
ret=$?
trap '' 0
exit $?
''')

    os.chmod(runfile, 0775)

    cmd = runfile
    if d.getVarFlag(func, 'fakeroot'):
        fakerootcmd = d.getVar('FAKEROOT', True)
        if fakerootcmd:
            cmd = [fakerootcmd, runfile]

    if bb.msg.loggerDefaultVerbose:
        logfile = LogTee(logger, sys.stdout)
    else:
        logfile = sys.stdout

    bb.debug(2, "Executing shell function %s" % func)

    try:
        with open(os.devnull, 'r+') as stdin:
            bb.process.run(cmd, shell=False, stdin=stdin, log=logfile)
    except bb.process.CmdError:
        logfn = d.getVar('BB_LOGFILE', True)
        raise FuncFailed(func, logfn)

    bb.debug(2, "Shell function %s finished" % func)

def _task_data(fn, task, d):
    localdata = bb.data.createCopy(d)
    localdata.setVar('BB_FILENAME', fn)
    localdata.setVar('BB_CURRENTTASK', task[3:])
    localdata.setVar('OVERRIDES', 'task-%s:%s' %
                     (task[3:].replace('_', '-'), d.getVar('OVERRIDES', False)))
    localdata.finalize()
    bb.data.expandKeys(localdata)
    return localdata

def _exec_task(fn, task, d, quieterr):
    """Execute a BB 'task'

    Execution of a task involves a bit more setup than executing a function,
    running it with its own local metadata, and with some useful variables set.
    """
    if not d.getVarFlag(task, 'task'):
        event.fire(TaskInvalid(task, d), d)
        logger.error("No such task: %s" % task)
        return 1

    logger.debug(1, "Executing task %s", task)

    localdata = _task_data(fn, task, d)
    tempdir = localdata.getVar('T', True)
    if not tempdir:
        bb.fatal("T variable not set, unable to build")

    # Change nice level if we're asked to
    nice = localdata.getVar("BB_TASK_NICE_LEVEL", True)
    if nice:
        curnice = os.nice(0)
        nice = int(nice) - curnice
        newnice = os.nice(nice)
        logger.debug(1, "Renice to %s " % newnice)

    bb.utils.mkdirhier(tempdir)

    # Determine the logfile to generate
    logfmt = localdata.getVar('BB_LOGFMT', True) or 'log.{task}.{pid}'
    logbase = logfmt.format(task=task, pid=os.getpid())

    # Document the order of the tasks...
    logorder = os.path.join(tempdir, 'log.task_order')
    try:
        with open(logorder, 'a') as logorderfile:
            logorderfile.write('{0} ({1}): {2}\n'.format(task, os.getpid(), logbase))
    except OSError:
        logger.exception("Opening log file '%s'", logorder)
        pass

    # Setup the courtesy link to the logfn
    loglink = os.path.join(tempdir, 'log.{0}'.format(task))
    logfn = os.path.join(tempdir, logbase)
    if loglink:
        bb.utils.remove(loglink)

        try:
           os.symlink(logbase, loglink)
        except OSError:
           pass

    prefuncs = localdata.getVarFlag(task, 'prefuncs', expand=True)
    postfuncs = localdata.getVarFlag(task, 'postfuncs', expand=True)

    class ErrorCheckHandler(logging.Handler):
        def __init__(self):
            self.triggered = False
            logging.Handler.__init__(self, logging.ERROR)
        def emit(self, record):
            self.triggered = True

    # Handle logfiles
    si = open('/dev/null', 'r')
    try:
        bb.utils.mkdirhier(os.path.dirname(logfn))
        logfile = open(logfn, 'w')
    except OSError:
        logger.exception("Opening log file '%s'", logfn)
        pass

    # Dup the existing fds so we dont lose them
    osi = [os.dup(sys.stdin.fileno()), sys.stdin.fileno()]
    oso = [os.dup(sys.stdout.fileno()), sys.stdout.fileno()]
    ose = [os.dup(sys.stderr.fileno()), sys.stderr.fileno()]

    # Replace those fds with our own
    os.dup2(si.fileno(), osi[1])
    os.dup2(logfile.fileno(), oso[1])
    os.dup2(logfile.fileno(), ose[1])

    # Ensure Python logging goes to the logfile
    handler = logging.StreamHandler(logfile)
    handler.setFormatter(logformatter)
    # Always enable full debug output into task logfiles
    handler.setLevel(logging.DEBUG - 2)
    bblogger.addHandler(handler)

    errchk = ErrorCheckHandler()
    bblogger.addHandler(errchk)

    localdata.setVar('BB_LOGFILE', logfn)
    localdata.setVar('BB_RUNTASK', task)

    flags = localdata.getVarFlags(task)

    event.fire(TaskStarted(task, logfn, flags, localdata), localdata)
    try:
        for func in (prefuncs or '').split():
            exec_func(func, localdata)
        exec_func(task, localdata)
        for func in (postfuncs or '').split():
            exec_func(func, localdata)
    except FuncFailed as exc:
        if quieterr:
            event.fire(TaskFailedSilent(task, logfn, localdata), localdata)
        else:
            errprinted = errchk.triggered
            logger.error(str(exc))
            event.fire(TaskFailed(task, logfn, localdata, errprinted), localdata)
        return 1
    finally:
        sys.stdout.flush()
        sys.stderr.flush()

        bblogger.removeHandler(handler)

        # Restore the backup fds
        os.dup2(osi[0], osi[1])
        os.dup2(oso[0], oso[1])
        os.dup2(ose[0], ose[1])

        # Close the backup fds
        os.close(osi[0])
        os.close(oso[0])
        os.close(ose[0])
        si.close()

        logfile.close()
        if os.path.exists(logfn) and os.path.getsize(logfn) == 0:
            logger.debug(2, "Zero size logfn %s, removing", logfn)
            bb.utils.remove(logfn)
            bb.utils.remove(loglink)
    event.fire(TaskSucceeded(task, logfn, localdata), localdata)

    if not localdata.getVarFlag(task, 'nostamp') and not localdata.getVarFlag(task, 'selfstamp'):
        make_stamp(task, localdata)

    return 0

def exec_task(fn, task, d, profile = False):
    try:
        quieterr = False
        if d.getVarFlag(task, "quieterrors") is not None:
            quieterr = True

        if profile:
            profname = "profile-%s.log" % (d.getVar("PN", True) + "-" + task)
            try:
                import cProfile as profile
            except:
                import profile
            prof = profile.Profile()
            ret = profile.Profile.runcall(prof, _exec_task, fn, task, d, quieterr)
            prof.dump_stats(profname)
            bb.utils.process_profilelog(profname)

            return ret
        else:
            return _exec_task(fn, task, d, quieterr)

    except Exception:
        from traceback import format_exc
        if not quieterr:
            logger.error("Build of %s failed" % (task))
            logger.error(format_exc())
            failedevent = TaskFailed(task, None, d, True)
            event.fire(failedevent, d)
        return 1

def stamp_internal(taskname, d, file_name, baseonly=False):
    """
    Internal stamp helper function
    Makes sure the stamp directory exists
    Returns the stamp path+filename

    In the bitbake core, d can be a CacheData and file_name will be set.
    When called in task context, d will be a data store, file_name will not be set
    """
    taskflagname = taskname
    if taskname.endswith("_setscene") and taskname != "do_setscene":
        taskflagname = taskname.replace("_setscene", "")

    if file_name:
        stamp = d.stamp_base[file_name].get(taskflagname) or d.stamp[file_name]
        extrainfo = d.stamp_extrainfo[file_name].get(taskflagname) or ""
    else:
        stamp = d.getVarFlag(taskflagname, 'stamp-base', True) or d.getVar('STAMP', True)
        file_name = d.getVar('BB_FILENAME', True)
        extrainfo = d.getVarFlag(taskflagname, 'stamp-extra-info', True) or ""

    if baseonly:
        return stamp

    if not stamp:
        return

    stamp = bb.parse.siggen.stampfile(stamp, file_name, taskname, extrainfo)

    stampdir = os.path.dirname(stamp)
    if bb.parse.cached_mtime_noerror(stampdir) == 0:
        bb.utils.mkdirhier(stampdir)

    return stamp

def stamp_cleanmask_internal(taskname, d, file_name):
    """
    Internal stamp helper function to generate stamp cleaning mask
    Returns the stamp path+filename

    In the bitbake core, d can be a CacheData and file_name will be set.
    When called in task context, d will be a data store, file_name will not be set
    """
    taskflagname = taskname
    if taskname.endswith("_setscene") and taskname != "do_setscene":
        taskflagname = taskname.replace("_setscene", "")

    if file_name:
        stamp = d.stamp_base_clean[file_name].get(taskflagname) or d.stampclean[file_name]
        extrainfo = d.stamp_extrainfo[file_name].get(taskflagname) or ""
    else:
        stamp = d.getVarFlag(taskflagname, 'stamp-base-clean', True) or d.getVar('STAMPCLEAN', True)
        file_name = d.getVar('BB_FILENAME', True)
        extrainfo = d.getVarFlag(taskflagname, 'stamp-extra-info', True) or ""

    if not stamp:
        return []

    cleanmask = bb.parse.siggen.stampcleanmask(stamp, file_name, taskname, extrainfo)

    return [cleanmask, cleanmask.replace(taskflagname, taskflagname + "_setscene")]

def make_stamp(task, d, file_name = None):
    """
    Creates/updates a stamp for a given task
    (d can be a data dict or dataCache)
    """
    cleanmask = stamp_cleanmask_internal(task, d, file_name)
    for mask in cleanmask:
        for name in glob.glob(mask):
            # Preserve sigdata files in the stamps directory
            if "sigdata" in name:
                continue
            # Preserve taint files in the stamps directory
            if name.endswith('.taint'):
                continue
            os.unlink(name)

    stamp = stamp_internal(task, d, file_name)
    # Remove the file and recreate to force timestamp
    # change on broken NFS filesystems
    if stamp:
        bb.utils.remove(stamp)
        open(stamp, "w").close()

    # If we're in task context, write out a signature file for each task
    # as it completes
    if not task.endswith("_setscene") and task != "do_setscene" and not file_name:
        stampbase = stamp_internal(task, d, None, True)
        file_name = d.getVar('BB_FILENAME', True)
        bb.parse.siggen.dump_sigtask(file_name, task, stampbase, True)

def del_stamp(task, d, file_name = None):
    """
    Removes a stamp for a given task
    (d can be a data dict or dataCache)
    """
    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
    (d can be a data dict or dataCache)
    """
    return stamp_internal(taskname, d, file_name)

def add_tasks(tasklist, deltasklist, d):
    task_deps = d.getVar('_task_deps')
    if not task_deps:
        task_deps = {}
    if not 'tasks' in task_deps:
        task_deps['tasks'] = []
    if not 'parents' in task_deps:
        task_deps['parents'] = {}

    for task in tasklist:
        task = d.expand(task)

        if task in deltasklist:
            continue

        d.setVarFlag(task, 'task', 1)

        if not task in task_deps['tasks']:
            task_deps['tasks'].append(task)

        flags = d.getVarFlags(task)
        def getTask(name):
            if not name in task_deps:
                task_deps[name] = {}
            if name in flags:
                deptask = d.expand(flags[name])
                task_deps[name][task] = deptask
        getTask('depends')
        getTask('rdepends')
        getTask('deptask')
        getTask('rdeptask')
        getTask('recrdeptask')
        getTask('recideptask')
        getTask('nostamp')
        getTask('fakeroot')
        getTask('noexec')
        getTask('umask')
        task_deps['parents'][task] = []
        if 'deps' in flags:
            for dep in flags['deps']:
                dep = d.expand(dep)
                task_deps['parents'][task].append(dep)

    # don't assume holding a reference
    d.setVar('_task_deps', task_deps)

def addtask(task, before, after, d):
    if task[:3] != "do_":
        task = "do_" + task

    d.setVarFlag(task, "task", 1)
    bbtasks = d.getVar('__BBTASKS') or []
    if not task in bbtasks:
        bbtasks.append(task)
    d.setVar('__BBTASKS', bbtasks)

    existing = d.getVarFlag(task, "deps") or []
    if after is not None:
        # set up deps for function
        for entry in after.split():
            if entry not in existing:
                existing.append(entry)
    d.setVarFlag(task, "deps", existing)
    if before is not None:
        # set up things that depend on this func
        for entry in before.split():
            existing = d.getVarFlag(entry, "deps") or []
            if task not in existing:
                d.setVarFlag(entry, "deps", [task] + existing)

def deltask(task, d):
    if task[:3] != "do_":
        task = "do_" + task

    bbtasks = d.getVar('__BBDELTASKS') or []
    if not task in bbtasks:
        bbtasks.append(task)
    d.setVar('__BBDELTASKS', bbtasks)