apenwarr-redo/redo-ifchange.py
Avery Pennarun 672b748394 Further improve handling of symlink targets/deps.
In commit redo-0.11-4-g34669fb, we changed os.stat into os.lstat to
avoid false positives in the "manual override" detector: a .do file
that generates $3 as a symlink would trigger manual override if the
*target* of that symlink ever changed, which is incorrect.

Unfortunately using os.lstat() leads to a different problem: if X
depends on Y and Y is a symlink to Z, then X would not be rebuilt when
Z changes, which is clearly wrong.

The fix is twofold:

1. read_stamp() should change on changes to both the link itself,
   *and* the target of the link.

2. We shouldn't mark a target as overridden under so many situations.
   We'll use *only* the primary mtime of the os.lstat(), not all the
   other bits in the stamp.

Step 2 fixes a few other false positives also.  For example, if you
'cp -a' a whole tree to another location, the st_ino of all the targets
will change, which would trigger a mass of "manual override" warnings.
Although a change in inode is sufficient to count an input as having
changed (just to be extra safe), it should *not* be considered a manual
override.  Now we can distinguish between the two.

Because the stamp format has changed, update the SCHEMA_VER field.  I
should have done this every other time I changed the stamp format, but
I forgot.  Sorry.  That leads to spurious "manually modified" warnings
after upgrading redo.
2018-11-21 16:28:14 -05:00

59 lines
1.7 KiB
Python
Executable file

#!/usr/bin/env python2
import os, sys, traceback
import vars_init
vars_init.init(sys.argv[1:])
import vars, state, builder, jwack, deps
from helpers import unlink
from logs import debug, debug2, err
def should_build(t):
f = state.File(name=t)
if f.is_failed():
raise builder.ImmediateReturn(32)
dirty = deps.isdirty(f, depth = '', max_changed = vars.RUNID,
already_checked=[])
return f.is_generated, dirty==[f] and deps.DIRTY or dirty
rv = 202
try:
if vars_init.is_toplevel:
builder.start_stdin_log_reader(status=True, details=True,
pretty=True, color=True, debug_locks=False, debug_pids=False)
if vars.TARGET and not vars.UNLOCKED:
me = os.path.join(vars.STARTDIR,
os.path.join(vars.PWD, vars.TARGET))
f = state.File(name=me)
debug2('TARGET: %r %r %r\n' % (vars.STARTDIR, vars.PWD, vars.TARGET))
else:
f = me = None
debug2('redo-ifchange: not adding depends.\n')
jwack.setup(1)
try:
targets = sys.argv[1:]
if f:
for t in targets:
f.add_dep('m', t)
f.save()
state.commit()
rv = builder.main(targets, should_build)
finally:
try:
state.rollback()
finally:
try:
jwack.force_return_tokens()
except Exception, e:
traceback.print_exc(100, sys.stderr)
err('unexpected error: %r\n' % e)
rv = 1
except KeyboardInterrupt:
if vars_init.is_toplevel:
builder.await_log_reader()
sys.exit(200)
state.commit()
if vars_init.is_toplevel:
builder.await_log_reader()
sys.exit(rv)