NULL_SHA1 is used to indicate an "invalid object name" throughout our
code (and the code of other git implementations), so it is vastly more
likely that an on-disk reference was set to this value due to a
software bug than that NULL_SHA1 is the legitimate SHA-1 of an actual
object. Therefore, if a loose reference has the value NULL_SHA1,
consider it to be broken.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If there is a loose reference file with invalid contents, "git
for-each-ref" incorrectly reports the problem as being a missing
object with name NULL_SHA1:
$ echo '12345678' >.git/refs/heads/nonsense
$ git for-each-ref
fatal: missing object 0000000000000000000000000000000000000000 for refs/heads/nonsense
With an explicit "--format" string, it can even report that the
reference validly points at NULL_SHA1:
$ git for-each-ref --format='%(objectname) %(refname)'
0000000000000000000000000000000000000000 refs/heads/nonsense
$ echo $?
0
This has been broken since
b7dd2d2 for-each-ref: Do not lookup objects when they will not be used (2009-05-27)
, which changed for-each-ref from using for_each_ref() to using
git_for_each_rawref() in order to avoid looking up the referred-to
objects unnecessarily. (When "git for-each-ref" is given a "--format"
string that doesn't include information about the pointed-to object,
it does not look up the object at all, which makes it considerably
faster. Iterating with DO_FOR_EACH_INCLUDE_BROKEN is essential to this
optimization because otherwise for_each_ref() would itself need to
check whether the object exists as part of its brokenness test.)
But for_each_rawref() includes broken references in the iteration, and
"git for-each-ref" doesn't itself reject references with REF_ISBROKEN.
The result is that broken references are processed *as if* they had
the value NULL_SHA1, which is the value stored in entries for broken
references.
Change "git for-each-ref" to emit warnings for references that are
REF_ISBROKEN but to otherwise skip them.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add tests that for-each-ref correctly reports broken loose reference
files and references that point at missing objects. In fact, two of
these tests fail, because (1) NULL_SHA1 is not recognized as an
invalid reference value, and (2) for-each-ref doesn't respect
REF_ISBROKEN. Fixes to come.
Note that when for-each-ref is run with a --format option that doesn't
require the object to be looked up, then we should still notice if a
loose reference file is corrupt or contains NULL_SHA1, but we don't
notice if it points at a missing object because we don't do an object
lookup. This is OK.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
