When we find ambiguous short sha1s, we may get a
disambiguation rule from our caller's context. But if we
don't, we fall back to treating all sha1s the same, even
though most projects will tend to refer only to commits by
their short sha1s.
This patch introduces a configuration option that lets the
user pick a different fallback (e.g., only commits). It's
possible that we may want to make this the default, but it's
a good idea to start as a config option for two reasons:
1. It lets people experiment with this and see if it's a
good idea (i.e., the "tend to" above is an assumption;
we don't really know if this will break some obscure
cases).
2. Even if we do flip the default, it gives people an
escape hatch if it causes problems (you can sometimes
override it by asking for "1234^{tree}", but not all
combinations are possible).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the user gives us an ambiguous short sha1, we print an
error and refuse to resolve it. In some cases, the next step
is for them to feed us more characters (e.g., if they were
retyping or cut-and-pasting from a full sha1). But in other
cases, that might be all they have. For example, an old
commit message may have used a 7-character hex that was
unique at the time, but is now ambiguous. Git doesn't
provide any information about the ambiguous objects it
found, so it's hard for the user to find out which one they
probably meant.
This patch teaches get_short_sha1() to list the sha1s of the
objects it found, along with a few bits of information that
may help the user decide which one they meant. Here's what
it looks like on git.git:
$ git rev-parse b2e1
error: short SHA1 b2e1 is ambiguous
hint: The candidates are:
hint: b2e1196 tag v2.8.0-rc1
hint: b2e11d1 tree
hint: b2e1632 commit 2007-11-14 - Merge branch 'bs/maint-commit-options'
hint: b2e1759 blob
hint: b2e18954 blob
hint: b2e1895c blob
fatal: ambiguous argument 'b2e1': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
We show the tagname for tags, and the date and subject for
commits. For trees and blobs, in theory we could dig in the
history to find the paths at which they were present. But
that's very expensive (on the order of 30s for the kernel),
and it's not likely to be all that helpful. Most short
references are to commits, so the useful information is
typically going to be that the object in question _isn't_ a
commit. So it's silly to spend a lot of CPU preemptively
digging up the path; the user can do it themselves if they
really need to.
And of course it's somewhat ironic that we abbreviate the
sha1s in the disambiguation hint. But full sha1s would cause
annoying line wrapping for the commit lines, and presumably
the user is going to just re-issue their command immediately
with the corrected sha1.
We also restrict the list to those that match any
disambiguation hint. E.g.:
$ git rev-parse b2e1:foo
error: short SHA1 b2e1 is ambiguous
hint: The candidates are:
hint: b2e1196 tag v2.8.0-rc1
hint: b2e11d1 tree
hint: b2e1632 commit 2007-11-14 - Merge branch 'bs/maint-commit-options'
fatal: Invalid object name 'b2e1'.
does not bother reporting the blobs, because they cannot
work as a treeish.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If an object appears multiple times in the object database
(e.g., in both loose and packed form, or in two separate
packs), the disambiguation machinery may see it more than
once. The get_short_sha1() function handles this already,
but for_each_abbrev() blindly fires the callback for each
instance it finds.
We can fix this by collecting the output in a sha1 array and
de-duplicating it. As a bonus, the sort done for the
de-duplication means that our output will be stable,
regardless of the order in which the objects are found.
Note that the old code normalized the callback's output to
0/1 to store in the 1-bit ds->ambiguous flag (which both
halted the iteration and was returned from the
for_each_abbrev function). Now that we are using sha1_array,
we can return the real value. In practice, it doesn't matter
as the sole caller only ever returns 0.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The treeish disambiguation function tries to peel tags, but
it does so by calling:
deref_tag(lookup_object(sha1), ...);
This will only work if we have previously looked at the tag
and created a "struct tag" for it. Since parsing revision
arguments typically happens before anything else, this is
usually not the case, and we would fail to peel the tag (we
are lucky that deref_tag() gracefully handles the NULL and
does not segfault).
Instead, we can use parse_object(). Note that this is the
same fix done by 94d75d1 (get_short_sha1(): correctly
disambiguate type-limited abbreviation, 2013-07-01), but
that commit fixed only the committish disambiguator, and
left the bug in the treeish one.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The get_sha1() function is actually implementation by many
sub-functions, but we do not always pass our flags around to
all of those functions. As a result, we may forget that our
caller asked us to resolve with GET_SHA1_QUIETLY and output
messages. The two triggerable cases are:
1. Resolving treeish:path will resolve the "treeish"
portion using GET_SHA1_TREEISH, dropping all other
flags.
2. The peel_onion() function did not take flags at all
but recurses to get_sha1_1(), which does.
The solution for both is to bitwise-OR their new flags with
the existing ones (after dropping any mutually exclusive
disambiguation flags).
This bug can trigger with "git rev-parse --quiet", which
asks for quiet resolution. But it can also happen in a more
vanilla code path when we do a follow-up ONLY_TO_DIE
invocation of get_sha1(), and that's what the tests check.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the revision code cannot parse an argument like
"HEAD:foo", it will call maybe_die_on_misspelt_object_name(),
which re-runs get_sha1() with an extra ONLY_TO_DIE flag. We
then spend more effort to generate a better error message.
Unfortunately, a side effect is that our second call may
repeat the same error messages from the original get_sha1()
call. You can see this with:
$ git show 0017
error: short SHA1 0017 is ambiguous.
error: short SHA1 0017 is ambiguous.
fatal: ambiguous argument '0017': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
where the second "error:" line comes from the ONLY_TO_DIE
call.
To fix this, we can make ONLY_TO_DIE imply QUIETLY. This is
a little odd, because the whole point of ONLY_TO_DIE is to
output error messages. But what we want to do is tell the
rest of the get_sha1() code (particularly get_sha1_1()) that
the _regular_ messages should be quiet, but the only-to-die
ones should not.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.
The backquoted form is the traditional method for command
substitution, and is supported by POSIX. However, all but the
simplest uses become complicated quickly. In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.
The patch was generated by:
for _f in $(find . -name "*.sh")
do
perl -i -pe 'BEGIN{undef $/;} s/`(.+?)`/\$(\1)/smg' "${_f}"
done
and then carefully proof-read.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A test that should have failed but didn't revealed a bug that needs
to be corrected.
* jc/t1512-fix:
get_short_sha1(): correctly disambiguate type-limited abbreviation
t1512: correct leftover constants from earlier edition
The earliest iteration of this test script used a magic string
110282 as the common prefix for ambiguous object names, but the
final edition switched the common prefix to 0000000000 (10 "0"s).
Unfortunately, instances of the original prefix were left in the
comments and a few tests. Replace them with the correct constants.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we get 40 hex digits, we immediately assume it's an SHA-1. This
is the right thing to do because we have no way else to specify an
object. If there is a ref with the same object name, it will be
ignored. Warn the user about this case because the ref with full
object name is likely a mistake, for example
git checkout -b $empty_var $(git rev-parse something)
advice.object_name_warning is not documented because frankly people
should not be aware about it until they encounter this situation.
While at there, warn about ambiguation with abbreviated SHA-1 too.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test creates 16 objects that share the same prefix, and two other
objects that do not. Tweak the test so that the other two share the
same prefix that is different from the one that is shared by the 16.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some implementations of sed (e.g. MacOS X) have whitespaces in the
output of "wc -l" that reads from the standard input. Ignore these
whitespaces by not quoting the command substitution to be compared
with the constant "16".
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The new option allows you to feed an ambiguous prefix and enumerate
all the objects that share it as a prefix of their object names.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is not strictly correct, in that resetting selected index
entries from corresponding paths out of a given tree without moving
HEAD is a valid operation, and in such case a tree-ish would suffice.
But the existing code already requires a committish in the codepath,
so let's be consistent with it for now.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "index" line read from the patch to reconstruct a partial
preimage tree records the object names of blob objects.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This teaches the revision parser that in "$name:$path" (used for a
blob object name), "$name" must be a tree-ish.
There are many more places where we know what types of objects are
called for. This patch adds support for "commit", "treeish", "tree",
and "blob", which could be used in the following contexts:
- "git apply --build-fake-ancestor" reads the "index" lines from
the patch; they must name blob objects (not even "blob-ish");
- "git commit-tree" reads a tree object name (not "tree-ish"), and
zero or more commit object names (not "committish");
- "git reset $rev" wants a committish; "git reset $rev -- $path"
wants a treeish.
They will come in later patches in the series.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a field to setup_revision_opt structure and allow these callers
to tell the setup_revisions command parsing machinery that short SHA1
it encounters are meant to name committish.
This step does not go all the way to connect the setup_revisions()
to sha1_name.c yet.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Many callers know that the user meant to name a committish by
syntactical positions where the object name appears. Calling this
function allows the machinery to disambiguate shorter-than-unique
abbreviated object names between committish and others.
Note that this does NOT error out when the named object is not a
committish. It is merely to give a hint to the disambiguation
machinery.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We know that the token "$name" that appear in "$name^{commit}",
"$name^4", "$name~4" etc. can only name a committish (either a
commit or a tag that peels to a commit). Teach get_short_sha1() to
take advantage of that knowledge when disambiguating an abbreviated
SHA-1 given as an object name.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach get_describe_name() to pass the disambiguation hint down the
callchain to get_short_sha1().
Also add tests to show various syntactic elements that we could take
advantage of the object type information to help disambiguration of
abbreviated object names. Many of them are marked as broken, and
some of them will be fixed in later patches in this series.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
