Re: Is "show-ref -h" a good test for an empty repository?
From: Jeff King <hidden>
Date: 2016-06-15 22:45:19
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-06-15 · Is "show-ref -h" a good test for an empty repository? · Eric Gerlach <hidden>
- 2016-06-15 · Re: Is "show-ref -h" a good test for an empty repository? · Jeff King <hidden>
- 2016-06-15 · Re: Is "show-ref -h" a good test for an empty repository? · Eric Gerlach <hidden>
- 2016-06-15 · Re: Is "show-ref -h" a good test for an empty repository? · Jeff King <hidden>
On Mon, Sep 08, 2008 at 09:24:39AM -0400, Eric Gerlach wrote:
The case I'm looking to protect against is the following: $ mkdir -p new-repo/debian $ cd new-repo $ git init $ vi debian/changelog (add a few lines) $ git add debian/changelog $ debcommit (which runs $ git diff --cached debian/changelog) If I can test before the git-diff, then I can run "diff debian/changelog /dev/null" instead of the git-diff and all is well.
In that case, I would use the "rev-parse --verify HEAD" I mentioned,
since it exactly covers the situation you are trying to avoid. What you
are saying is something like:
if there is a previous commit on the current branch
diff against previous commit on the current branch
else
diff against /dev/null
So your "show-ref" attempt could actually say "yes, the repo is
non-empty" but your diff would still fail (because the commits just
weren't on the current branch).
As an aside, it's too bad "--root" isn't more widely supported. Then
git diff --root --cached
would do what you want without the need for any conditionals. But it
seems that --root only works between trees. Something like the patch
below would help, but I'm sure this is covering only one of many cases.
---
diff --git a/builtin-diff.c b/builtin-diff.c
index 52470c7..43db970 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c@@ -317,8 +317,11 @@ int cmd_diff(int argc, const char **argv, const char *prefix) break; else if (!strcmp(arg, "--cached")) { add_head_to_pending(&rev); - if (!rev.pending.nr) - die("No HEAD commit to compare with (yet)"); + if (!rev.pending.nr) { + if (!rev.show_root_diff) + die("No HEAD commit to compare with (yet)"); + add_empty_to_pending(&rev); + } break; } }
diff --git a/revision.c b/revision.c
index 2f646de..7ec3990 100644
--- a/revision.c
+++ b/revision.c@@ -145,16 +145,27 @@ void add_pending_object(struct rev_info *revs, struct object *obj, const char *n add_pending_object_with_mode(revs, obj, name, S_IFINVALID); } -void add_head_to_pending(struct rev_info *revs) +static void add_to_pending_by_name(struct rev_info *revs, const char *name) { unsigned char sha1[20]; struct object *obj; - if (get_sha1("HEAD", sha1)) + if (get_sha1(name, sha1)) return; obj = parse_object(sha1); if (!obj) return; - add_pending_object(revs, obj, "HEAD"); + add_pending_object(revs, obj, name); +} + +void add_head_to_pending(struct rev_info *revs) +{ + add_to_pending_by_name(revs, "HEAD"); +} + +void add_empty_to_pending(struct rev_info *revs) +{ + add_to_pending_by_name(revs, + "4b825dc642cb6eb9a060e54bf8d69288fbee4904"); } static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
diff --git a/revision.h b/revision.h
index 2fdb2dd..8c990d5 100644
--- a/revision.h
+++ b/revision.h@@ -152,6 +152,7 @@ extern void add_object(struct object *obj, extern void add_pending_object(struct rev_info *revs, struct object *obj, const char *name); extern void add_head_to_pending(struct rev_info *); +extern void add_empty_to_pending(struct rev_info *); enum commit_action { commit_ignore,