| Message ID | 35b74eb972eed7e08190e826fabcf6b7a241f285.1701243201.git.ps@pks.im (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | refs: improve handling of special refs | expand |
On Wed, Nov 29, 2023 at 09:14:12AM +0100, Patrick Steinhardt wrote: > We read both the HEAD and ORIG_HEAD references directly from the > filesystem in order to figure out whether we're currently splitting a > commit. If both of the following are true: > > - HEAD points to the same object as "rebase-merge/amend". > > - ORIG_HEAD points to the same object as "rebase-merge/orig-head". > > Then we are currently splitting commits. > > The current code only works by chance because we only have a single > reference backend implementation. Refactor it to instead read both refs > via the refdb layer so that we'll also be compatible with alternate > reference backends. > > Note that we pass `RESOLVE_REF_NO_RECURSE` to `read_ref_full()`. This is > because we didn't resolve symrefs before either, and in practice none of > the refs in "rebase-merge/" would be symbolic. We thus don't want to > resolve symrefs with the new code either to retain the old behaviour. > > Signed-off-by: Patrick Steinhardt <ps@pks.im> > --- > wt-status.c | 17 +++++++++-------- > 1 file changed, 9 insertions(+), 8 deletions(-) > > diff --git a/wt-status.c b/wt-status.c > index 9f45bf6949..fe9e590b80 100644 > --- a/wt-status.c > +++ b/wt-status.c > @@ -1295,26 +1295,27 @@ static char *read_line_from_git_path(const char *filename) > static int split_commit_in_progress(struct wt_status *s) > { > int split_in_progress = 0; > - char *head, *orig_head, *rebase_amend, *rebase_orig_head; > + struct object_id head_oid, orig_head_oid; > + char *rebase_amend, *rebase_orig_head; > > if ((!s->amend && !s->nowarn && !s->workdir_dirty) || > !s->branch || strcmp(s->branch, "HEAD")) > return 0; > > - head = read_line_from_git_path("HEAD"); > - orig_head = read_line_from_git_path("ORIG_HEAD"); > + if (read_ref_full("HEAD", RESOLVE_REF_NO_RECURSE, &head_oid, NULL) || > + read_ref_full("ORIG_HEAD", RESOLVE_REF_NO_RECURSE, &orig_head_oid, NULL)) Switching to read_ref_full() here is going to have some slightly different behavior than just reading out the contents of "$GIT_DIR/HEAD", but I think that it should be OK. Before we would not have complained, if, for example, the contents of "$GIT_DIR/HEAD" were malformed, but now we will. I think that's OK, especially given that if that file is bogus, we'll have other problems before we get here ;-). Are there any other gotchas that we should be thinking about? > + return 0; > + > rebase_amend = read_line_from_git_path("rebase-merge/amend"); > rebase_orig_head = read_line_from_git_path("rebase-merge/orig-head"); > > - if (!head || !orig_head || !rebase_amend || !rebase_orig_head) > + if (!rebase_amend || !rebase_orig_head) > ; /* fall through, no split in progress */ > else if (!strcmp(rebase_amend, rebase_orig_head)) > - split_in_progress = !!strcmp(head, rebase_amend); > - else if (strcmp(orig_head, rebase_orig_head)) > + split_in_progress = !!strcmp(oid_to_hex(&head_oid), rebase_amend); > + else if (strcmp(oid_to_hex(&orig_head_oid), rebase_orig_head)) I did a double take at these strcmp(oid_to_hex(...)) calls, but I think that they are the best that we can do given that we're still reading the contents of "rebase-merge/amend" and "rebase-merge/orig-head" directly. I suppose we could go the other way and turn their contents into object_ids and then use oidcmp(), but it doesn't seem worth it IMHO. Thanks, Taylor
On Wed, Nov 29, 2023 at 04:45:00PM -0500, Taylor Blau wrote: > On Wed, Nov 29, 2023 at 09:14:12AM +0100, Patrick Steinhardt wrote: > > We read both the HEAD and ORIG_HEAD references directly from the > > filesystem in order to figure out whether we're currently splitting a > > commit. If both of the following are true: > > > > - HEAD points to the same object as "rebase-merge/amend". > > > > - ORIG_HEAD points to the same object as "rebase-merge/orig-head". > > > > Then we are currently splitting commits. > > > > The current code only works by chance because we only have a single > > reference backend implementation. Refactor it to instead read both refs > > via the refdb layer so that we'll also be compatible with alternate > > reference backends. > > > > Note that we pass `RESOLVE_REF_NO_RECURSE` to `read_ref_full()`. This is > > because we didn't resolve symrefs before either, and in practice none of > > the refs in "rebase-merge/" would be symbolic. We thus don't want to > > resolve symrefs with the new code either to retain the old behaviour. > > > > Signed-off-by: Patrick Steinhardt <ps@pks.im> > > --- > > wt-status.c | 17 +++++++++-------- > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > diff --git a/wt-status.c b/wt-status.c > > index 9f45bf6949..fe9e590b80 100644 > > --- a/wt-status.c > > +++ b/wt-status.c > > @@ -1295,26 +1295,27 @@ static char *read_line_from_git_path(const char *filename) > > static int split_commit_in_progress(struct wt_status *s) > > { > > int split_in_progress = 0; > > - char *head, *orig_head, *rebase_amend, *rebase_orig_head; > > + struct object_id head_oid, orig_head_oid; > > + char *rebase_amend, *rebase_orig_head; > > > > if ((!s->amend && !s->nowarn && !s->workdir_dirty) || > > !s->branch || strcmp(s->branch, "HEAD")) > > return 0; > > > > - head = read_line_from_git_path("HEAD"); > > - orig_head = read_line_from_git_path("ORIG_HEAD"); > > + if (read_ref_full("HEAD", RESOLVE_REF_NO_RECURSE, &head_oid, NULL) || > > + read_ref_full("ORIG_HEAD", RESOLVE_REF_NO_RECURSE, &orig_head_oid, NULL)) > > Switching to read_ref_full() here is going to have some slightly > different behavior than just reading out the contents of > "$GIT_DIR/HEAD", but I think that it should be OK. > > Before we would not have complained, if, for example, the contents of > "$GIT_DIR/HEAD" were malformed, but now we will. I think that's OK, > especially given that if that file is bogus, we'll have other problems > before we get here ;-). > > Are there any other gotchas that we should be thinking about? Not that I can think of. As you say, a repository with malformed HEAD will run into other problems anyway. And `read_ref_full()` would return errors if these refs were malformed, which would cause us to exit early from anyway. So unless "rebase-merge/amend" and "rebase-merge/orig-head" contained the same kind of garbage we'd retain the same behaviour as before, and that shouldn't really be happening. One interesting bit is that we don't set `RESOLVE_REF_READING`, so `read_ref_full()` may return successfully even if the ref doesn't exist. But in practice this is fine given that the resulting oid would be cleared in that case. Patrick > > + return 0; > > + > > rebase_amend = read_line_from_git_path("rebase-merge/amend"); > > rebase_orig_head = read_line_from_git_path("rebase-merge/orig-head"); > > > > - if (!head || !orig_head || !rebase_amend || !rebase_orig_head) > > + if (!rebase_amend || !rebase_orig_head) > > ; /* fall through, no split in progress */ > > else if (!strcmp(rebase_amend, rebase_orig_head)) > > - split_in_progress = !!strcmp(head, rebase_amend); > > - else if (strcmp(orig_head, rebase_orig_head)) > > + split_in_progress = !!strcmp(oid_to_hex(&head_oid), rebase_amend); > > + else if (strcmp(oid_to_hex(&orig_head_oid), rebase_orig_head)) > > I did a double take at these strcmp(oid_to_hex(...)) calls, but I think > that they are the best that we can do given that we're still reading the > contents of "rebase-merge/amend" and "rebase-merge/orig-head" directly. > > I suppose we could go the other way and turn their contents into > object_ids and then use oidcmp(), but it doesn't seem worth it IMHO. > > Thanks, > Taylor
On Thu, Nov 30, 2023 at 08:42:48AM +0100, Patrick Steinhardt wrote: > > Are there any other gotchas that we should be thinking about? > > Not that I can think of. As you say, a repository with malformed HEAD > will run into other problems anyway. And `read_ref_full()` would return > errors if these refs were malformed, which would cause us to exit early > from anyway. So unless "rebase-merge/amend" and "rebase-merge/orig-head" > contained the same kind of garbage we'd retain the same behaviour as > before, and that shouldn't really be happening. > > One interesting bit is that we don't set `RESOLVE_REF_READING`, so > `read_ref_full()` may return successfully even if the ref doesn't exist. > But in practice this is fine given that the resulting oid would be > cleared in that case. Thanks for thinking through these. I agree with your reasoning and think that this is fine as-is. (Off-topic, but can you please trim your replies to only include the quoted parts/context that you're replying to?) Thanks, Taylor
diff --git a/wt-status.c b/wt-status.c index 9f45bf6949..fe9e590b80 100644 --- a/wt-status.c +++ b/wt-status.c @@ -1295,26 +1295,27 @@ static char *read_line_from_git_path(const char *filename) static int split_commit_in_progress(struct wt_status *s) { int split_in_progress = 0; - char *head, *orig_head, *rebase_amend, *rebase_orig_head; + struct object_id head_oid, orig_head_oid; + char *rebase_amend, *rebase_orig_head; if ((!s->amend && !s->nowarn && !s->workdir_dirty) || !s->branch || strcmp(s->branch, "HEAD")) return 0; - head = read_line_from_git_path("HEAD"); - orig_head = read_line_from_git_path("ORIG_HEAD"); + if (read_ref_full("HEAD", RESOLVE_REF_NO_RECURSE, &head_oid, NULL) || + read_ref_full("ORIG_HEAD", RESOLVE_REF_NO_RECURSE, &orig_head_oid, NULL)) + return 0; + rebase_amend = read_line_from_git_path("rebase-merge/amend"); rebase_orig_head = read_line_from_git_path("rebase-merge/orig-head"); - if (!head || !orig_head || !rebase_amend || !rebase_orig_head) + if (!rebase_amend || !rebase_orig_head) ; /* fall through, no split in progress */ else if (!strcmp(rebase_amend, rebase_orig_head)) - split_in_progress = !!strcmp(head, rebase_amend); - else if (strcmp(orig_head, rebase_orig_head)) + split_in_progress = !!strcmp(oid_to_hex(&head_oid), rebase_amend); + else if (strcmp(oid_to_hex(&orig_head_oid), rebase_orig_head)) split_in_progress = 1; - free(head); - free(orig_head); free(rebase_amend); free(rebase_orig_head);
We read both the HEAD and ORIG_HEAD references directly from the filesystem in order to figure out whether we're currently splitting a commit. If both of the following are true: - HEAD points to the same object as "rebase-merge/amend". - ORIG_HEAD points to the same object as "rebase-merge/orig-head". Then we are currently splitting commits. The current code only works by chance because we only have a single reference backend implementation. Refactor it to instead read both refs via the refdb layer so that we'll also be compatible with alternate reference backends. Note that we pass `RESOLVE_REF_NO_RECURSE` to `read_ref_full()`. This is because we didn't resolve symrefs before either, and in practice none of the refs in "rebase-merge/" would be symbolic. We thus don't want to resolve symrefs with the new code either to retain the old behaviour. Signed-off-by: Patrick Steinhardt <ps@pks.im> --- wt-status.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)