From 806f83287f8d6c0568beed7ca5d603f936d53c40 Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Wed, 30 Jun 2021 17:29:58 +0000 Subject: [PATCH 1/3] t6423: test directory renames causing rename-to-self Directory rename detection can cause transitive renames, e.g. if the two different sides of history each do one half of: A/file -> B/file B/ -> C/ then directory rename detection transitively renames to give us C/file. Since the default for merge.directoryRenames is conflict, this results in an error message saying it is unclear whether the file should be placed at B/file or C/file. What if C/ is A/, though? In such a case, the transitive rename would give us A/file, the original name we started with. Logically, having an error message with B/file vs. A/file should be fine, as should leaving the file where it started. But the logic in both merge-recursive and merge-ort did not handle a case of a filename being renamed to itself correctly; merge-recursive had two bugs, and merge-ort had one. Add some testcases covering such a scenario. Based-on-testcase-by: Anders Kaseorg Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- t/t6423-merge-rename-directories.sh | 175 ++++++++++++++++++++++++++++ 1 file changed, 175 insertions(+) diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh index 7134769149fc53..afb88c347fc901 100755 --- a/t/t6423-merge-rename-directories.sh +++ b/t/t6423-merge-rename-directories.sh @@ -4966,6 +4966,181 @@ test_expect_success '12g: Testcase with two kinds of "relevant" renames' ' ) ' +# Testcase 12i, Directory rename causes rename-to-self +# Commit O: source/{subdir/foo, bar, baz_1} +# Commit A: source/{foo, bar, baz_1} +# Commit B: source/{subdir/{foo, bar}, baz_2} +# Expected: source/{foo, bar, baz_2}, with conflicts on +# source/bar vs. source/subdir/bar + +test_setup_12i () { + test_create_repo 12i && + ( + cd 12i && + + mkdir -p source/subdir && + echo foo >source/subdir/foo && + echo bar >source/bar && + echo baz >source/baz && + git add source && + git commit -m orig && + + git branch O && + git branch A && + git branch B && + + git switch A && + git mv source/subdir/foo source/foo && + git commit -m A && + + git switch B && + git mv source/bar source/subdir/bar && + echo more baz >>source/baz && + git commit -m B + ) +} + +test_expect_merge_algorithm failure failure '12i: Directory rename causes rename-to-self' ' + test_setup_12i && + ( + cd 12i && + + git checkout A^0 && + + test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 && + + test_path_is_missing source/subdir && + test_path_is_file source/bar && + test_path_is_file source/baz && + + git ls-files | uniq >tracked && + test_line_count = 3 tracked && + + git status --porcelain -uno >actual && + cat >expect <<-\EOF && + UU source/bar + M source/baz + EOF + test_cmp expect actual + ) +' + +# Testcase 12j, Directory rename to root causes rename-to-self +# Commit O: {subdir/foo, bar, baz_1} +# Commit A: {foo, bar, baz_1} +# Commit B: {subdir/{foo, bar}, baz_2} +# Expected: {foo, bar, baz_2}, with conflicts on bar vs. subdir/bar + +test_setup_12j () { + test_create_repo 12j && + ( + cd 12j && + + mkdir -p subdir && + echo foo >subdir/foo && + echo bar >bar && + echo baz >baz && + git add . && + git commit -m orig && + + git branch O && + git branch A && + git branch B && + + git switch A && + git mv subdir/foo foo && + git commit -m A && + + git switch B && + git mv bar subdir/bar && + echo more baz >>baz && + git commit -m B + ) +} + +test_expect_merge_algorithm failure failure '12j: Directory rename to root causes rename-to-self' ' + test_setup_12j && + ( + cd 12j && + + git checkout A^0 && + + test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 && + + test_path_is_missing subdir && + test_path_is_file bar && + test_path_is_file baz && + + git ls-files | uniq >tracked && + test_line_count = 3 tracked && + + git status --porcelain -uno >actual && + cat >expect <<-\EOF && + UU bar + M baz + EOF + test_cmp expect actual + ) +' + +# Testcase 12k, Directory rename with sibling causes rename-to-self +# Commit O: dirB/foo, dirA/{bar, baz_1} +# Commit A: dirA/{foo, bar, baz_1} +# Commit B: dirB/{foo, bar}, dirA/baz_2 +# Expected: dirA/{foo, bar, baz_2}, with conflicts on dirA/bar vs. dirB/bar + +test_setup_12k () { + test_create_repo 12k && + ( + cd 12k && + + mkdir dirA dirB && + echo foo >dirB/foo && + echo bar >dirA/bar && + echo baz >dirA/baz && + git add . && + git commit -m orig && + + git branch O && + git branch A && + git branch B && + + git switch A && + git mv dirB/* dirA/ && + git commit -m A && + + git switch B && + git mv dirA/bar dirB/bar && + echo more baz >>dirA/baz && + git commit -m B + ) +} + +test_expect_merge_algorithm failure failure '12k: Directory rename with sibling causes rename-to-self' ' + test_setup_12k && + ( + cd 12k && + + git checkout A^0 && + + test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 && + + test_path_is_missing dirB && + test_path_is_file dirA/bar && + test_path_is_file dirA/baz && + + git ls-files | uniq >tracked && + test_line_count = 3 tracked && + + git status --porcelain -uno >actual && + cat >expect <<-\EOF && + UU dirA/bar + M dirA/baz + EOF + test_cmp expect actual + ) +' + ########################################################################### # SECTION 13: Checking informational and conflict messages # From a492d5331cb93d8293e72741b4fb9e1ec4ff294b Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Wed, 30 Jun 2021 17:29:59 +0000 Subject: [PATCH 2/3] merge-ort: ensure we consult df_conflict and path_conflicts Path conflicts (typically rename path conflicts, e.g. rename/rename(1to2) or rename/add/delete), and directory/file conflicts should obviously result in files not being marked as clean in the merge. We had a codepath where we missed consulting the path_conflict and df_conflict flags, based on match_mask. Granted, it requires an unusual setup to trigger this codepath (directory rename causing rename-to-self is the only case I can think of), but we still need to handle it. To make it clear that we have audited the other codepaths that do not explicitly mention these flags, add some assertions that the flags are not set. Reported-by: Anders Kaseorg Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- merge-ort.c | 6 +++++- t/t6423-merge-rename-directories.sh | 6 +++--- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/merge-ort.c b/merge-ort.c index 4a9ce2a822bd61..8b0f2448f0fe1b 100644 --- a/merge-ort.c +++ b/merge-ort.c @@ -3002,7 +3002,7 @@ static void process_entry(struct merge_options *opt, * above. */ if (ci->match_mask) { - ci->merged.clean = 1; + ci->merged.clean = !ci->df_conflict && !ci->path_conflict; if (ci->match_mask == 6) { /* stages[1] == stages[2] */ ci->merged.result.mode = ci->stages[1].mode; @@ -3014,6 +3014,8 @@ static void process_entry(struct merge_options *opt, ci->merged.result.mode = ci->stages[side].mode; ci->merged.is_null = !ci->merged.result.mode; + if (ci->merged.is_null) + ci->merged.clean = 1; oidcpy(&ci->merged.result.oid, &ci->stages[side].oid); assert(othermask == 2 || othermask == 4); @@ -3186,6 +3188,7 @@ static void process_entry(struct merge_options *opt, path)) { ci->merged.is_null = 1; ci->merged.clean = 1; + assert(!ci->df_conflict && !ci->path_conflict); } else if (ci->path_conflict && oideq(&ci->stages[0].oid, &ci->stages[side].oid)) { /* @@ -3212,6 +3215,7 @@ static void process_entry(struct merge_options *opt, ci->merged.is_null = 1; ci->merged.result.mode = 0; oidcpy(&ci->merged.result.oid, null_oid()); + assert(!ci->df_conflict); ci->merged.clean = !ci->path_conflict; } diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh index afb88c347fc901..316339cb6c93d9 100755 --- a/t/t6423-merge-rename-directories.sh +++ b/t/t6423-merge-rename-directories.sh @@ -5000,7 +5000,7 @@ test_setup_12i () { ) } -test_expect_merge_algorithm failure failure '12i: Directory rename causes rename-to-self' ' +test_expect_merge_algorithm failure success '12i: Directory rename causes rename-to-self' ' test_setup_12i && ( cd 12i && @@ -5058,7 +5058,7 @@ test_setup_12j () { ) } -test_expect_merge_algorithm failure failure '12j: Directory rename to root causes rename-to-self' ' +test_expect_merge_algorithm failure success '12j: Directory rename to root causes rename-to-self' ' test_setup_12j && ( cd 12j && @@ -5116,7 +5116,7 @@ test_setup_12k () { ) } -test_expect_merge_algorithm failure failure '12k: Directory rename with sibling causes rename-to-self' ' +test_expect_merge_algorithm failure success '12k: Directory rename with sibling causes rename-to-self' ' test_setup_12k && ( cd 12k && From 3585d0ea232b1a9c5498ab5785b11f61e93967c8 Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Wed, 30 Jun 2021 17:30:00 +0000 Subject: [PATCH 3/3] merge-recursive: handle rename-to-self case Directory rename detection can cause transitive renames, e.g. if the two different sides of history each do one half of: A/file -> B/file B/ -> C/ then directory rename detection transitively renames to give us A/file -> C/file However, when C/ == A/, note that this gives us A/file -> A/file. merge-recursive assumed that any rename D -> E would have D != E. While that is almost always true, the above is a special case where it is not. So we cannot do things like delete the rename source, we cannot assume that a file existing at path E implies a rename/add conflict and we have to be careful about what stages end up in the output. This change feels a bit hackish. It took me surprisingly many hours to find, and given merge-recursive's design causing it to attempt to enumerate all combinations of edge and corner cases with special code for each combination, I'm worried there are other similar fixes needed elsewhere if we can just come up with the right special testcase. Perhaps an audit would rule it out, but I have not the energy. merge-recursive deserves to die, and since it is on its way out anyway, fixing this particular bug narrowly will have to be good enough. Reported-by: Anders Kaseorg Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- merge-recursive.c | 19 +++++++++++++------ t/t6423-merge-rename-directories.sh | 6 +++--- 2 files changed, 16 insertions(+), 9 deletions(-) diff --git a/merge-recursive.c b/merge-recursive.c index d146bb116f73cd..c895145a8f520c 100644 --- a/merge-recursive.c +++ b/merge-recursive.c @@ -2804,12 +2804,19 @@ static int process_renames(struct merge_options *opt, int renamed_stage = a_renames == renames1 ? 2 : 3; int other_stage = a_renames == renames1 ? 3 : 2; + /* + * Directory renames have a funny corner case... + */ + int renamed_to_self = !strcmp(ren1_src, ren1_dst); + /* BUG: We should only remove ren1_src in the base * stage and in other_stage (think of rename + * add-source case). */ - remove_file(opt, 1, ren1_src, - renamed_stage == 2 || !was_tracked(opt, ren1_src)); + if (!renamed_to_self) + remove_file(opt, 1, ren1_src, + renamed_stage == 2 || + !was_tracked(opt, ren1_src)); oidcpy(&src_other.oid, &ren1->src_entry->stages[other_stage].oid); @@ -2823,6 +2830,9 @@ static int process_renames(struct merge_options *opt, ren1->dir_rename_original_type == 'A') { setup_rename_conflict_info(RENAME_VIA_DIR, opt, ren1, NULL); + } else if (renamed_to_self) { + setup_rename_conflict_info(RENAME_NORMAL, + opt, ren1, NULL); } else if (oideq(&src_other.oid, null_oid())) { setup_rename_conflict_info(RENAME_DELETE, opt, ren1, NULL); @@ -3180,7 +3190,6 @@ static int handle_rename_normal(struct merge_options *opt, struct rename *ren = ci->ren1; struct merge_file_info mfi; int clean; - int side = (ren->branch == opt->branch1 ? 2 : 3); /* Merge the content and write it out */ clean = handle_content_merge(&mfi, opt, path, was_dirty(opt, path), @@ -3190,9 +3199,7 @@ static int handle_rename_normal(struct merge_options *opt, opt->detect_directory_renames == MERGE_DIRECTORY_RENAMES_CONFLICT && ren->dir_rename_original_dest) { if (update_stages(opt, path, - NULL, - side == 2 ? &mfi.blob : NULL, - side == 2 ? NULL : &mfi.blob)) + &mfi.blob, &mfi.blob, &mfi.blob)) return -1; clean = 0; /* not clean, but conflicted */ } diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh index 316339cb6c93d9..4d056f046514a4 100755 --- a/t/t6423-merge-rename-directories.sh +++ b/t/t6423-merge-rename-directories.sh @@ -5000,7 +5000,7 @@ test_setup_12i () { ) } -test_expect_merge_algorithm failure success '12i: Directory rename causes rename-to-self' ' +test_expect_success '12i: Directory rename causes rename-to-self' ' test_setup_12i && ( cd 12i && @@ -5058,7 +5058,7 @@ test_setup_12j () { ) } -test_expect_merge_algorithm failure success '12j: Directory rename to root causes rename-to-self' ' +test_expect_success '12j: Directory rename to root causes rename-to-self' ' test_setup_12j && ( cd 12j && @@ -5116,7 +5116,7 @@ test_setup_12k () { ) } -test_expect_merge_algorithm failure success '12k: Directory rename with sibling causes rename-to-self' ' +test_expect_success '12k: Directory rename with sibling causes rename-to-self' ' test_setup_12k && ( cd 12k &&