merge-recursive: Fix sorting order and directory change assumptions

We cannot assume that directory/file conflicts will appear in sorted
order; for example, 'letters.txt' comes between 'letters' and
'letters/file'.

Thanks to Johannes for a pointer about qsort stability issues with
Windows and suggested code change.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge-recursive.c b/merge-recursive.c
index 418246376b78d050a7f38b9ae6820ee188cf5cec..7757e5f1634c69d20a5537dedeec385d7a44a43b 100644 (file)
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -331,6 +331,37 @@ static struct string_list *get_unmerged(void)
        return unmerged;
 }
 
+static int string_list_df_name_compare(const void *a, const void *b)
+{
+       const struct string_list_item *one = a;
+       const struct string_list_item *two = b;
+       int onelen = strlen(one->string);
+       int twolen = strlen(two->string);
+       /*
+        * Here we only care that entries for D/F conflicts are
+        * adjacent, in particular with the file of the D/F conflict
+        * appearing before files below the corresponding directory.
+        * The order of the rest of the list is irrelevant for us.
+        *
+        * To achieve this, we sort with df_name_compare and provide
+        * the mode S_IFDIR so that D/F conflicts will sort correctly.
+        * We use the mode S_IFDIR for everything else for simplicity,
+        * since in other cases any changes in their order due to
+        * sorting cause no problems for us.
+        */
+       int cmp = df_name_compare(one->string, onelen, S_IFDIR,
+                                 two->string, twolen, S_IFDIR);
+       /*
+        * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
+        * that 'foo' comes before 'foo/bar'.
+        */
+       if (cmp)
+               return cmp;
+       return onelen - twolen;
+}
+
+
+
 static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
                                                      struct string_list *entries)
 {
@@ -343,11 +374,6 @@ static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
         * otherwise, if the file is not supposed to be removed by the
         * merge, the contents of the file will be placed in another
         * unique filename.
-        *
-        * NOTE: This function relies on the fact that entries for a
-        * D/F conflict will appear adjacent in the index, with the
-        * entries for the file appearing before entries for paths
-        * below the corresponding directory.
         */
        const char *last_file = NULL;
        int last_len = 0;
@@ -360,6 +386,10 @@ static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
        if (o->call_depth)
                return;
 
+       /* Ensure D/F conflicts are adjacent in the entries list. */
+       qsort(entries->items, entries->nr, sizeof(*entries->items),
+             string_list_df_name_compare);
+
        for (i = 0; i < entries->nr; i++) {
                const char *path = entries->items[i].string;
                int len = strlen(path);

diff --git a/t/t6020-merge-df.sh b/t/t6020-merge-df.sh
index eec8f4e3edd85e350f5b8d8c86415317cce2aba1..27c3d73961dfc9b50c3eafc7360662076cb31260 100755 (executable)
--- a/t/t6020-merge-df.sh
+++ b/t/t6020-merge-df.sh
@@ -59,15 +59,19 @@ test_expect_success 'setup modify/delete + directory/file conflict' '
        git add letters &&
        git commit -m initial &&
 
+       # Throw in letters.txt for sorting order fun
+       # ("letters.txt" sorts between "letters" and "letters/file")
        echo i >>letters &&
-       git add letters &&
+       echo "version 2" >letters.txt &&
+       git add letters letters.txt &&
        git commit -m modified &&
 
        git checkout -b delete HEAD^ &&
        git rm letters &&
        mkdir letters &&
        >letters/file &&
-       git add letters &&
+       echo "version 1" >letters.txt &&
+       git add letters letters.txt &&
        git commit -m deleted
 '
 
@@ -75,25 +79,31 @@ test_expect_success 'modify/delete + directory/file conflict' '
        git checkout delete^0 &&
        test_must_fail git merge modify &&
 
-       test 3 = $(git ls-files -s | wc -l) &&
-       test 2 = $(git ls-files -u | wc -l) &&
-       test 1 = $(git ls-files -o | wc -l) &&
+       test 5 -eq $(git ls-files -s | wc -l) &&
+       test 4 -eq $(git ls-files -u | wc -l) &&
+       test 1 -eq $(git ls-files -o | wc -l) &&
 
        test -f letters/file &&
+       test -f letters.txt &&
        test -f letters~modify
 '
 
 test_expect_success 'modify/delete + directory/file conflict; other way' '
+       # Yes, we really need the double reset since "letters" appears as
+       # both a file and a directory.
+       git reset --hard &&
        git reset --hard &&
        git clean -f &&
        git checkout modify^0 &&
+
        test_must_fail git merge delete &&
 
-       test 3 = $(git ls-files -s | wc -l) &&
-       test 2 = $(git ls-files -u | wc -l) &&
-       test 1 = $(git ls-files -o | wc -l) &&
+       test 5 -eq $(git ls-files -s | wc -l) &&
+       test 4 -eq $(git ls-files -u | wc -l) &&
+       test 1 -eq $(git ls-files -o | wc -l) &&
 
        test -f letters/file &&
+       test -f letters.txt &&
        test -f letters~HEAD
 '