On Wed, May 17, 2017 at 2:47 AM, Junio C Hamano [off-list ref] wrote:

Samuel Lijin [off-list ref] writes:

quoted

When we taught read_directory_recursive() to recurse into untracked
directories in search of ignored files given DIR_SHOW_IGNORED_TOO, that
had the side effect of teaching it to collect the untracked contents of
untracked directories. It doesn't always make sense to return these,
though (we do need them for `clean -d`), so we introduce a flag
(DIR_KEEP_UNTRACKED_CONTENTS) to control whether or not read_directory()
strips dir->entries of the untracked contents of untracked dirs.

We also introduce check_contains() to check if one dir_entry corresponds
to a path which contains the path corresponding to another dir_entry.

Signed-off-by: Samuel Lijin <redacted>
---
 dir.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 dir.h |  3 ++-
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/dir.c b/dir.c
index 6bd0350e9..214a148ee 100644
--- a/dir.c
+++ b/dir.c

@@ -1852,6 +1852,14 @@ static int cmp_name(const void *p1, const void *p2)
      return name_compare(e1->name, e1->len, e2->name, e2->len);
 }

+/* check if *out lexically contains *in */
+static int check_contains(const struct dir_entry *out, const struct dir_entry *in)
+{
+     return (out->len < in->len) &&
+                     (out->name[out->len - 1] == '/') &&
+                     !memcmp(out->name, in->name, out->len);
+}

OK, treat_one_path() and treat_pah_fast() both ensure that a path to
a directory is terminated with '/' before calling dir_add_name() and
dir_add_ignored(), so we know a dir_entry "out" that is a directory
must end with '/'.  Good.

The second and third line being overly indented is a bit
distracting, though.

quoted

 static int treat_leading_path(struct dir_struct *dir,
                            const char *path, int len,
                            const struct pathspec *pathspec)

@@ -2067,6 +2075,52 @@ int read_directory(struct dir_struct *dir, const char *path,
              read_directory_recursive(dir, path, len, untracked, 0, pathspec);
      QSORT(dir->entries, dir->nr, cmp_name);
      QSORT(dir->ignored, dir->ignored_nr, cmp_name);
+
+     // if DIR_SHOW_IGNORED_TOO, read_directory_recursive() will also pick
+     // up untracked contents of untracked dirs; by default we discard these,
+     // but given DIR_KEEP_UNTRACKED_CONTENTS we do not

        /*
         * Our multi-line comments are formatted like this
         * example.  No C++/C99 // comments, outside of
         * borrowed code and platform specific compat/ code,
         * please.
         */

Gahhhh, I keep forgetting about this, sorry. (There has to be a way to
tell my compiler to catch this, right? It's pretty embarrassing to get
called out for this twice...)

quoted

+     if ((dir->flags & DIR_SHOW_IGNORED_TOO)
+                  && !(dir->flags & DIR_KEEP_UNTRACKED_CONTENTS)) {

Both having && at the end and && at the beginning are valid C, but
please stick to one style in a single file.

Got it.

quoted

+             int i, j, nr_removed = 0;
+
+             // remove from dir->entries untracked contents of untracked dirs

        /* And our single-liner comments look like this */

quoted

+             for (i = 0; i < dir->nr; i++) {
+                     if (!dir->entries[i])
+                             continue;
+
+                     for (j = i + 1; j < dir->nr; j++) {
+                             if (!dir->entries[j])
+                                     continue;
+                             if (check_contains(dir->entries[i], dir->entries[j])) {
+                                     nr_removed++;
+                                     free(dir->entries[j]);
+                                     dir->entries[j] = NULL;
+                             }
+                             else {
+                                     break;
+                             }
+                     }
+             }

This loop is O(n^2).  I wonder if we can do better, especially we
know dir->entries[] is sorted already.

Now that I think about it, dropping an `i = j - 1` into the inner loop
right before the break should work:

+                             else {
+                                     i = j - 1;
+                                     break;
+                             }

Well, because it is sorted, if A/, A/B, and A/B/C are all untracked,
the first round that scans for A/ will nuke both A/B and A/B/C, so
we won't have to scan looking for entries inside A/B, which is a bit
of consolation ;-)

quoted

+                     for (i = 0;;) {
+                             while (i < dir->nr && dir->entries[i])
+                                     i++;
+                             if (i == dir->nr)
+                                     break;
+                             j = i;
+                             while (j < dir->nr && !dir->entries[j])
+                                     j++;
+                             if (j == dir->nr)
+                                     break;
+                             dir->entries[i] = dir->entries[j];
+                             dir->entries[j] = NULL;
+                     }
+                     dir->nr -= nr_removed;

This looks like an overly complicated way to scan an array and skip
NULLs.  Are you doing an equivalent of this loop, or am I missing
something subtle?

        for (src = dst = 0; src < nr; src++)
                if (array[src])
                        array[dst++] = src;
        nr = dst;

Nope, that's pretty much it. Just me overthinking the problem.