Make index add/append support core.filemode flag

This fixes git_index_add and git_index_append to behave more like
core git, preserving old filemode data in the index when adding
and/or appending with core.filemode = false.

This also has placeholder support for core.symlinks and
core.ignorecase, but those flags are not implemented (well,
symlinks has partial support for preserving mode information in
the same way that git does, but it isn't tested).

4 files changed, 80 insertions, 20 deletions

diff --git a/src/diff.c b/src/diff.c
index 02b89b46..bc8708e3 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -456,10 +456,10 @@ static int maybe_modified(
 	if (!diff_path_matches_pathspec(diff, oitem->path))
 		return 0;
 
-	/* on platforms with no symlinks, promote plain files to symlinks */
+	/* on platforms with no symlinks, preserve mode of existing symlinks */
 	if (S_ISLNK(omode) && S_ISREG(nmode) &&
 		!(diff->diffcaps & GIT_DIFFCAPS_HAS_SYMLINKS))
-		nmode = GIT_MODE_TYPE(omode) | (nmode & GIT_MODE_PERMS_MASK);
+		nmode = omode;
 
 	/* on platforms with no execmode, just preserve old mode */
 	if (!(diff->diffcaps & GIT_DIFFCAPS_TRUST_MODE_BITS) &&
diff --git a/src/index.c b/src/index.c
index f1ae9a71..3fedcd27 100644
--- a/src/index.c
+++ b/src/index.c
@@ -15,6 +15,7 @@
 #include "hash.h"
 #include "git2/odb.h"
 #include "git2/blob.h"
+#include "git2/config.h"
 
 #define entry_size(type,len) ((offsetof(type, path) + (len) + 8) & ~7)
 #define short_entry_size(len) entry_size(struct entry_short, len)
@@ -124,11 +125,27 @@ static unsigned int index_create_mode(unsigned int mode)
 {
 	if (S_ISLNK(mode))
 		return S_IFLNK;
+
 	if (S_ISDIR(mode) || (mode & S_IFMT) == (S_IFLNK | S_IFDIR))
 		return (S_IFLNK | S_IFDIR);
+
 	return S_IFREG | ((mode & 0100) ? 0755 : 0644);
 }
 
+static unsigned int index_merge_mode(
+	git_index *index, git_index_entry *existing, unsigned int mode)
+{
+	if (index->no_symlinks && S_ISREG(mode) &&
+		existing && S_ISLNK(existing->mode))
+		return existing->mode;
+
+	if (index->distrust_filemode && S_ISREG(mode))
+		return (existing && S_ISREG(existing->mode)) ?
+			existing->mode : index_create_mode(0666);
+
+	return index_create_mode(mode);
+}
+
 int git_index_open(git_index **index_out, const char *index_path)
 {
 	git_index *index;
@@ -208,6 +225,45 @@ void git_index_clear(git_index *index)
 	index->tree = NULL;
 }
 
+int git_index_set_caps(git_index *index, unsigned int caps)
+{
+	assert(index);
+
+	if (caps == GIT_INDEXCAP_FROM_OWNER) {
+		git_config *cfg;
+		int val;
+
+		if (INDEX_OWNER(index) == NULL ||
+			git_repository_config__weakptr(&cfg, INDEX_OWNER(index)) < 0)
+		{
+			giterr_set(GITERR_INDEX,
+				"Cannot get repository config to set index caps");
+			return -1;
+		}
+
+		if (git_config_get_bool(&val, cfg, "core.ignorecase") == 0)
+			index->ignore_case = (val != 0);
+		if (git_config_get_bool(&val, cfg, "core.filemode") == 0)
+			index->distrust_filemode = (val == 0);
+		if (git_config_get_bool(&val, cfg, "core.symlinks") == 0)
+			index->no_symlinks = (val != 0);
+	}
+	else {
+		index->ignore_case = ((caps & GIT_INDEXCAP_IGNORE_CASE) != 0);
+		index->distrust_filemode = ((caps & GIT_INDEXCAP_NO_FILEMODE) != 0);
+		index->no_symlinks = ((caps & GIT_INDEXCAP_NO_SYMLINKS) != 0);
+	}
+
+	return 0;
+}
+
+unsigned int git_index_caps(const git_index *index)
+{
+	return ((index->ignore_case ? GIT_INDEXCAP_IGNORE_CASE : 0) |
+			(index->distrust_filemode ? GIT_INDEXCAP_NO_FILEMODE : 0) |
+			(index->no_symlinks ? GIT_INDEXCAP_NO_SYMLINKS : 0));
+}
+
 int git_index_read(git_index *index)
 {
 	int error, updated;
@@ -383,7 +439,7 @@ static int index_insert(git_index *index, git_index_entry *entry, int replace)
 {
 	size_t path_length;
 	int position;
-	git_index_entry **entry_array;
+	git_index_entry **existing = NULL;
 
 	assert(index && entry && entry->path != NULL);
 
@@ -397,28 +453,24 @@ static int index_insert(git_index *index, git_index_entry *entry, int replace)
 	else
 		entry->flags |= GIT_IDXENTRY_NAMEMASK;;
 
-	/*
-	 * replacing is not requested: just insert entry at the end;
-	 * the index is no longer sorted
-	 */
-	if (!replace)
-		return git_vector_insert(&index->entries, entry);
-
 	/* look if an entry with this path already exists */
-	position = git_index_find(index, entry->path);
+	if ((position = git_index_find(index, entry->path)) >= 0) {
+		existing = (git_index_entry **)&index->entries.contents[position];
 
-	/*
-	 * if no entry exists add the entry at the end;
-	 * the index is no longer sorted
+		/* update filemode to existing values if stat is not trusted */
+		entry->mode = index_merge_mode(index, *existing, entry->mode);
+	}
+
+	/* if replacing is not requested or no existing entry exists, just
+	 * insert entry at the end; the index is no longer sorted
 	 */
-	if (position == GIT_ENOTFOUND)
+	if (!replace || !existing)
 		return git_vector_insert(&index->entries, entry);
 
 	/* exists, replace it */
-	entry_array = (git_index_entry **) index->entries.contents;
-	git__free(entry_array[position]->path);
-	git__free(entry_array[position]);
-	entry_array[position] = entry;
+	git__free((*existing)->path);
+	git__free(*existing);
+	*existing = entry;
 
 	return 0;
 }
@@ -475,7 +527,7 @@ int git_index_add2(git_index *index, const git_index_entry *source_entry)
 
 int git_index_append2(git_index *index, const git_index_entry *source_entry)
 {
-	return index_add2(index, source_entry, 1);
+	return index_add2(index, source_entry, 0);
 }
 
 int git_index_remove(git_index *index, int position)
diff --git a/src/index.h b/src/index.h
index 8515f4fc..a57da538 100644
--- a/src/index.h
+++ b/src/index.h
@@ -26,6 +26,11 @@ struct git_index {
 	git_vector entries;
 
 	unsigned int on_disk:1;
+
+	unsigned int ignore_case:1;
+	unsigned int distrust_filemode:1;
+	unsigned int no_symlinks:1;
+
 	git_tree_cache *tree;
 
 	git_vector unmerged;
diff --git a/src/repository.c b/src/repository.c
index 4e467e68..4806215e 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -573,6 +573,9 @@ int git_repository_index__weakptr(git_index **out, git_repository *repo)
 			return -1;
 
 		GIT_REFCOUNT_OWN(repo->_index, repo);
+
+		if (git_index_set_caps(repo->_index, GIT_INDEXCAP_FROM_OWNER) < 0)
+			return -1;
 	}
 
 	*out = repo->_index;