tree.c API: move read_tree() into builtin/ls-files.c

Since the read_tree() API was added around the same time as
read_tree_recursive() in 94537c78a82 (Move "read_tree()" to
"tree.c"[...], 2005-04-22) and b12ec373b8e ([PATCH] Teach read-tree
about commit objects, 2005-04-20) things have gradually migrated over
to the read_tree_recursive() version.

Now builtin/ls-files.c is the last user of this code, let's move all
the relevant code there. This allows for subsequent simplification of
it, and an eventual move to read_tree_recursive().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index f6f9e483b2..a445862281 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -12,6 +12,7 @@
 #include "dir.h"
 #include "builtin.h"
 #include "tree.h"
+#include "cache-tree.h"
 #include "parse-options.h"
 #include "resolve-undo.h"
 #include "string-list.h"
@@ -420,6 +421,96 @@ static int get_common_prefix_len(const char *common_prefix)
 	return common_prefix_len;
 }
 
+static int read_one_entry_opt(struct index_state *istate,
+			      const struct object_id *oid,
+			      const char *base, int baselen,
+			      const char *pathname,
+			      unsigned mode, int stage, int opt)
+{
+	int len;
+	struct cache_entry *ce;
+
+	if (S_ISDIR(mode))
+		return READ_TREE_RECURSIVE;
+
+	len = strlen(pathname);
+	ce = make_empty_cache_entry(istate, baselen + len);
+
+	ce->ce_mode = create_ce_mode(mode);
+	ce->ce_flags = create_ce_flags(stage);
+	ce->ce_namelen = baselen + len;
+	memcpy(ce->name, base, baselen);
+	memcpy(ce->name + baselen, pathname, len+1);
+	oidcpy(&ce->oid, oid);
+	return add_index_entry(istate, ce, opt);
+}
+
+static int read_one_entry(const struct object_id *oid, struct strbuf *base,
+			  const char *pathname, unsigned mode, int stage,
+			  void *context)
+{
+	struct index_state *istate = context;
+	return read_one_entry_opt(istate, oid, base->buf, base->len, pathname,
+				  mode, stage,
+				  ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+}
+
+/*
+ * This is used when the caller knows there is no existing entries at
+ * the stage that will conflict with the entry being added.
+ */
+static int read_one_entry_quick(const struct object_id *oid, struct strbuf *base,
+				const char *pathname, unsigned mode, int stage,
+				void *context)
+{
+	struct index_state *istate = context;
+	return read_one_entry_opt(istate, oid, base->buf, base->len, pathname,
+				  mode, stage,
+				  ADD_CACHE_JUST_APPEND);
+}
+
+
+static int read_tree(struct repository *r, struct tree *tree, int stage,
+		     struct pathspec *match, struct index_state *istate)
+{
+	read_tree_fn_t fn = NULL;
+	int i, err;
+
+	/*
+	 * Currently the only existing callers of this function all
+	 * call it with stage=1 and after making sure there is nothing
+	 * at that stage; we could always use read_one_entry_quick().
+	 *
+	 * But when we decide to straighten out git-read-tree not to
+	 * use unpack_trees() in some cases, this will probably start
+	 * to matter.
+	 */
+
+	/*
+	 * See if we have cache entry at the stage.  If so,
+	 * do it the original slow way, otherwise, append and then
+	 * sort at the end.
+	 */
+	for (i = 0; !fn && i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
+		if (ce_stage(ce) == stage)
+			fn = read_one_entry;
+	}
+
+	if (!fn)
+		fn = read_one_entry_quick;
+	err = read_tree_recursive(r, tree, "", 0, stage, match, fn, istate);
+	if (fn == read_one_entry || err)
+		return err;
+
+	/*
+	 * Sort the cache entry -- we need to nuke the cache tree, though.
+	 */
+	cache_tree_free(&istate->cache_tree);
+	QSORT(istate->cache, istate->cache_nr, cmp_cache_name_compare);
+	return 0;
+}
+
 /*
  * Read the tree specified with --with-tree option
  * (typically, HEAD) into stage #1 and then