Merge branch 'lt/xsha1'

* lt/xsha1:
  get_tree_entry(): make it available from tree-walk
  sha1_name.c: no need to include diff.h; tree-walk.h will do.
  sha1_name.c: prepare to make get_tree_entry() reusable from others.
  get_sha1() shorthands for blob/tree objects

sha1_name.c

@@ -3,6 +3,7 @@
 #include "commit.h"
 #include "tree.h"
 #include "blob.h"
+#include "tree-walk.h"
 
 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
 {
@@ -455,6 +456,19 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
  */
 int get_sha1(const char *name, unsigned char *sha1)
 {
+	int ret;
+	unsigned unused;
+
 	prepare_alt_odb();
-	return get_sha1_1(name, strlen(name), sha1);
+	ret = get_sha1_1(name, strlen(name), sha1);
+	if (ret < 0) {
+		const char *cp = strchr(name, ':');
+		if (cp) {
+			unsigned char tree_sha1[20];
+			if (!get_sha1_1(name, cp-name, tree_sha1))
+				return get_tree_entry(tree_sha1, cp+1, sha1,
+						      &unused);
+		}
+	}
+	return ret;
 }

tree-walk.c

@@ -115,3 +115,53 @@ void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callb
 	free(entry);
 }
 
+static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
+{
+	int namelen = strlen(name);
+	while (t->size) {
+		const char *entry;
+		const unsigned char *sha1;
+		int entrylen, cmp;
+
+		sha1 = tree_entry_extract(t, &entry, mode);
+		update_tree_entry(t);
+		entrylen = strlen(entry);
+		if (entrylen > namelen)
+			continue;
+		cmp = memcmp(name, entry, entrylen);
+		if (cmp > 0)
+			continue;
+		if (cmp < 0)
+			break;
+		if (entrylen == namelen) {
+			memcpy(result, sha1, 20);
+			return 0;
+		}
+		if (name[entrylen] != '/')
+			continue;
+		if (!S_ISDIR(*mode))
+			break;
+		if (++entrylen == namelen) {
+			memcpy(result, sha1, 20);
+			return 0;
+		}
+		return get_tree_entry(sha1, name + entrylen, result, mode);
+	}
+	return -1;
+}
+
+int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
+{
+	int retval;
+	void *tree;
+	struct tree_desc t;
+
+	tree = read_object_with_reference(tree_sha1, tree_type, &t.size, NULL);
+	if (!tree)
+		return -1;
+	t.buf = tree;
+	retval = find_tree_entry(&t, name, sha1, mode);
+	free(tree);
+	return retval;
+}
+

tree-walk.h

@@ -22,4 +22,6 @@ typedef void (*traverse_callback_t)(int n, unsigned long mask, struct name_entry
 
 void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback);
 
+int get_tree_entry(const unsigned char *, const char *, unsigned char *, unsigned *);
+
 #endif