From ea82b2a0857e3e0449bdce4e3987dee6adbc51ae Mon Sep 17 00:00:00 2001
From: "brian m. carlson" <sandals@crustytoothpaste.net>
Date: Tue, 15 Jan 2019 00:39:44 +0000
Subject: tree-walk: store object_id in a separate member

When parsing a tree, we read the object ID directly out of the tree
buffer. This is normally fine, but such an object ID cannot be used with
oidcpy, which copies GIT_MAX_RAWSZ bytes, because if we are using SHA-1,
there may not be that many bytes to copy.

Instead, store the object ID in a separate struct member. Since we can
no longer efficiently compute the path length, store that information as
well in struct name_entry. Ensure we only copy the object ID into the
new buffer if the path length is nonzero, as some callers will pass us
an empty path with no object ID following it, and we will not want to
read past the end of the buffer.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/grep.c b/builtin/grep.c
index bad9c0a..6fb93c0 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -566,7 +566,7 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 		strbuf_add(base, entry.path, te_len);
 
 		if (S_ISREG(entry.mode)) {
-			hit |= grep_oid(opt, entry.oid, base->buf, tn_len,
+			hit |= grep_oid(opt, &entry.oid, base->buf, tn_len,
 					 check_attr ? base->buf + tn_len : NULL);
 		} else if (S_ISDIR(entry.mode)) {
 			enum object_type type;
@@ -574,10 +574,10 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 			void *data;
 			unsigned long size;
 
-			data = lock_and_read_oid_file(entry.oid, &type, &size);
+			data = lock_and_read_oid_file(&entry.oid, &type, &size);
 			if (!data)
 				die(_("unable to read tree (%s)"),
-				    oid_to_hex(entry.oid));
+				    oid_to_hex(&entry.oid));
 
 			strbuf_addch(base, '/');
 			init_tree_desc(&sub, data, size);
@@ -585,7 +585,7 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 					 check_attr, repo);
 			free(data);
 		} else if (recurse_submodules && S_ISGITLINK(entry.mode)) {
-			hit |= grep_submodule(opt, repo, pathspec, entry.oid,
+			hit |= grep_submodule(opt, repo, pathspec, &entry.oid,
 					      base->buf, base->buf + tn_len);
 		}
 
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index 70f6fc9..4500c41 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -154,15 +154,15 @@ static void show_result(void)
 /* An empty entry never compares same, not even to another empty entry */
 static int same_entry(struct name_entry *a, struct name_entry *b)
 {
-	return	a->oid &&
-		b->oid &&
-		oideq(a->oid, b->oid) &&
+	return	!is_null_oid(&a->oid) &&
+		!is_null_oid(&b->oid) &&
+		oideq(&a->oid, &b->oid) &&
 		a->mode == b->mode;
 }
 
 static int both_empty(struct name_entry *a, struct name_entry *b)
 {
-	return !(a->oid || b->oid);
+	return is_null_oid(&a->oid) && is_null_oid(&b->oid);
 }
 
 static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
@@ -178,7 +178,7 @@ static struct merge_list *create_entry(unsigned stage, unsigned mode, const stru
 
 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
 {
-	char *path = xmallocz(traverse_path_len(info, n));
+	char *path = xmallocz(traverse_path_len(info, n) + the_hash_algo->rawsz);
 	return make_traverse_path(path, info, n);
 }
 
@@ -192,8 +192,8 @@ static void resolve(const struct traverse_info *info, struct name_entry *ours, s
 		return;
 
 	path = traverse_path(info, result);
-	orig = create_entry(2, ours->mode, ours->oid, path);
-	final = create_entry(0, result->mode, result->oid, path);
+	orig = create_entry(2, ours->mode, &ours->oid, path);
+	final = create_entry(0, result->mode, &result->oid, path);
 
 	final->link = orig;
 
@@ -217,7 +217,7 @@ static void unresolved_directory(const struct traverse_info *info,
 
 	newbase = traverse_path(info, p);
 
-#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? (e)->oid : NULL)
+#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
 	buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
 	buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
 	buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
@@ -243,7 +243,7 @@ static struct merge_list *link_entry(unsigned stage, const struct traverse_info
 		path = entry->path;
 	else
 		path = traverse_path(info, n);
-	link = create_entry(stage, n->mode, n->oid, path);
+	link = create_entry(stage, n->mode, &n->oid, path);
 	link->link = entry;
 	return link;
 }
@@ -318,7 +318,7 @@ static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, s
 	}
 
 	if (same_entry(entry+0, entry+1)) {
-		if (entry[2].oid && !S_ISDIR(entry[2].mode)) {
+		if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
 			/* We did not touch, they modified -- take theirs */
 			resolve(info, entry+1, entry+2);
 			return mask;
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 24bba81..327d917 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1334,7 +1334,7 @@ static void add_pbase_object(struct tree_desc *tree,
 		if (cmp < 0)
 			return;
 		if (name[cmplen] != '/') {
-			add_object_entry(entry.oid,
+			add_object_entry(&entry.oid,
 					 object_type(entry.mode),
 					 fullname, 1);
 			return;
@@ -1345,7 +1345,7 @@ static void add_pbase_object(struct tree_desc *tree,
 			const char *down = name+cmplen+1;
 			int downlen = name_cmp_len(down);
 
-			tree = pbase_tree_get(entry.oid);
+			tree = pbase_tree_get(&entry.oid);
 			if (!tree)
 				return;
 			init_tree_desc(&sub, tree->tree_data, tree->tree_size);
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 64a8df4..1f1010e 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -94,8 +94,8 @@ static int tree_is_complete(const struct object_id *oid)
 	init_tree_desc(&desc, tree->buffer, tree->size);
 	complete = 1;
 	while (tree_entry(&desc, &entry)) {
-		if (!has_sha1_file(entry.oid->hash) ||
-		    (S_ISDIR(entry.mode) && !tree_is_complete(entry.oid))) {
+		if (!has_sha1_file(entry.oid.hash) ||
+		    (S_ISDIR(entry.mode) && !tree_is_complete(&entry.oid))) {
 			tree->object.flags |= INCOMPLETE;
 			complete = 0;
 		}
diff --git a/cache-tree.c b/cache-tree.c
index 190c6e5..98cb665 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -675,7 +675,7 @@ static void prime_cache_tree_rec(struct repository *r,
 			cnt++;
 		else {
 			struct cache_tree_sub *sub;
-			struct tree *subtree = lookup_tree(r, entry.oid);
+			struct tree *subtree = lookup_tree(r, &entry.oid);
 			if (!subtree->object.parsed)
 				parse_tree(subtree);
 			sub = cache_tree_sub(it, entry.path);
@@ -724,7 +724,7 @@ int cache_tree_matches_traversal(struct cache_tree *root,
 
 	it = find_cache_tree_from_traversal(root, info);
 	it = cache_tree_find(it, ent->path);
-	if (it && it->entry_count > 0 && oideq(ent->oid, &it->oid))
+	if (it && it->entry_count > 0 && oideq(&ent->oid, &it->oid))
 		return it->entry_count;
 	return 0;
 }
diff --git a/delta-islands.c b/delta-islands.c
index 191a930..2186bd0 100644
--- a/delta-islands.c
+++ b/delta-islands.c
@@ -296,7 +296,7 @@ void resolve_tree_islands(struct repository *r,
 			if (S_ISGITLINK(entry.mode))
 				continue;
 
-			obj = lookup_object(r, entry.oid->hash);
+			obj = lookup_object(r, entry.oid.hash);
 			if (!obj)
 				continue;
 
diff --git a/fsck.c b/fsck.c
index 68502ce..2260adb 100644
--- a/fsck.c
+++ b/fsck.c
@@ -410,14 +410,14 @@ static int fsck_walk_tree(struct tree *tree, void *data, struct fsck_options *op
 			continue;
 
 		if (S_ISDIR(entry.mode)) {
-			obj = (struct object *)lookup_tree(the_repository, entry.oid);
+			obj = (struct object *)lookup_tree(the_repository, &entry.oid);
 			if (name && obj)
 				put_object_name(options, obj, "%s%s/", name,
 					entry.path);
 			result = options->walk(obj, OBJ_TREE, data, options);
 		}
 		else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode)) {
-			obj = (struct object *)lookup_blob(the_repository, entry.oid);
+			obj = (struct object *)lookup_blob(the_repository, &entry.oid);
 			if (name && obj)
 				put_object_name(options, obj, "%s%s", name,
 					entry.path);
diff --git a/http-push.c b/http-push.c
index cd48590..bb802d8 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1311,11 +1311,11 @@ static struct object_list **process_tree(struct tree *tree,
 	while (tree_entry(&desc, &entry))
 		switch (object_type(entry.mode)) {
 		case OBJ_TREE:
-			p = process_tree(lookup_tree(the_repository, entry.oid),
+			p = process_tree(lookup_tree(the_repository, &entry.oid),
 					 p);
 			break;
 		case OBJ_BLOB:
-			p = process_blob(lookup_blob(the_repository, entry.oid),
+			p = process_blob(lookup_blob(the_repository, &entry.oid),
 					 p);
 			break;
 		default:
diff --git a/list-objects.c b/list-objects.c
index cf7f25b..ee6aff0 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -123,15 +123,15 @@ static void process_tree_contents(struct traversal_context *ctx,
 		}
 
 		if (S_ISDIR(entry.mode)) {
-			struct tree *t = lookup_tree(ctx->revs->repo, entry.oid);
+			struct tree *t = lookup_tree(ctx->revs->repo, &entry.oid);
 			t->object.flags |= NOT_USER_GIVEN;
 			process_tree(ctx, t, base, entry.path);
 		}
 		else if (S_ISGITLINK(entry.mode))
-			process_gitlink(ctx, entry.oid->hash,
+			process_gitlink(ctx, entry.oid.hash,
 					base, entry.path);
 		else {
-			struct blob *b = lookup_blob(ctx->revs->repo, entry.oid);
+			struct blob *b = lookup_blob(ctx->revs->repo, &entry.oid);
 			b->object.flags |= NOT_USER_GIVEN;
 			process_blob(ctx, b, base, entry.path);
 		}
diff --git a/match-trees.c b/match-trees.c
index c2b7329..18ab825 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -106,7 +106,7 @@ static int score_trees(const struct object_id *hash1, const struct object_id *ha
 			update_tree_entry(&two);
 		} else {
 			/* path appears in both */
-			if (!oideq(one.entry.oid, two.entry.oid)) {
+			if (!oideq(&one.entry.oid, &two.entry.oid)) {
 				/* they are different */
 				score += score_differs(one.entry.mode,
 						       two.entry.mode,
diff --git a/notes.c b/notes.c
index 25cdce2..7f7cc4d 100644
--- a/notes.c
+++ b/notes.c
@@ -450,7 +450,7 @@ static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
 
 		l = xcalloc(1, sizeof(*l));
 		oidcpy(&l->key_oid, &object_oid);
-		oidcpy(&l->val_oid, entry.oid);
+		oidcpy(&l->val_oid, &entry.oid);
 		if (note_tree_insert(t, node, n, l, type,
 				     combine_notes_concatenate))
 			die("Failed to load %s %s into notes tree "
@@ -481,7 +481,7 @@ handle_non_note:
 			}
 			strbuf_addstr(&non_note_path, entry.path);
 			add_non_note(t, strbuf_detach(&non_note_path, NULL),
-				     entry.mode, entry.oid->hash);
+				     entry.mode, entry.oid.hash);
 		}
 	}
 	free(buf);
diff --git a/packfile.c b/packfile.c
index 8c6b47c..e38af1a 100644
--- a/packfile.c
+++ b/packfile.c
@@ -2100,7 +2100,7 @@ static int add_promisor_object(const struct object_id *oid,
 			 */
 			return 0;
 		while (tree_entry_gently(&desc, &entry))
-			oidset_insert(set, entry.oid);
+			oidset_insert(set, &entry.oid);
 	} else if (obj->type == OBJ_COMMIT) {
 		struct commit *commit = (struct commit *) obj;
 		struct commit_list *parents = commit->parents;
diff --git a/revision.c b/revision.c
index 13e0519..05fb390 100644
--- a/revision.c
+++ b/revision.c
@@ -67,10 +67,10 @@ static void mark_tree_contents_uninteresting(struct repository *r,
 	while (tree_entry(&desc, &entry)) {
 		switch (object_type(entry.mode)) {
 		case OBJ_TREE:
-			mark_tree_uninteresting(r, lookup_tree(r, entry.oid));
+			mark_tree_uninteresting(r, lookup_tree(r, &entry.oid));
 			break;
 		case OBJ_BLOB:
-			mark_blob_uninteresting(lookup_blob(r, entry.oid));
+			mark_blob_uninteresting(lookup_blob(r, &entry.oid));
 			break;
 		default:
 			/* Subproject commit - not in this repository */
diff --git a/tree-diff.c b/tree-diff.c
index 0e54324..4ffa00a 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -239,7 +239,7 @@ static struct combine_diff_path *emit_path(struct combine_diff_path *p,
 						DIFF_STATUS_ADDED;
 
 			if (tpi_valid) {
-				oid_i = tp[i].entry.oid;
+				oid_i = &tp[i].entry.oid;
 				mode_i = tp[i].entry.mode;
 			}
 			else {
@@ -280,7 +280,7 @@ static struct combine_diff_path *emit_path(struct combine_diff_path *p,
 			/* same rule as in emitthis */
 			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
 
-			parents_oid[i] = tpi_valid ? tp[i].entry.oid : NULL;
+			parents_oid[i] = tpi_valid ? &tp[i].entry.oid : NULL;
 		}
 
 		strbuf_add(base, path, pathlen);
@@ -491,7 +491,7 @@ static struct combine_diff_path *ll_diff_tree_paths(
 						continue;
 
 					/* diff(t,pi) != ø */
-					if (!oideq(t.entry.oid, tp[i].entry.oid) ||
+					if (!oideq(&t.entry.oid, &tp[i].entry.oid) ||
 					    (t.entry.mode != tp[i].entry.mode))
 						continue;
 
diff --git a/tree-walk.c b/tree-walk.c
index 1e040fc..56b951d 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -48,7 +48,8 @@ static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned l
 	/* Initialize the descriptor entry */
 	desc->entry.path = path;
 	desc->entry.mode = canon_mode(mode);
-	desc->entry.oid  = (const struct object_id *)(path + len);
+	desc->entry.pathlen = len - 1;
+	hashcpy(desc->entry.oid.hash, (const unsigned char *)path + len);
 
 	return 0;
 }
@@ -107,7 +108,7 @@ static void entry_extract(struct tree_desc *t, struct name_entry *a)
 static int update_tree_entry_internal(struct tree_desc *desc, struct strbuf *err)
 {
 	const void *buf = desc->buffer;
-	const unsigned char *end = desc->entry.oid->hash + the_hash_algo->rawsz;
+	const unsigned char *end = (const unsigned char *)desc->entry.path + desc->entry.pathlen + 1 + the_hash_algo->rawsz;
 	unsigned long size = desc->size;
 	unsigned long len = end - (const unsigned char *)buf;
 
@@ -175,9 +176,11 @@ void setup_traverse_info(struct traverse_info *info, const char *base)
 		pathlen--;
 	info->pathlen = pathlen ? pathlen + 1 : 0;
 	info->name.path = base;
-	info->name.oid = (void *)(base + pathlen + 1);
-	if (pathlen)
+	info->name.pathlen = pathlen;
+	if (pathlen) {
+		hashcpy(info->name.oid.hash, (const unsigned char *)base + pathlen + 1);
 		info->prev = &dummy;
+	}
 }
 
 char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
diff --git a/tree-walk.h b/tree-walk.h
index 1968310..08d349c 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -1,11 +1,14 @@
 #ifndef TREE_WALK_H
 #define TREE_WALK_H
 
+#include "cache.h"
+
 struct strbuf;
 
 struct name_entry {
-	const struct object_id *oid;
+	struct object_id oid;
 	const char *path;
+	int pathlen;
 	unsigned int mode;
 };
 
@@ -19,12 +22,12 @@ static inline const struct object_id *tree_entry_extract(struct tree_desc *desc,
 {
 	*pathp = desc->entry.path;
 	*modep = desc->entry.mode;
-	return desc->entry.oid;
+	return &desc->entry.oid;
 }
 
 static inline int tree_entry_len(const struct name_entry *ne)
 {
-	return (const char *)ne->oid - ne->path - 1;
+	return ne->pathlen;
 }
 
 /*
diff --git a/tree.c b/tree.c
index 215d3fd..7badea0 100644
--- a/tree.c
+++ b/tree.c
@@ -84,7 +84,7 @@ static int read_tree_1(struct tree *tree, struct strbuf *base,
 				continue;
 		}
 
-		switch (fn(entry.oid, base,
+		switch (fn(&entry.oid, base,
 			   entry.path, entry.mode, stage, context)) {
 		case 0:
 			continue;
@@ -95,19 +95,19 @@ static int read_tree_1(struct tree *tree, struct strbuf *base,
 		}
 
 		if (S_ISDIR(entry.mode))
-			oidcpy(&oid, entry.oid);
+			oidcpy(&oid, &entry.oid);
 		else if (S_ISGITLINK(entry.mode)) {
 			struct commit *commit;
 
-			commit = lookup_commit(the_repository, entry.oid);
+			commit = lookup_commit(the_repository, &entry.oid);
 			if (!commit)
 				die("Commit %s in submodule path %s%s not found",
-				    oid_to_hex(entry.oid),
+				    oid_to_hex(&entry.oid),
 				    base->buf, entry.path);
 
 			if (parse_commit(commit))
 				die("Invalid commit %s in submodule path %s%s",
-				    oid_to_hex(entry.oid),
+				    oid_to_hex(&entry.oid),
 				    base->buf, entry.path);
 
 			oidcpy(&oid, get_commit_tree_oid(commit));
diff --git a/unpack-trees.c b/unpack-trees.c
index 6d53cbf..734828f 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -679,7 +679,7 @@ static int switch_cache_bottom(struct traverse_info *info)
 
 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 {
-	return name_j->oid && name_k->oid && oideq(name_j->oid, name_k->oid);
+	return !is_null_oid(&name_j->oid) && !is_null_oid(&name_k->oid) && oideq(&name_j->oid, &name_k->oid);
 }
 
 static int all_trees_same_as_cache_tree(int n, unsigned long dirmask,
@@ -857,7 +857,7 @@ static int traverse_trees_recursive(int n, unsigned long dirmask,
 		else {
 			const struct object_id *oid = NULL;
 			if (dirmask & 1)
-				oid = names[i].oid;
+				oid = &names[i].oid;
 			buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 		}
 	}
@@ -981,7 +981,7 @@ static struct cache_entry *create_ce_entry(const struct traverse_info *info,
 	ce->ce_mode = create_ce_mode(n->mode);
 	ce->ce_flags = create_ce_flags(stage);
 	ce->ce_namelen = len;
-	oidcpy(&ce->oid, n->oid);
+	oidcpy(&ce->oid, &n->oid);
 	make_traverse_path(ce->name, info, n);
 
 	return ce;
diff --git a/walker.c b/walker.c
index 96990d8..d74ae59 100644
--- a/walker.c
+++ b/walker.c
@@ -50,13 +50,13 @@ static int process_tree(struct walker *walker, struct tree *tree)
 			continue;
 		if (S_ISDIR(entry.mode)) {
 			struct tree *tree = lookup_tree(the_repository,
-							entry.oid);
+							&entry.oid);
 			if (tree)
 				obj = &tree->object;
 		}
 		else {
 			struct blob *blob = lookup_blob(the_repository,
-							entry.oid);
+							&entry.oid);
 			if (blob)
 				obj = &blob->object;
 		}
-- 
cgit v0.10.2-6-g49f6