file: use the inode reference for the parent directory.

This change removes the `dir_inode` field from the `SqshFile` structure
and replaces it with a `parent_inode_ref` field. This field is used to
store the inode reference of the parent directory. This reduces the
number of inode lookups required to resolve the parent directory of a
file.

libsqsh/include/sqsh_file_private.h

@@ -207,6 +207,8 @@ SQSH_NO_EXPORT int sqsh__file_reader_cleanup(struct SqshFileReader *reader);
  * file/file.c
  */
 
+#define SQSH_INODE_REF_NULL UINT64_MAX
+
 /**
  * @brief The file type implementation
  */
@@ -249,8 +251,7 @@ struct SqshFile {
 	struct SqshArchive *archive;
 	const struct SqshInodeImpl *impl;
 	enum SqshFileType type;
-	bool has_dir_inode;
-	uint32_t dir_inode;
+	uint64_t parent_inode_ref;
 };
 
 /**
@@ -271,35 +272,24 @@ SQSH_NO_EXPORT SQSH_NO_UNUSED int sqsh__file_init(
 
 /**
  * @memberof SqshFile
- * @brief returns whether the file is an extended structure.
+ * @brief sets the parent inode reference.
  *
  * @param[in] context The file context.
- * @param[in] dir_inode The inode of the parent directory.
- *
- * @return int 0 on success, less than 0 on error.
+ * @param[in] parent_inode_ref The inode reference of the parent directory.
  */
-SQSH_NO_EXPORT SQSH_NO_UNUSED int
-sqsh__file_set_dir_inode(struct SqshFile *context, uint32_t dir_inode);
+SQSH_NO_EXPORT void sqsh__file_set_parent_inode_ref(
+		struct SqshFile *context, uint64_t parent_inode_ref);
 
 /**
- * @internal
  * @memberof SqshFile
- * @brief Retrieves the inode of the parent directory.
+ * @brief returns the parent inode reference if possible.
  *
- * @param context The file context.
- * @return The inode number.
- */
-SQSH_NO_EXPORT uint32_t sqsh__file_dir_inode(const struct SqshFile *context);
-
-/**
- * @internal
- * @memberof SqshFile
- * @brief Retrieves if the inode of the parent directory is set.
+ * @param[in] context The file context.
+ * @param[out] err Pointer to an int where the error code will be stored.
  *
- * @param context The file context.
- * @return true if the dir_inode is set, false otherwise.
+ * @return int 0 on success, less than 0 on error.
  */
-SQSH_NO_EXPORT bool sqsh__file_has_dir_inode(const struct SqshFile *context);
+uint64_t sqsh__file_parent_inode_ref(struct SqshFile *context, int *err);
 
 /**
  * @internal

libsqsh/src/archive/inode_map.c

@@ -38,8 +38,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#define EMPTY_INODE_REF UINT64_MAX
-
 // Funfact: In older versions of this library, the inode map used `0` as the
 // sentinal value for empty inodes. It turned out that this was a bad idea,
 // because `0` is a valid inode_ref (even if it is an invalid inode number
@@ -145,7 +143,7 @@ dyn_map_get(const struct SqshInodeMap *map, uint32_t inode_number, int *err) {
 		goto out;
 	}
 	inode_ref = ~inner_inode_refs[inner_index];
-	if (inode_ref == EMPTY_INODE_REF) {
+	if (inode_ref == SQSH_INODE_REF_NULL) {
 		rv = -SQSH_ERROR_NO_SUCH_ELEMENT;
 		inode_ref = 0;
 		goto out;
@@ -167,7 +165,7 @@ dyn_map_set(
 		struct SqshInodeMap *map, uint32_t inode_number, uint64_t inode_ref) {
 	int rv = 0;
 
-	if (inode_ref == EMPTY_INODE_REF) {
+	if (inode_ref == SQSH_INODE_REF_NULL) {
 		return -SQSH_ERROR_INVALID_ARGUMENT;
 	} else if (inode_number == 0 || inode_number - 1 >= map->inode_count) {
 		return -SQSH_ERROR_OUT_OF_BOUNDS;
@@ -191,7 +189,7 @@ dyn_map_set(
 	} else {
 		const uint64_t old_value = ~inner_inode_refs[inner_index];
 		inner_inode_refs[inner_index] = ~inode_ref;
-		if (old_value != EMPTY_INODE_REF && old_value != inode_ref) {
+		if (old_value != SQSH_INODE_REF_NULL && old_value != inode_ref) {
 			rv = -SQSH_ERROR_INODE_MAP_IS_INCONSISTENT;
 			goto out;
 		}

libsqsh/src/directory/directory_iterator.c

@@ -406,18 +406,15 @@ sqsh_directory_iterator_open_file(
 	int rv = 0;
 	struct SqshFile *file = NULL;
 	const uint64_t inode_ref = sqsh_directory_iterator_inode_ref(iterator);
-	const uint32_t dir_inode = sqsh_file_inode(iterator->file);
+	const uint64_t parent_inode_ref = sqsh_file_inode_ref(iterator->file);
 	struct SqshArchive *archive = iterator->file->archive;
 
 	file = sqsh_open_by_ref(archive, inode_ref, &rv);
 	if (rv < 0) {
 		goto out;
 	}
 
-	rv = sqsh__file_set_dir_inode(file, dir_inode);
-	if (rv < 0) {
-		goto out;
-	}
+	sqsh__file_set_parent_inode_ref(file, parent_inode_ref);
 
 	rv = check_file_consistency(iterator, file);
 

libsqsh/src/file/file.c

@@ -31,7 +31,6 @@
  * @file         file.c
  */
 
-#include <assert.h>
 #include <sqsh_file_private.h>
 
 #include <cextras/memory.h>
@@ -187,13 +186,7 @@ sqsh__file_init(
 		goto out;
 	}
 
-	if (sqsh_file_type(inode) == SQSH_FILE_TYPE_DIRECTORY) {
-		uint32_t parent_inode = sqsh_file_directory_parent_inode(inode);
-		rv = sqsh__file_set_dir_inode(inode, parent_inode);
-		if (rv < 0) {
-			goto out;
-		}
-	}
+	inode->parent_inode_ref = SQSH_INODE_REF_NULL;
 
 out:
 	if (rv < 0) {
@@ -207,42 +200,48 @@ sqsh_open_by_ref(struct SqshArchive *archive, uint64_t inode_ref, int *err) {
 	SQSH_NEW_IMPL(sqsh__file_init, struct SqshFile, archive, inode_ref);
 }
 
-int
-sqsh__file_set_dir_inode(struct SqshFile *file, uint32_t dir_inode) {
-	if (sqsh_file_inode(file) == dir_inode) {
-		return -SQSH_ERROR_INODE_PARENT_MISMATCH;
+void
+sqsh__file_set_parent_inode_ref(
+		struct SqshFile *file, uint64_t parent_inode_ref) {
+	file->parent_inode_ref = parent_inode_ref;
+}
+
+uint64_t
+sqsh__file_parent_inode_ref(struct SqshFile *file, int *err) {
+	uint64_t parent_inode_ref = SQSH_INODE_REF_NULL;
+	int rv = 0;
+	if (file->parent_inode_ref != SQSH_INODE_REF_NULL) {
+		parent_inode_ref = file->parent_inode_ref;
+		goto out;
 	}
 
-	if (sqsh_file_type(file) == SQSH_FILE_TYPE_DIRECTORY) {
-		const uint32_t parent_inode = sqsh_file_directory_parent_inode(file);
-		if (parent_inode != dir_inode) {
-			return -SQSH_ERROR_INODE_PARENT_MISMATCH;
-		}
-
-		if (dir_inode == 0) {
-			const struct SqshSuperblock *superblock =
-					sqsh_archive_superblock(file->archive);
-			if (file->inode_ref != sqsh_superblock_inode_root_ref(superblock)) {
-				return -SQSH_ERROR_INODE_PARENT_MISMATCH;
-			}
-		}
+	if (sqsh_file_type(file) != SQSH_FILE_TYPE_DIRECTORY) {
+		rv = -SQSH_ERROR_INODE_PARENT_UNSET;
+		goto out;
 	}
 
-	file->dir_inode = dir_inode;
-	file->has_dir_inode = true;
-	return 0;
-}
+	struct SqshInodeMap *inode_map;
+	rv = sqsh_archive_inode_map(file->archive, &inode_map);
+	if (rv < 0) {
+		goto out;
+	}
 
-bool
-sqsh__file_has_dir_inode(const struct SqshFile *context) {
-	return context->has_dir_inode;
-}
+	const uint32_t dir_inode = sqsh_file_directory_parent_inode(file);
+	parent_inode_ref = sqsh_inode_map_get2(inode_map, dir_inode, &rv);
+	if (rv == -SQSH_ERROR_NO_SUCH_ELEMENT) {
+		rv = -SQSH_ERROR_INODE_PARENT_UNSET;
+		goto out;
+	} else if (rv < 0) {
+		goto out;
+	}
 
-uint32_t
-sqsh__file_dir_inode(const struct SqshFile *context) {
-	assert(sqsh__file_has_dir_inode(context));
+	file->parent_inode_ref = parent_inode_ref;
+out:
+	if (err != NULL) {
+		*err = rv;
+	}
 
-	return context->dir_inode;
+	return parent_inode_ref;
 }
 
 bool
@@ -358,15 +357,30 @@ sqsh_file_type(const struct SqshFile *context) {
 	return context->type;
 }
 
+static int
+apply_parent(struct SqshFile *file, struct SqshPathResolver *resolver) {
+	int rv = sqsh_path_resolver_up(resolver);
+	if (rv == -SQSH_ERROR_WALKER_CANNOT_GO_UP) {
+		sqsh__file_set_parent_inode_ref(file, SQSH_INODE_REF_NULL);
+	} else if (rv < 0) {
+		return rv;
+	} else {
+		uint64_t new_parent_ref = sqsh_path_resolver_inode_ref(resolver);
+		sqsh__file_set_parent_inode_ref(file, new_parent_ref);
+	}
+	return 0;
+}
+
 static int
 symlink_resolve(struct SqshFile *context, bool follow_symlinks) {
 	int rv = 0;
 	if (sqsh_file_type(context) != SQSH_FILE_TYPE_SYMLINK) {
 		return -SQSH_ERROR_NOT_A_SYMLINK;
 	}
 
-	if (sqsh__file_has_dir_inode(context) == false) {
-		return -SQSH_ERROR_INODE_PARENT_UNSET;
+	uint64_t old_parent_ref = sqsh__file_parent_inode_ref(context, &rv);
+	if (rv < 0) {
+		goto out;
 	}
 
 	struct SqshPathResolver resolver = {0};
@@ -375,8 +389,7 @@ symlink_resolve(struct SqshFile *context, bool follow_symlinks) {
 		goto out;
 	}
 
-	uint32_t old_dir_inode = sqsh__file_dir_inode(context);
-	rv = sqsh__path_resolver_to_inode(&resolver, old_dir_inode);
+	rv = sqsh__path_resolver_to_ref(&resolver, old_parent_ref);
 	if (rv < 0) {
 		goto out;
 	}
@@ -390,13 +403,13 @@ symlink_resolve(struct SqshFile *context, bool follow_symlinks) {
 	}
 
 	const uint64_t inode_ref = sqsh_path_resolver_inode_ref(&resolver);
-	const uint32_t dir_inode = sqsh_path_resolver_dir_inode(&resolver);
 	sqsh__file_cleanup(context);
 	rv = sqsh__file_init(context, context->archive, inode_ref);
 	if (rv < 0) {
 		goto out;
 	}
-	rv = sqsh__file_set_dir_inode(context, dir_inode);
+
+	rv = apply_parent(context, &resolver);
 	if (rv < 0) {
 		goto out;
 	}
@@ -509,8 +522,7 @@ open_file(
 		goto out;
 	}
 
-	const uint32_t dir_inode = sqsh_path_resolver_dir_inode(&resolver);
-	rv = sqsh__file_set_dir_inode(inode, dir_inode);
+	rv = apply_parent(inode, &resolver);
 	if (rv < 0) {
 		goto out;
 	}

libsqsh/src/tree/path_resolver.c

@@ -313,17 +313,16 @@ sqsh_path_resolver_open_file(
 		const struct SqshPathResolver *resolver, int *err) {
 	int rv = 0;
 	struct SqshFile *file = NULL;
-	uint32_t dir_inode = sqsh_path_resolver_dir_inode(resolver);
 	uint64_t inode_ref = resolver->current_inode_ref;
 	file = sqsh_open_by_ref(resolver->archive, inode_ref, &rv);
 	if (rv < 0) {
 		goto out;
 	}
-	rv = sqsh__file_set_dir_inode(file, dir_inode);
-	if (rv < 0) {
-		goto out;
-	}
 
+	if (!is_beginning(resolver)) {
+		uint64_t parent_inode_ref = sqsh_file_inode_ref(&resolver->cwd);
+		sqsh__file_set_parent_inode_ref(file, parent_inode_ref);
+	}
 out:
 	if (rv < 0) {
 		sqsh__file_cleanup(file);
@@ -353,8 +352,8 @@ sqsh__path_resolver_follow_symlink(struct SqshPathResolver *resolver) {
 	}
 	resolver->current_symlink_depth++;
 
-	uint64_t inode_ref = sqsh_directory_iterator_inode_ref(&resolver->iterator);
-	uint32_t dir_inode = sqsh_path_resolver_dir_inode(resolver);
+	const uint64_t inode_ref =
+			sqsh_directory_iterator_inode_ref(&resolver->iterator);
 
 	rv = update_inode_from_cwd(resolver);
 	if (rv < 0) {
@@ -366,10 +365,6 @@ sqsh__path_resolver_follow_symlink(struct SqshPathResolver *resolver) {
 	if (rv < 0) {
 		goto out;
 	}
-	rv = sqsh__file_set_dir_inode(&file, dir_inode);
-	if (rv < 0) {
-		goto out;
-	}
 
 	const char *target = sqsh_file_symlink(&file);
 	size_t target_size = sqsh_file_symlink_size(&file);

libsqsh/src/tree/traversal.c

@@ -79,17 +79,15 @@ push_stack(struct SqshTreeTraversal *traversal) {
 	traversal->stack = element;
 
 	struct SqshArchive *archive = traversal->base_file->archive;
-	const uint32_t dir_inode = sqsh_file_inode(traversal->current_file);
+	const uint64_t parent_inode_ref =
+			sqsh_file_inode_ref(traversal->current_file);
 	const uint64_t inode_ref =
 			sqsh_directory_iterator_inode_ref(traversal->current_iterator);
 	rv = sqsh__file_init(&element->file, archive, inode_ref);
 	if (rv < 0) {
 		goto out;
 	}
-	rv = sqsh__file_set_dir_inode(&element->file, dir_inode);
-	if (rv < 0) {
-		goto out;
-	}
+	sqsh__file_set_parent_inode_ref(&element->file, parent_inode_ref);
 	traversal->current_file = &element->file;
 	traversal->state = SQSH_TREE_TRAVERSAL_STATE_DIRECTORY_BEGIN;
 out:
@@ -348,11 +346,8 @@ sqsh_tree_traversal_open_file(
 		if (rv < 0) {
 			goto out;
 		}
-		if (sqsh__file_has_dir_inode(traversal->base_file)) {
-			const uint32_t dir_inode =
-					sqsh__file_dir_inode(traversal->base_file);
-			rv = sqsh__file_set_dir_inode(file, dir_inode);
-		}
+		sqsh__file_set_parent_inode_ref(
+				file, traversal->base_file->parent_inode_ref);
 	} else {
 		file = sqsh_directory_iterator_open_file(
 				traversal->current_iterator, &rv);

test/libsqsh/file/file.c

@@ -152,8 +152,7 @@ UTEST(file, resolve_unkown_dir_inode) {
 	struct SqshFile *symlink = sqsh_lopen(&archive, "/src", &rv);
 	ASSERT_EQ(0, rv);
 	ASSERT_EQ(SQSH_FILE_TYPE_SYMLINK, sqsh_file_type(symlink));
-	symlink->dir_inode = 0;
-	symlink->has_dir_inode = false;
+	symlink->parent_inode_ref = UINT64_MAX;
 
 	rv = sqsh_file_symlink_resolve(symlink);
 	ASSERT_EQ(-SQSH_ERROR_INODE_PARENT_UNSET, rv);

test/libsqsh/tree/traversal.c

@@ -74,8 +74,6 @@ UTEST(traversal, test_recursive_directory) {
 	struct SqshFile file = {0};
 	rv = sqsh__file_init(&file, &archive, 0);
 	ASSERT_EQ(0, rv);
-	rv = sqsh__file_set_dir_inode(&file, 2);
-	ASSERT_EQ(0, rv);
 
 	struct SqshTreeTraversal traversal = {0};
 	rv = sqsh__tree_traversal_init(&traversal, &file);