Add an inode deep copy helper function to libsquashfs

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

2 files changed, 67 insertions, 0 deletions

diff --git a/include/sqfs/inode.h b/include/sqfs/inode.h
index 336a394..2b4a550 100644
--- a/include/sqfs/inode.h
+++ b/include/sqfs/inode.h
@@ -537,6 +537,24 @@ extern "C" {
 #endif
 
 /**
+ * @brief Create a deep copy of a generic inode.
+ *
+ * The @ref sqfs_inode_generic_t structure contains inlined fields that have a
+ * size depending on the inode data and pointers to the inlined fields. This
+ * helper function calculates the actual size of the structure in memory, makes
+ * a copy and propperly sets up the pointers.
+ *
+ * @param src The inode to copy.
+ * @param copy Returns a pointer to the copy on success. Can be released with a
+ *             single free call.
+ *
+ * @return Zero on success, an @ref SQFS_ERROR_CORRUPTED if the node has
+ *         an unknown type set.
+ */
+SQFS_API int sqfs_inode_copy(const sqfs_inode_generic_t *src,
+			     sqfs_inode_generic_t **copy);
+
+/**
  * @brief Get the extended attribute index of an inode
  *
  * For basic inodes, this returns the inode index 0xFFFFFFFF, i.e. the
diff --git a/lib/sqfs/inode.c b/lib/sqfs/inode.c
index 4a75e64..bb1ccef 100644
--- a/lib/sqfs/inode.c
+++ b/lib/sqfs/inode.c
@@ -10,6 +10,9 @@
 #include "sqfs/inode.h"
 #include "sqfs/error.h"
 
+#include <string.h>
+#include <stdlib.h>
+
 static int inverse_type[] = {
 	[SQFS_INODE_DIR] = SQFS_INODE_EXT_DIR,
 	[SQFS_INODE_FILE] = SQFS_INODE_EXT_FILE,
@@ -27,6 +30,52 @@ static int inverse_type[] = {
 	[SQFS_INODE_EXT_SOCKET] = SQFS_INODE_SOCKET,
 };
 
+int sqfs_inode_copy(const sqfs_inode_generic_t *src,
+		    sqfs_inode_generic_t **out)
+{
+	sqfs_inode_generic_t *copy;
+	size_t size = sizeof(*src);
+
+	switch (src->base.type) {
+	case SQFS_INODE_FILE:
+	case SQFS_INODE_EXT_FILE:
+		size += src->num_file_blocks;
+		break;
+	case SQFS_INODE_DIR:
+	case SQFS_INODE_EXT_DIR:
+		size += src->num_dir_idx_bytes;
+		break;
+	case SQFS_INODE_SLINK:
+		size += src->data.slink.target_size;
+		break;
+	case SQFS_INODE_EXT_SLINK:
+		size += src->data.slink_ext.target_size;
+		break;
+	case SQFS_INODE_BDEV:
+	case SQFS_INODE_CDEV:
+	case SQFS_INODE_FIFO:
+	case SQFS_INODE_SOCKET:
+	case SQFS_INODE_EXT_BDEV:
+	case SQFS_INODE_EXT_CDEV:
+	case SQFS_INODE_EXT_FIFO:
+	case SQFS_INODE_EXT_SOCKET:
+		break;
+	default:
+		return SQFS_ERROR_CORRUPTED;
+	}
+
+	copy = calloc(1, size);
+	if (copy == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	memcpy(copy, src, size);
+	copy->block_sizes = (sqfs_u32 *)copy->extra;
+	copy->slink_target = (char *)copy->extra;
+
+	*out = copy;
+	return 0;
+}
+
 int sqfs_inode_get_xattr_index(const sqfs_inode_generic_t *inode,
 			       sqfs_u32 *out)
 {