diff --git a/libisofs/trunk/libisofs/ecma119.c b/libisofs/trunk/libisofs/ecma119.c
index 13956cce..083a2885 100644
--- a/libisofs/trunk/libisofs/ecma119.c
+++ b/libisofs/trunk/libisofs/ecma119.c
@@ -20,6 +20,7 @@
 #include "tree.h"
 #include "util.h"
 #include "file.h"
+#include "file_src.h"
 #include "libisofs.h"
 #include "libburn/libburn.h"
 #include "eltorito.h"
@@ -553,67 +554,36 @@ wr_dir_records(struct ecma119_write_target *t, uint8_t *buf)
 static void
 wr_files(struct ecma119_write_target *t, uint8_t *buf)
 {
+	int res;
 	struct state_files *f_st = &t->state_files;
-	size_t nread;
 	struct iso_file *f = t->filelist[f_st->file];
-	
-	if (f->prev_img) {
-		int block;
-		assert( !t->ms_block && t->src );
+
+	if (!f_st->src) {
 		
-		/**
-		 * f->block block where file write begins
-		 * t->curblock block we're writting now
-		 * f->real_ino initial block for file on source
-		 */
-		block = t->curblock - f->block;
-		if ( t->src->read_block(t->src, f->real_ino + block, buf) ) {
-			iso_msg_sorry(LIBISO_CANT_READ_IMG, 
-				"Problem reading file from previous image");
-		}
-		if ( f->size <= (off_t) (block+1) * t->block_size ) {
-			f_st->file++;
-			if (f_st->file >= t->filelist_len)
-				next_state(t);
-		}
-	} else {
-		const char *path = f->path;
-	
-		if (!f_st->fd) {
-			
+		if (!f->prev_img) {
 			char msg[PATH_MAX + 14];
-			sprintf(msg, "Writing file %s", path);
+			sprintf(msg, "Writing file %s", f->path);
 			iso_msg_debug(msg);
-			
-			f_st->data_len = f->size;
-			f_st->fd = fopen(path, "r");
-			if (!f_st->fd) {
-				//FIXME instead of exit, just print a msg error and
-				//skip file (what about reading from /dev/zero? instead)
-				err(1, "couldn't open %s for reading", path);
-			}
-			assert(t->curblock + t->ms_block == f->block);
-		}
-	
-		nread = fread(buf, 1, t->block_size, f_st->fd);
-		f_st->pos += t->block_size;
-		if (nread < 0) {
-			char msg[PATH_MAX + 32];
-			sprintf(msg, "Problem reading from %s", path);
-			iso_msg_sorry(LIBISO_CANT_READ_FILE, msg);
-		} else if (nread != t->block_size && f_st->pos < f_st->data_len) {
-			char msg[PATH_MAX + 32];
-			sprintf(msg, "Incomplete read from %s", path);
-			iso_msg_sorry(LIBISO_CANT_READ_FILE, msg);
-		}
-		if (f_st->pos >= f_st->data_len) {
-			fclose(f_st->fd);
-			f_st->fd = 0;
-			f_st->pos = 0;
-			f_st->file++;
-			if (f_st->file >= t->filelist_len)
-				next_state(t);
+		} 
+		
+		f_st->src = f->src;
+		if ( f->src->open(f->src) <= 0) {
+			//FIXME instead of exit, just print a msg error and
+			//skip file (what about reading from /dev/zero? instead)
+			/* can only happen with new files */
+			err(1, "couldn't open %s for reading", f->path);
 		}
+		assert(t->curblock + t->ms_block == f->block);
+	}
+
+	res = f_st->src->read_block(f_st->src, buf);
+	if (res == 0) {
+		/* we have read the expected bytes from file */
+		f_st->src->close(f_st->src);
+		f_st->src = NULL;
+		f_st->file++;
+		if (f_st->file >= t->filelist_len)
+			next_state(t);
 	}
 }
 
@@ -932,8 +902,10 @@ bs_free_data(struct burn_source *bs)
 	free(t->state_data);
 	if (t->joliet)
 		joliet_tree_free(t->joliet_root);
-	if (t->state_files.fd)
-		fclose(t->state_files.fd);
+		
+	// TODO is this needed?
+	if (t->state_files.src)
+		t->state_files.src->close(t->state_files.src);
 }
 
 struct burn_source *iso_source_new_ecma119(struct iso_volset *volset,
diff --git a/libisofs/trunk/libisofs/ecma119.h b/libisofs/trunk/libisofs/ecma119.h
index 4d93b87e..bdc67a47 100644
--- a/libisofs/trunk/libisofs/ecma119.h
+++ b/libisofs/trunk/libisofs/ecma119.h
@@ -174,13 +174,14 @@ struct ecma119_write_target
 
 	/* for writing out files */
 	struct state_files {
-		off_t pos;	/* The number of bytes we have written
-				 * so far in the current file.
-				 */
-		off_t data_len;/* The number of bytes in the currently
-				 * open file.
-				 */
-		FILE *fd;	/* The currently open file. */
+//		off_t pos;	/* The number of bytes we have written
+//				 * so far in the current file.
+//				 */
+//		off_t data_len;/* The number of bytes in the currently
+//				 * open file.
+//				 */
+//		FILE *fd;	/* The currently open file. */
+		struct iso_file_src *src; /* source for reading from the file */
 		int file;	/* The index in filelist that we are
 				 * currently writing (or about to write). */
 	} state_files;
diff --git a/libisofs/trunk/libisofs/ecma119_tree.c b/libisofs/trunk/libisofs/ecma119_tree.c
index e49f6d9f..dc140fbc 100644
--- a/libisofs/trunk/libisofs/ecma119_tree.c
+++ b/libisofs/trunk/libisofs/ecma119_tree.c
@@ -183,7 +183,16 @@ create_file(struct ecma119_write_target *t,
 		 * If the file is not already added to the disc, we add it now
 		 * to the file table, and get a new inode number for it. 
 		 */
-		file = iso_file_new(iso);
+		file = iso_file_new(t, iso);
+		if (!file) {
+			/* 
+			 * That was an error.
+			 * TODO currently this cause the file to be ignored... Maybe
+			 * throw an error is a better alternative
+			 */
+			ecma119_tree_free(ret);
+			return NULL;
+		}
 		iso_file_table_add_file(t->file_table, file);
 		file->ino = ++t->ino;
 	} else {
diff --git a/libisofs/trunk/libisofs/file.c b/libisofs/trunk/libisofs/file.c
index 8e1d04cb..c726503a 100644
--- a/libisofs/trunk/libisofs/file.c
+++ b/libisofs/trunk/libisofs/file.c
@@ -1,23 +1,31 @@
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <unistd.h>       
+#include <unistd.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <string.h>
 #include <assert.h>
+#include <limits.h>
 
 #include "file.h"
 #include "tree.h"
+#include "file_src.h"
+#include "messages.h"
+#include "ecma119.h"
 
 //TODO: refactor both hash and this hash table into a single one??
 
 struct iso_file *
-iso_file_new(struct iso_tree_node_file *f)
+iso_file_new(struct ecma119_write_target *t, struct iso_tree_node_file *f)
 {
 	struct iso_file *file = calloc(1, sizeof(struct iso_file));
+	if (!file)
+		return NULL;
 	if (f->node.procedence == LIBISO_NEW) {
 		file->path = f->loc.path;  /*TODO strdup? it needs to be free on clear then */
 		file->real_dev = f->node.attrib.st_dev;
 		file->real_ino = f->node.attrib.st_ino;
+		file->src = iso_file_src_from_path(file->path);
 	} else {
 		file->block = f->loc.block;
 		file->prev_img = 1;
@@ -26,14 +34,28 @@ iso_file_new(struct iso_tree_node_file *f)
 		 * number is good enouht for this. Moreover, when we are modifying
 		 * an image, we will modify file->block with the block where the
 		 * file needs to be written in the new image. So, we store the block
-		 * in original image here, because we will need to use it for
-		 * reading file contents */
+		 * in original image here */
 		file->real_ino = f->loc.block;
+		file->src = iso_file_src_from_prev_img(t->src, f->loc.block, 
+		                                       f->node.attrib.st_size);
+	}
+	if (!file->src)
+		goto creation_error;
+	file->size = file->src->get_size(file->src);
+	
+	if (file->size != f->node.attrib.st_size) {
+		char msg[PATH_MAX + 32];
+		/* can only happen on path files */
+		assert(f->node.procedence == LIBISO_NEW);
+		sprintf(msg, "Size of file %s has changed\n", file->path);
+		iso_msg_sorry(LIBISO_CANT_READ_FILE, msg);
 	}
-	file->size = f->node.attrib.st_size;
 	file->nlink = 1;
 	file->sort_weight = f->sort_weight;
 	return file;
+creation_error:;
+	free(file);
+	return NULL;
 }
 
 static unsigned int
@@ -75,6 +97,7 @@ iso_file_table_node_new(struct iso_file *file)
 static void
 iso_file_table_node_free(struct iso_file_hash_node *node)
 {
+	iso_file_src_free(node->file->src);
 	free(node->file);
 	free(node);
 }
diff --git a/libisofs/trunk/libisofs/file.h b/libisofs/trunk/libisofs/file.h
index d751b072..c1253b1e 100644
--- a/libisofs/trunk/libisofs/file.h
+++ b/libisofs/trunk/libisofs/file.h
@@ -30,6 +30,7 @@ struct iso_file {
 	dev_t real_dev;
 	ino_t real_ino; /**< for lookup by inode caching */
 	int sort_weight;
+	struct iso_file_src *src;
 };
 
 struct iso_file_hash_node {
@@ -44,12 +45,14 @@ struct iso_file_table {
 };
 
 struct iso_tree_node_file;
+struct ecma119_write_target;
 
 /**
  * Create a struct that represents the specified iso_tree_node_file,
  * suitable to be stored into the table,
  */
-struct iso_file *iso_file_new(struct iso_tree_node_file*);
+struct iso_file *iso_file_new(struct ecma119_write_target *t, 
+                              struct iso_tree_node_file*);
 
 struct iso_file_table *iso_file_table_new(int cache_inodes);
 
diff --git a/libisofs/trunk/libisofs/file_src.c b/libisofs/trunk/libisofs/file_src.c
index f7ed4d86..04e9ec18 100644
--- a/libisofs/trunk/libisofs/file_src.c
+++ b/libisofs/trunk/libisofs/file_src.c
@@ -1,3 +1,10 @@
+/*
+ * Implementation of iso_file_src for:
+ * 
+ * a) read from local filesystem files
+ * b) read from previous session / image files
+ */
+
 #include <stdlib.h>       
 #include <stdio.h>       
 #include <sys/types.h>
@@ -10,9 +17,24 @@
 
 #include "file_src.h"
 #include "messages.h"
+#include "libisofs.h"
+#include "util.h"
 
 #define BLOCK_SIZE 2048
 
+
+void iso_file_src_free(struct iso_file_src *src)
+{
+	src->free_data(src);
+	free(src);
+}
+
+/*
+ * ==========================================================================
+ * A) FILE SRC FOR LOCAL FILESYSTEM FILES
+ * ==========================================================================
+ */
+
 struct local_file_data {
 	int fd; /* the file descriptor, once the file is opened */
 	off_t size; /* file size */
@@ -117,7 +139,10 @@ off_t lf_get_size(struct iso_file_src *src)
 static
 void lf_free_data(struct iso_file_src *src)
 {
-	free(src->data);
+	struct local_file_data *data;
+	data = (struct local_file_data*) src->data;
+	free(data->path);
+	free(data);
 }
 
 struct iso_file_src* 
@@ -161,3 +186,121 @@ iso_file_src_from_path(const char *path)
 	src->data = data;
 	return src;
 }
+
+
+/*
+ * ==========================================================================
+ * B) FILE SRC FOR PREVIOUS IMAGE FILES
+ * ==========================================================================
+ */
+
+struct prev_img_file_data {
+	int block; /* block where image begins */
+	off_t size; /* file size */
+	int nblocks; /* file size in blocks */
+	int current; /* last block read from file */
+	int error;
+	struct data_source *src; /* source for reading from previous image */
+};
+
+static
+int pi_open(struct iso_file_src *src)
+{
+	struct prev_img_file_data *data;
+	assert(src);
+	
+	data = (struct prev_img_file_data*) src->data;
+	data->current = data->block;
+	data->error = 0;
+	return 1;
+}
+
+static
+void pi_close(struct iso_file_src *src)
+{
+	/* nothing needed */
+	return;
+}
+
+static
+int pi_read_block(struct iso_file_src *src, unsigned char *buffer)
+{
+	int res;
+	struct prev_img_file_data *data;
+	assert(src);
+	assert(buffer);
+	
+	data = (struct prev_img_file_data*) src->data;
+	
+	if (data->current >= data->block + data->nblocks) {
+		return 0;
+	}
+	
+	if (data->error) {
+		memset(buffer, 0, BLOCK_SIZE);
+		data->current++;
+		return -2;
+	}
+	
+	res = data->src->read_block(data->src, data->current++, buffer);
+	if (res < 0) {
+		iso_msg_sorry(LIBISO_CANT_READ_IMG, 
+			"Problem reading file from previous image");
+		/* fill buffer with 0s and return */ 
+		memset(buffer, 0, BLOCK_SIZE);
+		return -1;
+	} 
+	
+	if (data->current >= data->block + data->nblocks) {
+		return 0;
+	} else {
+		return 1;
+	}
+}
+
+static
+off_t pi_get_size(struct iso_file_src *src)
+{
+	struct prev_img_file_data *data;
+	assert(src);
+	
+	data = (struct prev_img_file_data*) src->data;
+	return data->size;
+}
+
+static
+void pi_free_data(struct iso_file_src *src)
+{
+	free(src->data);
+}
+
+struct iso_file_src* 
+iso_file_src_from_prev_img(struct data_source* data_src, int block, off_t size)
+{
+	struct iso_file_src *src;
+	struct prev_img_file_data *data;
+	
+	data = malloc(sizeof(struct prev_img_file_data));
+	if (!data)
+		return NULL;
+	
+	src = malloc(sizeof(struct iso_file_src));	
+	if (!src) {
+		free(data);
+		return NULL;
+	}
+	
+	data->block = block;
+	data->size = size;
+	data->nblocks = div_up(size, BLOCK_SIZE);
+	data->src = data_src;
+	
+	src->open = pi_open;
+	src->close = pi_close;
+	src->read_block = pi_read_block;
+	src->get_size = pi_get_size;
+	src->free_data = pi_free_data;
+	
+	src->data = data;
+	return src;
+}
diff --git a/libisofs/trunk/libisofs/file_src.h b/libisofs/trunk/libisofs/file_src.h
index f0b3abfa..acf431ee 100644
--- a/libisofs/trunk/libisofs/file_src.h
+++ b/libisofs/trunk/libisofs/file_src.h
@@ -12,6 +12,8 @@
 
 #include <sys/types.h>
 
+struct data_source;
+
 struct iso_file_src {
 	
 	/**
@@ -74,7 +76,17 @@ struct iso_file_src {
 struct iso_file_src* iso_file_src_from_path(const char *path);
 
 /**
- * close and free a iso_file_src
+ * Get a iso_file_src() for reading from a previous image file.
+ * @param src data_source to read from previous image. It is not freed, 
+ *            so you need to free it when no more needed.
+ * @param block block on image where file begins
+ * @param nblocks number of block of the file
+ */
+struct iso_file_src* 
+iso_file_src_from_prev_img(struct data_source* src, int block, off_t size);
+
+/**
+ * free a iso_file_src
  */
 void iso_file_src_free(struct iso_file_src *src);
 
diff --git a/libisofs/trunk/libisofs/joliet.c b/libisofs/trunk/libisofs/joliet.c
index dda25799..8fc0df0b 100644
--- a/libisofs/trunk/libisofs/joliet.c
+++ b/libisofs/trunk/libisofs/joliet.c
@@ -36,7 +36,16 @@ create_node(struct ecma119_write_target *t,
 		struct iso_file *file;
 		file = iso_file_table_lookup(t->file_table, iso_f);
 		if ( file == NULL ) {
-			file = iso_file_new(iso_f);
+			file = iso_file_new(t, iso_f);
+			if (!file) {
+				/* 
+				 * That was an error.
+				 * TODO currently this cause the file to be ignored... Maybe
+				 * throw an error is a better alternative
+				 */
+				joliet_tree_free(ret);
+				return NULL;
+			}
 			iso_file_table_add_file(t->file_table, file);
 		}
 		ret->info.file = file;