Added files - part of MS patch

libisofs/data_source.c

@@ -0,0 +1,107 @@
+/*
+ * Contains a simple implementation of a data source that reads from a
+ * given file.
+ */
+
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "libisofs.h"
+
+#define BLOCK_SIZE 2048
+
+#define BLOCK_OUT_OF_FILE -1; 
+#define READ_ERROR -2; 
+#define SEEK_ERROR -3; 
+
+struct file_data_src {
+	int fd;
+	int nblocks;
+};
+
+static int 
+ds_read_block(struct data_source *src, int lba, unsigned char *buffer)
+{
+	struct file_data_src *data;
+	
+	assert(src && buffer);
+	
+	data = (struct file_data_src*)src->data;
+	
+	/* For block devices size is always 0, so this can't be used.
+	 * if (lba >= data->nblocks) 
+	 *	return BLOCK_OUT_OF_FILE;
+	 */
+	
+	/* goes to requested block */
+	if ( lseek(data->fd, (off_t)lba * (off_t)BLOCK_SIZE, SEEK_SET) == (off_t) -1 ) 
+		return SEEK_ERROR;
+	
+	if ( read(data->fd, buffer, BLOCK_SIZE) != BLOCK_SIZE ) 
+		return READ_ERROR;
+		
+	return 0;
+}
+	
+static int ds_get_size(struct data_source *src)
+{
+	struct file_data_src *data;
+	
+	assert(src);
+	
+	data = (struct file_data_src*)src->data;
+	return data->nblocks;
+}
+	
+static void ds_free_data(struct data_source *src)
+{
+	struct file_data_src *data;
+	
+	assert(src);
+	
+	data = (struct file_data_src*)src->data;
+	
+	/* close the file */
+	close(data->fd);
+	free(data);
+}
+ 
+struct data_source *data_source_from_file(const char *path)
+{
+	int fd;
+	struct stat info;
+	struct file_data_src *data;
+	struct data_source *ret;
+	
+	assert(path);
+	
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return NULL;
+		 
+	fstat(fd, &info);
+	
+	data = malloc(sizeof(struct file_data_src));
+	data->fd = fd;
+	data->nblocks = info.st_size / BLOCK_SIZE;
+	
+	ret = malloc(sizeof(struct data_source));
+	ret->refcount = 1;
+	ret->read_block = ds_read_block;
+	ret->get_size = ds_get_size;
+	ret->free_data = ds_free_data;
+	ret->data = data;
+	return ret;
+} 
+
+void data_source_free(struct data_source *src)
+{
+	if (--src->refcount == 0) {
+		src->free_data(src);
+		free(src);
+	}
+}