How to sanely read and dump structs to disk when some fields are pointers?
- by bp
Hello, I'm writing a FUSE plugin in C. I'm keeping track of data structures in the filesystem through structs like:
typedef struct {
block_number_t inode;
filename_t filename; //char[SOME_SIZE]
some_other_field_t other_field;
} fs_directory_table_item_t;
Obviously, I have to read (write) these structs from (to) disk at some point. I could treat the struct as a sequence of bytes and do something like this:
read(disk_fd, directory_table_item, sizeof(fs_directory_table_item_t));
...except that cannot possibly work as filename is actually a pointer to the char array.
I'd really like to avoid having to write code like:
read(disk_df, *directory_table_item.inode, sizeof(block_number_t));
read(disk_df, directory_table_item.filename, sizeof(filename_t));
read(disk_df, *directory_table_item.other_field, sizeof(some_other_field_t));
...for each struct in the code, because I'd have to replicate code and changes in no less than three different places (definition, reading, writing).
Any DRYer but still maintainable ideas?
