#define BLOCK_SIZE 512

#define TOO_MANY_FILES		-100
#define LOW_MEM			-101
#define BAD_DESCRIPTOR		-102
#define BUFFER_FULL		-103
#define NO_SUCH_BLOCK		-104
#define BLOCK_LOCKED		-105
#define BLOCK_NOT_LOCKED	-106

void InitBuffer(void);
int FileExists(char *file_name);
int OpenFile(char *file_name);
int CloseFile(int fd);
int GetNumBlocks(int fd);
int GetBlock(int fd, int block_num, void **buffer);
int AppendBlock(int fd, void **buffer);
int ReleaseBlock(int fd, int block_num, int modified);
int TruncateFile(int fd, int last_block);