Synopsis

typedef struct {
  CTL_MS_BLOCK_DRIVER_t *block_driver;
  CTL_MUTEX_t mutex;
  CTL_MS_VOLUME_STATE_t state;
  unsigned sectors_per_cluster;
  unsigned reserved_sector_count;
  unsigned root_entry_count;
  unsigned number_of_fats;
  CTL_MS_FILE_SYSTEM_FORMAT_t format;
  CTL_MS_LBA_t second_fat_offset;
  CTL_MS_LBA_t partition_addr;
  CTL_MS_LBA_t root_dir_sector;
  CTL_MS_LBA_t current_dir_sector;
  CTL_MS_LBA_t working_dir_sector;
  CTL_MS_LBA_t fat1_sector;
  CTL_MS_LBA_t fat2_sector;
  CTL_MS_LBA_t first_data_sector;
  CTL_MS_CLUSTER_t total_data_clusters;
  CTL_MS_CLUSTER_t free_cluster;
  CTL_MS_CLUSTER_t root_cluster;
  CTL_MS_LBA_t fsinfo_sector;
  CTL_STATUS_t error;
  char temp_name[];
  CTL_MS_FILE_tag *__open_files;
  CTL_MS_VOLUME_s *__next;
  const char *__name;
  const CTL_STREAM_DRIVER_t *methods;
  CTL_STATUS_t (*open_fcb)(CTL_MS_VOLUME_s *,  CTL_MS_FCB_t *, const char *, const char *, CTL_MS_MODE_t);
} CTL_MS_VOLUME_t;

Description

CTL_MS_VOLUME_t describes the internal state of a volume which the mass storage library uses. It is not publicized by any function and all data inside it, if you wish to examine members, should be considered read-only. We do not guarantee that the structure will be stable across releases of the mass storage library.

Only the members block_driver, mutex, and state are valid for volumes that are not mounted; all other members should be considered invalid for offline volumes.

Member	Description
block_driver	This is public knowledge and you're responsible for populating it. Methods to read and write a single 512-byte sector.
mutex	Volume mutex; this is a per-volume mutex that is locked when the volume is accessed by the mass storage library.
state	The internal state of the volume. A volume can be in offline, online, and mounted states.
sectors_per_cluster	The number of 512-byte sectors per FAT cluster.
reserved_sector_count	The number of sectors that are marked as reserved at the start of the media.
root_entry_count	The number of directory entries in the root directory for FAT12 and FAT16 volumes.
number_of_fats	The number of FATs contained on the volume. This is either one or two.
fat_type	The type of FAT volume, either FAT12, FAT16, or FAT32.
second_fat_offset	The LBA offset from the start of the volume for the second FAT.
partition_addr	The LBA of the first sector of the volume on the media.
root_dir_sector	The LBA of the first sector of the volume's root directory.
current_dir_sector	The LBA of the internal current working directory. This does not correspond to the ‘current directory’ that operating systems such as MS-DOS, Windows, and Unix have. This is purely an internal convenience for the implementation of the mass storage library.
working_dir_sector	The LBA of the internal working directory. This is purely an internal convenience for the implementation of the mass storage library.
fat1_sector	The LBA of the first sector of the first FAT.
fat2_sector	The LBA of the first sector of the second FAT; if there is no second FAT, this member is undefined.
first_data_sector	The LBA of the first data sector relative to the start of the volume. The first data sector follows the reserved sectors, FATs, and root directory entries.
total_data_clusters	The number of data clusters for the volume.
free_cluster	The index of the first potentially-free cluster on the volume. The first two clusters of a FAT volume are reserved. This member is maintained internally by the mass storage library to accelerate finding free clusters in the FAT.
root_cluster	The cluster index of the root directory for FAT32 volumes. This member is undefined for FAT12 and FAT16 volumes.
fsinfo_sector	The LBA of the FSInfo sector relative to the start of the volume. This member is undefined for FAT12 and FAT16 volumes.
error	The last reported error for the volume. This is maintained internally by the mass storage library and has no relevance for any client.
temp_name	A temporary working name store for the mass storage library. This is maintained internally by the mass storage library and has no relevance for any client.
open_files	A linked list of files that are open on the volume.