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80d3768
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flaneth
firmware
dosfs.h
added dosfs code to read FAT filesystems
Stefan Schuermans
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80d3768
at 2012-05-03 18:43:13
dosfs.h
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/* DOSFS Embedded FAT-Compatible Filesystem (C) 2005 Lewin A.R.W. Edwards (sysadm@zws.com) */ #ifndef _DOSFS_H #define _DOSFS_H #include <stdint.h> //=================================================================== // User-supplied functions uint32_t DFS_ReadSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count); uint32_t DFS_WriteSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count); //=================================================================== // Configurable items #define MAX_PATH 64 // Maximum path length (increasing this will // GREATLY increase stack requirements!) #define DIR_SEPARATOR '/' // character separating directory components // End of configurable items //=================================================================== //=================================================================== // 32-bit error codes #define DFS_OK 0 // no error #define DFS_EOF 1 // end of file (not an error) #define DFS_WRITEPROT 2 // volume is write protected #define DFS_NOTFOUND 3 // path or file not found #define DFS_PATHLEN 4 // path too long #define DFS_ALLOCNEW 5 // must allocate new directory cluster #define DFS_ERRMISC 0xffffffff // generic error //=================================================================== // File access modes #define DFS_READ 1 // read-only #define DFS_WRITE 2 // write-only //=================================================================== // Miscellaneous constants #define SECTOR_SIZE 512 // sector size in bytes //=================================================================== // Internal subformat identifiers #define FAT12 0 #define FAT16 1 #define FAT32 2 //=================================================================== // DOS attribute bits #define ATTR_READ_ONLY 0x01 #define ATTR_HIDDEN 0x02 #define ATTR_SYSTEM 0x04 #define ATTR_VOLUME_ID 0x08 #define ATTR_DIRECTORY 0x10 #define ATTR_ARCHIVE 0x20 #define ATTR_LONG_NAME (ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID) /* Directory entry structure note: if name[0] == 0xe5, this is a free dir entry if name[0] == 0x00, this is a free entry and all subsequent entries are free if name[0] == 0x05, the first character of the name is 0xe5 [a kanji nicety] Date format: bit 0-4 = day of month (1-31) bit 5-8 = month, 1=Jan..12=Dec bit 9-15 = count of years since 1980 (0-127) Time format: bit 0-4 = 2-second count, (0-29) bit 5-10 = minutes (0-59) bit 11-15= hours (0-23) */ typedef struct _tagDIRENT { uint8_t name[11]; // filename uint8_t attr; // attributes (see ATTR_* constant definitions) uint8_t reserved; // reserved, must be 0 uint8_t crttimetenth; // create time, 10ths of a second (0-199 are valid) uint8_t crttime_l; // creation time low byte uint8_t crttime_h; // creation time high byte uint8_t crtdate_l; // creation date low byte uint8_t crtdate_h; // creation date high byte uint8_t lstaccdate_l; // last access date low byte uint8_t lstaccdate_h; // last access date high byte uint8_t startclus_h_l; // high word of first cluster, low byte (FAT32) uint8_t startclus_h_h; // high word of first cluster, high byte (FAT32) uint8_t wrttime_l; // last write time low byte uint8_t wrttime_h; // last write time high byte uint8_t wrtdate_l; // last write date low byte uint8_t wrtdate_h; // last write date high byte uint8_t startclus_l_l; // low word of first cluster, low byte uint8_t startclus_l_h; // low word of first cluster, high byte uint8_t filesize_0; // file size, low byte uint8_t filesize_1; // uint8_t filesize_2; // uint8_t filesize_3; // file size, high byte } DIRENT, *PDIRENT; /* Partition table entry structure */ typedef struct _tagPTINFO { uint8_t active; // 0x80 if partition active uint8_t start_h; // starting head uint8_t start_cs_l; // starting cylinder and sector (low byte) uint8_t start_cs_h; // starting cylinder and sector (high byte) uint8_t type; // type ID byte uint8_t end_h; // ending head uint8_t end_cs_l; // ending cylinder and sector (low byte) uint8_t end_cs_h; // ending cylinder and sector (high byte) uint8_t start_0; // starting sector# (low byte) uint8_t start_1; // uint8_t start_2; // uint8_t start_3; // starting sector# (high byte) uint8_t size_0; // size of partition (low byte) uint8_t size_1; // uint8_t size_2; // uint8_t size_3; // size of partition (high byte) } PTINFO, *PPTINFO; /* Master Boot Record structure */ typedef struct _tagMBR { uint8_t bootcode[0x1be]; // boot sector PTINFO ptable[4]; // four partition table structures uint8_t sig_55; // 0x55 signature byte uint8_t sig_aa; // 0xaa signature byte } MBR, *PMBR; /* BIOS Parameter Block structure (FAT12/16) */ typedef struct _tagBPB { uint8_t bytepersec_l; // bytes per sector low byte (0x00) uint8_t bytepersec_h; // bytes per sector high byte (0x02) uint8_t secperclus; // sectors per cluster (1,2,4,8,16,32,64,128 are valid) uint8_t reserved_l; // reserved sectors low byte uint8_t reserved_h; // reserved sectors high byte uint8_t numfats; // number of FAT copies (2) uint8_t rootentries_l; // number of root dir entries low byte (0x00 normally) uint8_t rootentries_h; // number of root dir entries high byte (0x02 normally) uint8_t sectors_s_l; // small num sectors low byte uint8_t sectors_s_h; // small num sectors high byte uint8_t mediatype; // media descriptor byte uint8_t secperfat_l; // sectors per FAT low byte uint8_t secperfat_h; // sectors per FAT high byte uint8_t secpertrk_l; // sectors per track low byte uint8_t secpertrk_h; // sectors per track high byte uint8_t heads_l; // heads low byte uint8_t heads_h; // heads high byte uint8_t hidden_0; // hidden sectors low byte uint8_t hidden_1; // (note - this is the number of MEDIA sectors before uint8_t hidden_2; // first sector of VOLUME - we rely on the MBR instead) uint8_t hidden_3; // hidden sectors high byte uint8_t sectors_l_0; // large num sectors low byte uint8_t sectors_l_1; // uint8_t sectors_l_2; // uint8_t sectors_l_3; // large num sectors high byte } BPB, *PBPB; /* Extended BIOS Parameter Block structure (FAT12/16) */ typedef struct _tagEBPB { uint8_t unit; // int 13h drive# uint8_t head; // archaic, used by Windows NT-class OSes for flags uint8_t signature; // 0x28 or 0x29 uint8_t serial_0; // serial# uint8_t serial_1; // serial# uint8_t serial_2; // serial# uint8_t serial_3; // serial# uint8_t label[11]; // volume label uint8_t system[8]; // filesystem ID } EBPB, *PEBPB; /* Extended BIOS Parameter Block structure (FAT32) */ typedef struct _tagEBPB32 { uint8_t fatsize_0; // big FAT size in sectors low byte uint8_t fatsize_1; // uint8_t fatsize_2; // uint8_t fatsize_3; // big FAT size in sectors high byte uint8_t extflags_l; // extended flags low byte uint8_t extflags_h; // extended flags high byte uint8_t fsver_l; // filesystem version (0x00) low byte uint8_t fsver_h; // filesystem version (0x00) high byte uint8_t root_0; // cluster of root dir, low byte uint8_t root_1; // uint8_t root_2; // uint8_t root_3; // cluster of root dir, high byte uint8_t fsinfo_l; // sector pointer to FSINFO within reserved area, low byte (2) uint8_t fsinfo_h; // sector pointer to FSINFO within reserved area, high byte (0) uint8_t bkboot_l; // sector pointer to backup boot sector within reserved area, low byte (6) uint8_t bkboot_h; // sector pointer to backup boot sector within reserved area, high byte (0) uint8_t reserved[12]; // reserved, should be 0 uint8_t unit; // int 13h drive# uint8_t head; // archaic, used by Windows NT-class OSes for flags uint8_t signature; // 0x28 or 0x29 uint8_t serial_0; // serial# uint8_t serial_1; // serial# uint8_t serial_2; // serial# uint8_t serial_3; // serial# uint8_t label[11]; // volume label uint8_t system[8]; // filesystem ID } EBPB32, *PEBPB32; /* Logical Boot Record structure (volume boot sector) */ typedef struct _tagLBR { uint8_t jump[3]; // JMP instruction uint8_t oemid[8]; // OEM ID, space-padded BPB bpb; // BIOS Parameter Block union { EBPB ebpb; // FAT12/16 Extended BIOS Parameter Block EBPB32 ebpb32; // FAT32 Extended BIOS Parameter Block } ebpb; uint8_t code[420]; // boot sector code uint8_t sig_55; // 0x55 signature byte uint8_t sig_aa; // 0xaa signature byte } LBR, *PLBR; /* Volume information structure (Internal to DOSFS) */ typedef struct _tagVOLINFO { uint8_t unit; // unit on which this volume resides uint8_t filesystem; // formatted filesystem // These two fields aren't very useful, so support for them has been commented out to // save memory. (Note that the "system" tag is not actually used by DOS to determine // filesystem type - that decision is made entirely on the basis of how many clusters // the drive contains. DOSFS works the same way). // See tag: OEMID in dosfs.c // uint8_t oemid[9]; // OEM ID ASCIIZ // uint8_t system[9]; // system ID ASCIIZ uint8_t label[12]; // volume label ASCIIZ uint32_t startsector; // starting sector of filesystem uint8_t secperclus; // sectors per cluster uint16_t reservedsecs; // reserved sectors uint32_t numsecs; // number of sectors in volume uint32_t secperfat; // sectors per FAT uint16_t rootentries; // number of root dir entries uint32_t numclusters; // number of clusters on drive // The fields below are PHYSICAL SECTOR NUMBERS. uint32_t fat1; // starting sector# of FAT copy 1 uint32_t rootdir; // starting sector# of root directory (FAT12/FAT16) or cluster (FAT32) uint32_t dataarea; // starting sector# of data area (cluster #2) } VOLINFO, *PVOLINFO; /* Flags in DIRINFO.flags */ #define DFS_DI_BLANKENT 0x01 // Searching for blank entry /* Directory search structure (Internal to DOSFS) */ typedef struct _tagDIRINFO { uint32_t currentcluster; // current cluster in dir uint8_t currentsector; // current sector in cluster uint8_t currententry; // current dir entry in sector uint8_t *scratch; // ptr to user-supplied scratch buffer (one sector) uint8_t flags; // internal DOSFS flags } DIRINFO, *PDIRINFO; /* File handle structure (Internal to DOSFS) */ typedef struct _tagFILEINFO { PVOLINFO volinfo; // VOLINFO used to open this file uint32_t dirsector; // physical sector containing dir entry of this file uint8_t diroffset; // # of this entry within the dir sector uint8_t mode; // mode in which this file was opened uint32_t firstcluster; // first cluster of file uint32_t filelen; // byte length of file uint32_t cluster; // current cluster uint32_t pointer; // current (BYTE) pointer } FILEINFO, *PFILEINFO; /* Get starting sector# of specified partition on drive #unit NOTE: This code ASSUMES an MBR on the disk. scratchsector should point to a SECTOR_SIZE scratch area Returns 0xffffffff for any error. If pactive is non-NULL, this function also returns the partition active flag. If pptype is non-NULL, this function also returns the partition type. If psize is non-NULL, this function also returns the partition size. */ uint32_t DFS_GetPtnStart(uint8_t unit, uint8_t *scratchsector, uint8_t pnum, uint8_t *pactive, uint8_t *pptype, uint32_t *psize); /* Retrieve volume info from BPB and store it in a VOLINFO structure You must provide the unit and starting sector of the filesystem, and a pointer to a sector buffer for scratch Attempts to read BPB and glean information about the FS from that. Returns 0 OK, nonzero for any error. */ uint32_t DFS_GetVolInfo(uint8_t unit, uint8_t *scratchsector, uint32_t startsector, PVOLINFO volinfo); /* Open a directory for enumeration by DFS_GetNextDirEnt You must supply a populated VOLINFO (see DFS_GetVolInfo) The empty string or a string containing only the directory separator are considered to be the root directory. Returns 0 OK, nonzero for any error. */ uint32_t DFS_OpenDir(PVOLINFO volinfo, uint8_t *dirname, PDIRINFO dirinfo); /* Get next entry in opened directory structure. Copies fields into the dirent structure, updates dirinfo. Note that it is the _caller's_ responsibility to handle the '.' and '..' entries. A deleted file will be returned as a NULL entry (first char of filename=0) by this code. Filenames beginning with 0x05 will be translated to 0xE5 automatically. Long file name entries will be returned as NULL. returns DFS_EOF if there are no more entries, DFS_OK if this entry is valid, or DFS_ERRMISC for a media error */ uint32_t DFS_GetNext(PVOLINFO volinfo, PDIRINFO dirinfo, PDIRENT dirent); /* Open a file for reading or writing. You supply populated VOLINFO, a path to the file, mode (DFS_READ or DFS_WRITE) and an empty fileinfo structure. You also need to provide a pointer to a sector-sized scratch buffer. Returns various DFS_* error states. If the result is DFS_OK, fileinfo can be used to access the file from this point on. */ uint32_t DFS_OpenFile(PVOLINFO volinfo, uint8_t *path, uint8_t mode, uint8_t *scratch, PFILEINFO fileinfo); /* Read an open file You must supply a prepopulated FILEINFO as provided by DFS_OpenFile, and a pointer to a SECTOR_SIZE scratch buffer. Note that returning DFS_EOF is not an error condition. This function updates the successcount field with the number of bytes actually read. */ uint32_t DFS_ReadFile(PFILEINFO fileinfo, uint8_t *scratch, uint8_t *buffer, uint32_t *successcount, uint32_t len); /* Write an open file You must supply a prepopulated FILEINFO as provided by DFS_OpenFile, and a pointer to a SECTOR_SIZE scratch buffer. This function updates the successcount field with the number of bytes actually written. */ uint32_t DFS_WriteFile(PFILEINFO fileinfo, uint8_t *scratch, uint8_t *buffer, uint32_t *successcount, uint32_t len); /* Seek file pointer to a given position This function does not return status - refer to the fileinfo->pointer value to see where the pointer wound up. Requires a SECTOR_SIZE scratch buffer */ void DFS_Seek(PFILEINFO fileinfo, uint32_t offset, uint8_t *scratch); /* Delete a file scratch must point to a sector-sized buffer */ uint32_t DFS_UnlinkFile(PVOLINFO volinfo, uint8_t *path, uint8_t *scratch); #endif // _DOSFS_H
