114 lines
3.0 KiB
C++
114 lines
3.0 KiB
C++
// vfat.c
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// Author: Josh Holtrop
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// Date: 03/11/04
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// Modified: 03/22/04
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#include "vfat.h"
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#include "hos_defines.h"
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#include "fs/vfs.h"
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#include "mm/vmm.h"
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#include "lang/string.h"
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//From Microsoft's FAT32 File System Specification
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DSKSZTOSECPERCLUS DskTableFAT16 [] =
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{
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{ 8400, 0}, /* disks up to 4.1 MB, the 0 value for SecPerClusVal trips an error */
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{ 32680, 2}, /* disks up to 16 MB, 1k cluster */
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{ 262144, 4}, /* disks up to 128 MB, 2k cluster */
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{ 524288, 8}, /* disks up to 256 MB, 4k cluster */
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{ 1048576, 16}, /* disks up to 512 MB, 8k cluster */
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/* The entries after this point are not used unless FAT16 is forced */
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// { 2097152, 32}, /* disks up to 1 GB, 16k cluster */
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// { 4194304, 64}, /* disks up to 2 GB, 32k cluster */
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{ 0xFFFFFFFF, 0} /* any disk greater than 2GB, 0 value for SecPerClusVal trips an error */
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};
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//From Microsoft's FAT32 File System Specification
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DSKSZTOSECPERCLUS DskTableFAT32 [] =
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{
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{ 66600, 0}, /* disks up to 32.5 MB, the 0 value for SecPerClusVal trips an error */
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{ 532480, 1}, /* disks up to 260 MB, .5k cluster */
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{ 16777216, 8}, /* disks up to 8 GB, 4k cluster */
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{ 33554432, 16}, /* disks up to 16 GB, 8k cluster */
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{ 67108864, 32}, /* disks up to 32 GB, 16k cluster */
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{ 0xFFFFFFFF, 64}/* disks greater than 32GB, 32k cluster */
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};
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int vfat_identify(vfat_bpb *bpb)
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{
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int rootDirSectors = ((bpb->rootEntries * 32) + (bpb->bytesPerSector - 1)) / bpb->bytesPerSector;
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int totalSectors = bpb->totalSectors16 ? bpb->totalSectors16 : bpb->totalSectors32;
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int fatSectors = bpb->sectorsPerFAT16 ? bpb->sectorsPerFAT16 : bpb->sectorsPerFAT32;
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int dataSectors = totalSectors - (bpb->reservedSectors + bpb->numFATs * fatSectors + rootDirSectors);
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int clusters = dataSectors / bpb->sectorsPerCluster;
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if (clusters < 4085)
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return 12;
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if (clusters < 65525)
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return 16;
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return 32;
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}
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int vfat_format(Volume *vol)
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{
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}
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FILE *vfat_open(char *fileName, dword attributes, Volume *vol)
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{
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while (*fileName == '/')
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++fileName;
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if (strlen(fileName) < 1)
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return 0;
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vfat_bpb *bpb = vfat_getBootSector(vol);
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if (!bpb) return 0;
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byte *fat = vfat_loadFAT(vol, bpb);
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if (!fat)
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{
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free(bpb);
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return 0;
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}
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int segs = string_split(fileName); //number of sections of path (1=file is in root directory)
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int me = vfat_identify(bpb);
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if (me != 32)
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{
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if (segs == 1) //we are looking for the file in the root directory
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{
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vfat_getEntryInRoot(vol, bpb, fileName, 0);
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}
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}
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else
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{
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}
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}
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byte *vfat_loadFAT(Volume *vol, vfat_bpb *bpb)
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{
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int fatSize = bpb->sectorsPerFAT16 ? bpb->sectorsPerFAT16 : bpb->sectorsPerFAT32;
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byte *fat = malloc(fatSize << 9); //512 bytes per sector
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if (!fat) return 0;
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if (vfs_readSectorn(vol, bpb->reservedSectors, fat, fatSize))
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{
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free(fat);
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return 0;
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}
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return fat;
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}
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vfat_bpb *vfat_getBootSector(Volume *vol)
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{
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vfat_bpb *bs;
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if (!(bs = malloc(512)))
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return 0;
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vfs_readSector(vol, 0, bs);
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return bs;
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}
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int vfat_close(FILE *fp)
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{
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return free(fp);
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}
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