120 lines
3.5 KiB
C++
120 lines
3.5 KiB
C++
#pragma once
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#include <cstdint>
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#include <functional>
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#include "Structs.h"
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// https://www.pjrc.com/tech/8051/ide/fat32.html
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namespace FAT32 {
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template <typename BlockDev> class FS {
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static constexpr const char* NAME = "FAT32";
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BlockDev& dev;
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AbsOffset offset;
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FSDesc desc;
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Precomputed tmp;
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bool valid = false;
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public:
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#include "File.h"
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#include "DirIterator.h"
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#include "WriteFile.h"
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#include "FreeClusterIterator.h"
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/** ctor with the absolute offset addr (in bytes) */
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FS(BlockDev& dev, AbsOffset offset) : dev(dev), offset(offset) {
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init();
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}
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/** is the detected FS valid? */
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bool isValid() const {
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return valid;
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}
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/** get an iterator for the root directory */
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DirIterator getRoot() {
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return DirIterator(*this, desc.rootDirFirstCluster);
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}
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/** open the given file for reading*/
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File open(const DirEntry& de) {
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return File(*this, de.size, de.getFirstCluster());
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}
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// /** create a new file for writing, in the given directory */
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// WriteFile newFile(DirEntry& de, const uint32_t size) {
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// if (!de.isDirectory()) {return nullptr;}
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// uint32_t allocSize = 0;
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// FreeClusterIterator fci(*this);
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// while(allocSize < size) {
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// ClusterNr = fci.next();
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// }
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// }
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private:
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void init() {
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Log::addInfo(NAME, "init @ %d", offset);
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uint8_t buf[512];
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dev.read(offset, 512, buf);
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desc.bytesPerSector = getU16(&buf[0x0B]);
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desc.sectorsPerCluster = getU8(&buf[0x0D]);
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desc.numReservedSectors = getU16(&buf[0x0E]);
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desc.numberOfFATs = getU8(&buf[0x10]);
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desc.sectorsPerFAT = getU32(&buf[0x24]);
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desc.rootDirFirstCluster = getU32(&buf[0x2C]);
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// basic sanity check based on constants
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valid = (desc.bytesPerSector == 512) && (desc.numberOfFATs == 2) && (getU16(&buf[0x1FE]) == 0xAA55);
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tmp.bytesPerCluster = desc.sectorsPerCluster * desc.bytesPerSector;
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tmp.startOfFAT = offset + (desc.numReservedSectors * desc.bytesPerSector);
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tmp.startOfFirstDataCluster = offset + (desc.numReservedSectors * desc.bytesPerSector) + (desc.numberOfFATs * desc.sectorsPerFAT * desc.bytesPerSector);
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tmp.startOfFirstRootDirCluster = clusterToAbsPos(desc.rootDirFirstCluster);
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tmp.dirEntriesPerSector = desc.bytesPerSector / sizeof(DirEntry);
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Log::addInfo(NAME, "Bytes/Sector: %d, Sector/Cluster: %d, FATs: %d, RootDir: %d", desc.bytesPerSector, desc.sectorsPerCluster, desc.numberOfFATs, desc.rootDirFirstCluster);
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/*
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std::cout << (int)desc.bytesPerSector << std::endl;
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std::cout << (int)desc.sectorsPerCluster << std::endl;
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std::cout << (int)desc.numReservedSectors << std::endl;
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std::cout << (int)desc.numberOfFATs << std::endl;
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std::cout << (int)desc.sectorsPerFAT << std::endl;
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std::cout << (int)desc.rootDirFirstCluster << std::endl;
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std::cout << tmp.startOfFAT << std::endl;
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std::cout << tmp.startOfFirstDataCluster << std::endl;
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std::cout << tmp.startOfFirstRootDirCluster << std::endl;
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*/
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}
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/** determine the ClusterNr following the given ClusterNr */
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ClusterNr getNextCluster(ClusterNr clusterNr) {
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const AbsPos pos = tmp.startOfFAT + ((clusterNr) * sizeof(uint32_t));
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ClusterNr next = 0;
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dev.read(pos, 4, reinterpret_cast<uint8_t*>(&next));
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Log::addInfo(NAME, "nextCluster(%d) -> %d", clusterNr, next);
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return next;
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}
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/** convert ClusterNr into an absolute position on disk */
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AbsPos clusterToAbsPos(ClusterNr clusterNr) {
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return tmp.startOfFirstDataCluster + ((clusterNr - 2) * desc.sectorsPerCluster * desc.bytesPerSector);
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}
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};
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}
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