fatfs.cpp

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/*
 * Copyright 2004 Martin Fuchs
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */


 //
 // Explorer clone
 //
 // fatfs.cpp
 //
 // Martin Fuchs, 01.02.2004
 //


#include <precomp.h>

#include "fatfs.h"


static union DEntry* link_dir_entries(struct dirent* dir, struct Kette* K, int cnt)
{
    union DEntry* Ent = (union DEntry*) dir;
    struct Kette* L = NULL;

    for(; cnt; cnt--) {
        K->Rueck = L;
        (L=K)->Ent = Ent;
        AddP(K, sizeof(struct Kette));
        L->Vorw = K;
        AddP(Ent, sizeof(union DEntry));
    }

    L->Vorw = NULL;

    return Ent;
}

void FATDirectory::read_directory(int scan_flags)
{
    CONTEXT("FATDirectory::read_directory()");

    read_dir();

    union DEntry* p = (union DEntry*) _dir;
    int i = 0;

    do {
/*      if (!IS_LNAME(p->E.attr) && p->E.name[0]!=FAT_DEL_CHAR)
            gesBytes += p->E.size;
*/

        AddP(p, sizeof(union DEntry));
    } while(++i<_ents && p->E.name[0]);

    _alloc = (struct Kette*) malloc((size_t)((_ents=i)+8)*sizeof(struct Kette));
    if (!_alloc)
        return;

    link_dir_entries(_dir, _alloc, i);

    Entry* first_entry = NULL;
    int level = _level + 1;

    Entry* last = NULL;

    WIN32_FIND_DATA w32fd;
    FAT_attribute attr;
    String long_name;

    TCHAR buffer[MAX_PATH];

    _tcscpy(buffer, (LPCTSTR)_path);
    LPTSTR pname = buffer + _tcslen(buffer);
    int plen = COUNTOF(buffer) - _tcslen(buffer);

    *pname++ = '\\';
    --plen;

    for(Kette*p=_alloc; p; p=p->Vorw) {
        memset(&w32fd, 0, sizeof(WIN32_FIND_DATA));

        DEntry_E& e = p->Ent->E;

         // get file/directory attributes
        attr.b = e.attr;

        if (attr.b & (_A_DELETED | _A_ILLEGAL))
            attr.b |= _A_ILLEGAL;

        const char* s = e.name;
        LPTSTR d = w32fd.cFileName;

        if (!IS_LNAME(attr.b) || e.name[0]==FAT_DEL_CHAR) {
            if (e.name[0] == FAT_DEL_CHAR)
                w32fd.dwFileAttributes |= ATTRIBUTE_ERASED;
            else if (IS_LNAME(attr.b))
                w32fd.dwFileAttributes |= ATTRIBUTE_LONGNAME;
            else if (attr.a.directory)
                w32fd.dwFileAttributes |= FILE_ATTRIBUTE_DIRECTORY;
            else if (attr.a.volume)
                w32fd.dwFileAttributes |= ATTRIBUTE_VOLNAME;    //@@ -> in Volume-Name der Root kopieren

             // get file name
            *d++ = *s==FAT_DEL_CHAR? '?': *s;
            ++s;

            for(i=0; i<7; ++i)
                *d++ = *s++;

            while(d>w32fd.cFileName && d[-1]==' ')
                --d;

            *d++ = '.';

            for(; i<10; ++i)
                *d++ = *s++;

            while(d>w32fd.cFileName && d[-1]==' ')
                --d;

            if (d>w32fd.cFileName && d[-1]=='.')
                --d;

            *d = '\0';
        } else {
            s = (const char*)p->Ent->B; // no change of the pointer, just to avoid overung warnings in code checkers

             // read long file name
            TCHAR lname[] = {s[1], s[3], s[5], s[7], s[9], s[14], s[16], s[18], s[20], s[22], s[24], s[28], s[30]};

            long_name = String(lname, 13) + long_name;
        }

        if (!IS_LNAME(attr.b) && !attr.a.volume) {
             // get file size
            w32fd.nFileSizeLow = e.size;

             // convert date/time attribute into FILETIME
            const filedate& date = e.date;
            const filetime& time = e.time;
            SYSTEMTIME stime;
            FILETIME ftime;

            stime.wYear = date.year + 1980;
            stime.wMonth = date.month;
            stime.wDayOfWeek = (WORD)-1;
            stime.wDay = date.day;
            stime.wHour = time.hour;
            stime.wMinute = time.min;
            stime.wSecond = time.sec2 * 2;
            stime.wMilliseconds = 0;

            if (SystemTimeToFileTime(&stime, &ftime))
                LocalFileTimeToFileTime(&ftime, &w32fd.ftLastWriteTime);

            if (!(w32fd.dwFileAttributes & ATTRIBUTE_ERASED)) { //@@
                Entry* entry;

                if (w32fd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
                    _tcscpy_s(pname, plen, w32fd.cFileName);
                    entry = new FATDirectory(_drive, this, buffer, e.fclus);
                } else
                    entry = new FATEntry(this, e.fclus);

                memcpy(&entry->_data, &w32fd, sizeof(WIN32_FIND_DATA));

                if (!long_name.empty()) {
                    entry->_content = _tcsdup(long_name);
                    long_name.erase();
                }

                if (!first_entry)
                    first_entry = entry;

                if (last)
                    last->_next = entry;

                entry->_level = level;

                last = entry;
            }
        }
    }

    if (last)
        last->_next = NULL;

    _down = first_entry;
    _scanned = true;
}


const void* FATDirectory::get_next_path_component(const void* p) const
{
    LPCTSTR s = (LPCTSTR) p;

    while(*s && *s!=TEXT('\\') && *s!=TEXT('/'))
        ++s;

    while(*s==TEXT('\\') || *s==TEXT('/'))
        ++s;

    if (!*s)
        return NULL;

    return s;
}


Entry* FATDirectory::find_entry(const void* p)
{
    LPCTSTR name = (LPCTSTR)p;

    for(Entry*entry=_down; entry; entry=entry->_next) {
        LPCTSTR p = name;
        LPCTSTR q = entry->_data.cFileName;

        do {
            if (!*p || *p==TEXT('\\') || *p==TEXT('/'))
                return entry;
        } while(tolower(*p++) == tolower(*q++));

        p = name;
        q = entry->_data.cAlternateFileName;

        do {
            if (!*p || *p==TEXT('\\') || *p==TEXT('/'))
                return entry;
        } while(tolower(*p++) == tolower(*q++));
    }

    return NULL;
}


 // get full path of specified directory entry
bool FATEntry::get_path(PTSTR path, size_t path_count) const
{
    return get_path_base ( path, path_count, ET_FAT );
}

ShellPath FATEntry::create_absolute_pidl() const
{
    CONTEXT("WinEntry::create_absolute_pidl()");

    return (LPCITEMIDLIST)NULL;
/* prepend root path if the drive is currently actually mounted in the file system -> return working PIDL
    TCHAR path[MAX_PATH];

    if (get_path(path, COUNTOF(path)))
        return ShellPath(path);

    return ShellPath();
*/
}


FATDirectory::FATDirectory(FATDrive& drive, LPCTSTR root_path)
 :  FATEntry(),
    _drive(drive)
{
    _path = _tcsdup(root_path);

    _secarr     = NULL;
    _cur_bufs   = 0;
    _ents       = 0;
    _dir        = NULL;
    _cluster    = 0;
}

FATDirectory::FATDirectory(FATDrive& drive, Entry* parent, LPCTSTR path, unsigned cluster)
 :  FATEntry(parent, cluster),
    _drive(drive)
{
    _path = _tcsdup(path);

    _secarr     = NULL;
    _cur_bufs   = 0;
    _ents       = 0;
    _dir        = NULL;
}

FATDirectory::~FATDirectory()
{
    free(_path);
    _path = NULL;
}

bool FATDirectory::read_dir()
{
    int i;

    if (_cluster == 0) {
        if (!_drive._boot_sector.SectorsPerFAT) {   // FAT32? [boot_sector32->reserved0==0]
            BootSector32* boot_sector32 = (BootSector32*) &_drive._boot_sector;
            DWORD sect = _drive._boot_sector.ReservedSectors + _drive._boot_sector.NumberFATs*boot_sector32->SectorsPerFAT32;  // lese Root-Directory ein
            int RootEntries = boot_sector32->RootSectors * 32;  //@@

            _secarr = (struct dirsecz*)malloc(sizeof(DWORD) * (_cur_bufs = (int)((_ents=RootEntries)/_drive._bufents)));

            for(i=0; i<_cur_bufs; i++)
                _secarr->s[i] = sect+i;

            _dir = (struct dirent*)malloc((size_t)(_ents+16)*sizeof(union DEntry));
            if (!_dir)
                return false;

            if (!(_drive.read_sector(*_secarr->s,(Buffer*)_dir,_cur_bufs)))
                return false;
        } else {
            DWORD sect = _drive._boot_sector.ReservedSectors + _drive._boot_sector.NumberFATs*_drive._boot_sector.SectorsPerFAT;  // read in root directory

            _secarr = (struct dirsecz*)malloc(sizeof(DWORD) * (_cur_bufs = (int)((_ents=_drive._boot_sector.RootEntries)/_drive._bufents)));

            for(i=0; i<_cur_bufs; i++)
                _secarr->s[i] = sect+i;

            _dir = (struct dirent*)malloc((size_t)(_ents+16)*sizeof(union DEntry));
            if (!_dir)
                return false;

            if (!_drive.read_sector(*_secarr->s,(Buffer*)_dir,_cur_bufs))
                return false;
        }
    } else {
        Buffer* buf;
        bool ok;

        DWORD h = _cluster;

        _cur_bufs = 0;

        do {
            h = _drive.read_FAT(h, ok);

            if (!ok)
                return false;

            _cur_bufs++;
        } while (h<0x0ffffff0 && h);

        _secarr = (struct dirsecz*) malloc(sizeof(DWORD) * _cur_bufs);

        if (!_secarr)
            return false;

        _ents = _drive._bufents * (size_t)_cur_bufs * _drive._SClus;

        if ((buf=(Buffer*)(_dir=(struct dirent*)malloc((size_t) (_ents+16)*sizeof(union DEntry)))) == NULL)
            return false;

        h = _cluster;

        DWORD fdatsec;

        if (!_drive._boot_sector.SectorsPerFAT) {   // FAT32 ?
            BootSector32* boot_sector32 = (BootSector32*) &_drive._boot_sector;
            //int RootEntries = boot_sector32->RootSectors * 32;    //@@
            //fdatsec = _drive._boot_sector.ReservedSectors + _drive._boot_sector.NumberFATs*boot_sector32->SectorsPerFAT32 + RootEntries*sizeof(DEntry)/_drive._boot_sector.BytesPerSector;    // dpb.fdirsec
            fdatsec = _drive._boot_sector.ReservedSectors +
                        _drive._boot_sector.NumberFATs*boot_sector32->SectorsPerFAT32 + boot_sector32->RootSectors;
        } else
            fdatsec = _drive._boot_sector.ReservedSectors +
                        _drive._boot_sector.NumberFATs*_drive._boot_sector.SectorsPerFAT +
                        _drive._boot_sector.RootEntries*sizeof(DEntry)/_drive._boot_sector.BytesPerSector;  // dpb.fdirsec

            for(i=0; i<_cur_bufs; i++) {
                _secarr->s[i] = fdatsec + (DWORD)_drive._SClus*(h-2);

                h = _drive.read_FAT(h, ok);

                if (!ok)
                    return false;
            }

            for(i=0; i<_cur_bufs; i++) {
                if ((ok = (_drive.read_sector(_secarr->s[i], buf, _drive._SClus))) == true)
                    AddP(buf, _drive._bufl*_drive._SClus)
                else {
                    //@@FPara = _secarr->s[i];
                    return false;
                }
            }

        buf->dat[0] = 0;     // Endekennzeichen für Rekurs setzen
    }

    return true;
}


#ifdef _MSC_VER
#pragma warning(disable: 4355)
#endif

FATDrive::FATDrive(LPCTSTR path)
 :  FATDirectory(*this, TEXT("\\"))
{
    _bufl = 0;
    _bufents = 0;
    _SClus = 0;
    _FATCache = NULL;
    _CacheCount = 0;
    _CacheSec = NULL;
    _CacheCnt = NULL;
    _CacheDty = NULL;
    _Caches = 0;

    _hDrive = CreateFile(path, GENERIC_READ|GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, 0);

    if (_hDrive != INVALID_HANDLE_VALUE) {
        _boot_sector.BytesPerSector = 512;

        if (read_sector(0, (Buffer*)&_boot_sector, 1)) {
            _bufl = _boot_sector.BytesPerSector;
            _SClus = _boot_sector.SectorsPerCluster;
            _bufents = _bufl / sizeof(union DEntry);
        }

        small_cache();
    }
}

FATDrive::~FATDrive()
{
    if (_hDrive != INVALID_HANDLE_VALUE)
        CloseHandle(_hDrive);

    free(_path);
    _path = NULL;
}

void FATDrive::small_cache()
{
    if (_FATCache)
        free(_FATCache);

    if (_CacheSec) {
        free(_CacheSec), _CacheSec = NULL;
        free(_CacheCnt);
        free(_CacheDty);
    }

    _Caches = CACHE_SIZE_LOW;
    _FATCache = (struct Cache *) malloc((_Caches+1) * _drive._bufl);

    reset_cache();
}

void FATDrive::reset_cache()    // mark cache as empty
{
    int i;

    if (!_CacheSec) {
        _CacheSec = (DWORD*) malloc(_Caches * sizeof(DWORD));
        _CacheCnt = (int*) malloc(_Caches * sizeof(int));
        _CacheDty = (bool*) malloc(_Caches * sizeof(bool));
    } else {
        _CacheSec = (DWORD*) realloc(_CacheSec, _Caches * sizeof(DWORD));
        _CacheCnt = (int*) realloc(_CacheCnt, _Caches * sizeof(int));
        _CacheDty = (bool*) realloc(_CacheDty, _Caches * sizeof(bool));
    }

    for(i=0; i<_Caches; i++)
        _CacheSec[i] = 0;

    _read_ahead = (_Caches+1) / 2;
}

bool FATDrive::read_sector(DWORD sec, Buffer* buf, int len)
{
    sec += 63;  //@@ jump to first partition

    if (SetFilePointer(_hDrive, sec*_drive._boot_sector.BytesPerSector, 0, 0) == INVALID_SET_FILE_POINTER)
        return false;

    DWORD read;

    if (!ReadFile(_hDrive, buf, len*_drive._boot_sector.BytesPerSector, &read, 0))
        return false;

    return true;
}

DWORD FATDrive::read_FAT(DWORD cluster, bool& ok)   //@@ use exception handling
{
    DWORD nClus;
    Buffer* FATBuf;

    DWORD nclus = (_boot_sector.Sectors32? _boot_sector.Sectors32: _boot_sector.Sectors16) / _boot_sector.SectorsPerCluster;    

    if (cluster > nclus) {
        ok = false;
        return (DWORD)-1;
    }

    if (nclus >= 65536) {       // FAT32
        DWORD FATsec = cluster / (_boot_sector.BytesPerSector/4);
        DWORD z = (cluster - _boot_sector.BytesPerSector/4 * FATsec)*4;
        FATsec += _boot_sector.ReservedSectors;
        if (!read_cache(FATsec, &FATBuf))
            ok = false;
        nClus = dpeek(&FATBuf->dat[z]);
    } else if (nclus >= 4096) { // 16 Bit-FAT
        DWORD FATsec = cluster / (_boot_sector.BytesPerSector/2);
        DWORD z = (cluster - _boot_sector.BytesPerSector/2 * FATsec)*2;
        FATsec += _boot_sector.ReservedSectors;
        if (!read_cache(FATsec, &FATBuf))
            ok = false;
        nClus = wpeek(&FATBuf->dat[z]);

        if (nClus >= 0xfff0)
            nClus |= 0x0fff0000;
    } else {                        // 12 Bit-FAT
        DWORD FATsec = cluster*3 / (_boot_sector.BytesPerSector*2);
        DWORD z = (cluster*3 - _boot_sector.BytesPerSector*2*FATsec)/2;
        FATsec += _boot_sector.ReservedSectors;
        if (!read_cache(FATsec,&FATBuf))
            ok = false;
        BYTE a = FATBuf->dat[z++];

        if (z >= _boot_sector.BytesPerSector)
            if (!read_cache(FATsec+1,&FATBuf))
                ok = false;
        z = 0;

        BYTE b = FATBuf->dat[z];

        if (cluster & 1)
            nClus = (a>>4) | (b<<4);
        else
            nClus = a | ((b & 0xf)<<8);

        if (nClus >= 0xff0)
            nClus |= 0x0ffff000;
    }

    return nClus;
}

bool FATDrive::read_cache(DWORD sec, Buffer** bufptr)
{
 int i, C, anz;

 if (_boot_sector.BytesPerSector != BufLen)  // no standard sector size?
  return read_sector(sec, *bufptr=(Buffer*)&_FATCache[0], 1);

 _CacheCount++;

 for(i=0; _CacheSec[i]!=sec && i<_Caches; )
  ++i;

 if (i < _Caches)
  {
   *bufptr = (Buffer*) &_FATCache[i];    // FAT-Sektor schon gepuffert
   _CacheCnt[i]++;
   return true;
  }

 i = get_cache_buffer();

 if (_cache_empty)      // von get_cache_buffer() gesetzt
  {
   C = _CacheCount-1;
   anz = _boot_sector.SectorsPerFAT*_boot_sector.NumberFATs - sec;

   if (anz > _read_ahead)
    anz = _read_ahead;

   for(i=0; i<anz; i++) {
    _CacheSec[i] = sec++;
    _CacheCnt[i] = C;
    _CacheDty[i] = 0;
   }

   _CacheCnt[0] = _CacheCount;

   return read_sector(_CacheSec[0], *bufptr=(Buffer*) &_FATCache[0], anz);
  }
 else
  {
   _CacheDty[i] = 0;
   _CacheCnt[i] = _CacheCount;

   return read_sector(_CacheSec[i]=sec, *bufptr=(Buffer*) &_FATCache[i], 1);
  }
}

int FATDrive::get_cache_buffer()    // search for free cache buffer
{
 int i, j, minCnt;

 for(i=0; i<_Caches; i++)
  if (_CacheSec[i])
   break;

 _cache_empty = i==_Caches? true: false;

 for(i=0; _CacheSec[i] && i<_Caches; )
  ++i;

 if (i < _Caches)
  j = i;
 else
  {
   minCnt = 0;          // search for least used buffer

   for(j=i=0; i<_Caches; i++)
    if (minCnt < _CacheCnt[i]) {
     minCnt = _CacheCnt[i];
     j = i;
    }

  }

 return j;
}