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[#18] MS-DOS source code bugfixes and minor improvements (Part 27: Re…
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…using empty directory entries instead of allocating new ones)
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@tomas-nestorovic
tomas-nestorovic committed Apr 30, 2023
1 parent c04c871 commit e99f166
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Showing 5 changed files with 67 additions and 69 deletions.
5 changes: 5 additions & 0 deletions Main/src/Dos.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1235,6 +1235,11 @@ reportError:Utils::Information(buf);
return nullptr; // Null = cannot allocate new Empty entry (aka. this Directory has fixed number of entries)
}

CDos::PFile CDos::TDirectoryTraversal::GetOrAllocateEmptyEntries(BYTE,PFile *){
// finds or allocates specified Count of empty entries in current Directory; returns pointer to the first entry, or Null if not all entries could be found/allocated (e.g. because disk full)
return nullptr;
}

CDos::PFile CDos::TDirectoryTraversal::GetNextFileOrSubdir(){
// finds and returns the next File or Subdirectory in current Directory; returns Null if not found
while (AdvanceToNextEntry())
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1 change: 1 addition & 0 deletions Main/src/Dos.h
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,7 @@
TDirectoryTraversal(PCFile directory,WORD entrySize); // ctor

virtual PFile AllocateNewEntry();
virtual PFile GetOrAllocateEmptyEntries(BYTE count,PFile *pOutEmptyEntriesBuffer);
virtual bool AdvanceToNextEntry()=0;
virtual void ResetCurrentEntry(BYTE directoryFillerByte)=0;
PFile GetNextFileOrSubdir();
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120 changes: 56 additions & 64 deletions Main/src/MSDOS7.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@
: 0;
if (IsDirectory(file)){
item.chs=boot.GetPhysicalAddress(); // certainly not any Directory's PhysicalAddress
for( TMsdos7DirectoryTraversal dt(this,file); dt.__existsNextEntry__(); item.value++ )
for( TMsdos7DirectoryTraversal dt(this,file); dt.AdvanceToNextEntry(); item.value++ )
if (item.chs!=dt.chs){
item.chs=dt.chs;
if (!rFatPath.AddItem(&item)) break; // also sets an error in FatPath
Expand Down Expand Up @@ -405,7 +405,7 @@
::ZeroMemory(tmpBuf,sizeof(tmpBuf));
BYTE i=0;
TMsdos7DirectoryTraversal dt(this,currentDir);
while (dt.__existsNextEntry__())
while (dt.AdvanceToNextEntry())
if (dt.entryType!=TDirectoryTraversal::TDirEntryType::WARNING)
if (( tmpBuf[i=++i&(LONG_FILE_NAME_ENTRIES_COUNT_MAX-1)]=(PDirectoryEntry)dt.entry )==de)
break;
Expand Down Expand Up @@ -558,7 +558,7 @@
// - making sure that the NewName+NewExt combination is not empty
//TODO
// - making sure that the NewName+NewExt combination isn't used by another File in CurrentDirectory
for( TMsdos7DirectoryTraversal dt(this,currentDir); dt.__existsNextEntry__(); )
for( TMsdos7DirectoryTraversal dt(this,currentDir); dt.AdvanceToNextEntry(); )
if (dt.entry!=de)
if (dt.entryType==TDirectoryTraversal::FILE || dt.entryType==TDirectoryTraversal::SUBDIR){
TCHAR tmpName[MAX_PATH],tmpExt[MAX_PATH];
Expand Down Expand Up @@ -646,7 +646,7 @@
// - making sure that the NewNameAndExtension is not empty
//TODO
// - making sure that the NewNameAndExtension isn't used by another File in CurrentDirectory
for( TMsdos7DirectoryTraversal dt(this,currentDir); dt.__existsNextEntry__(); )
for( TMsdos7DirectoryTraversal dt(this,currentDir); dt.AdvanceToNextEntry(); )
if (dt.entry!=de)
if (dt.entryType==TDirectoryTraversal::FILE || dt.entryType==TDirectoryTraversal::SUBDIR){
__getShortFileNameAndExt__( (PCDirectoryEntry)dt.entry, tmpName, tmpExt );
Expand All @@ -672,40 +672,35 @@
if (*newExt)
::lstrcat( ::lstrcat( longNameAndExt, _T(".") ), newExt );
// . allocating necessary number of DirectoryEntries to accommodate the long NameAndExtension
PDirectoryEntry longNameEntries[LONG_FILE_NAME_ENTRIES_COUNT_MAX], *plnde=longNameEntries;
TMsdos7DirectoryTraversal dt(this,currentDir);
for( BYTE n=(::lstrlen(longNameAndExt)+12)/13,i=n; i--; ) // 13 = number of characters in one LongNameEntry
if (!( *plnde++=dt.__allocateNewEntry__() ))
if (dt.entryType==TDirectoryTraversal::WARNING && dt.warning==ERROR_SECTOR_NOT_FOUND)
// simply retry after the bad Sector, marking all DirectoryEntries where the long name didn't fit in, as Empty
for( plnde--; ++i<n; *(PBYTE)*--plnde=UDirectoryEntry::EMPTY_ENTRY );
else
return Utils::ErrorByOs( ERROR_VOLMGR_DISK_NOT_ENOUGH_SPACE, ERROR_CANNOT_MAKE );
if (!( rRenamedFile=dt.__allocateNewEntry__() ))
return Utils::ErrorByOs( ERROR_VOLMGR_DISK_NOT_ENOUGH_SPACE, ERROR_CANNOT_MAKE );
PFile longNameEntries[LONG_FILE_NAME_ENTRIES_COUNT_MAX+1]; // "+1" = short name entry
const BYTE nLongNameEntries=(::lstrlen(longNameAndExt)+12)/13; // 13 = number of characters in one LongNameEntry
if (!TMsdos7DirectoryTraversal(this,currentDir).GetOrAllocateEmptyEntries( nLongNameEntries+1, longNameEntries )) // "+1" = short name entry
return ERROR_CANNOT_MAKE;
rRenamedFile=(PDirectoryEntry)longNameEntries[nLongNameEntries];
// - initializing allocated LongNameEntries
WCHAR bufW[256], *pw=(PWCHAR)::memset(bufW,-1,sizeof(bufW));
#ifdef UNICODE
static_assert( false, "Unicode support not implemented" );
#else
::MultiByteToWideChar( CP_ACP,0, longNameAndExt,-1, bufW,ARRAYSIZE(bufW) );
#endif
for( BYTE n=1,const checksum=(*rRenamedFile=*de).shortNameEntry.__getChecksum__(); plnde!=longNameEntries; ){
const PDirectoryEntry p=*--plnde;
p->longNameEntry.sequenceNumber=n++;
const BYTE shortNameChecksum=( *rRenamedFile=*de ).shortNameEntry.__getChecksum__();
for( BYTE n=nLongNameEntries,seqNum=1; n>0; ){
const PDirectoryEntry p=(PDirectoryEntry)longNameEntries[--n];
p->longNameEntry.sequenceNumber=seqNum++;
::memcpy( p->longNameEntry.name1, pw, 10 ), pw+=5;
p->longNameEntry.attributes=FILE_ATTRIBUTE_LONGNAME;
p->longNameEntry.zero1=0, p->longNameEntry.zero2=0;
p->longNameEntry.checksum=checksum;
p->longNameEntry.checksum=shortNameChecksum;
::memcpy( p->longNameEntry.name2, pw, 12 ), pw+=6;
::memcpy( p->longNameEntry.name3, pw, 4 ), pw+=2;
MarkDirectorySectorAsDirty(p);
}
(*plnde)->longNameEntry.sequenceNumber|=UDirectoryEntry::LONG_NAME_END;
((PDirectoryEntry)longNameEntries[0])->longNameEntry.sequenceNumber|=UDirectoryEntry::LONG_NAME_END;
MarkDirectorySectorAsDirty(rRenamedFile);
// - removing original short and long NameAndExtension
for( BYTE n=__getLongFileNameEntries__(de,longNameEntries); n--; ){
const PDirectoryEntry p=*plnde++;
for( BYTE n=__getLongFileNameEntries__(de,(PDirectoryEntry *)longNameEntries); n>0; ){
const PDirectoryEntry p=(PDirectoryEntry)longNameEntries[--n];
*(PBYTE)p=UDirectoryEntry::EMPTY_ENTRY;
MarkDirectorySectorAsDirty(p);
}
Expand Down Expand Up @@ -767,7 +762,7 @@
return err;
}
if (rCreatedSubdir==&tmp) // new Subdirectory's name follows the "8.3" convention
if ( rCreatedSubdir=TMsdos7DirectoryTraversal(this,currentDir).__allocateNewEntry__() ){
if ( rCreatedSubdir=TMsdos7DirectoryTraversal(this,currentDir).GetOrAllocateEmptyEntry() ){
*rCreatedSubdir=tmp;
MarkDirectorySectorAsDirty(rCreatedSubdir);
}else{
Expand All @@ -776,10 +771,10 @@
}
// - creating the "dot" and "dotdot" entries in newly created Subdirectory
TMsdos7DirectoryTraversal dt(this,rCreatedSubdir);
const PDirectoryEntry dot=dt.__allocateNewEntry__();
const PDirectoryEntry dot=dt.GetOrAllocateEmptyEntry();
*dot=*rCreatedSubdir;
*(PCHAR)::memset( dot, ' ', MSDOS7_FILE_NAME_LENGTH_MAX+MSDOS7_FILE_EXT_LENGTH_MAX )='.';
const PDirectoryEntry dotdot=dt.__allocateNewEntry__();
const PDirectoryEntry dotdot=dt.GetOrAllocateEmptyEntry();
( *dotdot=*dot ).shortNameEntry.name[1]='.';
dotdot->shortNameEntry.__setFirstCluster__( currentDir!=MSDOS7_DIR_ROOT ? ((PCDirectoryEntry)currentDir)->shortNameEntry.__getFirstCluster__() : 0 );
return ERROR_SUCCESS;
Expand Down Expand Up @@ -813,7 +808,7 @@
return err;
// - if moving a File with "8.3" name (e.g. "MYFILE.TXT"), moving the single DirectoryEntry "manually"
if (rMovedFile==de) // a "8.3" named File - the above "registration" didn't function for it
if (const PDirectoryEntry newDe=TMsdos7DirectoryTraversal(this,currentDir).__allocateNewEntry__()){
if (const PDirectoryEntry newDe=TMsdos7DirectoryTraversal(this,currentDir).GetOrAllocateEmptyEntry()){
*newDe=*de;
*(PBYTE)de=UDirectoryEntry::EMPTY_ENTRY;
}else
Expand All @@ -840,7 +835,7 @@
if (IsDirectory(de)){
// Directory - finding out how much space it occupies on the disk (NOT including its content!)
DWORD sizeOnDisk=0;
for( TMsdos7DirectoryTraversal dt(this,de); dt.__existsNextEntry__(); sizeOnDisk+=sizeof(UDirectoryEntry) );
for( TMsdos7DirectoryTraversal dt(this,de); dt.AdvanceToNextEntry(); sizeOnDisk+=sizeof(UDirectoryEntry) );
return sizeOnDisk;
}else{
// File
Expand Down Expand Up @@ -906,7 +901,7 @@
if (!de->shortNameEntry.__isDotOrDotdot__()){ // "dot" and "dotdot" Entries skipped
// . recurrently deleting the content of a Directory
if (IsDirectory(de))
for( TMsdos7DirectoryTraversal dt(this,de); dt.__existsNextEntry__(); )
for( TMsdos7DirectoryTraversal dt(this,de); dt.AdvanceToNextEntry(); )
switch (dt.entryType){
case TDirectoryTraversal::SUBDIR:
// Directory
Expand Down Expand Up @@ -1090,7 +1085,7 @@
for( bfsDirectories.AddTail(rlnp.msdos->currentDir); bfsDirectories.GetCount(); ){
if (pAction->Cancelled) return ERROR_CANCELLED;
TMsdos7DirectoryTraversal dt( rlnp.msdos, bfsDirectories.RemoveHead() );
while (dt.__existsNextEntry__()){
while (dt.AdvanceToNextEntry()){
const PDirectoryEntry de=(PDirectoryEntry)dt.entry;
switch (dt.entryType){
case TDirectoryTraversal::SUBDIR:
Expand Down Expand Up @@ -1356,7 +1351,7 @@ error: return Utils::FatalError( _T("Cannot initialize the medium"), ::GetLastE
}
}

bool CMSDOS7::TMsdos7DirectoryTraversal::__existsNextEntry__(){
bool CMSDOS7::TMsdos7DirectoryTraversal::AdvanceToNextEntry(){
// True <=> another Entry in current Directory exists (Empty or not), otherwise False
if (const PCBootSector bootSector=msdos7->boot.GetSectorData()){
// . getting next LogicalSector of CurrentDirectory
Expand Down Expand Up @@ -1426,42 +1421,39 @@ error: return Utils::FatalError( _T("Cannot initialize the medium"), ::GetLastE
return false;
}

bool CMSDOS7::TMsdos7DirectoryTraversal::AdvanceToNextEntry(){
// True <=> found another entry in current Directory (Empty or not), otherwise False
return __existsNextEntry__();
}

CMSDOS7::PDirectoryEntry CMSDOS7::TMsdos7DirectoryTraversal::__allocateNewEntry__(){
// allocates new DirectoryEntry at the end of CurrentDirectory and returns the DirectoryEntry; returns Null if new DirectoryEntry cannot be allocated (e.g. because disk is full)
CDos::PFile CMSDOS7::TMsdos7DirectoryTraversal::GetOrAllocateEmptyEntries(BYTE count,PFile *pOutEmptyEntriesBuffer){
// finds or allocates specified Count of empty entries in current Directory; returns pointer to the first entry, or Null if not all entries could be found/allocated (e.g. because disk full)
BYTE nEmptyEntriesFound=0;
PDirectoryEntry deFirst=nullptr;
do{
// . moving pointer to the end of CurrentDirectory
while (__existsNextEntry__() && !foundEndOfDirectory); // cycle as long as there exists another Entry and the Entry isn't the end of CurrentDirectory
if (!foundEndOfDirectory) // if end of CurrentDirectory not found (e.g. because Sector unreadable or FAT error) ...
return nullptr; // ... we are unsuccessfully done
// . if an Empty DirectoryEntry found, we are successfully done
if (entryType==TDirectoryTraversal::EMPTY)
break;
// . at this point, we have found end of CurrentDirectory but without an Empty DirectoryEntry - allocating new Cluster and returning the first DirectoryEntry in it
switch (msdos7->fat.type){
case CFat::FAT12:
case CFat::FAT16:
if (directory==MSDOS7_DIR_ROOT) // for root Directory of FAT12/FAT16 ...
return nullptr; // ... cannot be allocated a new Cluster
//fallthrough
case CFat::FAT32:
if (( next=msdos7->__allocateAndResetDirectoryCluster__() )==MSDOS7_FAT_CLUSTER_EOF)
return nullptr; // failed to allocate a new Directory Cluster
msdos7->fat.SetClusterValue(cluster,next);
foundEndOfDirectory=false; // toggling the flag back - thanks to the newly allocated Cluster, the CurrentDirectory doesn't yet end
break;
}
if (!AdvanceToNextEntry()) // cannot continue in traversal?
if (foundEndOfDirectory && MARKS_CLUSTER_EOF(next)) // is it because regular end of Directory has been reached?
switch (msdos7->fat.type){ // can we allocate new Directory Cluster?
case CFat::FAT12:
case CFat::FAT16:
if (directory==MSDOS7_DIR_ROOT) // for root Directory of FAT12/FAT16 ...
return nullptr; // ... cannot be allocated a new Cluster
//fallthrough
case CFat::FAT32:
if (( next=msdos7->__allocateAndResetDirectoryCluster__() )==MSDOS7_FAT_CLUSTER_EOF)
return nullptr; // failed to allocate a new Directory Cluster
msdos7->fat.SetClusterValue(cluster,next);
foundEndOfDirectory=false; // toggling the flag back - thanks to the newly allocated Cluster, the CurrentDirectory doesn't yet end
continue;
}
else
return nullptr;
if (entryType==TDirectoryTraversal::EMPTY){
if (!nEmptyEntriesFound)
deFirst=(PDirectoryEntry)entry;
if (pOutEmptyEntriesBuffer)
pOutEmptyEntriesBuffer[nEmptyEntriesFound]=entry;
if (++nEmptyEntriesFound==count)
return deFirst;
}else
nEmptyEntriesFound=0;
}while (true);
return (PDirectoryEntry)entry;
}

CDos::PFile CMSDOS7::TMsdos7DirectoryTraversal::AllocateNewEntry(){
// allocates and returns new entry at the end of current Directory and returns; returns Null if new entry cannot be allocated (e.g. because disk is full)
return __allocateNewEntry__();
return nullptr;
}

void CMSDOS7::TMsdos7DirectoryTraversal::ResetCurrentEntry(BYTE directoryFillerByte){
Expand Down
6 changes: 3 additions & 3 deletions Main/src/MSDOS7.h
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Original file line number Diff line number Diff line change
Expand Up @@ -211,11 +211,11 @@
BYTE nRemainingEntriesInSector;
public:
TMsdos7DirectoryTraversal(const CMSDOS7 *_msdos7,PCFile directory); // ctor
PFile AllocateNewEntry() override;
PDirectoryEntry __allocateNewEntry__();

PFile GetOrAllocateEmptyEntries(BYTE count,PFile *pOutEmptyEntriesBuffer=nullptr) override;
inline PDirectoryEntry GetOrAllocateEmptyEntry(){ return (PDirectoryEntry)GetOrAllocateEmptyEntries(1); }
bool AdvanceToNextEntry() override;
void ResetCurrentEntry(BYTE directoryFillerByte) override;
bool __existsNextEntry__();
};

class CMsdos7BootView sealed:public CBootView{
Expand Down
4 changes: 2 additions & 2 deletions Main/src/MSDOS7_Boot.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -393,7 +393,7 @@
return;
}
//rParam.label.length=0; // assumption (Label doesn't exist); commented out as already zeroed by the caller
for( TMsdos7DirectoryTraversal dt(msdos,MSDOS7_DIR_ROOT); dt.__existsNextEntry__(); )
for( TMsdos7DirectoryTraversal dt(msdos,MSDOS7_DIR_ROOT); dt.AdvanceToNextEntry(); )
if (dt.entryType==TDirectoryTraversal::CUSTOM
&&
(((PCDirectoryEntry)dt.entry)->shortNameEntry.attributes&FILE_ATTRIBUTE_VOLUME)!=0
Expand Down Expand Up @@ -470,7 +470,7 @@
bool WINAPI CMSDOS7::CMsdos7BootView::__pg_createLabel__(PropGrid::PCustomParam,int hyperlinkId,LPCTSTR hyperlinkName){
// True <=> PropertyGrid's Editor can be destroyed after this function has terminated, otherwise False
const PMSDOS7 msdos=(PMSDOS7)CDos::GetFocused();
if (const PDirectoryEntry de=TMsdos7DirectoryTraversal(msdos,MSDOS7_DIR_ROOT).__allocateNewEntry__()){
if (const PDirectoryEntry de=TMsdos7DirectoryTraversal(msdos,MSDOS7_DIR_ROOT).GetOrAllocateEmptyEntry()){
de->shortNameEntry.attributes=FILE_ATTRIBUTE_VOLUME;
::memcpy( ::memset(de->shortNameEntry.name,' ',MSDOS7_LABEL_LENGTH_MAX),
VOLUME_LABEL_DEFAULT_ANSI_8CHARS,
Expand Down

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