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Fix handling of ProDOS disks with short volume directories

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The ProDOS code was assuming that the volume directory was 4 blocks
long.  Some disks, such as the ProDOS 2.4.2 distribution disk, only
use the first two blocks.  CiderPress now scans the volume directory
to determine the actual length.

Fixes issue #32.
This commit is contained in:
Andy McFadden 2020-07-23 14:12:16 -07:00
parent 21151cd76a
commit fb25998be5
2 changed files with 52 additions and 10 deletions
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1
diskimg/DiskImgDetail.h
View File

@ -1596,6 +1596,7 @@ private:
DIError Initialize(InitMode initMode);
DIError LoadVolHeader(void);
DIError DetermineVolDirLen(uint16_t nextBlock, uint16_t* pBlocksUsed);
void SetVolumeID(void);
void DumpVolHeader(void);
DIError ScanVolBitmap(void);

61
diskimg/ProDOS.cpp
View File

@ -30,7 +30,7 @@
const int kBlkSize = 512;
const int kVolHeaderBlock = 2; // block where Volume Header resides
const int kVolDirExpectedNumBlocks = 4; // customary #of volume header blocks
const int kFormatVolDirNumBlocks = 4; // #of volume header blocks for new volumes
const int kMinReasonableBlocks = 16; // min size for ProDOS volume
const int kExpectedBitmapStart = 6; // block# where vol bitmap should start
const int kMaxCatalogIterations = 1024; // theoretical max is 32768?
@ -360,8 +360,11 @@ DIError DiskFSProDOS::LoadVolHeader(void)
pEntry->fileName[nameLen] = '\0';
pEntry->fileType = kTypeDIR;
pEntry->keyPointer = kVolHeaderBlock;
pEntry->blocksUsed = kVolDirExpectedNumBlocks;
pEntry->eof = kVolDirExpectedNumBlocks * 512;
dierr = DetermineVolDirLen(GetShortLE(&blkBuf[0x02]), &pEntry->blocksUsed);
if (dierr != kDIErrNone) {
goto bail;
}
pEntry->eof = pEntry->blocksUsed * 512;
pEntry->createWhen = GetLongLE(&blkBuf[0x1c]);
pEntry->version = blkBuf[0x20];
pEntry->minVersion = blkBuf[0x21];
@ -375,8 +378,47 @@ DIError DiskFSProDOS::LoadVolHeader(void)
pFile->fSparseRsrcEof = -1;
AddFileToList(pFile);
pFile = NULL;
bail:
delete pFile;
return dierr;
}
DIError DiskFSProDOS::DetermineVolDirLen(uint16_t nextBlock, uint16_t* pBlocksUsed) {
DIError dierr = kDIErrNone;
uint8_t blkBuf[kBlkSize];
uint16_t blocksUsed = 1;
int iterCount = 0;
// Traverse the volume directory chain, counting blocks. Normally this will have 4, but
// variations are possible.
while (nextBlock != 0) {
blocksUsed++;
if (nextBlock < 2 || nextBlock >= fpImg->GetNumBlocks()) {
LOGI(" ProDOS ERROR: invalid volume dir link block %u", nextBlock);
dierr = kDIErrInvalidBlock;
goto bail;
}
dierr = fpImg->ReadBlock(nextBlock, blkBuf);
if (dierr != kDIErrNone) {
goto bail;
}
nextBlock = GetShortLE(&blkBuf[0x02]);
// Watch for infinite loop.
iterCount++;
if (iterCount > fpImg->GetNumBlocks()) {
LOGI(" ProDOS ERROR: infinite vol directory loop found");
dierr = kDIErrDirectoryLoop;
goto bail;
}
}
bail:
*pBlocksUsed = blocksUsed;
return dierr;
}
@ -552,7 +594,7 @@ DIError DiskFSProDOS::ScanVolBitmap(void)
}
/*
* Generate an empty block use map.
* Generate an empty block use map. Used by disk formatter.
*/
DIError DiskFSProDOS::CreateEmptyBlockMap(void)
{
@ -569,7 +611,7 @@ DIError DiskFSProDOS::CreateEmptyBlockMap(void)
*/
long block;
long firstEmpty =
kVolHeaderBlock + kVolDirExpectedNumBlocks + GetNumBitmapBlocks();
kVolHeaderBlock + kFormatVolDirNumBlocks + GetNumBitmapBlocks();
for (block = 0; block < firstEmpty; block++)
SetBlockUseEntry(block, true);
for ( ; block < fTotalBlocks; block++)
@ -1494,10 +1536,10 @@ DIError DiskFSProDOS::Format(DiskImg* pDiskImg, const char* volName)
*/
int i;
memset(blkBuf, 0, sizeof(blkBuf));
for (i = kVolHeaderBlock+1; i < kVolHeaderBlock+kVolDirExpectedNumBlocks; i++)
for (i = kVolHeaderBlock+1; i < kVolHeaderBlock+kFormatVolDirNumBlocks; i++)
{
PutShortLE(&blkBuf[0x00], i-1);
if (i == kVolHeaderBlock+kVolDirExpectedNumBlocks-1)
if (i == kVolHeaderBlock+kFormatVolDirNumBlocks-1)
PutShortLE(&blkBuf[0x02], 0);
else
PutShortLE(&blkBuf[0x02], i+1);
@ -1540,7 +1582,7 @@ DIError DiskFSProDOS::Format(DiskImg* pDiskImg, const char* volName)
blkBuf[0x23] = 0x27; // entry_length: always $27
blkBuf[0x24] = 0x0d; // entries_per_block: always $0d
/* file_count is zero - does not include volume dir */
PutShortLE(&blkBuf[0x27], kVolHeaderBlock + kVolDirExpectedNumBlocks); // bit_map_pointer
PutShortLE(&blkBuf[0x27], kVolHeaderBlock + kFormatVolDirNumBlocks); // bit_map_pointer
PutShortLE(&blkBuf[0x29], (uint16_t) formatBlocks); // total_blocks
dierr = fpImg->WriteBlock(kVolHeaderBlock, blkBuf);
if (dierr != kDIErrNone) {
@ -1558,8 +1600,7 @@ DIError DiskFSProDOS::Format(DiskImg* pDiskImg, const char* volName)
/*
* Generate the initial block usage map. The only entries in use are
* right at the start of the disk. When we finish, scan what we just
* created into
* right at the start of the disk.
*/
CreateEmptyBlockMap();