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rstsflx: Add support to properly size disk containers with simh disk metadata #3

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rstsflx: Add support to properly size disk containers with simh disk metadata #3

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35 changes: 34 additions & 1 deletion extracters/rstsflx/diskio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -106,17 +106,50 @@ void getsize (const char *name, long *tsize, long *rsize, int *dec166)
}
}

typedef struct {
char Signature[4]; /* must be 'simh' */
char CreatingSimulator[64]; /* name of simulator */
char DriveType[16];
lword32 SectorSize; /* Stored in Network Byte Order */
lword32 SectorCount; /* Stored in Network Byte Order */
char Reserved[420]; /* Currently unimportant */
} simh_footer;

long byteswap32 (lword32 value)
{
unsigned char *b = (unsigned char *)&value;

return (long)((b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3]);
}

/* adjsize takes as input a container file size. it returns the
* corresponding RSTS size, based on a match against a table of
* known disk sizes. if it finds a match, it returns the RSTS
* size given in the table; otherwise it returns the value that
* was passed.
* was passed. This process adjust for simh disk container
* metadata if present at the end of the container file.
*/

long adjsize (long tsize)
{
const diskent *d;

if (rstsfile != NULL)
{
struct stat sbuf;

if ((fstat (fileno(rstsfile), &sbuf) == 0) &&
((sbuf.st_size % BLKSIZE) == 0)) /* get info about disk/file */
{
simh_footer f;

if ((fseek (rstsfile, sbuf.st_size - BLKSIZE, SEEK_SET) == 0) &&
(fread (&f, sizeof (f), 1, rstsfile) == 1) &&
(memcmp (f.Signature, "simh", 4) == 0) &&
((byteswap32(f.SectorSize) * byteswap32(f.SectorCount)) == (long)(sbuf.st_size - BLKSIZE)))
return (long)((byteswap32(f.SectorSize) * byteswap32(f.SectorCount)) / BLKSIZE);
}
}
for (d = sizetbl; d->name != NULL; d++)
if (d->tsize == tsize)
return d->rsize;
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