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sys: detect small FAT32 as FAT32 (zero in word SPF)

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Also checks that the total amount of clusters is possible
for the detected file system, erroring out otherwise.
Small FAT32 is displayed in the verbose output specifically.
This commit is contained in:
C. Masloch 2023-01-10 12:51:12 +01:00 committed by Kenneth J Davis
parent 7115d69cd2
commit 384e68529a
1 changed files with 20 additions and 7 deletions
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27
sys/sys.c
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@ -394,6 +394,7 @@ struct bootsectortype32 {
* globals needed by put_boot & check_space
*/
enum {FAT12 = 12, FAT16 = 16, FAT32 = 32} fs; /* file system type */
unsigned smallfat32;
/* static */ struct xfreespace x; /* we make this static to be 0 by default -
this avoids FAT misdetections */
@ -1507,13 +1508,25 @@ void put_boot(SYSOptions *opts)
dataSectors = totalSectors
- bs32->bsResSectors - (bs32->bsFATs * fatSize) - rootDirSectors;
clusters = dataSectors / (((bs32->bsSecPerClust - 1) & 0xFF) + 1);
if (clusters < FAT_MAGIC) /* < 4085 */
fs = FAT12;
else if (clusters < FAT_MAGIC16) /* < 65525 */
fs = FAT16;
else
if (bs32->bsFATsecs == 0) {
if (clusters >= 0xFFFfff5) { /* FAT32 has 28 significant bits */
printf("Too many clusters (%lXh) for FAT32 file system!\n", clusters);
exit(1);
}
fs = FAT32;
if (clusters < FAT_MAGIC16)
smallfat32 = 1;
} else {
if (clusters < FAT_MAGIC) /* < 4085 */
fs = FAT12;
else if (clusters < FAT_MAGIC16) /* < 65525 */
fs = FAT16;
else {
printf("Too many clusters (%lXh) for non-FAT32 file system!\n", clusters);
exit(1);
}
}
}
/* bit 0 set if function to use current BPB, clear if Device
@ -1526,7 +1539,7 @@ void put_boot(SYSOptions *opts)
if (fs == FAT32)
{
if (opts->verbose)
printf("FAT type: FAT32\n");
printf("FAT type: FAT32%s\n", smallfat32 ? " (small)" : "");
/* get default bpb (but not for floppies) */
if (opts->dstDrive >= 2 &&
generic_block_ioctl(opts->dstDrive + 1, 0x4860, default_bpb) == 0)