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Avoid mixing cluster numbers and sector numbers. Makes code more readable.

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Obtained from:	NetBSD
MFC after:	2 weeks
This commit is contained in:
Xin LI 2019-09-15 19:41:54 +00:00
parent 7887a5a140
commit eb1c42c1f0
3 changed files with 19 additions and 11 deletions
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16
sbin/fsck_msdosfs/boot.c
View File

@ -259,12 +259,18 @@ readboot(int dosfs, struct bootblock *boot)
return FSFATAL;
}
boot->ClusterOffset = (boot->bpbRootDirEnts * 32 +
boot->FirstCluster = (boot->bpbRootDirEnts * 32 +
boot->bpbBytesPerSec - 1) / boot->bpbBytesPerSec +
boot->bpbResSectors + boot->bpbFATs * boot->FATsecs -
CLUST_FIRST * boot->bpbSecPerClust;
boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) /
boot->bpbSecPerClust;
boot->bpbResSectors + boot->bpbFATs * boot->FATsecs;
if (boot->FirstCluster + boot->bpbSecPerClust > boot->NumSectors) {
pfatal("Cluster offset too large (%u clusters)\n",
boot->FirstCluster);
return FSFATAL;
}
boot->NumClusters = (boot->NumSectors - boot->FirstCluster) / boot->bpbSecPerClust +
CLUST_FIRST;
if (boot->flags & FAT32)
boot->ClustMask = CLUST32_MASK;

12
sbin/fsck_msdosfs/dir.c
View File

@ -317,7 +317,8 @@ delete(int f, struct bootblock *boot, struct fatEntry *fat, cl_t startcl,
break;
e = delbuf + endoff;
}
off = startcl * boot->bpbSecPerClust + boot->ClusterOffset;
off = (startcl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
off *= boot->bpbBytesPerSec;
if (lseek(f, off, SEEK_SET) != off) {
perr("Unable to lseek to %" PRId64, off);
@ -457,7 +458,7 @@ check_subdirectory(int f, struct bootblock *boot, struct dosDirEntry *dir)
off = boot->bpbResSectors + boot->bpbFATs *
boot->FATsecs;
} else {
off = cl * boot->bpbSecPerClust + boot->ClusterOffset;
off = (cl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
}
/*
@ -538,7 +539,7 @@ readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat,
boot->FATsecs;
} else {
last = boot->bpbSecPerClust * boot->bpbBytesPerSec;
off = cl * boot->bpbSecPerClust + boot->ClusterOffset;
off = (cl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
}
off *= boot->bpbBytesPerSec;
@ -1069,8 +1070,9 @@ reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
lfcl = (lostDir->head < boot->NumClusters) ? lostDir->head : 0;
return FSERROR;
}
lfoff = lfcl * boot->ClusterSize
+ boot->ClusterOffset * boot->bpbBytesPerSec;
lfoff = (lfcl - CLUST_FIRST) * boot->ClusterSize
+ boot->FirstCluster * boot->bpbBytesPerSec;
if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
|| (size_t)read(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
perr("could not read LOST.DIR");

2
sbin/fsck_msdosfs/dosfs.h
View File

@ -74,7 +74,7 @@ struct bootblock {
u_int32_t NumSectors; /* how many sectors are there */
u_int32_t FATsecs; /* how many sectors are in FAT */
u_int32_t NumFatEntries; /* how many entries really are there */
u_int ClusterOffset; /* at what sector would sector 0 start */
u_int FirstCluster; /* at what sector is Cluster CLUST_FIRST */
u_int ClusterSize; /* Cluster size in bytes */
/* Now some statistics: */