fstype: make copy of first sector in /env to avoid unaligned reads on the disk (for...

devfs crypto partitions do not support unaligned reads,
so we make a copy of the first in /env/block and then
slice it to find filesystem signatures.

thanks mykhal for reporting the issue.

diff --git a/rc/bin/fstype b/rc/bin/fstype
index 71e3adba940c09a863caaa807390f8c6425a7b2d..67c3cd20b081cb3c59ae2ef8be4d8dd89d340165 100755 (executable)
--- a/rc/bin/fstype
+++ b/rc/bin/fstype
@@ -6,15 +6,16 @@ if(~ $"m 01CD00101){
        echo 9660
        exit
 }
+dd -if $1 -count 1 >/env/block >[2]/dev/null
 fn fat {
-       m=`{dd -if $1 -bs 1 -count 3 -skip $2 >[2]/dev/null}
+       m=`{dd -if /env/block -bs 1 -count 3 -skip $1 >[2]/dev/null}
        ~ $"m FAT
 }
-if(fat $1 54 || fat $1 82){
+if(fat 54 || fat 82){
        echo dos
        exit
 }
-m=`{dd -if $1 -bs 4 -count 1 >[2]/dev/null | xd | sed 's,0000000  ,,;q'}
+m=`{dd -if /env/block -bs 4 -count 1 >[2]/dev/null | xd | sed 's,0000000  ,,;q'}
 if(~ $"m 529ab12b){
        echo paqfs
        exit
@@ -23,13 +24,12 @@ if(~ $"m 011ce50d){
        echo hjfs
        exit
 }
-m=`{dd -if $1 -bs 16 -count 1 -skip 16 >[2]/dev/null}
+m=`{dd -if /env/block -bs 16 -count 1 -skip 16 >[2]/dev/null}
 if(~ $"m 'kfs wren device'){
        echo kfs
        exit
 }
-dd -if $1 -count 1 >[2]/dev/null | \
-awk '
+</env/block awk '
 /^(blocksize|daddrbits|daddrbits|indirblks|dirblks|namelen)/{p[$1]=$2}
 END{
        ca["fs", "blocksize"] = 4*1024