sfsck - check/repair an SFS filesystem
/sbin/sfsck raw-device
host-sfsck disk-image-file
sfsck checks the SFS filesystem on the specified device for correctness and consistency. Various possible errors and corrupt states are detected and reported; some (but not all) can be corrected.
If sfsck is used under OS/161, the first form should be used, where raw-device is a raw device name (such as "lhd1raw:"). Don't use a device that's currently mounted.
sfsck can also be used on the System/161 host OS, in which case the second form should be used. The host-compiled version of sfsck knows how to deal with the header on System/161 disk images and does the right thing.
sfsck uses the following system calls:
sfsck should function properly under OS/161 once you have implemented the basic system calls, sbrk in the VM system, and fstat.
The host version of sfsck, since it runs outside of OS/161, should always work regardless of what you have and have not implemented.
You will likely need to make some changes to sfsck in the course of doing the file system assignment. If you are implementing crash recovery for your file system, be sure to update sfsck to know about any extra on-disk structures you add. You will want to be able to use it to cross-check your recovery code... and so will the course staff.