Fault injection testing is used to validate error paths in CRIU. Faults are artificially generated in peeked places of the code to check for particular roll-backs.
Faults are enforced by setting the CRIU_FAULT env before executing CRIU binary. Values are described in criu/include/fault-injection.h header file.
Fatal faults
These make CRIU abort the current operation and exit with error.
Abort dump early
FI_DUMP_EARLY == 1. Makes CRIU abort duming right after infecting the task with parasite code. Checks that parasite unloading on error works OK.
Abort restore early
FI_RESTORE_ROOT_ONLY == 2. Makes CRIU stop restoring right after spawning (and pre-restoring) the root task. Checks that early preparations (such as invisible files pre-creation) doesn't leave garbage in the system.
= Abort link-remap file opening
FI_RESTORE_OPEN_LINK_REMAP == 3. Make CRIU fail the very first attempt opening the link remap file. Additional check for invisible files cleanup.
Abort connection to parasite code
FI_PARASITE_CONNECT == 4. Makes CRIU simulate impossibility for parasite code to connect back to CRIU.
Non fatal faults
These just make CRIU chose different paths on dump/restore, trying harder to get work done.
Abort open-by-handle
FI_CHECK_OPEN_HANDLE == 128. Simulates failure of the open_by_handle_at system call. Forces the irmap engine to work.
Abort memfd creation
FI_NO_MEMFD == 129. Forces parasite code use shmem-based blob instead of memfd-based. Used for older kernels (not having the memfd_create() system call) to work.
Abort breakpoints injectioin
FI_NO_BREAKPOINTS == 130. Disables breakpoints and makes CRIU unload code blobs by step-by-step tracing.