fix(enclave): write the LUKS keyfile atomically (tmp + rename)#198
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setup-persistent-luks (seismic-images) polls for this exact path at 1Hz, but create+truncate+write makes the file visible at open(), an instant before its 64 bytes land — a poller waking inside that window reads a short keyfile. Write to luks-keys.tmp and rename into place so existence implies fully written; the script-side wait now relies on exactly that. rename also fixes a pre-existing restart wrinkle: the keyfile is mode 0400, so reopening it with truncate(true) is EACCES even for the owner — an enclave-server restart before the script consumed the previous keyfile would have failed here. rename replaces the stale file without opening it. The stale .tmp from a crashed earlier run is removed up front, since create_new would refuse it for the same permission reason (and it holds key material worth scrubbing).
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setup-persistent-luks (seismic-images) polls for this exact path at 1Hz, but create+truncate+write makes the file visible at open(), an instant before its 64 bytes land — a poller waking inside that window reads a short keyfile. Write to luks-keys.tmp and rename into place so existence implies fully written; the script-side wait now relies on exactly that.
rename also fixes a pre-existing restart wrinkle: the keyfile is mode 0400, so reopening it with truncate(true) is EACCES even for the owner — an enclave-server restart before the script consumed the previous keyfile would have failed here. rename replaces the stale file without opening it. The stale .tmp from a crashed earlier run is removed up front, since create_new would refuse it for the same permission reason (and it holds key material worth scrubbing).