Read Semgrep config without following symlinks#20
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The adapter validated and hashed the operator config with os.Stat and os.ReadFile, which follow symlinks. A symlinked config passed startup validation, and each analyze-time read could resolve to different bytes than the ones validated. Read the config with O_NOFOLLOW and verify the descriptor stays a stable regular file instead, so a symlinked or swapped config fails closed as config_digest_mismatch or snapshot_invalid.
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Summary
os.Stat/os.ReadFile, both of which follow symlinks — a symlinkedroom.ymlpassed startup checks and each analyze-time read could resolve to different bytes than the ones validated.configMatches, snapshot build) now go through a sharedreadRegularFDhelper:O_NOFOLLOW+O_NONBLOCKopen, regular-file + 64 MiB fstat check, and a post-read fstat comparison — the same disciplinereadRegularBeneathalready applied to diff targets.config_digest_mismatch(analyze) orsnapshot_invalid, and startup rejects non-regular configs including FIFOs instead of blocking on them.Test plan
config_digest_mismatch(both verified to fail against the pre-fix code)go test ./...andgo vetcleanROOM_SEMGREP_CORE=… go test -tags=semgrep_integration ./cmd/room-semgrep— realsemgrep-core1.139.0 suite passesO_NONBLOCK