fix(upgrade): replace Bun.mmap with arrayBuffer on macOS to prevent SIGKILL#340
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fix(upgrade): replace Bun.mmap with arrayBuffer on macOS to prevent SIGKILL#340
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…IGKILL Bun.mmap() always requests PROT_WRITE regardless of the `shared` flag. On macOS, AMFI code signing enforcement sends an uncatchable SIGKILL for ANY writable mapping (MAP_SHARED or MAP_PRIVATE) on code-signed Mach-O binaries — which all Bun-compiled binaries are. The previous fix (PR #339, { shared: false }) was insufficient because MAP_PRIVATE with PROT_WRITE is also rejected. Sentry telemetry confirmed: zero successful macOS upgrade traces from delta-enabled versions, while Linux worked fine. Use a platform check: on macOS, read the old binary into memory via Bun.file().arrayBuffer() (~100 MB heap, freed after patching). On Linux, keep the zero-heap Bun.mmap() path since ELF binaries have no such restriction.
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Summary
`Bun.mmap()` always requests `PROT_WRITE` in its implementation regardless of the `shared` flag. On macOS, AMFI code signing enforcement sends an uncatchable `SIGKILL` for any writable mapping (`MAP_SHARED` or `MAP_PRIVATE`) on code-signed Mach-O binaries — which all Bun-compiled binaries are.
PR #339's `{ shared: false }` (MAP_PRIVATE) fix was insufficient. Sentry telemetry confirmed: zero successful macOS upgrade traces from delta-enabled versions, while Linux worked fine.
Fix
Platform-conditional old file loading in `src/lib/bspatch.ts`:
Evidence