Enable sparse file support on macOS - #468
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AdityaPainuli wants to merge 1 commit into
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Sparse file detection in Builder is cfg-gated to Linux, Android, and FreeBSD, so macOS silently falls back to dense copies. The existing implementation already works on macOS unchanged: the non-Linux path probes fpathconf(_PC_MIN_HOLE_SIZE) before using SEEK_HOLE/SEEK_DATA, and APFS supports all three (libc exposes the constants for apple targets).
This PR adds target_os = "macos" to the three cfg gates in src/builder.rs and enables the writing_sparse size assertion on macOS.
I found this while debugging snapshot write amplification in qdrant (qdrant/qdrant#9858). Archiving a 32 MiB hole-backed file with 4 KiB of data via append_path_with_name:
Same code, same file, the gate was the only difference.
Verified on macOS 15 (arm64, APFS): full test suite passes including all 5 sparse tests, and writing_sparse measures 37,888 bytes, the same 4k-block bound as ext4, so the assertion reuses the 37 KiB limit.