File size discrepancy with du when repeatedly encoding point clouds

[bisejdiu]

Issue Description

When repeatedly encoding point clouds using draco_encoder on macOS without deleting the output file between runs, du reports increased file sizes for subsequent runs while the actual file size remains unchanged. This occurs specifically when encoding point clouds (either directly or from PLY files with faces removed).

Steps to Reproduce

1. Remove faces from a PLY file to create a point cloud:

sed -e '10d' -e '11d' -e '/^3 /d' testdata/bun_zipper.ply > bz_mod.ply

2. Run encoder multiple times without deleting output:

build_dir/draco_encoder -i bz_mod.ply -o bz_out.drc
du -h bz_out.drc  # Reports 76K
build_dir/draco_encoder -i bz_mod.ply -o bz_out.drc
du -h bz_out.drc  # Reports 136K

Observed Behavior

• First encoding: du reports expected file size
• Subsequent encodings: du reports larger file size
• Actual file size (via ls -l, stat, etc.) remains constant
• Extended attributes (@ flag) appear on the file
• Issue persists across repeated runs until file is deleted

Environment

• OS: macOS 15.1
• Chip: Arm64 (M3)
• Version: 1.5.7 (recent clone from the main branch)
• Different builds tested:
  • cmake ..
  • cmake .. -DCMAKE_BUILD_TYPE=Release -DDRACO_TESTS=ON
    • All tests pass