erofs-freebsd-out-tree/tests/TC085-lz4-large-file.md

Test Case: LZ4 Compression Large File Handling

Test ID: TC085-lz4-large-file

G5 fixture contract: Use G5-MANUAL-SETUP.md. Its generated paths, source comparisons, structured corruption offsets, and cleanup rules supersede placeholder examples in this file. Category: Compression
Priority: High
Regression: None

Objective

Verify LZ4 decompression correctness for large files (>100MB).

Preconditions

• Generated image: images/lz4-large.erofs
• Test file: /large.bin, exactly 268435456 bytes
• Reference: sources/large/large.bin and its generated SHA256
• Mount point: /mnt/test

Test Steps

1. Mount the image:

   mount -t erofs /dev/md0 /mnt/test
   

2. Verify file size reported correctly:

   stat -f %z /mnt/test/files/large-lz4.bin
   

3. Read entire file and compute checksum:

   sha256 -q /mnt/test/large.bin
   sha256 -q sources/large/large.bin
   cmp sources/large/large.bin /mnt/test/large.bin
   

4. Test partial reads at various offsets:

   read_probe pread /mnt/test/large.bin 52428800 10485760 guest.bin
   read_probe pread sources/large/large.bin 52428800 10485760 source.bin
   cmp source.bin guest.bin
   read_probe pread /mnt/test/large.bin 209715200 10485760 guest.bin
   read_probe pread sources/large/large.bin 209715200 10485760 source.bin
   cmp source.bin guest.bin
   

5. Test random access reads:

   # Compare both guest ranges with the same source offsets.
   read_probe pread /mnt/test/large.bin 4096000 4096 chunk1
   read_probe pread /mnt/test/large.bin 204800000 4096 chunk2
   

Expected Results

• Step 2: Size is 268435456 bytes (256MB)
• Step 3: Checksum matches reference value
• Step 4: Partial reads succeed, no errors
• Step 5: Random access works correctly

Verification Method

• Verify data integrity via checksum
• Confirm partial/random reads decompress correctly
• Test memory usage during decompression reasonable
• Verify no memory leaks or buffer overflows

Cleanup

umount /mnt/test
mdconfig -d -u "${unit#md}"
rm /tmp/chunk1 /tmp/chunk2

Notes

• Large file decompression tests pcluster handling
• LZ4 decompression should be streaming (low memory)
• Related tests: TC089 (pcluster mapping)