Fix off-by-one boundary in lpEncodeBacklen() for 3 values#3601
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The function lpEncodeBacklen() uses `<= 127` for the 1-byte case but `< 16383`, `< 2097151`, and `< 268435455` for the subsequent cases. This means the exact values 16383, 2097151, and 268435455 (i.e. 2^14-1, 2^21-1, 2^28-1) unnecessarily use one extra byte than needed. For example, 16383 (0x3FFF) can be encoded in 2 bytes but is currently encoded in 3 bytes due to the boundary check being off by one. Signed-off-by: fanpei91 <fanpei91@gmail.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## unstable #3601 +/- ##
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- Coverage 76.64% 76.62% -0.03%
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Files 160 160
Lines 80475 80475
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- Hits 61684 61660 -24
- Misses 18791 18815 +24
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lucasyonge
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May 11, 2026
The function lpEncodeBacklen() uses `<= 127` for the 1-byte case but `< 16383`, `< 2097151`, and `< 268435455` for the subsequent cases. This means the exact values 16383, 2097151, and 268435455 (i.e. 2^14-1, 2^21-1, 2^28-1) unnecessarily use one extra byte than needed: - `l < 16383` → `16383` (2^14-1) uses 3 bytes instead of 2 - `l < 2097151` → `2097151` (2^21-1) uses 4 bytes instead of 3 - `l < 268435455` → `268435455` (2^28-1) uses 5 bytes instead of 4 The decoding side (`lpDecodeBacklen`) is unaffected since it parses continuation bits continuously without discrete range checks. This is a correctness issue and has no impact on data integrity since encoding and decoding use the same function boundaries, but it wastes up to 1 byte per affected entry. Signed-off-by: fanpei91 <fanpei91@gmail.com>
lucasyonge
pushed a commit
that referenced
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May 12, 2026
The function lpEncodeBacklen() uses `<= 127` for the 1-byte case but `< 16383`, `< 2097151`, and `< 268435455` for the subsequent cases. This means the exact values 16383, 2097151, and 268435455 (i.e. 2^14-1, 2^21-1, 2^28-1) unnecessarily use one extra byte than needed: - `l < 16383` → `16383` (2^14-1) uses 3 bytes instead of 2 - `l < 2097151` → `2097151` (2^21-1) uses 4 bytes instead of 3 - `l < 268435455` → `268435455` (2^28-1) uses 5 bytes instead of 4 The decoding side (`lpDecodeBacklen`) is unaffected since it parses continuation bits continuously without discrete range checks. This is a correctness issue and has no impact on data integrity since encoding and decoding use the same function boundaries, but it wastes up to 1 byte per affected entry. Signed-off-by: fanpei91 <fanpei91@gmail.com>
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The function lpEncodeBacklen() uses
<= 127for the 1-byte case but< 16383,< 2097151, and< 268435455for the subsequent cases. This means the exact values 16383, 2097151, and 268435455 (i.e. 2^14-1, 2^21-1, 2^28-1) unnecessarily use one extra byte than needed:l < 16383→16383(2^14-1) uses 3 bytes instead of 2l < 2097151→2097151(2^21-1) uses 4 bytes instead of 3l < 268435455→268435455(2^28-1) uses 5 bytes instead of 4The decoding side (
lpDecodeBacklen) is unaffected since it parses continuation bits continuously without discrete range checks.This is a correctness issue and has no impact on data integrity since encoding and decoding use the same function boundaries, but it wastes up to 1 byte per affected entry.