Struct CoverageReport 

pub struct CoverageReport {
    pub covered_offsets: u32,
    pub bitmap_size: u32,
    pub bitmap: Vec<u8>,
}

Bytecode coverage tracking.

When enabled, the QuickJS interpreter records which bytecode offsets execute. This is essential for:

• Fuzzing feedback — Soleno’s MCTS uses coverage to guide exploration. Inputs that cover new bytecodes score higher.
• Detonation completeness — Sear verifies that the payload actually executed (not just parsed) by checking coverage against the script’s bytecode.
• Evasion detection — if a script has bytecodes that never execute regardless of input, those may be dead code or environment-gated payloads.

How it works

1. Host allocates a coverage bitmap in WASM linear memory via jsdet_alloc
2. Host calls jsdet_set_coverage(bitmap_ptr, size) to register it
3. QuickJS interpreter sets bits as bytecodes execute
4. After execution, host reads the bitmap back
5. jsdet_count_coverage() returns the number of executed bytecodes
6. jsdet_clear_coverage() resets for the next run

The bitmap is bit-packed: byte N, bit M = bytecode offset (N*8 + M).

Coverage statistics from one execution.

Fields

covered_offsets: u32

Total bytecode offsets covered (bits set in the bitmap).

bitmap_size: u32

Size of the coverage bitmap in bytes.

bitmap: Vec<u8>

Raw bitmap data (for differential analysis between runs).

Implementations

impl CoverageReport

pub fn coverage_ratio(&self) -> f64

Coverage ratio: covered / (bitmap_size * 8).

pub fn new_coverage_since(&self, previous: &CoverageReport) -> u32

Count new offsets covered compared to a previous run. This is the MCTS reward signal — new coverage = high reward.

pub fn merge(&mut self, other: &CoverageReport)

Merge coverage from another report (union of bitmaps).

Trait Implementations

impl Clone for CoverageReport

fn clone(&self) -> CoverageReport

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CoverageReport

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CoverageReport

fn default() -> CoverageReport

Returns the “default value” for a type.

impl Serialize for CoverageReport

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.