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Deal with decoding failures explicitly in asmap Interpret

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This commit is contained in:
Pieter Wuille 2020-04-03 10:43:38 -07:00
parent 1479007a33
commit 2b3dbfa5a6
1 changed files with 11 additions and 4 deletions
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15
src/util/asmap.cpp
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@ -8,6 +8,8 @@
namespace {
constexpr uint32_t INVALID = 0xFFFFFFFF;
uint32_t DecodeBits(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos, uint8_t minval, const std::vector<uint8_t> &bit_sizes)
{
uint32_t val = minval;
@ -25,7 +27,7 @@ uint32_t DecodeBits(std::vector<bool>::const_iterator& bitpos, const std::vector
val += (1 << *bit_sizes_it);
} else {
for (int b = 0; b < *bit_sizes_it; b++) {
if (bitpos == endpos) break;
if (bitpos == endpos) return INVALID; // Reached EOF in mantissa
bit = *bitpos;
bitpos++;
val += bit << (*bit_sizes_it - 1 - b);
@ -33,7 +35,7 @@ uint32_t DecodeBits(std::vector<bool>::const_iterator& bitpos, const std::vector
return val;
}
}
return -1;
return INVALID; // Reached EOF in exponent
}
enum class Instruction : uint32_t
@ -83,9 +85,12 @@ uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
while (pos != endpos) {
opcode = DecodeType(pos, endpos);
if (opcode == Instruction::RETURN) {
return DecodeASN(pos, endpos);
default_asn = DecodeASN(pos, endpos);
if (default_asn == INVALID) break; // ASN straddles EOF
return default_asn;
} else if (opcode == Instruction::JUMP) {
jump = DecodeJump(pos, endpos);
if (jump == INVALID) break; // Jump offset straddles EOF
if (bits == 0) break;
if (ip[ip.size() - bits]) {
if (jump >= endpos - pos) break;
@ -94,6 +99,7 @@ uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
bits--;
} else if (opcode == Instruction::MATCH) {
match = DecodeMatch(pos, endpos);
if (match == INVALID) break; // Match bits straddle EOF
matchlen = CountBits(match) - 1;
for (uint32_t bit = 0; bit < matchlen; bit++) {
if (bits == 0) break;
@ -104,8 +110,9 @@ uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
}
} else if (opcode == Instruction::DEFAULT) {
default_asn = DecodeASN(pos, endpos);
if (default_asn == INVALID) break; // ASN straddles EOF
} else {
break;
break; // Instruction straddles EOF
}
}
return 0; // 0 is not a valid ASN