aboutsummaryrefslogtreecommitdiffstats
path: root/common
diff options
context:
space:
mode:
authorJeffrey Wilcke <jeffrey@ethereum.org>2017-01-05 03:17:24 +0800
committerJeffrey Wilcke <jeffrey@ethereum.org>2017-02-14 04:44:25 +0800
commitc12f4df910e2da1cc5dd28c5c4bbe2d8721e1057 (patch)
treeda94063644627d9da853a91c28bc37f2df341dd1 /common
parent72dcd3c58bec0a281280d5d42ed53b6e429ce4af (diff)
downloadgo-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar.gz
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar.bz2
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar.lz
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar.xz
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.tar.zst
go-tangerine-c12f4df910e2da1cc5dd28c5c4bbe2d8721e1057.zip
params: core, core/vm, miner: 64bit gas instructions
Reworked the EVM gas instructions to use 64bit integers rather than arbitrary size big ints. All gas operations, be it additions, multiplications or divisions, are checked and guarded against 64 bit integer overflows. In additon, most of the protocol paramaters in the params package have been converted to uint64 and are now constants rather than variables. * common/math: added overflow check ops * core: vmenv, env renamed to evm * eth, internal/ethapi, les: unmetered eth_call and cancel methods * core/vm: implemented big.Int pool for evm instructions * core/vm: unexported intPool methods & verification methods * core/vm: added memoryGasCost overflow check and test
Diffstat (limited to 'common')
-rw-r--r--common/math/integer.go25
-rw-r--r--common/math/integer_test.go50
2 files changed, 75 insertions, 0 deletions
diff --git a/common/math/integer.go b/common/math/integer.go
new file mode 100644
index 000000000..8162b1985
--- /dev/null
+++ b/common/math/integer.go
@@ -0,0 +1,25 @@
+package math
+
+import gmath "math"
+
+/*
+ * NOTE: The following methods need to be optimised using either bit checking or asm
+ */
+
+// SafeSub returns subtraction result and whether overflow occurred.
+func SafeSub(x, y uint64) (uint64, bool) {
+ return x - y, x < y
+}
+
+// SafeAdd returns the result and whether overflow occurred.
+func SafeAdd(x, y uint64) (uint64, bool) {
+ return x + y, y > gmath.MaxUint64-x
+}
+
+// SafeMul returns multiplication result and whether overflow occurred.
+func SafeMul(x, y uint64) (uint64, bool) {
+ if x == 0 {
+ return 0, false
+ }
+ return x * y, x != 0 && y != 0 && y > gmath.MaxUint64/x
+}
diff --git a/common/math/integer_test.go b/common/math/integer_test.go
new file mode 100644
index 000000000..198114e5e
--- /dev/null
+++ b/common/math/integer_test.go
@@ -0,0 +1,50 @@
+package math
+
+import (
+ gmath "math"
+ "testing"
+)
+
+type operation byte
+
+const (
+ sub operation = iota
+ add
+ mul
+)
+
+func TestOverflow(t *testing.T) {
+ for i, test := range []struct {
+ x uint64
+ y uint64
+ overflow bool
+ op operation
+ }{
+ // add operations
+ {gmath.MaxUint64, 1, true, add},
+ {gmath.MaxUint64 - 1, 1, false, add},
+
+ // sub operations
+ {0, 1, true, sub},
+ {0, 0, false, sub},
+
+ // mul operations
+ {10, 10, false, mul},
+ {gmath.MaxUint64, 2, true, mul},
+ {gmath.MaxUint64, 1, false, mul},
+ } {
+ var overflows bool
+ switch test.op {
+ case sub:
+ _, overflows = SafeSub(test.x, test.y)
+ case add:
+ _, overflows = SafeAdd(test.x, test.y)
+ case mul:
+ _, overflows = SafeMul(test.x, test.y)
+ }
+
+ if test.overflow != overflows {
+ t.Errorf("%d failed. Expected test to be %v, got %v", i, test.overflow, overflows)
+ }
+ }
+}