common/compiler: simplify solc wrapper

Support for legacy version 0.9.x is gone. The compiler version is no
longer cached. Compilation results (and the version) are read directly
from stdout using the --combined-json flag. As a workaround for
ethereum/solidity#651, source code is written to a temporary file before
compilation.

Integration of solc in package ethapi and cmd/abigen is now much simpler
because the compiler wrapper is no longer passed around as a pointer.

Fixes #2806, accidentally

3 files changed, 90 insertions, 73 deletions

diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 88bacc45b..ac9e2151d 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"encoding/hex"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"math/big"
 	"strings"
@@ -30,7 +29,6 @@ import (
 	"github.com/ethereum/ethash"
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/common/compiler"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -50,14 +48,12 @@ const defaultGas = uint64(90000)
 // PublicEthereumAPI provides an API to access Ethereum related information.
 // It offers only methods that operate on public data that is freely available to anyone.
 type PublicEthereumAPI struct {
-	b        Backend
-	solcPath *string
-	solc     **compiler.Solidity
+	b Backend
 }
 
 // NewPublicEthereumAPI creates a new Etheruem protocol API.
-func NewPublicEthereumAPI(b Backend, solcPath *string, solc **compiler.Solidity) *PublicEthereumAPI {
-	return &PublicEthereumAPI{b, solcPath, solc}
+func NewPublicEthereumAPI(b Backend) *PublicEthereumAPI {
+	return &PublicEthereumAPI{b}
 }
 
 // GasPrice returns a suggestion for a gas price.
@@ -65,39 +61,6 @@ func (s *PublicEthereumAPI) GasPrice(ctx context.Context) (*big.Int, error) {
 	return s.b.SuggestPrice(ctx)
 }
 
-func (s *PublicEthereumAPI) getSolc() (*compiler.Solidity, error) {
-	var err error
-	solc := *s.solc
-	if solc == nil {
-		solc, err = compiler.New(*s.solcPath)
-	}
-	return solc, err
-}
-
-// GetCompilers returns the collection of available smart contract compilers
-func (s *PublicEthereumAPI) GetCompilers() ([]string, error) {
-	solc, err := s.getSolc()
-	if err == nil && solc != nil {
-		return []string{"Solidity"}, nil
-	}
-
-	return []string{}, nil
-}
-
-// CompileSolidity compiles the given solidity source
-func (s *PublicEthereumAPI) CompileSolidity(source string) (map[string]*compiler.Contract, error) {
-	solc, err := s.getSolc()
-	if err != nil {
-		return nil, err
-	}
-
-	if solc == nil {
-		return nil, errors.New("solc (solidity compiler) not found")
-	}
-
-	return solc.Compile(source)
-}
-
 // ProtocolVersion returns the current Ethereum protocol version this node supports
 func (s *PublicEthereumAPI) ProtocolVersion() *rpc.HexNumber {
 	return rpc.NewHexNumber(s.b.ProtocolVersion())
@@ -1416,31 +1379,6 @@ func (s *PublicTransactionPoolAPI) Resend(ctx context.Context, tx *Tx, gasPrice,
 	return common.Hash{}, fmt.Errorf("Transaction %#x not found", tx.Hash)
 }
 
-// PrivateAdminAPI is the collection of Etheruem APIs exposed over the private
-// admin endpoint.
-type PrivateAdminAPI struct {
-	b        Backend
-	solcPath *string
-	solc     **compiler.Solidity
-}
-
-// NewPrivateAdminAPI creates a new API definition for the private admin methods
-// of the Ethereum service.
-func NewPrivateAdminAPI(b Backend, solcPath *string, solc **compiler.Solidity) *PrivateAdminAPI {
-	return &PrivateAdminAPI{b, solcPath, solc}
-}
-
-// SetSolc sets the Solidity compiler path to be used by the node.
-func (api *PrivateAdminAPI) SetSolc(path string) (string, error) {
-	var err error
-	*api.solcPath = path
-	*api.solc, err = compiler.New(path)
-	if err != nil {
-		return "", err
-	}
-	return (*api.solc).Info(), nil
-}
-
 // PublicDebugAPI is the collection of Etheruem APIs exposed over the public
 // debugging endpoint.
 type PublicDebugAPI struct {
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index d112a6aef..791a06925 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -22,7 +22,6 @@ import (
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/common/compiler"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -69,12 +68,13 @@ type State interface {
 	GetNonce(ctx context.Context, addr common.Address) (uint64, error)
 }
 
-func GetAPIs(apiBackend Backend, solcPath *string, solc **compiler.Solidity) []rpc.API {
-	return []rpc.API{
+func GetAPIs(apiBackend Backend, solcPath string) []rpc.API {
+	compiler := makeCompilerAPIs(solcPath)
+	all := []rpc.API{
 		{
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   NewPublicEthereumAPI(apiBackend, solcPath, solc),
+			Service:   NewPublicEthereumAPI(apiBackend),
 			Public:    true,
 		}, {
 			Namespace: "eth",
@@ -92,10 +92,6 @@ func GetAPIs(apiBackend Backend, solcPath *string, solc **compiler.Solidity) []r
 			Service:   NewPublicTxPoolAPI(apiBackend),
 			Public:    true,
 		}, {
-			Namespace: "admin",
-			Version:   "1.0",
-			Service:   NewPrivateAdminAPI(apiBackend, solcPath, solc),
-		}, {
 			Namespace: "debug",
 			Version:   "1.0",
 			Service:   NewPublicDebugAPI(apiBackend),
@@ -116,4 +112,5 @@ func GetAPIs(apiBackend Backend, solcPath *string, solc **compiler.Solidity) []r
 			Public:    false,
 		},
 	}
+	return append(compiler, all...)
 }
diff --git a/internal/ethapi/solc.go b/internal/ethapi/solc.go
new file mode 100644
index 000000000..b9acc518b
--- /dev/null
+++ b/internal/ethapi/solc.go
@@ -0,0 +1,82 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package ethapi
+
+import (
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common/compiler"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+func makeCompilerAPIs(solcPath string) []rpc.API {
+	c := &compilerAPI{solc: solcPath}
+	return []rpc.API{
+		{
+			Namespace: "eth",
+			Version:   "1.0",
+			Service:   (*PublicCompilerAPI)(c),
+			Public:    true,
+		},
+		{
+			Namespace: "admin",
+			Version:   "1.0",
+			Service:   (*CompilerAdminAPI)(c),
+			Public:    true,
+		},
+	}
+}
+
+type compilerAPI struct {
+	// This lock guards the solc path set through the API.
+	// It also ensures that only one solc process is used at
+	// any time.
+	mu   sync.Mutex
+	solc string
+}
+
+type CompilerAdminAPI compilerAPI
+
+// SetSolc sets the Solidity compiler path to be used by the node.
+func (api *CompilerAdminAPI) SetSolc(path string) (string, error) {
+	api.mu.Lock()
+	defer api.mu.Unlock()
+	info, err := compiler.SolidityVersion(path)
+	if err != nil {
+		return "", err
+	}
+	api.solc = path
+	return info.FullVersion, nil
+}
+
+type PublicCompilerAPI compilerAPI
+
+// CompileSolidity compiles the given solidity source.
+func (api *PublicCompilerAPI) CompileSolidity(source string) (map[string]*compiler.Contract, error) {
+	api.mu.Lock()
+	defer api.mu.Unlock()
+	return compiler.CompileSolidityString(api.solc, source)
+}
+
+func (api *PublicCompilerAPI) GetCompilers() ([]string, error) {
+	api.mu.Lock()
+	defer api.mu.Unlock()
+	if _, err := compiler.SolidityVersion(api.solc); err == nil {
+		return []string{"Solidity"}, nil
+	}
+	return []string{}, nil
+}