in the embedded world, we use a different oracle

minigeth/oracle/embedded.go

+//go:build mips
+
+package oracle
+
+import (
+	"fmt"
+	"io/ioutil"
+	"math/big"
+	"os"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+func Preimage(hash common.Hash) []byte {
+	f, err := os.Open(fmt.Sprintf("/tmp/eth/%s", hash))
+	if err != nil {
+		panic("missing preimage")
+	}
+
+	defer f.Close()
+	ret, err := ioutil.ReadAll(f)
+	if err != nil {
+		panic("preimage read failed")
+	}
+	return ret
+}
+
+// these are stubs in embedded world
+func PrefetchStorage(blockNumber *big.Int, addr common.Address, skey common.Hash) {}
+func PrefetchAccount(blockNumber *big.Int, addr common.Address)                   {}
+func PrefetchCode(blockNumber *big.Int, addrHash common.Hash)                     {}

minigeth/oracle/prefetch.go

+//go:build !mips
+
 package oracle
 
 import (
@@ -65,7 +67,7 @@ type Account struct {
 var nodeUrl = "https://mainnet.infura.io/v3/9aa3d95b3bc440fa88ea12eaa4456161"
 
 func toFilename(key string) string {
-	return fmt.Sprintf("/tmp/eth/%s", key)
+	return fmt.Sprintf("/tmp/eth/json_%s", key)
 }
 
 func cacheRead(key string) []byte {

minigeth/oracle/preimage.go

+//go:build !mips
+
 package oracle
 
 import (
 	"fmt"
+	"io/ioutil"
 
 	"github.com/ethereum/go-ethereum/common"
 )
@@ -10,6 +13,8 @@ var preimages = make(map[common.Hash][]byte)
 
 func Preimage(hash common.Hash) []byte {
 	val, ok := preimages[hash]
+	key := fmt.Sprintf("/tmp/eth/%s", hash)
+	ioutil.WriteFile(key, val, 0644)
 	if !ok {
 		fmt.Println("can't find preimage", hash)
 		panic("preimage missing")

risc/build.sh

@@ -5,5 +5,4 @@ cp go-ethereum ../risc/go-ethereum
 cd ../risc
 file go-ethereum
 
-GOOS=linux GOARCH=mips go build test.go
-
+#GOOS=linux GOARCH=mips go build test.go

risc/data

+../data/
\ No newline at end of file

risc/run.py

@@ -16,9 +16,11 @@ regs = ["at", "v0", "v1", "a0", "a1", "a2", "a3"]
 SIZE = 16*1024*1024
 heap_start = 16*1024*1024
 
+tfd = 10
+files = {}
 fcnt = 0
 def hook_interrupt(uc, intno, user_data):
-  global heap_start, fcnt
+  global heap_start, fcnt, files, tfd
   pc = uc.reg_read(UC_MIPS_REG_PC)
   if intno == 17:
     syscall_no = uc.reg_read(UC_MIPS_REG_V0)
@@ -42,12 +44,15 @@ def hook_interrupt(uc, intno, user_data):
     if syscall_no == 4005:
       filename = uc.reg_read(UC_MIPS_REG_A0)
       print('open("%s")' % uc.mem_read(filename, 0x100).split(b"\x00")[0].decode('utf-8'))
-      # open fd=4
       uc.reg_write(UC_MIPS_REG_V0, 4)
     elif syscall_no == 4288:
       dfd = uc.reg_read(UC_MIPS_REG_A0)
       filename = uc.reg_read(UC_MIPS_REG_A1)
-      print('openat(%d, "%s")' % (dfd, uc.mem_read(filename, 0x100).split(b"\x00")[0].decode('utf-8')))
+      filename = uc.mem_read(filename, 0x100).split(b"\x00")[0].decode('utf-8')
+      print('openat(%d, "%s")' % (dfd, filename))
+      files[tfd] = open(filename, "rb")
+      uc.reg_write(UC_MIPS_REG_V0, tfd)
+      tfd += 1
     elif syscall_no == 4238:
       addr = uc.reg_read(UC_MIPS_REG_A0)
       print("futex", hex(addr))
@@ -76,8 +81,13 @@ def hook_interrupt(uc, intno, user_data):
       buf = uc.reg_read(UC_MIPS_REG_A1)
       count = uc.reg_read(UC_MIPS_REG_A2)
       print("read", fd, hex(buf), count)
+      if fd == 4:
         uc.mem_write(buf, b"16384\n\x00")
         uc.reg_write(UC_MIPS_REG_V0, 6)
+      else:
+        ret = files[fd].read(count)
+        uc.mem_write(buf, ret)
+        uc.reg_write(UC_MIPS_REG_V0, len(ret))
     elif syscall_no == 4246:
       print("EXIT")
       return False