src: load symbols from shared lib

PR-URL: #154
Fixes: #153
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: joyeecheung

src/llv8-constants.cc

@@ -31,13 +31,27 @@ void Module::Assign(SBTarget target, Common* common) {
 }
 
 
+template <typename T>
+T ReadSymbolFromTarget(SBTarget& target, SBAddress& start,
+                       const char* name, Error& err) {
+  SBError sberr;
+  T res = 0;
+  target.ReadMemory(start, &res, sizeof(T), sberr);
+  if (!sberr.Fail()) {
+    err = Error::Ok();
+  } else {
+    err = Error::Failure("Failed to read symbol %s", name);
+  }
+  return res;
+}
+
 static int64_t LookupConstant(SBTarget target, const char* name, int64_t def,
                               Error& err) {
-  int64_t res;
-
+  int64_t res = 0;
   res = def;
 
   SBSymbolContextList context_list = target.FindSymbols(name);
+
   if (!context_list.IsValid() || context_list.GetSize() == 0) {
     err = Error::Failure("Failed to find symbol %s", name);
     return res;
@@ -46,42 +60,31 @@ static int64_t LookupConstant(SBTarget target, const char* name, int64_t def,
   SBSymbolContext context = context_list.GetContextAtIndex(0);
   SBSymbol symbol = context.GetSymbol();
   if (!symbol.IsValid()) {
-    err = Error::Failure("Failed to fetch symbol %s", name);
+    err = Error::Failure("Failed to fetch symbol %s from context", name);
     return res;
   }
 
   SBAddress start = symbol.GetStartAddress();
   SBAddress end = symbol.GetEndAddress();
   uint32_t size = end.GetOffset() - start.GetOffset();
 
-  SBError sberr;
-
-  SBProcess process = target.GetProcess();
-  addr_t addr = start.GetFileAddress();
-
   // NOTE: size could be bigger for at the end symbols
   if (size >= 8) {
-    res = process.ReadUnsignedFromMemory(addr, 8, sberr);
+    res = ReadSymbolFromTarget<int64_t>(target, start, name, err);
   } else if (size == 4) {
-    int32_t tmp = process.ReadUnsignedFromMemory(addr, size, sberr);
+    int32_t tmp = ReadSymbolFromTarget<int32_t>(target, start, name, err);
     res = static_cast<int64_t>(tmp);
   } else if (size == 2) {
-    int16_t tmp = process.ReadUnsignedFromMemory(addr, size, sberr);
+    int16_t tmp = ReadSymbolFromTarget<int16_t>(target, start, name, err);
     res = static_cast<int64_t>(tmp);
   } else if (size == 1) {
-    int8_t tmp = process.ReadUnsignedFromMemory(addr, size, sberr);
+    int8_t tmp = ReadSymbolFromTarget<int8_t>(target, start, name, err);
     res = static_cast<int64_t>(tmp);
   } else {
     err = Error::Failure("Unexpected symbol size %" PRIu32 " of symbol %s",
                          size, name);
-    return res;
   }
 
-  if (sberr.Fail())
-    err = Error::Failure("Failed to load symbol %s", name);
-  else
-    err = Error::Ok();
-
   return res;
 }