more flexibility in section reading in binary format code

1 files changed, 23 insertions, 16 deletions

diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index a6c388c52..821b11270 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -388,6 +388,7 @@ public:
   }
 
   void writeMemory() {
+    if (wasm->memory.max == 0) return;
     if (debug) std::cerr << "== writeMemory" << std::endl;
     o << int8_t(BinaryConsts::Memory) << int8_t(log2(wasm->memory.initial))
                                       << int8_t(log2(wasm->memory.max))
@@ -395,6 +396,7 @@ public:
   }
 
   void writeSignatures() {
+    if (wasm->functionTypes.size() == 0) return;
     if (debug) std::cerr << "== writeSignatures" << std::endl;
     o << int8_t(BinaryConsts::Signatures) << LEB128(wasm->functionTypes.size());
     for (auto* type : wasm->functionTypes) {
@@ -456,6 +458,7 @@ public:
   }
 
   void writeFunctions() {
+    if (wasm->functions.size() + wasm->imports.size() == 0) return;
     if (debug) std::cerr << "== writeFunctions" << std::endl;
     size_t total = wasm->imports.size() + wasm->functions.size();
     o << int8_t(BinaryConsts::Functions) << LEB128(total);
@@ -505,6 +508,7 @@ public:
   }
 
   void writeDataSegments() {
+    if (wasm->memory.segments.size() == 0) return;
     o << int8_t(BinaryConsts::DataSegments) << LEB128(wasm->memory.segments.size());
     for (auto& segment : wasm->memory.segments) {
       o << int32_t(segment.offset);
@@ -526,6 +530,7 @@ public:
   }
 
   void writeFunctionTable() {
+    if (wasm->table.names.size() == 0) return;
     if (debug) std::cerr << "== writeFunctionTable" << std::endl;
     o << int8_t(BinaryConsts::FunctionTable) << LEB128(wasm->table.names.size());
     for (auto name : wasm->table.names) {
@@ -924,12 +929,24 @@ public:
   WasmBinaryBuilder(AllocatingModule& wasm, std::vector<char>& input, bool debug) : wasm(wasm), allocator(wasm.allocator), input(input), debug(debug), pos(0) {}
 
   void read() {
-    readMemory();
-    readSignatures();
-    readFunctions();
-    readDataSegments();
-    readFunctionTable();
-    readEnd();
+    // read sections until the end
+    while (1) {
+      int8_t section = getInt8();
+
+      if (section == BinaryConsts::End) {
+        if (debug) std::cerr << "== readEnd" << std::endl;
+        break;
+      }
+
+      switch (section) {
+        case BinaryConsts::Memory:        readMemory(); break;
+        case BinaryConsts::Signatures:    readSignatures(); break;
+        case BinaryConsts::Functions:     readFunctions(); break;
+        case BinaryConsts::DataSegments:  readDataSegments(); break;
+        case BinaryConsts::FunctionTable: readFunctionTable(); break;
+        default: abort();
+      }
+    }
 
     processFunctions();
   }
@@ -1026,7 +1043,6 @@ public:
 
   void readMemory() {
     if (debug) std::cerr << "== readMemory" << std::endl;
-    verifyInt8(BinaryConsts::Memory);
     wasm.memory.initial = std::pow<size_t>(2, getInt8());
     wasm.memory.max = std::pow<size_t>(2, getInt8());
     verifyInt8(1); // export memory
@@ -1034,7 +1050,6 @@ public:
 
   void readSignatures() {
     if (debug) std::cerr << "== readSignatures" << std::endl;
-    verifyInt8(BinaryConsts::Signatures);
     size_t numTypes = getLEB128();
     if (debug) std::cerr << "num: " << numTypes << std::endl;
     for (size_t i = 0; i < numTypes; i++) {
@@ -1060,7 +1075,6 @@ public:
 
   void readFunctions() {
     if (debug) std::cerr << "== readFunctions" << std::endl;
-    verifyInt8(BinaryConsts::Functions);
     size_t total = getLEB128(); // imports and functions
     for (size_t i = 0; i < total; i++) {
       if (debug) std::cerr << "read one at " << pos << std::endl;
@@ -1165,7 +1179,6 @@ public:
 
   void readDataSegments() {
     if (debug) std::cerr << "== readDataSegments" << std::endl;
-    verifyInt8(BinaryConsts::DataSegments);
     auto num = getLEB128();
     for (size_t i = 0; i < num; i++) {
       auto curr = allocator.alloc<Memory::Segment>();
@@ -1182,18 +1195,12 @@ public:
 
   void readFunctionTable() {
     if (debug) std::cerr << "== readFunctionTable" << std::endl;
-    verifyInt8(BinaryConsts::FunctionTable);
     auto num = getLEB128();
     for (size_t i = 0; i < num; i++) {
       wasm.table.names.push_back(mappedFunctions[getInt16()]);
     }
   }
 
-  void readEnd() {
-    if (debug) std::cerr << "== readEnd" << std::endl;
-    verifyInt8(BinaryConsts::End);
-  }
-
   // AST reading
 
   int depth; // only for debugging