[WebAssembly] Object: Improve error messages on invalid section

[tlively]

Might be nice to have a test, but understandable if that doesn't seem worth the effort.

[sbc100]

• add test]

llvm/trunk/lib/Object/WasmObjectFile.cpp

case wasm::WASM_SEC_ELEM:
     return parseElemSection(Ctx);
   case wasm::WASM_SEC_CODE:
     return parseCodeSection(Ctx);
   case wasm::WASM_SEC_DATA:
     return parseDataSection(Ctx);
   case wasm::WASM_SEC_DATACOUNT:
     return parseDataCountSection(Ctx);
   default:
-    return make_error<GenericBinaryError>("Bad section type",
-                                          object_error::parse_failed);
+    return make_error<GenericBinaryError>(
+        "Invalid section type: " + Twine(Sec.Type), object_error::parse_failed);
   }
 }
 
 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
   HasDylinkSection = true;
   DylinkInfo.MemorySize = readVaruint32(Ctx);
   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
case wasm::WASM_SEC_CODE:
     return WASM_SEC_ORDER_CODE;
   case wasm::WASM_SEC_DATA:
     return WASM_SEC_ORDER_DATA;
   case wasm::WASM_SEC_DATACOUNT:
     return WASM_SEC_ORDER_DATACOUNT;
   case wasm::WASM_SEC_EVENT:
     return WASM_SEC_ORDER_EVENT;
   default:
-    llvm_unreachable("invalid section");
+    return WASM_SEC_ORDER_NONE;
   }
 }
 
 // Represents the edges in a directed graph where any node B reachable from node
 // A is not allowed to appear before A in the section ordering, but may appear
 // afterward.
 int WasmSectionOrderChecker::DisallowedPredecessors[WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
   {}, // WASM_SEC_ORDER_NONE

llvm/trunk/test/Object/wasm-invalid-file.yaml

 # RUN: yaml2obj %s > %t.wasm
 # RUN: echo -e -n "\x01" >> %t.wasm
 # Append a new section but truncate the encoding of the section size
 # RUN: not llvm-objdump -h %t.wasm 2>&1 | FileCheck %s -check-prefix=CHECK-LEB-DECODE
 
 !WASM
 FileHeader:
   Version:         0x00000001
 
 # CHECK-LEB-DECODE: malformed uleb128, extends past end
 
 # RUN: echo -en "\x99hello" >> %t.wasm
 # Append a section size that extends beyond the end of the file
 # RUN: not llvm-objdump -h %t.wasm 2>&1 | FileCheck %s -check-prefix=CHECK-SECTION-SIZE
 
 # CHECK-SECTION-SIZE: '{{.*}}.wasm': Section too large
+
+# RUN: yaml2obj %s > %t.wasm
+# # Append an section with invalid type (type 0x20, size 0x1, content 0x0)
+# RUN: echo -e -n "\x20\x01\x00" >> %t.wasm
+# RUN: not llvm-objdump -h %t.wasm 2>&1 | FileCheck %s -check-prefix=CHECK-SECTION-TYPE
+# CHECK-SECTION-TYPE: '{{.*}}.wasm': Invalid section type: 32