[Frontend] Return an error on bad inputs to PrecompiledPreabmle

Summary:
Instead of failing with assertions. Fixes a crash found by oss-fuzz:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12865

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62137

llvm-svn: 361376

2 files changed, 10 insertions, 8 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 95d1bf27d7b..c4085b699e0 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1368,6 +1368,7 @@ ASTUnit::getMainBufferWithPrecompiledPreamble(
       case BuildPreambleError::CouldntCreateTargetInfo:
       case BuildPreambleError::BeginSourceFileFailed:
       case BuildPreambleError::CouldntEmitPCH:
+      case BuildPreambleError::BadInputs:
         // These erros are more likely to repeat, retry after some period.
         PreambleRebuildCountdown = DefaultPreambleRebuildInterval;
         return nullptr;
diff --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp
index 25f128fe11a..1fe8bfcb745 100644
--- a/clang/lib/Frontend/PrecompiledPreamble.cpp
+++ b/clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -299,14 +299,13 @@ llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
   // created. This complexity should be lifted elsewhere.
   Clang->getTarget().adjust(Clang->getLangOpts());
 
-  assert(Clang->getFrontendOpts().Inputs.size() == 1 &&
-         "Invocation must have exactly one source file!");
-  assert(Clang->getFrontendOpts().Inputs[0].getKind().getFormat() ==
-             InputKind::Source &&
-         "FIXME: AST inputs not yet supported here!");
-  assert(Clang->getFrontendOpts().Inputs[0].getKind().getLanguage() !=
-             InputKind::LLVM_IR &&
-         "IR inputs not support here!");
+  if (Clang->getFrontendOpts().Inputs.size() != 1 ||
+      Clang->getFrontendOpts().Inputs[0].getKind().getFormat() !=
+          InputKind::Source ||
+      Clang->getFrontendOpts().Inputs[0].getKind().getLanguage() ==
+          InputKind::LLVM_IR) {
+    return BuildPreambleError::BadInputs;
+  }
 
   // Clear out old caches and data.
   Diagnostics.Reset();
@@ -784,6 +783,8 @@ std::string BuildPreambleErrorCategory::message(int condition) const {
     return "BeginSourceFile() return an error";
   case BuildPreambleError::CouldntEmitPCH:
     return "Could not emit PCH";
+  case BuildPreambleError::BadInputs:
+    return "Command line arguments must contain exactly one source file";
   }
   llvm_unreachable("unexpected BuildPreambleError");
 }