Add SKSL fuzzer

fuzz/fuzz.cpp

Index: fuzz/fuzz.cpp
diff --git a/fuzz/fuzz.cpp b/fuzz/fuzz.cpp
index 549194619a7d1b3bd3578fec258fc0eb56f30d5f..4114f6692818efb784bdbda0dade910e18e61348 100644
--- a/fuzz/fuzz.cpp
+++ b/fuzz/fuzz.cpp
@@ -16,6 +16,7 @@
 #include "SkPicture.h"
 #include "SkPicture.h"
 #include "SkPicture.h"
+#include "SkSLCompiler.h"
 #include "SkStream.h"
 
 #include <cmath>
@@ -39,6 +40,7 @@ static int fuzz_img(sk_sp<SkData>, uint8_t, uint8_t);
 static int fuzz_skp(sk_sp<SkData>);
 static int fuzz_icc(sk_sp<SkData>);
 static int fuzz_color_deserialize(sk_sp<SkData>);
+static int fuzz_sksl2glsl(sk_sp<SkData>);
 
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
@@ -68,7 +70,11 @@ int main(int argc, char** argv) {
                 }
                 // image_mode
                 return fuzz_img(bytes, 0, option);
-            case 's': return fuzz_skp(bytes);
+            case 's':
+                if (FLAGS_type[0][2] == 's') { //sksl2glsl

[mtklein_C, 2016/10/14 15:26:18]

It may be time to rewrite this parsing.  It's getting kind of complex now, and
it'd be easier to read with strings, e.g.

...
if (0 == strcmp("skp"      , FLAGS_type[0]) { return fuzz_skp      (bytes); }
if (0 == strcmp("sksl2glsl", FLAGS_type[0]) { return fuzz_sksl2glsl(bytes); }
...

Side note: I just had to type sksl2glsl a couple times and it's a complete
finger twister.  It can probably be something pithier like sksl?

[kjlubick, 2016/10/14 16:28:05]

Done.  I'm keeping sksl2glsl because I imagine we'll want to have sksl2spirv in
the near future.

+                    return fuzz_sksl2glsl(bytes);
+                }
+            return fuzz_skp(bytes);
         }
     }
     return printUsage(argv[0]);
@@ -400,6 +406,34 @@ int fuzz_color_deserialize(sk_sp<SkData> bytes) {
     return 0;
 }
 
+static SkSL::GLCaps default_caps() {
+    return {
+             400,
+             SkSL::GLCaps::kGL_Standard,
+             false, // isCoreProfile
+             false, // usesPrecisionModifiers;
+             false, // mustDeclareFragmentShaderOutput
+             true,   // canUseMinAndAbsTogether
+             false  // mustForceNegatedAtanParamToFloat
+           };
+}
+
+int fuzz_sksl2glsl(sk_sp<SkData> bytes) {
+    SkSL::Compiler compiler;
+    std::string output;
+    bool result = compiler.toGLSL(SkSL::Program::kFragment_Kind,
+        reinterpret_cast<const char*>(bytes->data()), default_caps(), &output);

[mtklein_C, 2016/10/14 15:26:18]

This probably shouldn't be reinterpret_cast.  It'll work fine but it gives off a
strong "I am doing something weird and byte-punny here" vibe.  Really we're just
turning bytes into bytes... nothing weird.

Try (const char*)bytes->data(), or maybe just bytes->bytes() if that works?

[kjlubick, 2016/10/14 16:28:05]

Done.  bytes->bytes() did not work

+
+    if (!result) {
+        //SkDebugf("%s\n", compiler.errorText().c_str());
+        SkDebugf("[terminated] Couldn't compile input.\n");
+        return 1;
+    }
+    //SkDebugf("%s\n", output.c_str());
+    SkDebugf("[terminated] Success! Compiled input.\n");
+    return 0;
+}
+
 Fuzz::Fuzz(sk_sp<SkData> bytes) : fBytes(bytes), fNextByte(0) {}
 
 void Fuzz::signalBug   () { SkDebugf("Signal bug\n"); raise(SIGSEGV); }