Add ability to fuzz images using scaling and different modes

fuzz/fuzz.cpp

Index: fuzz/fuzz.cpp
diff --git a/fuzz/fuzz.cpp b/fuzz/fuzz.cpp
index 02bf76e6653fe6cb1a09ee1730e316b5a38d387e..596000d408b380aa81bf761356bea79cb8917b10 100644
--- a/fuzz/fuzz.cpp
+++ b/fuzz/fuzz.cpp
@@ -20,21 +20,23 @@
 #include <signal.h>
 #include <stdlib.h>
 
+// TODO(kjlubick): Remove once http://crrev.com/1671193002 lands
 __SK_FORCE_IMAGE_DECODER_LINKING;
 
 DEFINE_string2(bytes, b, "", "A path to a file.  This can be the fuzz bytes or a binary to parse.");
 DEFINE_string2(name, n, "", "If --type is 'api', fuzz the API with this name.");
 
-DEFINE_string2(type, t, "api", "How to interpret --bytes, either 'image', 'skp', or 'api'.");
-DEFINE_string2(dump, d, "", "If not empty, dump 'image' or 'skp' types as a PNG with this name.");
+DEFINE_string2(type, t, "api", "How to interpret --bytes, either 'image_scale', 'image_mode', 'skp', or 'api'.");
+DEFINE_string2(dump, d, "", "If not empty, dump 'image*' or 'skp' types as a PNG with this name.");
 
 static int printUsage(const char* name) {
     SkDebugf("Usage: %s -t <type> -b <path/to/file> [-n api-to-fuzz]\n", name);
     return 1;
 }
+static uint8_t calculate_option(SkData*);
 
 static int fuzz_api(SkData*);
-static int fuzz_img(SkData*);
+static int fuzz_img(SkData*, uint8_t, uint8_t);
 static int fuzz_skp(SkData*);
 
 int main(int argc, char** argv) {
@@ -47,16 +49,39 @@ int main(int argc, char** argv) {
         return 2;
     }
 
+    uint8_t option = calculate_option(bytes);
+
     if (!FLAGS_type.isEmpty()) {
         switch (FLAGS_type[0][0]) {
             case 'a': return fuzz_api(bytes);
-            case 'i': return fuzz_img(bytes);
+
+            case 'i':
+                // We only allow one degree of freedom to avoid a search space explosion for afl-fuzz.
+                if (FLAGS_type[0][6] == 's') { // image_scale
+                    return fuzz_img(bytes, option, 0);
+                }
+                // image_mode
+                return fuzz_img(bytes, 0, option);
             case 's': return fuzz_skp(bytes);
         }
     }
     return printUsage(argv[0]);
 }
 
+// This adds up the first 1024 bytes and returns it as an 8 bit integer.  This allows afl-fuzz to
+// deterministically excercise different paths, or *options* (such as different scaling sizes or
+// different image modes) without needing to introduce a parameter.  This way we don't need a
+// image_scale1, image_scale2, image_scale4, etc fuzzer, we can just have a image_scale fuzzer.
+// Clients are expected to transform this number into a different range, e.g. with modulo (%).
+static uint8_t calculate_option(SkData* bytes) {
+    uint8_t total = 0;
+    const uint8_t* data = bytes->bytes();
+    for (size_t i = 0; i < 1024 && i < bytes->size(); i++) {
+        total += data[i];
+    }
+    return total;
+}
+
 int fuzz_api(SkData* bytes) {
     const char* name = FLAGS_name.isEmpty() ? "" : FLAGS_name[0];
 
@@ -86,7 +111,17 @@ static void dump_png(SkBitmap bitmap) {
     }
 }
 
-int fuzz_img(SkData* bytes) {
+int fuzz_img(SkData* bytes, uint8_t scale, uint8_t mode) {
+    // We can scale 1x, 2x, 4x, 8x, 16x
+    scale = scale % 5;
+    float fscale = pow(2.0f, scale);
+    SkDebugf("Scaling factor: %d\n", fscale);
+
+    // We have 4 different modes of decoding, just like DM.
+    mode = mode % 4;
+    SkDebugf("Mode: %d\n", mode);
+
+    // This is mostly copied from DMSrcSink's CodecSrc::draw method.
     SkDebugf("Decoding\n");
     SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(bytes));
     if (nullptr == codec.get()) {
@@ -95,6 +130,10 @@ int fuzz_img(SkData* bytes) {
     }
 
     SkImageInfo decodeInfo = codec->getInfo();
+
+    SkISize size = codec->getScaledDimensions(fscale);
+    decodeInfo = decodeInfo.makeWH(size.width(), size.height());
+
     // Construct a color table for the decode if necessary
     SkAutoTUnref<SkColorTable> colorTable(nullptr);
     SkPMColor* colorPtr = nullptr;
@@ -112,27 +151,203 @@ int fuzz_img(SkData* bytes) {
     SkCodec::Options options;
     options.fZeroInitialized = SkCodec::kYes_ZeroInitialized;
 
-    if (!bitmap.tryAllocPixels(decodeInfo, &zeroFactory, nullptr)) {
+    if (!bitmap.tryAllocPixels(decodeInfo, &zeroFactory, colorTable.get())) {
         SkDebugf("[terminated] Could not allocate memory.  Image might be too large (%d x %d)",
-                    decodeInfo.width(), decodeInfo.height());
+                 decodeInfo.width(), decodeInfo.height());
         return 4;
     }
 
-    switch (codec->getPixels(decodeInfo, bitmap.getPixels(), bitmap.rowBytes(), &options,
-            colorPtr, colorCountPtr)) {
-        case SkCodec::kSuccess:
+    switch (mode) {
+        case 0: {//kCodecZeroInit_Mode, kCodec_Mode
+            switch (codec->getPixels(decodeInfo, bitmap.getPixels(), bitmap.rowBytes(), &options,
+                                     colorPtr, colorCountPtr)) {
+                case SkCodec::kSuccess:
+                    SkDebugf("[terminated] Success!\n");
+                    break;
+                case SkCodec::kIncompleteInput:
+                    SkDebugf("[terminated] Partial Success\n");
+                    break;
+                case SkCodec::kInvalidConversion:
+                    SkDebugf("Incompatible colortype conversion\n");
+                    // Crash to allow afl-fuzz to know this was a bug.
+                    raise(SIGSEGV);
+                default:
+                    SkDebugf("[terminated] Couldn't getPixels.\n");
+                    return 6;
+            }
+            break;
+        }
+        case 1: {//kScanline_Mode
+            if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, NULL, colorPtr,
+                                                                colorCountPtr)) {
+                    SkDebugf("[terminated] Could not start scanline decoder\n");
+                    return 7;
+                }
+
+            void* dst = bitmap.getAddr(0, 0);
+            size_t rowBytes = bitmap.rowBytes();
+            uint32_t height = decodeInfo.height();
+            switch (codec->getScanlineOrder()) {
+                case SkCodec::kTopDown_SkScanlineOrder:
+                case SkCodec::kBottomUp_SkScanlineOrder:
+                case SkCodec::kNone_SkScanlineOrder:
+                    // We do not need to check the return value.  On an incomplete
+                    // image, memory will be filled with a default value.
+                    codec->getScanlines(dst, height, rowBytes);
+                    break;
+                case SkCodec::kOutOfOrder_SkScanlineOrder: {
+                    for (int y = 0; y < decodeInfo.height(); y++) {
+                        int dstY = codec->outputScanline(y);
+                        void* dstPtr = bitmap.getAddr(0, dstY);
+                        // We complete the loop, even if this call begins to fail
+                        // due to an incomplete image.  This ensures any uninitialized
+                        // memory will be filled with the proper value.
+                        codec->getScanlines(dstPtr, 1, bitmap.rowBytes());
+                    }
+                    break;
+                }
+            }
+            SkDebugf("[terminated] Success!\n");
+            break;
+        }
+        case 2: { //kStripe_Mode
+            const int height = decodeInfo.height();
+            // This value is chosen arbitrarily.  We exercise more cases by choosing a value that
+            // does not align with image blocks.
+            const int stripeHeight = 37;
+            const int numStripes = (height + stripeHeight - 1) / stripeHeight;
+
+            // Decode odd stripes
+            if (SkCodec::kSuccess != codec->startScanlineDecode(decodeInfo, NULL, colorPtr,
+                                                                colorCountPtr)
+                    || SkCodec::kTopDown_SkScanlineOrder != codec->getScanlineOrder()) {
+                // This mode was designed to test the new skip scanlines API in libjpeg-turbo.
+                // Jpegs have kTopDown_SkScanlineOrder, and at this time, it is not interesting
+                // to run this test for image types that do not have this scanline ordering.
+                SkDebugf("[terminated] Could not start top-down scanline decoder\n");
+                return 8;
+            }
+
+            for (int i = 0; i < numStripes; i += 2) {
+                // Skip a stripe
+                const int linesToSkip = SkTMin(stripeHeight, height - i * stripeHeight);
+                codec->skipScanlines(linesToSkip);
+
+                // Read a stripe
+                const int startY = (i + 1) * stripeHeight;
+                const int linesToRead = SkTMin(stripeHeight, height - startY);
+                if (linesToRead > 0) {
+                    codec->getScanlines(bitmap.getAddr(0, startY), linesToRead, bitmap.rowBytes());
+                }
+            }
+
+            // Decode even stripes
+            const SkCodec::Result startResult = codec->startScanlineDecode(decodeInfo, nullptr,
+                    colorPtr, colorCountPtr);
+            if (SkCodec::kSuccess != startResult) {
+                SkDebugf("[terminated] Failed to restart scanline decoder with same parameters.\n");
+                return 9;
+            }
+            for (int i = 0; i < numStripes; i += 2) {
+                // Read a stripe
+                const int startY = i * stripeHeight;
+                const int linesToRead = SkTMin(stripeHeight, height - startY);
+                codec->getScanlines(bitmap.getAddr(0, startY), linesToRead, bitmap.rowBytes());
+
+                // Skip a stripe
+                const int linesToSkip = SkTMin(stripeHeight, height - (i + 1) * stripeHeight);
+                if (linesToSkip > 0) {
+                    codec->skipScanlines(linesToSkip);
+                }
+            }
             SkDebugf("[terminated] Success!\n");
             break;
-        case SkCodec::kIncompleteInput:
-            SkDebugf("[terminated] Partial Success\n");
+        }
+        case 3: { //kSubset_Mode
+            // Arbitrarily choose a divisor.
+            int divisor = 2;
+            // Total width/height of the image.
+            const int W = codec->getInfo().width();
+            const int H = codec->getInfo().height();
+            if (divisor > W || divisor > H) {
+                SkDebugf("[terminated] Cannot codec subset: divisor %d is too big "
+                         "with dimensions (%d x %d)\n", divisor, W, H);
+                return 10;
+            }
+            // subset dimensions
+            // SkWebpCodec, the only one that supports subsets, requires even top/left boundaries.
+            const int w = SkAlign2(W / divisor);
+            const int h = SkAlign2(H / divisor);
+            SkIRect subset;
+            SkCodec::Options opts;
+            opts.fSubset = &subset;
+            SkBitmap subsetBm;
+            // We will reuse pixel memory from bitmap.
+            void* pixels = bitmap.getPixels();
+            // Keep track of left and top (for drawing subsetBm into canvas). We could use
+            // fscale * x and fscale * y, but we want integers such that the next subset will start
+            // where the last one ended. So we'll add decodeInfo.width() and height().
+            int left = 0;
+            for (int x = 0; x < W; x += w) {
+                int top = 0;
+                for (int y = 0; y < H; y+= h) {
+                    // Do not make the subset go off the edge of the image.
+                    const int preScaleW = SkTMin(w, W - x);
+                    const int preScaleH = SkTMin(h, H - y);
+                    subset.setXYWH(x, y, preScaleW, preScaleH);
+                    // And fscale
+                    // FIXME: Should we have a version of getScaledDimensions that takes a subset
+                    // into account?
+                    decodeInfo = decodeInfo.makeWH(
+                            SkTMax(1, SkScalarRoundToInt(preScaleW * fscale)),
+                            SkTMax(1, SkScalarRoundToInt(preScaleH * fscale)));
+                    size_t rowBytes = decodeInfo.minRowBytes();
+                    if (!subsetBm.installPixels(decodeInfo, pixels, rowBytes, colorTable.get(),
+                                                nullptr, nullptr)) {
+                        SkDebugf("[terminated] Could not install pixels.\n");
+                        return 11;
+                    }
+                    const SkCodec::Result result = codec->getPixels(decodeInfo, pixels, rowBytes,
+                            &opts, colorPtr, colorCountPtr);
+                    switch (result) {
+                        case SkCodec::kSuccess:
+                        case SkCodec::kIncompleteInput:
+                            SkDebugf("okay\n");
+                            break;
+                        case SkCodec::kInvalidConversion:
+                            if (0 == (x|y)) {
+                                // First subset is okay to return unimplemented.
+                                SkDebugf("[terminated] Incompatible colortype conversion\n");
+                                return 12;
+                            }
+                            // If the first subset succeeded, a later one should not fail.
+                            // fall through to failure
+                        case SkCodec::kUnimplemented:
+                            if (0 == (x|y)) {
+                                // First subset is okay to return unimplemented.
+                                SkDebugf("[terminated] subset codec not supported\n");
+                                return 13;
+                            }
+                            // If the first subset succeeded, why would a later one fail?
+                            // fall through to failure
+                        default:
+                            SkDebugf("[terminated] subset codec failed to decode (%d, %d, %d, %d) "
+                                                  "with dimensions (%d x %d)\t error %d\n",
+                                                  x, y, decodeInfo.width(), decodeInfo.height(),
+                                                  W, H, result);
+                            return 14;
+                    }
+                    // translate by the scaled height.
+                    top += decodeInfo.height();
+                }
+                // translate by the scaled width.
+                left += decodeInfo.width();
+            }
+            SkDebugf("[terminated] Success!\n");
             break;
-        case SkCodec::kInvalidConversion:
-            SkDebugf("[terminated] Incompatible colortype conversion\n");
-            return 5;
+        }
         default:
-            // Everything else is considered a failure.
-            SkDebugf("[terminated] Couldn't getPixels.\n");
-            return 6;
+            SkDebugf("[terminated] Mode not implemented yet\n");
     }
 
     dump_png(bitmap);