Merge pull request #2350 from stweil/fuzzing

Add test code for fuzzing

Makefile.am

@@ -64,3 +64,17 @@ doc-clean:
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = tesseract.pc
+
+# fuzzer-api is used for fuzzing tests.
+# They are run by OSS-Fuzz https://oss-fuzz.com/, but can also be run locally.
+# Note: -fsanitize=fuzzer currently requires the clang++ compiler.
+fuzzer-api: all
+fuzzer-api: $(top_srcdir)/unittest/fuzzers/fuzzer-api.cpp
+	$(CXX) $(CXXFLAGS) -g -fsanitize=fuzzer \
+          -I $(top_srcdir)/src/api \
+          -I $(top_srcdir)/src/ccmain \
+          -I $(top_srcdir)/src/ccstruct \
+          -I $(top_srcdir)/src/ccutil \
+          -I src/api \
+          $< \
+          src/api/.libs/libtesseract.a $(LEPTONICA_LIBS) $(libarchive_LIBS) -o $@

unittest/fuzzers/fuzzer-api.cpp

@@ -0,0 +1,93 @@
+#include "baseapi.h"
+#include "leptonica/allheaders.h"
+
+#include <libgen.h>     // for dirname
+#include <cstdio>       // for printf
+#include <cstdlib>      // for std::getenv, std::setenv
+#include <string>       // for std::string
+
+class BitReader {
+ private:
+  uint8_t const* data;
+  size_t size;
+  size_t shift;
+
+ public:
+  BitReader(const uint8_t* data, size_t size)
+      : data(data), size(size), shift(0) {}
+
+  int Read(void) {
+    if (size == 0) {
+      return 0;
+    }
+
+    const int ret = ((*data) >> shift) & 1;
+
+    shift++;
+    if (shift >= 8) {
+      shift = 0;
+      data++;
+      size--;
+    }
+
+    return ret;
+  }
+};
+
+static tesseract::TessBaseAPI* api = nullptr;
+
+extern "C" int LLVMFuzzerInitialize(int* /*pArgc*/, char*** pArgv) {
+  if (std::getenv("TESSDATA_PREFIX") == nullptr) {
+    std::string binary_path = *pArgv[0];
+    const std::string filepath = dirname(&binary_path[0]);
+
+    const std::string tessdata_path = filepath + "/" + "tessdata";
+    if (setenv("TESSDATA_PREFIX", tessdata_path.c_str(), 1) != 0) {
+      printf("Setenv failed\n");
+      std::abort();
+    }
+  }
+
+  api = new tesseract::TessBaseAPI();
+  if (api->Init(nullptr, "eng") != 0) {
+    printf("Cannot initialize API\n");
+    abort();
+  }
+
+  /* Silence output */
+  api->SetVariable("debug_file", "/dev/null");
+
+  return 0;
+}
+
+static PIX* createPix(BitReader& BR, const size_t width, const size_t height) {
+  Pix* pix = pixCreate(width, height, 1);
+
+  if (pix == nullptr) {
+    printf("pix creation failed\n");
+    abort();
+  }
+
+  for (size_t i = 0; i < width; i++) {
+    for (size_t j = 0; j < height; j++) {
+      pixSetPixel(pix, i, j, BR.Read());
+    }
+  }
+
+  return pix;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  BitReader BR(data, size);
+
+  auto pix = createPix(BR, 100, 100);
+
+  api->SetImage(pix);
+
+  char* outText = api->GetUTF8Text();
+
+  pixDestroy(&pix);
+  delete[] outText;
+
+  return 0;
+}