Merge pull request #2022 from stweil/coverity

Fix several issues reported by Coverity Scan

src/ccmain/osdetect.cpp

@@ -17,6 +17,10 @@
 //
 ///////////////////////////////////////////////////////////////////////
 
+#include <algorithm>
+#include <cmath>        // for std::fabs
+#include <memory>
+
 #include "osdetect.h"
 
 #include "blobbox.h"
@@ -33,9 +37,6 @@
 #include "tesseractclass.h"
 #include "textord.h"
 
-#include <algorithm>
-#include <memory>
-
 const float kSizeRatioToReject = 2.0;
 const int kMinAcceptableBlobHeight = 10;
 
@@ -252,7 +253,10 @@ int os_detect(TO_BLOCK_LIST* port_blocks, OSResults* osr,
       TBOX      box = blob->bounding_box();
       ++blobs_total;
 
-      float y_x = fabs((box.height() * 1.0) / box.width());
+      // Catch illegal value of box width and avoid division by zero.
+      if (box.width() == 0) continue;
+      // TODO: Can height and width be negative? If not, remove fabs.
+      float y_x = std::fabs((box.height() * 1.0f) / box.width());
       float x_y = 1.0f / y_x;
       // Select a >= 1.0 ratio
       float ratio = x_y > y_x ? x_y : y_x;

src/classify/errorcounter.cpp

@@ -46,7 +46,7 @@ double ErrorCounter::ComputeErrorRate(ShapeClassifier* classifier,
   GenericVector<UnicharRating> results;
 
   clock_t start = clock();
-  int total_samples = 0;
+  unsigned total_samples = 0;
   double unscaled_error = 0.0;
   // Set a number of samples on which to run the classify debug mode.
   int error_samples = report_level > 3 ? report_level * report_level : 0;
@@ -89,7 +89,7 @@ double ErrorCounter::ComputeErrorRate(ShapeClassifier* classifier,
                                         fontinfo_table,
                                         *it, unichar_error, fonts_report);
   if (scaled_error != nullptr) *scaled_error = counter.scaled_error_;
-  if (report_level > 1) {
+  if (report_level > 1 && total_samples > 0) {
     // It is useful to know the time in microseconds/char.
     tprintf("Errors computed in %.2fs at %.1f μs/char\n",
             total_time, 1000000.0 * total_time / total_samples);

src/textord/colpartition.cpp

@@ -663,10 +663,12 @@ void ColPartition::Absorb(ColPartition* other, WidthCallback* cb) {
   // Update the special_blobs_densities_.
   memset(special_blobs_densities_, 0, sizeof(special_blobs_densities_));
   for (int type = 0; type < BSTT_COUNT; ++type) {
-    int w1 = boxes_.length(), w2 = other->boxes_.length();
+    unsigned w1 = boxes_.length();
+    unsigned w2 = other->boxes_.length();
     float new_val = special_blobs_densities_[type] * w1 +
         other->special_blobs_densities_[type] * w2;
     if (!w1 || !w2) {
+      ASSERT_HOST((w1 + w2) > 0);
       special_blobs_densities_[type] = new_val / (w1 + w2);
     }
   }