fix #35 by using utfcpp for utf8 string validation

cmake/xlnt.cmake

@@ -29,7 +29,7 @@ include_directories(../include/xlnt)
 include_directories(../source)
 include_directories(../third-party/miniz)
 include_directories(../third-party/pugixml/src)
-include_directories(../third-party/utfcpp)
+include_directories(../third-party/utfcpp/source)
 
 FILE(GLOB ROOT_HEADERS ../include/xlnt/*.hpp)
 FILE(GLOB CELL_HEADERS ../include/xlnt/cell/*.hpp)

include/xlnt/utils/utf8string.hpp

@@ -0,0 +1,25 @@
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include <utf8.h>
+
+namespace xlnt {
+
+class utf8string
+{
+public:
+    static utf8string from_utf8(const std::string &s);
+    static utf8string from_latin1(const std::string &s);
+    static utf8string from_utf16(const std::string &s);
+    static utf8string from_utf32(const std::string &s);
+
+    static bool is_valid(const std::string &s);
+
+    bool is_valid() const;
+
+private:
+    std::vector<std::uint8_t> bytes_;
+};
+
+} // namespace xlnt

source/cell/cell.cpp

@@ -14,6 +14,7 @@
 #include <xlnt/utils/time.hpp>
 #include <xlnt/utils/timedelta.hpp>
 #include <xlnt/utils/exceptions.hpp>
+#include <xlnt/utils/utf8string.hpp>
 #include <xlnt/workbook/workbook.hpp>
 #include <xlnt/worksheet/column_properties.hpp>
 #include <xlnt/worksheet/row_properties.hpp>
@@ -61,108 +62,26 @@ std::string cell::check_string(const std::string &to_check)
         break;
     case encoding::utf8:
     {
-        std::vector<std::uint8_t> bytes;
+	if(!utf8string::is_valid(s))
-
-        for (char c : s)
         {
-            auto byte = static_cast<std::uint8_t>(c);
+            throw xlnt::unicode_decode_error('0');
-
+        } 
-            if (byte < 128)
+        break;
+    }
+    case encoding::utf16:
     {
-                if(!bytes.empty())
+	if(!utf8string::from_utf16(s).is_valid())
         {
-                    throw xlnt::unicode_decode_error(c);
+            throw xlnt::unicode_decode_error('0');
         } 
+        break;
     }
-            else
+    case encoding::utf32:
     {
-                if(!bytes.empty())
+	if(!utf8string::from_utf32(s).is_valid())
         {
-                    if(byte >> 6 != 2)
+            throw xlnt::unicode_decode_error('0');
-                    {
-                        throw xlnt::unicode_decode_error(c);
         } 
-                }
-            }
-
-            bytes.push_back(byte);
-
-            auto first_byte = bytes[0];
-            auto num_bytes = 0;
-
-            if(first_byte < 128)
-            {
-                num_bytes = 1;
-            }
-            else if(first_byte >> 5 == 0b110)
-            {
-                num_bytes = 2;
-            }
-            else if(first_byte >> 4 == 0b1110)
-            {
-                num_bytes = 3;
-            }
-            else if(first_byte >> 3 == 0b11110)
-            {
-                num_bytes = 4;
-            }
-            else if(first_byte >> 2 == 0b111110)
-            {
-                num_bytes = 5;
-            }
-            else if(first_byte >> 1 == 0b1111110)
-            {
-                num_bytes = 6;
-            }
-
-            if(num_bytes > bytes.size())
-            {
-                throw xlnt::unicode_decode_error(c);
-            }
-
-            if(num_bytes == bytes.size())
-            {
-                bytes.clear();
-            }
-        }
-
-        // Check last code point
-        if(!bytes.empty())
-        {
-            auto first_byte = bytes[0];
-            auto num_bytes = 0;
-
-            if(first_byte < 128)
-            {
-                num_bytes = 1;
-            }
-            else if(first_byte >> 5 == 0b110)
-            {
-                num_bytes = 2;
-            }
-            else if(first_byte >> 4 == 0b1110)
-            {
-                num_bytes = 3;
-            }
-            else if(first_byte >> 3 == 0b11110)
-            {
-                num_bytes = 4;
-            }
-            else if(first_byte >> 2 == 0b111110)
-            {
-                num_bytes = 5;
-            }
-            else if(first_byte >> 1 == 0b1111110)
-            {
-                num_bytes = 6;
-            }
-
-            if(num_bytes > bytes.size())
-            {
-                throw xlnt::unicode_decode_error();
-            }
-        }
-
         break;
     }
     default:

source/cell/tests/test_cell.hpp

@@ -448,4 +448,43 @@ public:
         cell.set_quote_prefix(true);
         TS_ASSERT(cell.quote_prefix());
     }
+
+    void test_check_string()
+    {
+        xlnt::workbook utf8_wb(xlnt::encoding::utf8);
+        auto ws = utf8_wb.get_active_sheet();
+        auto cell = ws[xlnt::cell_reference("A1")];
+
+	std::vector<std::string> valid_utf8_strings = 
+        {
+            "a",
+            "\xc3\xa0",
+            "\xc3\xb1",
+	    "\xe2\x82\xa1",
+	    "\xf0\x90\x8c\xbc",
+	};
+
+	for(auto valid : valid_utf8_strings)
+        {
+	    TS_ASSERT_THROWS_NOTHING(cell.check_string(valid));
+	    TS_ASSERT_THROWS_NOTHING(cell.set_value(valid));
+        }
+
+	std::vector<std::string> invalid_utf8_strings = 
+        {
+            "\xc3\x28",
+	    "\xa0\xa1",
+	    "\xe2\x28\xa1",
+	    "\xe2\x82\x28",
+	    "\xf0\x28\x8c\xbc",
+	    "\xf0\x90\x28\xbc",
+	    "\xf0\x28\x8c\x28",
+        };
+
+	for(auto invalid : invalid_utf8_strings)
+        {
+	    TS_ASSERT_THROWS(cell.check_string(invalid), xlnt::unicode_decode_error);
+	    TS_ASSERT_THROWS(cell.set_value(invalid), xlnt::unicode_decode_error);
+        }
+    }
 };

source/utils/utf8string.cpp

@@ -0,0 +1,47 @@
+#include <xlnt/utils/utf8string.hpp>
+
+namespace xlnt {
+
+utf8string utf8string::from_utf8(const std::string &s)
+{
+    utf8string result;
+    std::copy(s.begin(), s.end(), std::back_inserter(result.bytes_));
+
+    return result;
+}
+
+utf8string utf8string::from_latin1(const std::string &s)
+{
+    utf8string result;
+    std::copy(s.begin(), s.end(), std::back_inserter(result.bytes_));
+
+    return result;
+}
+
+utf8string utf8string::from_utf16(const std::string &s)
+{
+    utf8string result;
+    utf8::utf16to8(s.begin(), s.end(), std::back_inserter(result.bytes_));
+
+    return result;
+}
+
+utf8string utf8string::from_utf32(const std::string &s)
+{
+    utf8string result;
+    utf8::utf32to8(s.begin(), s.end(), std::back_inserter(result.bytes_));
+
+    return result;
+}
+
+bool utf8string::is_valid(const std::string &s)
+{
+    return utf8::is_valid(s.begin(), s.end());
+}
+
+bool utf8string::is_valid() const
+{
+    return utf8::is_valid(bytes_.begin(), bytes_.end());
+}
+
+} // namespace xlnt