Add QUtil::hex_decode

Jay Berkenbilt
1 parent 68572df2
Showing 4 changed files with 95 additions and 0 deletions
include/qpdf/QUtil.hh
libqpdf/QUtil.cc
libtests/qtest/qutil/qutil.out
libtests/qutil.cc
@@ -104,6 +104,14 @@ namespace QUtil
     QPDF_DLL
     std::string hex_encode(std::string const&);
+    // Returns a string that is the result of decoding the input
+    // string. The input string may consist of mixed case hexadecimal
+    // digits. Any characters that are not hexadecimal digits will be
+    // silently ignored. If there are an odd number of hexadecimal
+    // digits, a trailing 0 will be assumed.
+    QPDF_DLL
+    std::string hex_decode(std::string const&);
+
     // Set stdin, stdout to binary mode
     QPDF_DLL
     void binary_stdout();
@@ -290,6 +290,50 @@ QUtil::hex_encode(std::string const&amp; input)
     return result;
 }
+std::string
+QUtil::hex_decode(std::string const& input)
+{
+    std::string result;
+    size_t pos = 0;
+    for (std::string::const_iterator p = input.begin(); p != input.end(); ++p)
+    {
+        char ch = *p;
+        bool skip = false;
+        if ((*p >= 'A') && (*p <= 'F'))
+        {
+            ch -= 'A';
+            ch += 10;
+        }
+        else if ((*p >= 'a') && (*p <= 'f'))
+        {
+            ch -= 'a';
+            ch += 10;
+        }
+        else if ((*p >= '0') && (*p <= '9'))
+        {
+            ch -= '0';
+        }
+        else
+        {
+            skip = true;
+        }
+        if (! skip)
+        {
+            if (pos == 0)
+            {
+                result.push_back(ch << 4);
+                pos = 1;
+            }
+            else
+            {
+                result.back() += ch;
+                pos = 0;
+            }
+        }
+    }
+    return result;
+}
+
 void
 QUtil::binary_stdout()
 {
@@ -54,3 +54,6 @@ file1: --, file2: -qutil.out-; same: 0: PASS
 This file is used for qutil testing.
 It has mixed newlines.
 Some lines are very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very 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+----
+begin hex encode/decode
+end hex encode/decode
@@ -247,6 +247,44 @@ void read_lines_from_file_test()
     }
 }
+void assert_hex_encode(std::string const& input, std::string const& expected)
+{
+    std::string actual = QUtil::hex_encode(input);
+    if (expected != actual)
+    {
+        std::cout << "hex encode " << input
+                  << ": expected = " << expected
+                  << "; actual = " << actual
+                  << std::endl;
+    }
+}
+
+void assert_hex_decode(std::string const& input, std::string const& expected)
+{
+    std::string actual = QUtil::hex_decode(input);
+    if (expected != actual)
+    {
+        std::cout << "hex encode " << input
+                  << ": expected = " << expected
+                  << "; actual = " << actual
+                  << std::endl;
+    }
+}
+
+void hex_encode_decode_test()
+{
+    std::cout << "begin hex encode/decode\n";
+    assert_hex_encode("", "");
+    assert_hex_encode("Potato", "506f7461746f");
+    std::string with_null("a\367" "00w");
+    with_null[3] = '\0';
+    assert_hex_encode(with_null, "61f7300077");
+    assert_hex_decode("", "");
+    assert_hex_decode("61F7-3000-77", with_null);
+    assert_hex_decode("41455", "AEP");
+    std::cout << "end hex encode/decode\n";
+}
+
 int main(int argc, char* argv[])
 {
     try
@@ -266,6 +304,8 @@ int main(int argc, char* argv[])
 	same_file_test();
 	std::cout << "----" << std::endl;
 	read_lines_from_file_test();
+	std::cout << "----" << std::endl;
+	hex_encode_decode_test();
     }
     catch (std::exception& e)
     {