Add QUtil::hex_decode

4 files changed, 95 insertions, 0 deletions

diff --git a/include/qpdf/QUtil.hh b/include/qpdf/QUtil.hh
index e8b9e8e1..a6be68f8 100644
--- a/include/qpdf/QUtil.hh
+++ b/include/qpdf/QUtil.hh
@@ -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();
diff --git a/libqpdf/QUtil.cc b/libqpdf/QUtil.cc
index 93374568..1cc5449a 100644
--- a/libqpdf/QUtil.cc
+++ b/libqpdf/QUtil.cc
@@ -290,6 +290,50 @@ QUtil::hex_encode(std::string const& 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()
 {
diff --git a/libtests/qtest/qutil/qutil.out b/libtests/qtest/qutil/qutil.out
index c76beb2b..df86c3d6 100644
--- a/libtests/qtest/qutil/qutil.out
+++ b/libtests/qtest/qutil/qutil.out
@@ -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
diff --git a/libtests/qutil.cc b/libtests/qutil.cc
index 7fc5960d..e6416ac1 100644
--- a/libtests/qutil.cc
+++ b/libtests/qutil.cc
@@ -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)
     {