From 952a665a4ed51400b5925e7cd69f08f0aeb374fe Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Thu, 21 Jun 2018 14:03:45 -0400
Subject: Better support for creating Unicode strings

---
 libqpdf/QPDF_String.cc | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

(limited to 'libqpdf/QPDF_String.cc')

diff --git a/libqpdf/QPDF_String.cc b/libqpdf/QPDF_String.cc
index 60a3e0df..eb31a808 100644
--- a/libqpdf/QPDF_String.cc
+++ b/libqpdf/QPDF_String.cc
@@ -64,6 +64,58 @@ QPDF_String::~QPDF_String()
 {
 }
 
+QPDF_String*
+QPDF_String::new_utf16(std::string const& utf8_val)
+{
+    std::string result = "\xfe\xff";
+    size_t len = utf8_val.length();
+    for (size_t i = 0; i < len; ++i)
+    {
+        unsigned char ch = static_cast<unsigned char>(utf8_val.at(i));
+        if (ch < 128)
+        {
+            result += QUtil::toUTF16(ch);
+        }
+        else
+        {
+            size_t bytes_needed = 0;
+            unsigned bit_check = 0x40;
+            unsigned char to_clear = 0x80;
+            while (ch & bit_check)
+            {
+                ++bytes_needed;
+                to_clear |= bit_check;
+                bit_check >>= 1;
+            }
+
+            if (((bytes_needed > 5) || (bytes_needed < 1)) ||
+                ((i + bytes_needed) >= len))
+            {
+                result += "\xff\xfd";
+            }
+            else
+            {
+                unsigned long codepoint = (ch & ~to_clear);
+                while (bytes_needed > 0)
+                {
+                    --bytes_needed;
+                    ch = utf8_val.at(++i);
+                    if ((ch & 0xc0) != 0x80)
+                    {
+                        --i;
+                        codepoint = 0xfffd;
+                        break;
+                    }
+                    codepoint <<= 6;
+                    codepoint += (ch & 0x3f);
+                }
+                result += QUtil::toUTF16(codepoint);
+            }
+        }
+    }
+    return new QPDF_String(result);
+}
+
 std::string
 QPDF_String::unparse()
 {
-- 
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