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Fix UTF-16 supplementary character encoding #659

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Merged
swebb2066 merged 1 commit into from
May 12, 2026
Merged

Fix UTF-16 supplementary character encoding #659

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4 changes: 2 additions & 2 deletions src/main/cpp/transcoder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,7 @@ size_t Transcoder::encodeUTF16BE(unsigned int ch, char* dst)
unsigned char w = (unsigned char) ((ch >> 16) - 1);
dst[0] = (char) (0xD8 + (w >> 2));
dst[1] = (char) (((w & 0x03) << 6) + ((ch >> 10) & 0x3F));
dst[2] = (char) (0xDC + ((ch & 0x30) >> 4));
dst[2] = (char) (0xDC + ((ch >> 8) & 0x03));
dst[3] = (char) (ch & 0xFF);
return 4;
}
Expand Down Expand Up @@ -194,7 +194,7 @@ size_t Transcoder::encodeUTF16LE(unsigned int ch, char* dst)
unsigned char w = (unsigned char) ((ch >> 16) - 1);
dst[1] = (char) (0xD8 + (w >> 2));
dst[0] = (char) (((w & 0x03) << 6) + ((ch >> 10) & 0x3F));
dst[3] = (char) (0xDC + ((ch & 0x30) >> 4));
dst[3] = (char) (0xDC + ((ch >> 8) & 0x03));
dst[2] = (char) (ch & 0xFF);
return 4;
}
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42 changes: 42 additions & 0 deletions src/test/cpp/helpers/transcodertestcase.cpp
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Expand Up @@ -16,6 +16,7 @@
*/

#include <log4cxx/helpers/transcoder.h>
#include <log4cxx/helpers/bytebuffer.h>
#include "../insertwide.h"
#include "../logunit.h"

Expand Down Expand Up @@ -63,6 +64,9 @@ LOGUNIT_CLASS(TranscoderTestCase)
LOGUNIT_TEST(testDecodeUTF8_2);
LOGUNIT_TEST(testDecodeUTF8_3);
LOGUNIT_TEST(testDecodeUTF8_4);
LOGUNIT_TEST(testEncodeUTF16BE_BMP);
LOGUNIT_TEST(testEncodeUTF16BE_Supplementary);
LOGUNIT_TEST(testEncodeUTF16LE_Supplementary);
#if LOG4CXX_UNICHAR_API
LOGUNIT_TEST(udecode2);
LOGUNIT_TEST(udecode4);
Expand Down Expand Up @@ -312,6 +316,44 @@ LOGUNIT_CLASS(TranscoderTestCase)
LOGUNIT_ASSERT_EQUAL(true, iter == out.end());
}

void testEncodeUTF16BE_BMP()
{
char raw[4] = { 0, 0, 0, 0 };
ByteBuffer buf(raw, sizeof(raw));
Transcoder::encodeUTF16BE(0x4E03, buf); // CJK 七
LOGUNIT_ASSERT_EQUAL((size_t) 2, buf.position());
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x4E, (unsigned char) raw[0]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x03, (unsigned char) raw[1]);
}

// U+1F600 (GRINNING FACE) encodes to UTF-16BE as D8 3D DE 00.
// Before the fix the low surrogate's high byte was derived from bits 4-5
// of the code point, yielding 0xDC here instead of 0xDE — corrupting the
// pair into two unpaired surrogates.
void testEncodeUTF16BE_Supplementary()
{
char raw[4] = { 0, 0, 0, 0 };
ByteBuffer buf(raw, sizeof(raw));
Transcoder::encodeUTF16BE(0x1F600, buf);
LOGUNIT_ASSERT_EQUAL((size_t) 4, buf.position());
LOGUNIT_ASSERT_EQUAL((unsigned char) 0xD8, (unsigned char) raw[0]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x3D, (unsigned char) raw[1]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0xDE, (unsigned char) raw[2]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x00, (unsigned char) raw[3]);
}

void testEncodeUTF16LE_Supplementary()
{
char raw[4] = { 0, 0, 0, 0 };
ByteBuffer buf(raw, sizeof(raw));
Transcoder::encodeUTF16LE(0x1F600, buf);
LOGUNIT_ASSERT_EQUAL((size_t) 4, buf.position());
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x3D, (unsigned char) raw[0]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0xD8, (unsigned char) raw[1]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0x00, (unsigned char) raw[2]);
LOGUNIT_ASSERT_EQUAL((unsigned char) 0xDE, (unsigned char) raw[3]);
}


#if LOG4CXX_UNICHAR_API
void udecode2()
Expand Down
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