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Add warnings for Invalid language escape sequences in text strings #689

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Merged
MaximPlusov merged 3 commits into from
Dec 18, 2025
Merged

Add warnings for Invalid language escape sequences in text strings #689

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43aace0
Add warnings for Invalid language escape sequences in text strings
LonelyMidoriya Dec 17, 2025
7d90e11
Update COSString.java
LonelyMidoriya Dec 18, 2025
656b2d3
Add StringWarnings
LonelyMidoriya Dec 18, 2025
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7 changes: 7 additions & 0 deletions src/main/java/org/verapdf/as/warnings/StringWarnings.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
package org.verapdf.as.warnings;

public class StringWarnings {
public static final String NOT_ASCII_LETTER = "Text string language escape sequence contains not ASCII letter";
public static final String INVALID_LANGUAGE_ESCAPE_SEQUENCE_LENGTH = "Text string language escape sequence has invalid length";
public static final String NOT_SUPPORTED_UTF16LE_ENCODING = "String object uses encoding UTF16-LE not supported by PDF";
}
71 changes: 70 additions & 1 deletion src/main/java/org/verapdf/cos/COSString.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
*/
package org.verapdf.cos;

import org.verapdf.as.warnings.StringWarnings;
import org.verapdf.cos.filters.COSFilterASCIIHexEncode;
import org.verapdf.cos.visitor.ICOSVisitor;
import org.verapdf.cos.visitor.IVisitor;
Expand Down Expand Up @@ -111,7 +112,7 @@ public String getString() {
return new String(value, 2, value.length - 2, StandardCharsets.UTF_16BE);
}
if ((value[0] & 0xFF) == 0xFF && (value[1] & 0xFF) == 0xFE) {
LOGGER.log(Level.WARNING, "String object uses encoding UTF16-LE not supported by PDF");
LOGGER.log(Level.WARNING, StringWarnings.NOT_SUPPORTED_UTF16LE_ENCODING);
}
}
if (value.length >= 3) {
Expand Down Expand Up @@ -221,17 +222,85 @@ public String getASCIIString() {
public boolean isTextString() {
if (value.length > 2) {
if ((value[0] & 0xFF) == 0xFE && (value[1] & 0xFF) == 0xFF) {
checkUTF16BEEscapeSequence(value);
return true;
}
}
if (value.length > 3) {
if ((value[0] & 0xFF) == 0xEF && (value[1] & 0xFF) == 0xBB && (value[2] & 0xFF) == 0xBF) {
checkUTF8EscapeSequence(value);
return true;
}
}
return PDFDocEncoding.isPDFDocEncodingString(value);
}

private boolean checkUTF16BEEscapeSequence(byte[] value) {
for (int i = 0; i < value.length; i++) {
if (i + 1 < value.length && value[i] == 0x00 && value[i + 1] == 0x1B) {
if (i + 5 < value.length && value[i + 4] == 0x00 && value[i + 5] == 0x1B) {
if (isASCIILetter(value[i + 2]) && isASCIILetter(value[i + 3])) {
i += 5;
continue;
} else {
LOGGER.log(Level.WARNING, StringWarnings.NOT_ASCII_LETTER);
return false;
}
}

if (i + 7 < value.length && value[i + 6] == 0x00 && value[i + 7] == 0x1B) {
if (isASCIILetter(value[i + 2]) && isASCIILetter(value[i + 3]) &&
isASCIILetter(value[i + 4]) && isASCIILetter(value[i + 5])) {
i += 7;
continue;
} else {
LOGGER.log(Level.WARNING, StringWarnings.NOT_ASCII_LETTER);
return false;
}
}
LOGGER.log(Level.WARNING,StringWarnings.INVALID_LANGUAGE_ESCAPE_SEQUENCE_LENGTH);
return false;
}
}
return true;
}

private boolean checkUTF8EscapeSequence(byte[] value) {
for (int i = 0; i < value.length; i++) {
if (value[i] == 0x1B) {
if (i + 3 < value.length && value[i + 3] == 0x1B) {
if (isASCIILetter(value[i + 1]) && isASCIILetter(value[i + 2])) {
i += 3;
continue;
} else {
LOGGER.log(Level.WARNING, StringWarnings.NOT_ASCII_LETTER);
return false;
}
}

if (i + 5 < value.length && value[i + 5] == 0x1B) {
if (isASCIILetter(value[i + 1]) && isASCIILetter(value[i + 2]) &&
isASCIILetter(value[i + 3]) && isASCIILetter(value[i + 4])) {
i += 5;
continue;
} else {
LOGGER.log(Level.WARNING, StringWarnings.NOT_ASCII_LETTER);
return false;
}
}

LOGGER.log(Level.WARNING,StringWarnings.INVALID_LANGUAGE_ESCAPE_SEQUENCE_LENGTH);
return false;
}
}
return true;
}

private boolean isASCIILetter(byte b) {
int c = b & 0xFF;
return (c >= 0x41 && c <= 0x5A) || (c >= 0x61 && c <= 0x7A);
}

protected String toLitString() {
StringBuilder result = new StringBuilder();
result.append('(');
Expand Down