/**
* read a < hex string >. The initial < has already been read.
*
* @param objNum the object number of the object containing the dictionary being read; negative
* only if the object number is unavailable, which should only happen if we're reading a
* string placed directly in the trailer
* @param objGen the object generation of the object containing the object being read; negative
* only if the objNum is unavailable
* @param decrypter the decrypter to use
*/
private PDFObject readHexString(int objNum, int objGen, PDFDecrypter decrypter)
throws IOException {
// we've already read the <. Now get the hex bytes until >
int val;
StringBuffer sb = new StringBuffer();
while ((val = readHexPair()) >= 0) {
sb.append((char) val);
}
if (this.buf.get() != '>') {
throw new PDFParseException("Bad character in Hex String");
}
return new PDFObject(
this, PDFObject.STRING, decrypter.decryptString(objNum, objGen, sb.toString()));
}
/**
* read the cross reference table from a PDF file. When this method is called, the file pointer
* must point to the start of the word "xref" in the file. Reads the xref table and the trailer
* dictionary. If dictionary has a /Prev entry, move file pointer and read new trailer
*
* @param password
*/
private void readTrailer(PDFPassword password)
throws IOException, PDFAuthenticationFailureException,
EncryptionUnsupportedByProductException, EncryptionUnsupportedByPlatformException {
// the table of xrefs
this.objIdx = new PDFXref[50];
int pos = this.buf.position();
PDFDecrypter newDefaultDecrypter = null;
// read a bunch of nested trailer tables
while (true) {
// make sure we are looking at an xref table
if (!nextItemIs("xref")) {
this.buf.position(pos);
readTrailer15(password);
return;
// throw new PDFParseException("Expected 'xref' at start of table");
}
// read a bunch of linked tabled
while (true) {
// read until the word "trailer"
PDFObject obj = readObject(-1, -1, IdentityDecrypter.getInstance());
if (obj.getType() == PDFObject.KEYWORD && obj.getStringValue().equals("trailer")) {
break;
}
// read the starting position of the reference
if (obj.getType() != PDFObject.NUMBER) {
throw new PDFParseException("Expected number for first xref entry");
}
int refstart = obj.getIntValue();
// read the size of the reference table
obj = readObject(-1, -1, IdentityDecrypter.getInstance());
if (obj.getType() != PDFObject.NUMBER) {
throw new PDFParseException("Expected number for length of xref table");
}
int reflen = obj.getIntValue();
// skip a line
readLine();
if (refstart == 1) { // Check and try to fix incorrect Object Number Start
int startPos = this.buf.position();
try {
byte[] refline = new byte[20];
this.buf.get(refline);
if (refline[17] == 'f') { // free
PDFXref objIndex = new PDFXref(refline);
if (objIndex.getID() == 0
&& objIndex.getGeneration() == 65535) { // The highest generation number possible
refstart--;
}
}
} catch (Exception e) { // in case of error ignore
}
this.buf.position(startPos);
}
// extend the objIdx table, if necessary
if (refstart + reflen >= this.objIdx.length) {
PDFXref nobjIdx[] = new PDFXref[refstart + reflen];
System.arraycopy(this.objIdx, 0, nobjIdx, 0, this.objIdx.length);
this.objIdx = nobjIdx;
}
// read reference lines
for (int refID = refstart; refID < refstart + reflen; refID++) {
// each reference line is 20 bytes long
byte[] refline = new byte[20];
this.buf.get(refline);
// ignore this line if the object ID is already defined
if (this.objIdx[refID] != null) {
continue;
}
// see if it's an active object
if (refline[17] == 'n') {
this.objIdx[refID] = new PDFXref(refline);
} else {
this.objIdx[refID] = new PDFXref(null);
}
}
}
// at this point, the "trailer" word (not EOL) has been read.
PDFObject trailerdict = readObject(-1, -1, IdentityDecrypter.getInstance());
if (trailerdict.getType() != PDFObject.DICTIONARY) {
throw new IOException("Expected dictionary after \"trailer\"");
}
// read the root object location
if (this.root == null) {
this.root = trailerdict.getDictRef("Root");
if (this.root != null) {
this.root.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
}
// read the encryption information
if (this.encrypt == null) {
this.encrypt = trailerdict.getDictRef("Encrypt");
if (this.encrypt != null) {
this.encrypt.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
if (this.encrypt != null && !PDFDecrypterFactory.isFilterExist(this.encrypt)) {
this.encrypt = null; // the filter is not located at this trailer, we will try later again
} else {
newDefaultDecrypter =
PDFDecrypterFactory.createDecryptor(
this.encrypt, trailerdict.getDictRef("ID"), password);
}
}
if (this.info == null) {
this.info = trailerdict.getDictRef("Info");
if (this.info != null) {
if (!this.info.isIndirect()) {
throw new PDFParseException("Info in trailer must be an indirect reference");
}
this.info.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
}
// support for hybrid-PDFs containing an additional compressed-xref-stream
PDFObject xrefstmPos = trailerdict.getDictRef("XRefStm");
if (xrefstmPos != null) {
int pos14 = this.buf.position();
this.buf.position(xrefstmPos.getIntValue());
readTrailer15(password);
this.buf.position(pos14);
}
// read the location of the previous xref table
PDFObject prevloc = trailerdict.getDictRef("Prev");
if (prevloc != null) {
this.buf.position(prevloc.getIntValue());
} else {
break;
}
// see if we have an optional Version entry
if (this.root.getDictRef("Version") != null) {
processVersion(this.root.getDictRef("Version").getStringValue());
}
}
// make sure we found a root
if (this.root == null) {
throw new PDFParseException("No /Root key found in trailer dictionary");
}
if (this.encrypt != null && newDefaultDecrypter != null) {
PDFObject permissions = this.encrypt.getDictRef("P");
if (permissions != null && !newDefaultDecrypter.isOwnerAuthorised()) {
int perms = permissions != null ? permissions.getIntValue() : 0;
if (permissions != null) {
this.printable = (perms & 4) != 0;
this.saveable = (perms & 16) != 0;
}
}
// Install the new default decrypter only after the trailer has
// been read, as nothing we're reading passing through is encrypted
this.defaultDecrypter = newDefaultDecrypter;
}
// dereference the root object
this.root.dereference();
}
/**
* read a ( character string ). The initial ( has already been read. Read until a *balanced* )
* appears.
*
* <p>Section 3.2.3 of PDF Refernce version 1.7 defines the format of String objects. Regarding
* literal strings:
*
* <blockquote>
*
* Within a literal string, the backslash (\) is used as an escape character for various purposes,
* such as to include newline characters, nonprinting ASCII characters, unbalanced parentheses, or
* the backslash character itself in the string. The character immediately following the backslash
* determines its precise interpretation (see Table 3.2). If the character following the backslash
* is not one of those shown in the table, the backslash is ignored.
*
* </blockquote>
*
* *
*
* <p>This only reads 8 bit basic character 'strings' so as to avoid a text string interpretation
* when one is not desired (e.g., for byte strings, as used by the decryption mechanism). For an
* interpretation of a string returned from this method, where the object type is defined as a
* 'text string' as per Section 3.8.1, Table 3.31 "PDF Data Types", {@link
* PDFStringUtil#asTextString} ()} or {@link PDFObject#getTextStringValue()} must be employed.
*
* @param objNum the object number of the object containing the dictionary being read; negative
* only if the object number is unavailable, which should only happen if we're reading a
* dictionary placed directly in the trailer
* @param objGen the object generation of the object containing the object being read; negative
* only if the objNum is unavailable
* @param decrypter the decrypter to use
*/
private PDFObject readLiteralString(int objNum, int objGen, PDFDecrypter decrypter)
throws IOException {
int c;
// we've already read the (. now get the characters until a
// *balanced* ) appears. Translate \r \n \t \b \f \( \) \\ \ddd
// if a cr/lf follows a backslash, ignore the cr/lf
int parencount = 1;
StringBuffer sb = new StringBuffer();
while (parencount > 0) {
c = this.buf.get() & 0xFF;
// process unescaped parenthesis
if (c == '(') {
parencount++;
} else if (c == ')') {
parencount--;
if (parencount == 0) {
c = -1;
break;
}
} else if (c == '\\') {
// From the spec:
// Within a literal string, the backslash (\) is used as an
// escape character for various purposes, such as to include
// newline characters, nonprinting ASCII characters,
// unbalanced parentheses, or the backslash character itself
// in the string. The character immediately following the
// backslash determines its precise interpretation (see
// Table 3.2). If the character following the backslash is not
// one of those shown in the table, the backslash is ignored.
//
// summary of rules:
//
// \n \r \t \b \f 2-char sequences are used to represent their
// 1-char counterparts
//
// \( and \) are used to escape parenthesis
//
// \\ for a literal backslash
//
// \ddd (1-3 octal digits) for a character code
//
// \<EOL> is used to put formatting newlines into the
// file, but aren't actually part of the string; EOL may be
// CR, LF or CRLF
//
// any other sequence should see the backslash ignored
// grab the next character to see what we're dealing with
c = this.buf.get() & 0xFF;
if (c >= '0' && c < '8') {
// \ddd form - one to three OCTAL digits
int count = 0;
int val = 0;
while (c >= '0' && c < '8' && count < 3) {
val = val * 8 + c - '0';
c = this.buf.get() & 0xFF;
count++;
}
// we'll have read one character too many
this.buf.position(this.buf.position() - 1);
c = val;
} else if (c == 'n') {
c = '\n';
} else if (c == 'r') {
c = '\r';
} else if (c == 't') {
c = '\t';
} else if (c == 'b') {
c = '\b';
} else if (c == 'f') {
c = '\f';
} else if (c == '\r') {
// escaped CR to be ignored; look for a following LF
c = this.buf.get() & 0xFF;
if (c != '\n') {
// not an LF, we'll consume this character on
// the next iteration
this.buf.position(this.buf.position() - 1);
}
c = -1;
} else if (c == '\n') {
// escaped LF to be ignored
c = -1;
}
// any other c should be used as is, as it's either
// one of ()\ in which case it should be used literally,
// or the backslash should just be ignored
}
if (c >= 0) {
sb.append((char) c);
}
}
return new PDFObject(
this, PDFObject.STRING, decrypter.decryptString(objNum, objGen, sb.toString()));
}
/**
* read the cross reference table from a PDF file. When this method is called, the file pointer
* must point to the start of the word "xref" in the file. Reads the xref table and the trailer
* dictionary. If dictionary has a /Prev entry, move file pointer and read new trailer
*
* @param password
*/
private void readTrailer15(PDFPassword password)
throws IOException, PDFAuthenticationFailureException,
EncryptionUnsupportedByProductException, EncryptionUnsupportedByPlatformException {
// the table of xrefs
// objIdx is initialized from readTrailer(), do not overwrite here data from hybrid PDFs
// objIdx = new PDFXref[50];
PDFDecrypter newDefaultDecrypter = null;
while (true) {
PDFObject xrefObj = readObject(-1, -1, IdentityDecrypter.getInstance());
PDFObject pdfObject = xrefObj.getDictionary().get("W");
if (pdfObject == null) {
break;
}
PDFObject[] wNums = pdfObject.getArray();
int l1 = wNums[0].getIntValue();
int l2 = wNums[1].getIntValue();
int l3 = wNums[2].getIntValue();
int size = xrefObj.getDictionary().get("Size").getIntValue();
byte[] strmbuf = xrefObj.getStream();
int strmPos = 0;
PDFObject idxNums = xrefObj.getDictionary().get("Index");
int[] idxArray;
if (idxNums == null) {
idxArray = new int[] {0, size};
} else {
PDFObject[] idxNumArr = idxNums.getArray();
idxArray = new int[idxNumArr.length];
for (int i = 0; i < idxNumArr.length; i++) {
idxArray[i] = idxNumArr[i].getIntValue();
}
}
int idxLen = idxArray.length;
int idxPos = 0;
while (idxPos < idxLen) {
int refstart = idxArray[idxPos++];
int reflen = idxArray[idxPos++];
// extend the objIdx table, if necessary
if (refstart + reflen >= this.objIdx.length) {
PDFXref nobjIdx[] = new PDFXref[refstart + reflen];
System.arraycopy(this.objIdx, 0, nobjIdx, 0, this.objIdx.length);
this.objIdx = nobjIdx;
}
// read reference lines
for (int refID = refstart; refID < refstart + reflen; refID++) {
int type = readNum(strmbuf, strmPos, l1);
strmPos += l1;
int id = readNum(strmbuf, strmPos, l2);
strmPos += l2;
int gen = readNum(strmbuf, strmPos, l3);
strmPos += l3;
// ignore this line if the object ID is already defined
if (this.objIdx[refID] != null) {
continue;
}
// see if it's an active object
if (type == 0) { // inactive
this.objIdx[refID] = new PDFXref(null);
} else if (type == 1) { // active uncompressed
this.objIdx[refID] = new PDFXref(id, gen);
} else { // active compressed
this.objIdx[refID] = new PDFXref(id, gen, true);
}
}
}
HashMap<String, PDFObject> trailerdict = xrefObj.getDictionary();
// read the root object location
if (this.root == null) {
this.root = trailerdict.get("Root");
if (this.root != null) {
this.root.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
}
// read the encryption information
if (this.encrypt == null) {
this.encrypt = trailerdict.get("Encrypt");
if (this.encrypt != null) {
this.encrypt.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
if (this.encrypt != null && !PDFDecrypterFactory.isFilterExist(this.encrypt)) {
this.encrypt = null; // the filter is not located at this trailer, we will try later again
} else {
newDefaultDecrypter =
PDFDecrypterFactory.createDecryptor(this.encrypt, trailerdict.get("ID"), password);
}
}
if (this.info == null) {
this.info = trailerdict.get("Info");
if (this.info != null) {
if (!this.info.isIndirect()) {
throw new PDFParseException("Info in trailer must be an indirect reference");
}
this.info.setObjectId(PDFObject.OBJ_NUM_TRAILER, PDFObject.OBJ_NUM_TRAILER);
}
}
// read the location of the previous xref table
PDFObject prevloc = trailerdict.get("Prev");
if (prevloc != null) {
this.buf.position(prevloc.getIntValue());
} else {
break;
}
// see if we have an optional Version entry
if (this.root.getDictRef("Version") != null) {
processVersion(this.root.getDictRef("Version").getStringValue());
}
}
// make sure we found a root
if (this.root == null) {
throw new PDFParseException("No /Root key found in trailer dictionary");
}
// check what permissions are relevant
if (this.encrypt != null && newDefaultDecrypter != null) {
PDFObject permissions = this.encrypt.getDictRef("P");
if (permissions != null && !newDefaultDecrypter.isOwnerAuthorised()) {
int perms = permissions != null ? permissions.getIntValue() : 0;
if (permissions != null) {
this.printable = (perms & 4) != 0;
this.saveable = (perms & 16) != 0;
}
}
// Install the new default decrypter only after the trailer has
// been read, as nothing we're reading passing through is encrypted
this.defaultDecrypter = newDefaultDecrypter;
}
// dereference the root object
this.root.dereference();
}
