✏️ Editing: pdf_parser.php

<?php

//
//  FPDI - Version 1.2
//
//    Copyright 2004-2007 Setasign - Jan Slabon
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

if (!defined('PDF_TYPE_NULL'))
    define('PDF_TYPE_NULL', 0);
if (!defined('PDF_TYPE_NUMERIC'))
    define('PDF_TYPE_NUMERIC', 1);
if (!defined('PDF_TYPE_TOKEN'))
    define('PDF_TYPE_TOKEN', 2);
if (!defined('PDF_TYPE_HEX'))
    define('PDF_TYPE_HEX', 3);
if (!defined('PDF_TYPE_STRING'))
    define('PDF_TYPE_STRING', 4);
if (!defined('PDF_TYPE_DICTIONARY'))
    define('PDF_TYPE_DICTIONARY', 5);
if (!defined('PDF_TYPE_ARRAY'))
    define('PDF_TYPE_ARRAY', 6);
if (!defined('PDF_TYPE_OBJDEC'))
    define('PDF_TYPE_OBJDEC', 7);
if (!defined('PDF_TYPE_OBJREF'))
    define('PDF_TYPE_OBJREF', 8);
if (!defined('PDF_TYPE_OBJECT'))
    define('PDF_TYPE_OBJECT', 9);
if (!defined('PDF_TYPE_STREAM'))
    define('PDF_TYPE_STREAM', 10);

class pdf_parser {

/**
     * Filename
     * @var string
     */
    var $filename;

/**
     * File resource
     * @var resource
     */
    var $f;

/**
     * PDF Context
     * @var object pdf_context-Instance
     */
    var $c;

/**
     * xref-Data
     * @var array
     */
    var $xref;

/**
     * root-Object
     * @var array
     */
    var $root;
    // mPDF 4.0 Added flag to show success on loading file
    var $success;
    var $errormsg;

/**
     * Constructor
     *
     * @param string $filename  Source-Filename
     */
    function pdf_parser($filename) {
        $this->filename = $filename;
        // mPDF 4.0
        $this->success = true;

$this->f = @fopen($this->filename, "rb");

if (!$this->f) {
            $this->success = false;
            $this->errormsg = sprintf("Cannot open %s !", $filename);
            return false;
        }
        // mPDF 5.0 Removed pass by reference =&
        $this->c = new pdf_context($this->f);
        // Read xref-Data
        $offset = $this->pdf_find_xref();
        if ($offset === false) {
            $this->success = false;
            $this->errormsg = sprintf("Cannot open %s !", $filename);
            return false;
        }
        $this->pdf_read_xref($this->xref, $offset);
        if ($this->success == false) {
            return false;
        }

// Check for Encryption
        $this->getEncryption();
        if ($this->success == false) {
            return false;
        }

// Read root
        $this->pdf_read_root();
        if ($this->success == false) {
            return false;
        }
    }

/**
     * Close the opened file
     */
    function closeFile() {
        if (isset($this->f)) {
            fclose($this->f);
            unset($this->f);
        }
    }

/**
     * Print Error and die
     *
     * @param string $msg  Error-Message
     */
    function error($msg) {
        die("<b>PDF-Parser Error:</b> " . $msg);
    }

/**
     * Check Trailer for Encryption
     */
    function getEncryption() {
        if (isset($this->xref['trailer'][1]['/Encrypt'])) {
            // mPDF 4.0
            $this->success = false;
            $this->errormsg = sprintf("File is encrypted!");
            return false;
        }
    }

/**
     * Find/Return /Root
     *
     * @return array
     */
    function pdf_find_root() {
        if ($this->xref['trailer'][1]['/Root'][0] != PDF_TYPE_OBJREF) {
            // mPDF 4.0
            $this->success = false;
            $this->errormsg = sprintf("Wrong Type of Root-Element! Must be an indirect reference");
            return false;
        }
        return $this->xref['trailer'][1]['/Root'];
    }

/**
     * Read the /Root
     */
    function pdf_read_root() {
        // read root
        $root = $this->pdf_find_root();
        if ($root === false) {
            $this->success = false;
            return false;
        }
        $this->root = $this->pdf_resolve_object($this->c, $root);
    }

/**
     * Find the xref-Table
     */
    function pdf_find_xref() {
        fseek($this->f, -min(filesize($this->filename), 1500), SEEK_END);
        $data = fread($this->f, 1500);

$pos = strlen($data) - strpos(strrev($data), strrev('startxref'));
        $data = substr($data, $pos);

if (!preg_match('/\s*(\d+).*$/s', $data, $matches)) {
            // mPDF 4.0
            $this->success = false;
            $this->errormsg = sprintf("Unable to find pointer to xref table");
            return false;
        }

return (int) $matches[1];
    }

/**
     * Read xref-table
     *
     * @param array $result Array of xref-table
     * @param integer $offset of xref-table
     * @param integer $start start-position in xref-table
     * @param integer $end end-position in xref-table
     */
    function pdf_read_xref(&$result, $offset, $start = null, $end = null) {
        if (is_null($start) || is_null($end)) {
            fseek($this->f, $o_pos = $offset);
            $data = trim(fgets($this->f, 1024));

if (strlen($data) == 0)
                $data = trim(fgets($this->f, 1024));

if ($data !== 'xref') {
                fseek($this->f, $o_pos);
                $data = trim(_fgets($this->f, true));
                if ($data !== 'xref') {
                    if (preg_match('/(.*xref)(.*)/m', $data, $m)) { // xref 0 128 - in one line
                        fseek($this->f, $o_pos + strlen($m[1]));
                    } elseif (preg_match('/(x|r|e|f)+/', $data, $m)) { // correct invalid xref-pointer
                        $tmpOffset = $offset - 4 + strlen($m[0]);
                        $this->pdf_read_xref($result, $tmpOffset, $start, $end);
                        return;
                    } else {
                        // mPDF 4.0
                        $this->success = false;
                        $this->errormsg = sprintf("Unable to find xref table - Maybe a Problem with 'auto_detect_line_endings'");
                        return;
                    }
                }
            }

$o_pos = ftell($this->f);
            $data = explode(' ', trim(fgets($this->f, 1024)));
            if (count($data) != 2) {
                fseek($this->f, $o_pos);
                $data = explode(' ', trim(_fgets($this->f, true)));

if (count($data) != 2) {
                    if (count($data) > 2) { // no lineending
                        $n_pos = $o_pos + strlen($data[0]) + strlen($data[1]) + 2;
                        fseek($this->f, $n_pos);
                    } else {
                        // mPDF 4.0
                        $this->success = false;
                        $this->errormsg = sprintf("Unexpected header in xref table");
                        return;
                    }
                }
            }
            $start = $data[0];
            $end = $start + $data[1];
        }

if (!isset($result['xref_location'])) {
            $result['xref_location'] = $offset;
        }

if (!isset($result['max_object']) || $end > $result['max_object']) {
            $result['max_object'] = $end;
        }

for (; $start < $end; $start++) {
            $data = ltrim(fread($this->f, 20)); // Spezifications says: 20 bytes including newlines
            $offset = substr($data, 0, 10);
            $generation = substr($data, 11, 5);

if (!isset($result['xref'][$start][(int) $generation])) {
                $result['xref'][$start][(int) $generation] = (int) $offset;
            }
        }

$o_pos = ftell($this->f);
        $data = fgets($this->f, 1024);
        if (strlen(trim($data)) == 0)
            $data = fgets($this->f, 1024);

if (preg_match("/trailer/", $data)) {
            if (preg_match("/(.*trailer[ \n\r]*)/", $data, $m)) {
                fseek($this->f, $o_pos + strlen($m[1]));
            }

// mPDF 5.0 Removed pass by reference =&
            $c = new pdf_context($this->f);
            $trailer = $this->pdf_read_value($c);

if (isset($trailer[1]['/Prev'])) {
                $this->pdf_read_xref($result, $trailer[1]['/Prev'][1]);
                $result['trailer'][1] = array_merge($result['trailer'][1], $trailer[1]);
            } else {
                $result['trailer'] = $trailer;
            }
        } else {
            $data = explode(' ', trim($data));

if (count($data) != 2) {
                fseek($this->f, $o_pos);
                $data = explode(' ', trim(_fgets($this->f, true)));

if (count($data) != 2) {
                    // mPDF 4.0
                    $this->success = false;
                    $this->errormsg = sprintf("Unexpected data in xref table");
                    return;
                }
            }

$this->pdf_read_xref($result, null, (int) $data[0], (int) $data[0] + (int) $data[1]);
        }
    }

/**
     * Reads an Value
     *
     * @param object $c pdf_context
     * @param string $token a Token
     * @return mixed
     */
    function pdf_read_value(&$c, $token = null) {
        if (is_null($token)) {
            $token = $this->pdf_read_token($c);
        }

if ($token === false) {
            return false;
        }

switch ($token) {
            case '<':
                // This is a hex string.
                // Read the value, then the terminator

$pos = $c->offset;

while (1) {

$match = strpos($c->buffer, '>', $pos);

// If you can't find it, try
                    // reading more data from the stream

if ($match === false) {
                        if (!$c->increase_length()) {
                            return false;
                        } else {
                            continue;
                        }
                    }

$result = substr($c->buffer, $c->offset, $match - $c->offset);
                    $c->offset = $match + 1;

return array(PDF_TYPE_HEX, $result);
                }

break;
            case '<<':
                // This is a dictionary.

$result = array();

// Recurse into this function until we reach
                // the end of the dictionary.
                while (($key = $this->pdf_read_token($c)) !== '>>') {
                    if ($key === false) {
                        return false;
                    }

if (($value = $this->pdf_read_value($c)) === false) {
                        return false;
                    }
                    $result[$key] = $value;
                }

return array(PDF_TYPE_DICTIONARY, $result);

case '[':
                // This is an array.

$result = array();

// Recurse into this function until we reach
                // the end of the array.
                while (($token = $this->pdf_read_token($c)) !== ']') {
                    if ($token === false) {
                        return false;
                    }

if (($value = $this->pdf_read_value($c, $token)) === false) {
                        return false;
                    }

$result[] = $value;
                }

return array(PDF_TYPE_ARRAY, $result);

case '(' :
                // This is a string

$pos = $c->offset;

while (1) {

// Start by finding the next closed
                    // parenthesis

$match = strpos($c->buffer, ')', $pos);

// If you can't find it, try
                    // reading more data from the stream

// Make sure that there is no backslash
                    // before the parenthesis. If there is,
                    // move on. Otherwise, return the string.
                    $esc = preg_match('/([\\\\]+)$/', $tmpresult = substr($c->buffer, $c->offset, $match - $c->offset), $m);

if ($esc === 0 || strlen($m[1]) % 2 == 0) {
                        $result = $tmpresult;
                        $c->offset = $match + 1;
                        return array(PDF_TYPE_STRING, $result);
                    } else {
                        $pos = $match + 1;

if ($pos > $c->offset + $c->length) {
                            $c->increase_length();
                        }
                    }
                }

case "stream":
                $o_pos = ftell($c->file) - strlen($c->buffer);
                $o_offset = $c->offset;

$c->reset($startpos = $o_pos + $o_offset);

$e = 0; // ensure line breaks in front of the stream
                if ($c->buffer[0] == chr(10) || $c->buffer[0] == chr(13))
                    $e++;
                if ($c->buffer[1] == chr(10) && $c->buffer[0] != chr(10))
                    $e++;

if ($this->actual_obj[1][1]['/Length'][0] == PDF_TYPE_OBJREF) {
                    // mPDF 5.0 Removed pass by reference =&
                    $tmp_c = new pdf_context($this->f);
                    $tmp_length = $this->pdf_resolve_object($tmp_c, $this->actual_obj[1][1]['/Length']);
                    $length = $tmp_length[1][1];
                } else {
                    $length = $this->actual_obj[1][1]['/Length'][1];
                }

if ($length > 0) {
                    $c->reset($startpos + $e, $length);
                    $v = $c->buffer;
                } else {
                    $v = '';
                }
                $c->reset($startpos + $e + $length + 9); // 9 = strlen("endstream")

return array(PDF_TYPE_STREAM, $v);

default :
                if (is_numeric($token)) {
                    // A numeric token. Make sure that
                    // it is not part of something else.
                    if (($tok2 = $this->pdf_read_token($c)) !== false) {
                        if (is_numeric($tok2)) {

// Two numeric tokens in a row.
                            // In this case, we're probably in
                            // front of either an object reference
                            // or an object specification.
                            // Determine the case and return the data
                            if (($tok3 = $this->pdf_read_token($c)) !== false) {
                                switch ($tok3) {
                                    case 'obj' :
                                        return array(PDF_TYPE_OBJDEC, (int) $token, (int) $tok2);
                                    case 'R' :
                                        return array(PDF_TYPE_OBJREF, (int) $token, (int) $tok2);
                                }
                                // If we get to this point, that numeric value up
                                // there was just a numeric value. Push the extra
                                // tokens back into the stack and return the value.
                                array_push($c->stack, $tok3);
                            }
                        }

array_push($c->stack, $tok2);
                    }

return array(PDF_TYPE_NUMERIC, $token);
                } else {

// Just a token. Return it.
                    return array(PDF_TYPE_TOKEN, $token);
                }
        }
    }

/**
     * Resolve an object
     *
     * @param object $c pdf_context
     * @param array $obj_spec The object-data
     * @param boolean $encapsulate Must set to true, cause the parsing and fpdi use this method only without this para
     */
    function pdf_resolve_object(&$c, $obj_spec, $encapsulate = true) {
        // Exit if we get invalid data
        if (!is_array($obj_spec)) {
            return false;
        }

if ($obj_spec[0] == PDF_TYPE_OBJREF) {

// This is a reference, resolve it
            if (isset($this->xref['xref'][$obj_spec[1]][$obj_spec[2]])) {

// Save current file position
                // This is needed if you want to resolve
                // references while you're reading another object
                // (e.g.: if you need to determine the length
                // of a stream)

$old_pos = ftell($c->file);

// Reposition the file pointer and
                // load the object header.

$c->reset($this->xref['xref'][$obj_spec[1]][$obj_spec[2]]);

$header = $this->pdf_read_value($c, null, true);

if ($header[0] != PDF_TYPE_OBJDEC || $header[1] != $obj_spec[1] || $header[2] != $obj_spec[2]) {
                    // mPDF 4.0
                    $this->success = false;
                    $this->errormsg = sprintf("Unable to find object ({$obj_spec[1]}, {$obj_spec[2]}) at expected location");
                    return false;
                }

// If we're being asked to store all the information
                // about the object, we add the object ID and generation
                // number for later use
                $this->actual_obj = & $result;
                if ($encapsulate) {
                    $result = array(
                        PDF_TYPE_OBJECT,
                        'obj' => $obj_spec[1],
                        'gen' => $obj_spec[2]
                    );
                } else {
                    $result = array();
                }

// Now simply read the object data until
                // we encounter an end-of-object marker
                while (1) {
                    $value = $this->pdf_read_value($c);
                    if ($value === false || count($result) > 4) {
                        // in this case the parser coudn't find an endobj so we break here
                        break;
                    }

if ($value[0] == PDF_TYPE_TOKEN && $value[1] === 'endobj') {
                        break;
                    }

$result[] = $value;
                }

$c->reset($old_pos);

if (isset($result[2][0]) && $result[2][0] == PDF_TYPE_STREAM) {
                    $result[0] = PDF_TYPE_STREAM;
                }

return $result;
            }
        } else {
            return $obj_spec;
        }
    }

/**
     * Reads a token from the file
     *
     * @param object $c pdf_context
     * @return mixed
     */
    function pdf_read_token(&$c) {
        // If there is a token available
        // on the stack, pop it out and
        // return it.

if (count($c->stack)) {
            return array_pop($c->stack);
        }

// Strip away any whitespace

do {
            if (!$c->ensure_content()) {
                return false;
            }
            $c->offset += _strspn($c->buffer, " \n\r\t", $c->offset);
        } while ($c->offset >= $c->length - 1);

// Get the first character in the stream

$char = $c->buffer[$c->offset++];

switch ($char) {

case '[' :
            case ']' :
            case '(' :
            case ')' :

// This is either an array or literal string
                // delimiter, Return it

return $char;

case '<' :
            case '>' :

// This could either be a hex string or
                // dictionary delimiter. Determine the
                // appropriate case and return the token

if ($c->buffer[$c->offset] == $char) {
                    if (!$c->ensure_content()) {
                        return false;
                    }
                    $c->offset++;
                    return $char . $char;
                } else {
                    return $char;
                }

default :

// This is "another" type of token (probably
                // a dictionary entry or a numeric value)
                // Find the end and return it.

if (!$c->ensure_content()) {
                    return false;
                }

while (1) {

// Determine the length of the token

$pos = _strcspn($c->buffer, " []<>()\r\n\t/", $c->offset);
                    if ($c->offset + $pos <= $c->length - 1) {
                        break;
                    } else {
                        // If the script reaches this point,
                        // the token may span beyond the end
                        // of the current buffer. Therefore,
                        // we increase the size of the buffer
                        // and try again--just to be safe.

$c->increase_length();
                    }
                }

$result = substr($c->buffer, $c->offset - 1, $pos + 1);

$c->offset += $pos;
                return $result;
        }
    }

}

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