Add QPDFObjectHandle::parseContentStream method

This method allows parsing of the PDF objects in a content stream or
array of content streams.

ChangeLog

@@ -1,5 +1,9 @@
 2013-01-20  Jay Berkenbilt  <ejb@ql.org>
 
+	* Added QPDFObjectHandle::parseContentStream, which parses the
+	objects in a content stream and calls handlers in a callback
+	class.  The example pdf-parse-content illustrates it use.
+
 	* Added QPDF_Keyword and QPDF_InlineImage types along with
 	appropriate wrapper methods in QPDFObjectHandle.  These new object
 	types are to facilitate content stream parsing.

examples/build.mk

@@ -4,7 +4,8 @@ BINS_examples = \
 	pdf-npages \
 	pdf-double-page-size \
 	pdf-invert-images \
-	pdf-create
+	pdf-create \
+	pdf-parse-content
 CBINS_examples = pdf-linearize
 
 TARGETS_examples = $(foreach B,$(BINS_examples) $(CBINS_examples),examples/$(OUTPUT_DIR)/$(call binname,$(B)))

examples/pdf-parse-content.cc

@@ -0,0 +1,97 @@
+#include <iostream>
+#include <string.h>
+#include <stdlib.h>
+
+#include <qpdf/QPDF.hh>
+#include <qpdf/QUtil.hh>
+
+static char const* whoami = 0;
+
+void usage()
+{
+    std::cerr << "Usage: " << whoami << " filename page-number" << std::endl
+	      << "Prints a dump of the objects in the content streams"
+              << " of the given page." << std::endl
+              << "Pages are numbered from 1." << std::endl;
+    exit(2);
+}
+
+class ParserCallbacks: public QPDFObjectHandle::ParserCallbacks
+{
+  public:
+    virtual ~ParserCallbacks()
+    {
+    }
+
+    virtual void handleObject(QPDFObjectHandle);
+    virtual void handleEOF();
+};
+
+void
+ParserCallbacks::handleObject(QPDFObjectHandle obj)
+{
+    if (obj.isInlineImage())
+    {
+        std::string val = obj.getInlineImageValue();
+        std::cout << "inline image: ";
+        char buf[3];
+        buf[2] = '\0';
+        for (size_t i = 0; i < val.length(); ++i)
+        {
+            sprintf(buf, "%02x", (unsigned char)(val[i]));
+            std::cout << buf;
+        }
+        std::cout << std::endl;
+    }
+    else
+    {
+        std::cout << obj.unparse() << std::endl;
+    }
+}
+
+void
+ParserCallbacks::handleEOF()
+{
+    std::cout << "-EOF-" << std::endl;
+}
+
+int main(int argc, char* argv[])
+{
+    whoami = QUtil::getWhoami(argv[0]);
+
+    // For libtool's sake....
+    if (strncmp(whoami, "lt-", 3) == 0)
+    {
+	whoami += 3;
+    }
+
+    if (argc != 3)
+    {
+	usage();
+    }
+    char const* filename = argv[1];
+    int pageno = atoi(argv[2]);
+
+    try
+    {
+	QPDF pdf;
+	pdf.processFile(filename);
+        std::vector<QPDFObjectHandle> pages = pdf.getAllPages();
+        if ((pageno < 1) || (pageno > (int)pages.size()))
+        {
+            usage();
+        }
+
+        QPDFObjectHandle page = pages[pageno-1];
+        QPDFObjectHandle contents = page.getKey("/Contents");
+        ParserCallbacks cb;
+        QPDFObjectHandle::parseContentStream(contents, &cb);
+    }
+    catch (std::exception& e)
+    {
+	std::cerr << whoami << ": " << e.what() << std::endl;
+	exit(2);
+    }
+
+    return 0;
+}

examples/qtest/parse-content.test

@@ -0,0 +1,17 @@
+#!/usr/bin/env perl
+require 5.008;
+BEGIN { $^W = 1; }
+use strict;
+
+chdir("parse-content");
+
+require TestDriver;
+
+my $td = new TestDriver('pdf-parse-content');
+
+$td->runtest("parse content",
+	     {$td->COMMAND => "pdf-parse-content input.pdf 1"},
+	     {$td->FILE => "content.out", $td->EXIT_STATUS => 0},
+	     $td->NORMALIZE_NEWLINES);
+
+$td->report(1);

examples/qtest/parse-content/content.out

@@ -0,0 +1,11 @@
+BT
+/F1
+24
+Tf
+72
+720
+Td
+(Potato)
+Tj
+ET
+-EOF-

include/qpdf/QPDFObjectHandle.hh

@@ -71,6 +71,21 @@ class QPDFObjectHandle
         virtual void decryptString(std::string& val) = 0;
     };
 
+    // This class is used by parseContentStream.  Callers must
+    // instantiate a subclass of this with handlers defined to accept
+    // QPDFObjectHandles that are parsed from the stream.
+    class ParserCallbacks
+    {
+      public:
+        QPDF_DLL
+        virtual ~ParserCallbacks()
+        {
+        }
+        virtual void handleObject(QPDFObjectHandle) = 0;
+        virtual void handleEOF() = 0;
+    };
+
+
     QPDF_DLL
     QPDFObjectHandle();
     QPDF_DLL
@@ -138,6 +153,11 @@ class QPDFObjectHandle
                                   StringDecrypter* decrypter,
                                   QPDF* context);
 
+    // Helpers for parsing content streams
+    QPDF_DLL
+    static void parseContentStream(QPDFObjectHandle stream_or_array,
+                                   ParserCallbacks* callbacks);
+
     // Type-specific factories
     QPDF_DLL
     static QPDFObjectHandle newNull();
@@ -571,7 +591,10 @@ class QPDFObjectHandle
         std::string const& object_description,
         QPDFTokenizer& tokenizer, bool& empty,
         StringDecrypter* decrypter, QPDF* context,
-        bool in_array, bool in_dictionary);
+        bool in_array, bool in_dictionary,
+        bool content_stream);
+    static void parseContentStream_internal(
+        QPDFObjectHandle stream, ParserCallbacks* callbacks);
 
     bool initialized;
 

include/qpdf/QPDFTokenizer.hh

@@ -18,6 +18,8 @@
 class QPDFTokenizer
 {
   public:
+    // Token type tt_eof is only returned of allowEOF() is called on
+    // the tokenizer.  tt_eof was introduced in QPDF version 4.1.
     enum token_type_e
     {
 	tt_bad,
@@ -34,6 +36,7 @@ class QPDFTokenizer
 	tt_null,
 	tt_bool,
 	tt_word,
+        tt_eof,
     };
 
     class Token
@@ -97,6 +100,12 @@ class QPDFTokenizer
     QPDF_DLL
     void allowPoundAnywhereInName();
 
+    // If called, treat EOF as a separate token type instead of an
+    // error.  This was introduced in QPDF 4.1 to facilitate
+    // tokenizing content streams.
+    QPDF_DLL
+    void allowEOF();
+
     // Mode of operation:
 
     // Keep presenting characters and calling getToken() until
@@ -140,6 +149,7 @@ class QPDFTokenizer
 	   st_literal, st_in_hexstring, st_token_ready } state;
 
     bool pound_special_in_name;
+    bool allow_eof;
 
     // Current token accumulation
     token_type_e type;

libqpdf/QPDFObjectHandle.cc

@@ -680,6 +680,106 @@ QPDFObjectHandle::parse(std::string const& object_str,
     return result;
 }
 
+void
+QPDFObjectHandle::parseContentStream(QPDFObjectHandle stream_or_array,
+                                     ParserCallbacks* callbacks)
+{
+    std::vector<QPDFObjectHandle> streams;
+    if (stream_or_array.isArray())
+    {
+        streams = stream_or_array.getArrayAsVector();
+    }
+    else
+    {
+        streams.push_back(stream_or_array);
+    }
+    for (std::vector<QPDFObjectHandle>::iterator iter = streams.begin();
+         iter != streams.end(); ++iter)
+    {
+        QPDFObjectHandle stream = *iter;
+        if (! stream.isStream())
+        {
+            throw std::logic_error(
+                "QPDFObjectHandle: parseContentStream called on non-stream");
+        }
+        parseContentStream_internal(stream, callbacks);
+    }
+    callbacks->handleEOF();
+}
+
+void
+QPDFObjectHandle::parseContentStream_internal(QPDFObjectHandle stream,
+                                              ParserCallbacks* callbacks)
+{
+    stream.assertStream();
+    PointerHolder<Buffer> stream_data = stream.getStreamData();
+    size_t length = stream_data->getSize();
+    std::string description = "content stream object " +
+        QUtil::int_to_string(stream.getObjectID()) + " " +
+        QUtil::int_to_string(stream.getGeneration());
+    PointerHolder<InputSource> input =
+        new BufferInputSource(description, stream_data.getPointer());
+    QPDFTokenizer tokenizer;
+    tokenizer.allowEOF();
+    bool empty = false;
+    while ((size_t) input->tell() < length)
+    {
+        QPDFObjectHandle obj =
+            parseInternal(input, "content", tokenizer, empty,
+                          0, 0, false, false, true);
+        if (! obj.isInitialized())
+        {
+            // EOF
+            break;
+        }
+
+        callbacks->handleObject(obj);
+        if (obj.isKeyword() && (obj.getKeywordValue() == "ID"))
+        {
+            // Discard next character; it is the space after ID that
+            // terminated the token.  Read until end of inline image.
+            char ch;
+            input->read(&ch, 1);
+            char buf[4];
+            memset(buf, '\0', sizeof(buf));
+            bool done = false;
+            std::string inline_image;
+            while (! done)
+            {
+                if (input->read(&ch, 1) == 0)
+                {
+                    QTC::TC("qpdf", "QPDFObjectHandle EOF in inline image");
+                    throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
+                                  "stream data", input->tell(),
+                                  "EOF found while reading inline image");
+                }
+                inline_image += ch;
+                memmove(buf, buf + 1, sizeof(buf) - 1);
+                buf[sizeof(buf) - 1] = ch;
+                if (strchr(" \t\n\v\f\r", buf[0]) &&
+                    (buf[1] == 'E') &&
+                    (buf[2] == 'I') &&
+                    strchr(" \t\n\v\f\r", buf[3]))
+                {
+                    // We've found an EI operator.
+                    done = true;
+                    input->seek(-3, SEEK_CUR);
+                    for (int i = 0; i < 4; ++i)
+                    {
+                        if (inline_image.length() > 0)
+                        {
+                            inline_image.erase(inline_image.length() - 1);
+                        }
+                    }
+                }
+            }
+            QTC::TC("qpdf", "QPDFObjectHandle inline image token");
+            callbacks->handleObject(
+                QPDFObjectHandle::newInlineImage(inline_image));
+        }
+    }
+}
+
 QPDFObjectHandle
 QPDFObjectHandle::parse(PointerHolder<InputSource> input,
                         std::string const& object_description,
@@ -687,7 +787,7 @@ QPDFObjectHandle::parse(PointerHolder<InputSource> input,
                         StringDecrypter* decrypter, QPDF* context)
 {
     return parseInternal(input, object_description, tokenizer, empty,
-                         decrypter, context, false, false);
+                         decrypter, context, false, false, false);
 }
 
 QPDFObjectHandle
@@ -695,7 +795,8 @@ QPDFObjectHandle::parseInternal(PointerHolder<InputSource> input,
                                 std::string const& object_description,
                                 QPDFTokenizer& tokenizer, bool& empty,
                                 StringDecrypter* decrypter, QPDF* context,
-                                bool in_array, bool in_dictionary)
+                                bool in_array, bool in_dictionary,
+                                bool content_stream)
 {
     empty = false;
     if (in_dictionary && in_array)
@@ -721,6 +822,21 @@ QPDFObjectHandle::parseInternal(PointerHolder<InputSource> input,
 
 	switch (token.getType())
 	{
+          case QPDFTokenizer::tt_eof:
+            if (content_stream)
+            {
+                // Return uninitialized object to indicate EOF
+                return object;
+            }
+            else
+            {
+                // When not in content stream mode, EOF is tt_bad and
+                // throws an exception before we get here.
+                throw std::logic_error(
+                    "EOF received while not in content stream mode");
+            }
+            break;
+
 	  case QPDFTokenizer::tt_brace_open:
 	  case QPDFTokenizer::tt_brace_close:
 	    // Don't know what to do with these for now
@@ -764,13 +880,13 @@ QPDFObjectHandle::parseInternal(PointerHolder<InputSource> input,
 	  case QPDFTokenizer::tt_array_open:
 	    object = parseInternal(
 		input, object_description, tokenizer, empty,
-                decrypter, context, true, false);
+                decrypter, context, true, false, content_stream);
 	    break;
 
 	  case QPDFTokenizer::tt_dict_open:
 	    object = parseInternal(
 		input, object_description, tokenizer, empty,
-                decrypter, context, false, true);
+                decrypter, context, false, true, content_stream);
 	    break;
 
 	  case QPDFTokenizer::tt_bool:
@@ -826,6 +942,10 @@ QPDFObjectHandle::parseInternal(PointerHolder<InputSource> input,
 		    input->seek(input->getLastOffset(), SEEK_SET);
                     empty = true;
 		}
+		else if (content_stream)
+                {
+                    object = QPDFObjectHandle::newKeyword(token.getValue());
+                }
 		else
 		{
 		    throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),

libqpdf/QPDFTokenizer.cc

@@ -22,7 +22,8 @@ static bool is_space(char ch)
 }
 
 QPDFTokenizer::QPDFTokenizer() :
-    pound_special_in_name(true)
+    pound_special_in_name(true),
+    allow_eof(false)
 {
     reset();
 }
@@ -34,6 +35,12 @@ QPDFTokenizer::allowPoundAnywhereInName()
     this->pound_special_in_name = false;
 }
 
+void
+QPDFTokenizer::allowEOF()
+{
+    this->allow_eof = true;
+}
+
 void
 QPDFTokenizer::reset()
 {
@@ -441,9 +448,17 @@ QPDFTokenizer::presentEOF()
     }
     else if (state != st_token_ready)
     {
-        QTC::TC("qpdf", "QPDF_Tokenizer EOF reading token");
-	type = tt_bad;
-	error_message = "EOF while reading token";
+        QTC::TC("qpdf", "QPDF_Tokenizer EOF reading token",
+                this->allow_eof ? 1 : 0);
+        if (this->allow_eof)
+        {
+            type = tt_eof;
+        }
+        else
+        {
+            type = tt_bad;
+            error_message = "EOF while reading token";
+        }
     }
 
     state = st_token_ready;

qpdf/qpdf.testcov

@@ -236,7 +236,7 @@ QPDFWriter copy use_aes 1
 QPDFObjectHandle indirect without context 0
 QPDFObjectHandle trailing data in parse 0
 qpdf pages encryption password 0
-QPDF_Tokenizer EOF reading token 0
+QPDF_Tokenizer EOF reading token 1
 QPDF_Tokenizer EOF reading appendable token 0
 QPDFWriter extra header text no newline 0
 QPDFWriter extra header text add newline 0
@@ -259,3 +259,5 @@ QPDFWriter remove Crypt 0
 qpdf-c called qpdf_get_pdf_extension_level 0
 qpdf-c called qpdf_set_r5_encryption_parameters 0
 qpdf-c called qpdf_set_r6_encryption_parameters 0
+QPDFObjectHandle EOF in inline image 0
+QPDFObjectHandle inline image token 0

qpdf/qtest/qpdf.test

@@ -199,7 +199,7 @@ $td->runtest("remove page we don't have",
 show_ntests();
 # ----------
 $td->notify("--- Miscellaneous Tests ---");
-$n_tests += 57;
+$n_tests += 59;
 
 $td->runtest("qpdf version",
 	     {$td->COMMAND => "qpdf --version"},
@@ -468,6 +468,16 @@ $td->runtest("check file with leading junk",
              {$td->COMMAND => "qpdf --check leading-junk.pdf"},
              {$td->FILE => "leading-junk.out", $td->EXIT_STATUS => 0},
              $td->NORMALIZE_NEWLINES);
+$td->runtest("EOF inside inline image",
+             {$td->COMMAND => "test_driver 37 eof-in-inline-image.pdf"},
+             {$td->FILE => "eof-in-inline-image.out",
+              $td->EXIT_STATUS => 2},
+             $td->NORMALIZE_NEWLINES);
+$td->runtest("tokenize content streams",
+             {$td->COMMAND => "test_driver 37 tokenize-content-streams.pdf"},
+             {$td->FILE => "tokenize-content-streams.out",
+              $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
 
 show_ntests();
 # ----------

qpdf/qtest/qpdf/eof-in-inline-image.out

@@ -0,0 +1,25 @@
+BT
+/F1
+24
+Tf
+72
+720
+Td
+(Potato)
+Tj
+ET
+BI
+/CS
+/G
+/W
+1
+/H
+1
+/BPC
+8
+/F
+/Fl
+/DP
+<< /Columns 1 /Predictor 15 >>
+ID
+content stream object 4 0 (stream data, file position 139): EOF found while reading inline image

qpdf/qtest/qpdf/tokenize-content-streams.out

@@ -0,0 +1,95 @@
+BT
+/F1
+24
+Tf
+72
+720
+Td
+(Potato)
+Tj
+ET
+-EOF-
+0.1
+0
+0
+0.1
+0
+0
+cm
+q
+0
+1.1999
+-1.1999
+0
+121.19
+150.009
+cm
+BI
+/CS
+/G
+/W
+1
+/H
+1
+/BPC
+8
+/F
+/Fl
+/DP
+<< /Columns 1 /Predictor 15 >>
+ID
+inline image: 789c63fc0f0001030101
+EI
+Q
+q
+0
+35.997
+-128.389
+0
+431.964
+7269.02
+cm
+BI
+/CS
+/G
+/W
+30
+/H
+107
+/BPC
+8
+/F
+/Fl
+/DP
+<< /Columns 30 /Predictor 15 >>
+ID
+inline image: 789cedd1a11100300800b1b2ffd06503148283bc8dfcf8af2a306ee352eff2e06318638c31c63b3801627b620a
+EI
+Q
+q
+0
+38.3968
+-93.5922
+0
+431.964
+7567.79
+cm
+BI
+/CS
+/G
+/W
+32
+/H
+78
+/BPC
+8
+/F
+/Fl
+/DP
+<< /Columns 32 /Predictor 15 >>
+ID
+inline image: 789c63fccf801f308e2a185530aa60882a20203faa605401890a0643aa1e5530aa6054010d140000bdd03c13
+EI
+Q
+-EOF-
+test 37 done

qpdf/test_driver.cc

@@ -58,6 +58,45 @@ class Provider: public QPDFObjectHandle::StreamDataProvider
     bool bad_length;
 };
 
+class ParserCallbacks: public QPDFObjectHandle::ParserCallbacks
+{
+  public:
+    virtual ~ParserCallbacks()
+    {
+    }
+
+    virtual void handleObject(QPDFObjectHandle);
+    virtual void handleEOF();
+};
+
+void
+ParserCallbacks::handleObject(QPDFObjectHandle obj)
+{
+    if (obj.isInlineImage())
+    {
+        std::string val = obj.getInlineImageValue();
+        std::cout << "inline image: ";
+        char buf[3];
+        buf[2] = '\0';
+        for (size_t i = 0; i < val.length(); ++i)
+        {
+            sprintf(buf, "%02x", (unsigned char)(val[i]));
+            std::cout << buf;
+        }
+        std::cout << std::endl;
+    }
+    else
+    {
+        std::cout << obj.unparse() << std::endl;
+    }
+}
+
+void
+ParserCallbacks::handleEOF()
+{
+    std::cout << "-EOF-" << std::endl;
+}
+
 static std::string getPageContents(QPDFObjectHandle page)
 {
     PointerHolder<Buffer> b1 =
@@ -1245,6 +1284,19 @@ void runtest(int n, char const* filename1, char const* arg2)
             }
         }
     }
+    else if (n == 37)
+    {
+        // Parse content streams of all pages
+        std::vector<QPDFObjectHandle> pages = pdf.getAllPages();
+        for (std::vector<QPDFObjectHandle>::iterator iter = pages.begin();
+             iter != pages.end(); ++iter)
+        {
+            QPDFObjectHandle page = *iter;
+            QPDFObjectHandle contents = page.getKey("/Contents");
+            ParserCallbacks cb;
+            QPDFObjectHandle::parseContentStream(contents, &cb);
+        }
+    }
     else
     {
 	throw std::runtime_error(std::string("invalid test ") +