Add new private method QPDF::readStream

m-holger
1 parent 2643ed4d
Showing 2 changed files with 82 additions and 76 deletions
include/qpdf/QPDF.hh
libqpdf/QPDF.cc
@@ -1008,6 +1008,7 @@ class QPDF
     void setLastObjectDescription(std::string const& description, QPDFObjGen const& og);
     QPDFObjectHandle readTrailer();
     QPDFObjectHandle readObject(std::string const& description, QPDFObjGen og);
+    void readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset);
     QPDFObjectHandle readObjectInStream(std::shared_ptr<InputSource>, QPDFObjGen og);
     size_t recoverStreamLength(
         std::shared_ptr<InputSource> input, QPDFObjGen const& og, qpdf_offset_t stream_offset);
@@ -1296,7 +1296,7 @@ QPDF::readObject(std::string const&amp; description, QPDFObjGen og)
     std::shared_ptr<StringDecrypter> decrypter_ph;
     StringDecrypter* decrypter = nullptr;
     if (m->encp->encrypted) {
-        decrypter_ph = std::make_shared<StringDecrypter>(this, og);
+        decrypter_ph = std::make_unique<StringDecrypter>(this, og);
         decrypter = decrypter_ph.get();
     }
     auto object = QPDFParser(m->file, m->last_object_description, m->tokenizer, decrypter, this)
@@ -1309,93 +1309,98 @@ QPDF::readObject(std::string const&amp; description, QPDFObjGen og)
         // check for stream
         qpdf_offset_t cur_offset = m->file->tell();
         if (readToken(m->file).isWord("stream")) {
-            // The PDF specification states that the word "stream" should be followed by either a
-            // carriage return and a newline or by a newline alone.  It specifically disallowed
-            // following it by a carriage return alone since, in that case, there would be no way to
-            // tell whether the NL in a CR NL sequence was part of the stream data.  However, some
-            // readers, including Adobe reader, accept a carriage return by itself when followed by
-            // a non-newline character, so that's what we do here. We have also seen files that have
-            // extraneous whitespace between the stream keyword and the newline.
-            bool done = false;
-            while (!done) {
-                done = true;
-                char ch;
-                if (m->file->read(&ch, 1) == 0) {
-                    // A premature EOF here will result in some other problem that will get reported
-                    // at another time.
-                } else if (ch == '\n') {
-                    // ready to read stream data
-                    QTC::TC("qpdf", "QPDF stream with NL only");
-                } else if (ch == '\r') {
-                    // Read another character
-                    if (m->file->read(&ch, 1) != 0) {
-                        if (ch == '\n') {
-                            // Ready to read stream data
-                            QTC::TC("qpdf", "QPDF stream with CRNL");
-                        } else {
-                            // Treat the \r by itself as the whitespace after endstream and start
-                            // reading stream data in spite of not having seen a newline.
-                            QTC::TC("qpdf", "QPDF stream with CR only");
-                            m->file->unreadCh(ch);
-                            warn(damagedPDF(
-                                m->file->tell(),
-                                "stream keyword followed by carriage return only"));
-                        }
-                    }
-                } else if (QUtil::is_space(ch)) {
-                    warn(damagedPDF(
-                        m->file->tell(), "stream keyword followed by extraneous whitespace"));
-                    done = false;
+            readStream(object, og, offset);
+        } else {
+            m->file->seek(cur_offset, SEEK_SET);
+        }
+    }
+
+    // Override last_offset so that it points to the beginning of the object we just read
+    m->file->setLastOffset(offset);
+    return object;
+}
+
+// After reading stream dictionary and stream keyword, read rest of stream.
+void
+QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
+{
+    // The PDF specification states that the word "stream" should be followed by either a carriage
+    // return and a newline or by a newline alone.  It specifically disallowed following it by a
+    // carriage return alone since, in that case, there would be no way to tell whether the NL in a
+    // CR NL sequence was part of the stream data.  However, some readers, including Adobe reader,
+    // accept a carriage return by itself when followed by a non-newline character, so that's what
+    // we do here. We have also seen files that have extraneous whitespace between the stream
+    // keyword and the newline.
+    bool done = false;
+    while (!done) {
+        done = true;
+        char ch;
+        if (m->file->read(&ch, 1) == 0) {
+            // A premature EOF here will result in some other problem that will get reported at
+            // another time.
+        } else if (ch == '\n') {
+            // ready to read stream data
+            QTC::TC("qpdf", "QPDF stream with NL only");
+        } else if (ch == '\r') {
+            // Read another character
+            if (m->file->read(&ch, 1) != 0) {
+                if (ch == '\n') {
+                    // Ready to read stream data
+                    QTC::TC("qpdf", "QPDF stream with CRNL");
                 } else {
-                    QTC::TC("qpdf", "QPDF stream without newline");
+                    // Treat the \r by itself as the whitespace after endstream and start reading
+                    // stream data in spite of not having seen a newline.
+                    QTC::TC("qpdf", "QPDF stream with CR only");
                     m->file->unreadCh(ch);
                     warn(damagedPDF(
-                        m->file->tell(), "stream keyword not followed by proper line terminator"));
+                        m->file->tell(), "stream keyword followed by carriage return only"));
                 }
             }
+        } else if (QUtil::is_space(ch)) {
+            warn(damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace"));
+            done = false;
+        } else {
+            QTC::TC("qpdf", "QPDF stream without newline");
+            m->file->unreadCh(ch);
+            warn(damagedPDF(
+                m->file->tell(), "stream keyword not followed by proper line terminator"));
+        }
+    }
  
-            // Must get offset before accessing any additional objects since resolving a previously
-            // unresolved indirect object will change file position.
-            qpdf_offset_t stream_offset = m->file->tell();
-            size_t length = 0;
-
-            try {
-                auto length_obj = object.getKey("/Length");
+    // Must get offset before accessing any additional objects since resolving a previously
+    // unresolved indirect object will change file position.
+    qpdf_offset_t stream_offset = m->file->tell();
+    size_t length = 0;
  
-                if (!length_obj.isInteger()) {
-                    if (length_obj.isNull()) {
-                        QTC::TC("qpdf", "QPDF stream without length");
-                        throw damagedPDF(offset, "stream dictionary lacks /Length key");
-                    }
-                    QTC::TC("qpdf", "QPDF stream length not integer");
-                    throw damagedPDF(offset, "/Length key in stream dictionary is not an integer");
-                }
+    try {
+        auto length_obj = object.getKey("/Length");
  
-                length = toS(length_obj.getUIntValue());
-                // Seek in two steps to avoid potential integer overflow
-                m->file->seek(stream_offset, SEEK_SET);
-                m->file->seek(toO(length), SEEK_CUR);
-                if (!readToken(m->file).isWord("endstream")) {
-                    QTC::TC("qpdf", "QPDF missing endstream");
-                    throw damagedPDF("expected endstream");
-                }
-            } catch (QPDFExc& e) {
-                if (m->attempt_recovery) {
-                    warn(e);
-                    length = recoverStreamLength(m->file, og, stream_offset);
-                } else {
-                    throw;
-                }
+        if (!length_obj.isInteger()) {
+            if (length_obj.isNull()) {
+                QTC::TC("qpdf", "QPDF stream without length");
+                throw damagedPDF(offset, "stream dictionary lacks /Length key");
             }
-            object = newIndirect(og, QPDF_Stream::create(this, og, object, stream_offset, length));
+            QTC::TC("qpdf", "QPDF stream length not integer");
+            throw damagedPDF(offset, "/Length key in stream dictionary is not an integer");
+        }
+
+        length = toS(length_obj.getUIntValue());
+        // Seek in two steps to avoid potential integer overflow
+        m->file->seek(stream_offset, SEEK_SET);
+        m->file->seek(toO(length), SEEK_CUR);
+        if (!readToken(m->file).isWord("endstream")) {
+            QTC::TC("qpdf", "QPDF missing endstream");
+            throw damagedPDF("expected endstream");
+        }
+    } catch (QPDFExc& e) {
+        if (m->attempt_recovery) {
+            warn(e);
+            length = recoverStreamLength(m->file, og, stream_offset);
         } else {
-            m->file->seek(cur_offset, SEEK_SET);
+            throw;
         }
     }
-
-    // Override last_offset so that it points to the beginning of the object we just read
-    m->file->setLastOffset(offset);
-    return object;
+    object = newIndirect(og, QPDF_Stream::create(this, og, object, stream_offset, length));
 }
  
 QPDFObjectHandle