Fixing bad usages of DataBuf (when it is empty)

app/actions.cpp

@@ -170,8 +170,8 @@ int setModeAndPrintStructure(Exiv2::PrintStructureOption option, const std::stri
   if (binary && option == Exiv2::kpsIccProfile) {
     std::stringstream output(std::stringstream::out | std::stringstream::binary);
     result = printStructure(output, option, path);
-    if (result == 0) {
     std::string str = output.str();
+    if (result == 0 && !str.empty()) {
       Exiv2::DataBuf iccProfile(str.size());
       Exiv2::DataBuf ascii(str.size() * 3 + 1);
       ascii.write_uint8(str.size() * 3, 0);
@@ -549,10 +549,12 @@ bool Print::printMetadatum(const Exiv2::Metadatum& md, const Exiv2::Image* pImag
   if (Params::instance().printItems_ & Params::prHex) {
     if (!first)
       std::cout << std::endl;
+    if (md.size() > 0) {
       Exiv2::DataBuf buf(md.size());
       md.copy(buf.data(), pImage->byteOrder());
       Exiv2::hexdump(std::cout, buf.c_data(), buf.size());
     }
+  }
   std::cout << std::endl;
   return true;
 }  // Print::printMetadatum

samples/addmoddel.cpp

@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
+
 // Sample program showing how to add, modify and delete Exif metadata.
 
 #include <exiv2/exiv2.hpp>

src/bmffimage.cpp

@@ -620,7 +620,7 @@ void BmffImage::printStructure(std::ostream& out, Exiv2::PrintStructureOption op
       break;  // do nothing
 
     case kpsIccProfile: {
-      out.write(iccProfile_.c_str(), iccProfile_.size());
+      out.write(iccProfile_.empty() ? nullptr : iccProfile_.c_str(), iccProfile_.size());
     } break;
 
 #ifdef EXV_HAVE_XMP_TOOLKIT

src/crwimage_int.cpp

@@ -853,7 +853,7 @@ void CrwMap::encodeBasic(const Image& image, const CrwMapping* pCrwMapping, Ciff
   auto ed = image.exifData().findKey(ek);
 
   // Set the new value or remove the entry
-  if (ed != image.exifData().end()) {
+  if (ed != image.exifData().end() && ed->size() > 0) {
     DataBuf buf(ed->size());
     ed->copy(buf.data(), pHead->byteOrder());
     pHead->add(pCrwMapping->crwTagId_, pCrwMapping->crwDir_, std::move(buf));

src/jpgimage.cpp

@@ -184,8 +184,9 @@ void JpegBase::readMetadata() {
 #ifdef EXIV2_DEBUG_MESSAGES
       std::cerr << "Found app13 segment, size = " << size << "\n";
 #endif
-      // Append to psBlob
+      if (buf.size() > 16) {  // Append to psBlob
         append(psBlob, buf.c_data(16), size - 16);
+      }
       // Check whether psBlob is complete
       if (!psBlob.empty() && Photoshop::valid(&psBlob[0], psBlob.size())) {
         --search;
@@ -745,9 +746,9 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
           bo = littleEndian;
           setByteOrder(bo);
         }
-        WriteMethod wm = ExifParser::encode(blob, rawExif.c_data(), rawExif.size(), bo, exifData_);
-        const byte* pExifData = rawExif.c_data();
+        const byte* pExifData = rawExif.empty() ? nullptr : rawExif.c_data();
         size_t exifSize = rawExif.size();
+        WriteMethod wm = ExifParser::encode(blob, pExifData, exifSize, bo, exifData_);
         if (wm == wmIntrusive) {
           pExifData = !blob.empty() ? &blob[0] : nullptr;
           exifSize = blob.size();
@@ -844,7 +845,7 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
         // IPTC block if there is no new IPTC data to write
         DataBuf newPsData = Photoshop::setIptcIrb(!psBlob.empty() ? psBlob.data() : nullptr, psBlob.size(), iptcData_);
         const long maxChunkSize = 0xffff - 16;
-        const byte* chunkStart = newPsData.c_data();
+        const byte* chunkStart = newPsData.empty() ? nullptr : newPsData.c_data();
         const byte* chunkEnd = newPsData.empty() ? nullptr : newPsData.c_data(newPsData.size() - 1);
         while (chunkStart < chunkEnd) {
           // Determine size of next chunk

src/pngchunk_int.cpp

@@ -56,6 +56,7 @@ void PngChunk::decodeTXTChunk(Image* pImage, const DataBuf& data, TxtChunkType t
 #ifdef EXIV2_DEBUG_MESSAGES
   std::cout << "Exiv2::PngChunk::decodeTXTChunk: TXT chunk data: " << std::string(arr.c_str(), arr.size()) << std::endl;
 #endif
+  if (!key.empty())
     parseChunkContent(pImage, key.c_data(), key.size(), arr);
 }
 
@@ -558,8 +559,10 @@ DataBuf PngChunk::readRawProfile(const DataBuf& text, bool iTXt) {
     return {};
   }
 
-  // Copy profile, skipping white space and column 1 "=" signs
+  if (info.empty())  // Early return
+    return info;
 
+  // Copy profile, skipping white space and column 1 "=" signs
   unsigned char* dp = info.data();  // decode pointer
   size_t nibbles = length * 2;
 

src/pngimage.cpp

@@ -234,8 +234,10 @@ void PngImage::printStructure(std::ostream& out, PrintStructureOption option, in
       }
 
       DataBuf buff(dataOffset);
+      if (dataOffset > 0) {
         bufRead = io_->read(buff.data(), dataOffset);
         enforce(bufRead == dataOffset, ErrorCode::kerFailedToReadImageData);
+      }
       io_->seek(restore, BasicIo::beg);
 
       // format output
@@ -426,7 +428,9 @@ void PngImage::readMetadata() {
     if (chunkType == "IEND" || chunkType == "IHDR" || chunkType == "tEXt" || chunkType == "zTXt" ||
         chunkType == "eXIf" || chunkType == "iTXt" || chunkType == "iCCP") {
       DataBuf chunkData(chunkLength);
+      if (chunkLength > 0) {
         readChunk(chunkData, *io_);  // Extract chunk data.
+      }
 
       if (chunkType == "IEND") {
         return;  // Last chunk found: we stop parsing.

src/rafimage.cpp

@@ -259,13 +259,15 @@ void RafImage::readMetadata() {
   if (io_->seek(jpg_img_off + 12, BasicIo::beg) != 0)
     throw Error(ErrorCode::kerFailedToReadImageData);
 
+  if (!buf.empty()) {
     io_->read(buf.data(), buf.size());
     if (io_->error() || io_->eof())
       throw Error(ErrorCode::kerFailedToReadImageData);
+  }
 
-  io_->seek(0, BasicIo::beg);  // rewind
+  //  io_->seek(0, BasicIo::beg);  // rewind
 
-  ByteOrder bo = TiffParser::decode(exifData_, iptcData_, xmpData_, buf.c_data(), buf.size());
+  ByteOrder bo = TiffParser::decode(exifData_, iptcData_, xmpData_, buf.empty() ? nullptr : buf.c_data(), buf.size());
 
   exifData_["Exif.Image2.JPEGInterchangeFormat"] = getULong(jpg_img_offset, bigEndian);
   exifData_["Exif.Image2.JPEGInterchangeFormatLength"] = getULong(jpg_img_length, bigEndian);

src/tiffcomposite_int.cpp

@@ -976,7 +976,7 @@ uint32_t TiffDirectory::writeDirEntry(IoWrapper& ioWrapper, ByteOrder byteOrder,
 
 uint32_t TiffEntryBase::doWrite(IoWrapper& ioWrapper, ByteOrder byteOrder, int64_t /*offset*/, uint32_t /*valueIdx*/,
                                 uint32_t /*dataIdx*/, uint32_t& /*imageIdx*/) {
-  if (!pValue_)
+  if (!pValue_ || pValue_->size() == 0)
     return 0;
 
   DataBuf buf(pValue_->size());
@@ -1182,6 +1182,7 @@ uint32_t TiffDataEntry::doWriteData(IoWrapper& ioWrapper, ByteOrder /*byteOrder*
     return 0;
 
   DataBuf buf = pValue()->dataArea();
+  if (!buf.empty())
     ioWrapper.write(buf.c_data(), buf.size());
   // Align data to word boundary
   uint32_t align = (buf.size() & 1);

src/webpimage.cpp

@@ -162,11 +162,13 @@ void WebPImage::doWriteMetadata(BasicIo& outIo) {
     // Check that `size_u32` is safe to cast to `long`.
     enforce(size_u32 <= std::numeric_limits<uint32_t>::max(), Exiv2::ErrorCode::kerCorruptedMetadata);
     DataBuf payload(size_u32);
+    if (!payload.empty()) {
       io_->readOrThrow(payload.data(), payload.size(), Exiv2::ErrorCode::kerCorruptedMetadata);
       if (payload.size() % 2) {
         byte c = 0;
         io_->readOrThrow(&c, 1, Exiv2::ErrorCode::kerCorruptedMetadata);
       }
+    }
 
     /* Chunk with information about features
      used in the file. */
@@ -528,7 +530,9 @@ void WebPImage::decodeChunks(long filesize) {
 
     DataBuf payload(size);
 
-    if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8X) && !has_canvas_data) {
+    if (payload.empty()) {
+      io_->seek(size, BasicIo::cur);
+    } else if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8X) && !has_canvas_data) {
       enforce(size >= 10, Exiv2::ErrorCode::kerCorruptedMetadata);
 
       has_canvas_data = true;

tests/bugfixes/github/test_issue_960.py

@@ -14,8 +14,7 @@ class WebPImageGetHeaderOffset(metaclass=CaseMeta):
     commands = ["$exiv2 $filename1"]
     stdout = [""]
     stderr = [
-"""Warning: Failed to decode Exif metadata.
-Exiv2 exception in print action for file $filename1:
+"""Exiv2 exception in print action for file $filename1:
 $kerCorruptedMetadata
 """
 ]