use actual array instead of C string

C strings in C++ have an extra member for NULL termination. replacing
copy_n with copy like this will allow eventual conversion to
std::ranges.

Signed-off-by: Rosen Penev <[email protected]>

Author: neheb

src/jpgimage.cpp

@@ -73,10 +73,15 @@ constexpr Internal::TagDetails jpegProcessMarkerTags[] = {
     {sof15_, N_("Lossless, differential arithmetic coding")},
 };
 
-constexpr auto exifId_ = "Exif\0\0";  //!< Exif identifier
-// constexpr auto jfifId_ = "JFIF\0";                         //!< JFIF identifier
-constexpr auto xmpId_ = "http://ns.adobe.com/xap/1.0/\0";  //!< XMP packet identifier
-constexpr auto iccId_ = "ICC_PROFILE\0";                   //!< ICC profile identifier
+constexpr std::array<byte, 6> exifId_{
+    'E', 'x', 'i', 'f', '\0', '\0',
+};  //!< Exif identifier
+constexpr std::array<byte, 29> xmpId_{
+    'h', 't', 't', 'p', ':', '/', '/', 'n', 's', '.', 'a', 'd', 'o', 'b', 'e',
+    '.', 'c', 'o', 'm', '/', 'x', 'a', 'p', '/', '1', '.', '0', '/', 0x0,
+};  //!< XMP packet identifier
+// constexpr auto jfifId_ = "JFIF";     //!< JFIF identifier
+constexpr auto iccId_ = "ICC_PROFILE";  //!< ICC profile identifier
 
 constexpr bool inRange(int lo, int value, int hi) {
   return lo <= value && value <= hi;
@@ -183,7 +188,7 @@ void JpegBase::readMetadata() {
     }
 
     if (!foundExifData && marker == app1_ && size >= 8  // prevent out-of-bounds read in memcmp on next line
-        && buf.cmpBytes(2, exifId_, 6) == 0) {
+        && buf.cmpBytes(2, exifId_.data(), 6) == 0) {
       ByteOrder bo = ExifParser::decode(exifData_, buf.c_data(8), size - 8);
       setByteOrder(bo);
       if (size > 8 && byteOrder() == invalidByteOrder) {
@@ -195,7 +200,7 @@ void JpegBase::readMetadata() {
       --search;
       foundExifData = true;
     } else if (!foundXmpData && marker == app1_ && size >= 31  // prevent out-of-bounds read in memcmp on next line
-               && buf.cmpBytes(2, xmpId_, 29) == 0) {
+               && buf.cmpBytes(2, xmpId_.data(), 29) == 0) {
       xmpPacket_.assign(buf.c_str(31), size - 31);
       if (!xmpPacket_.empty() && XmpParser::decode(xmpData_, xmpPacket_)) {
 #ifndef SUPPRESS_WARNINGS
@@ -646,7 +651,7 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
       insertPos = count + 1;
     } else if (skipApp1Exif == notfound && marker == app1_ &&
                buf.size() >= 8 &&  // prevent out-of-bounds read in memcmp on next line
-               buf.cmpBytes(2, exifId_, 6) == 0) {
+               buf.cmpBytes(2, exifId_.data(), 6) == 0) {
       skipApp1Exif = count;
       ++search;
       if (buf.size() > 8) {
@@ -655,7 +660,7 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
       }
     } else if (skipApp1Xmp == notfound && marker == app1_ &&
                buf.size() >= 31 &&  // prevent out-of-bounds read in memcmp on next line
-               buf.cmpBytes(2, xmpId_, 29) == 0) {
+               buf.cmpBytes(2, xmpId_.data(), 29) == 0) {
       skipApp1Xmp = count;
       ++search;
     } else if (marker == app2_ && buf.size() >= 13 &&  // prevent out-of-bounds read in memcmp on next line
@@ -756,7 +761,7 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
           if (exifSize > 0xffff - 8)
             throw Error(ErrorCode::kerTooLargeJpegSegment, "Exif");
           us2Data(tmpBuf.data() + 2, static_cast<uint16_t>(exifSize + 8), bigEndian);
-          std::copy_n(exifId_, 6, tmpBuf.begin() + 4);
+          std::copy(exifId_.begin(), exifId_.end(), tmpBuf.begin() + 4);
           if (outIo.write(tmpBuf.data(), 10) != 10)
             throw Error(ErrorCode::kerImageWriteFailed);
 
@@ -783,7 +788,7 @@ void JpegBase::doWriteMetadata(BasicIo& outIo) {
         if (xmpPacket_.size() > 0xffff - 31)
           throw Error(ErrorCode::kerTooLargeJpegSegment, "XMP");
         us2Data(tmpBuf.data() + 2, static_cast<uint16_t>(xmpPacket_.size() + 31), bigEndian);
-        std::copy_n(xmpId_, 29, tmpBuf.begin() + 4);
+        std::copy(xmpId_.begin(), xmpId_.end(), tmpBuf.begin() + 4);
         if (outIo.write(tmpBuf.data(), 33) != 33)
           throw Error(ErrorCode::kerImageWriteFailed);
 

src/pngimage.cpp

@@ -529,11 +529,9 @@ void PngImage::doWriteMetadata(BasicIo& outIo) {
     if (bufRead != dataOffset + 4)
       throw Error(ErrorCode::kerInputDataReadFailed);
 
-    char szChunk[5];
-    std::copy(cheaderBuf.begin() + 4, cheaderBuf.end(), szChunk);
-    szChunk[4] = 0;
+    const std::string szChunk(cheaderBuf.begin() + 4, cheaderBuf.end());
 
-    if (!strcmp(szChunk, "IEND")) {
+    if (szChunk == "IEND") {
       // Last chunk found: we write it and done.
 #ifdef EXIV2_DEBUG_MESSAGES
       std::cout << "Exiv2::PngImage::doWriteMetadata: Write IEND chunk (length: " << dataOffset << ")\n";
@@ -542,14 +540,14 @@ void PngImage::doWriteMetadata(BasicIo& outIo) {
         throw Error(ErrorCode::kerImageWriteFailed);
       return;
     }
-    if (!strcmp(szChunk, "eXIf") || !strcmp(szChunk, "iCCP")) {
+    if (szChunk == "eXIf" || szChunk == "iCCP") {
       // do nothing (strip): Exif metadata is written following IHDR
       // together with the ICC profile as fresh eXIf and iCCP chunks
 #ifdef EXIV2_DEBUG_MESSAGES
       std::cout << "Exiv2::PngImage::doWriteMetadata: strip " << szChunk << " chunk (length: " << dataOffset << ")"
                 << '\n';
 #endif
-    } else if (!strcmp(szChunk, "IHDR")) {
+    } else if (szChunk == "IHDR") {
 #ifdef EXIV2_DEBUG_MESSAGES
       std::cout << "Exiv2::PngImage::doWriteMetadata: Write IHDR chunk (length: " << dataOffset << ")\n";
 #endif
@@ -646,7 +644,7 @@ void PngImage::doWriteMetadata(BasicIo& outIo) {
           throw Error(ErrorCode::kerImageWriteFailed);
         }
       }
-    } else if (!strcmp(szChunk, "tEXt") || !strcmp(szChunk, "zTXt") || !strcmp(szChunk, "iTXt")) {
+    } else if (szChunk == "tEXt" || szChunk == "zTXt" || szChunk == "iTXt") {
       DataBuf key = PngChunk::keyTXTChunk(chunkBuf, true);
       if (!key.empty() && (compare("Raw profile type exif", key) || compare("Raw profile type APP1", key) ||
                            compare("Raw profile type iptc", key) || compare("Raw profile type xmp", key) ||

src/preview.cpp

@@ -943,10 +943,9 @@ DataBuf makePnm(size_t width, size_t height, const DataBuf& rgb) {
   }
 
   const std::string header = "P6\n" + std::to_string(width) + " " + std::to_string(height) + "\n255\n";
-  const auto headerBytes = reinterpret_cast<const byte*>(header.data());
 
   dest = DataBuf(header.size() + rgb.size());
-  std::copy_n(headerBytes, header.size(), dest.begin());
+  std::copy(header.begin(), header.end(), dest.begin());
   std::copy(rgb.cbegin(), rgb.cend(), dest.begin() + header.size());
   return dest;
 }