size_t RenderV1ToFile(ID3_TagImpl& tag, fstream& file)
{
if (!file)
{
return 0;
}
if (ID3_V1_LEN > tag.GetAppendedBytes())
{
file.seekp(0, ios::end);
}
else
{
// We want to check if there is already an id3v1 tag, so we can write over
// it. First, seek to the beginning of any possible id3v1 tag
file.seekg(0-ID3_V1_LEN, ios::end);
char sID[ID3_V1_LEN_ID];
// Read in the TAG characters
file.read(sID, ID3_V1_LEN_ID);
// If those three characters are TAG, then there's a preexisting id3v1 tag,
// so we should set the file cursor so we can overwrite it with a new tag.
if (memcmp(sID, "TAG", ID3_V1_LEN_ID) == 0)
{
file.seekp(0-ID3_V1_LEN, ios::end);
}
// Otherwise, set the cursor to the end of the file so we can append on
// the new tag.
else
{
file.seekp(0, ios::end);
}
}
ID3_IOStreamWriter out(file);
id3::v1::render(out, tag);
return ID3_V1_LEN;
}
size_t ID3_GetDataSize(const ID3_TagImpl& tag)
{
return tag.GetFileSize() - tag.GetPrependedBytes() - tag.GetAppendedBytes();
}
