Something similar to this may have been asked earlier, I could not find an exact answer to my problem to decided to ask here. I am working with a 3rd party framework that has it's own classes defined to handle image files. It only accepts the file name and the whole implementation is around being able to open these filestreams and perform reads/writes. I'd like to input an image buffer (that I obtain through some pre-processing on an image open earlier) and feed it to this framework. The problem being I cannot feed a buffer to it, only a filename string.
I am looking at the best way to convert my buffer to a filestream so it can be seekable and be ingested by the framework. Please help me figure out what I should be looking at. I tried reading about streambuf (filebuf and stringbuf) and tried assigning the buffer to these types, but no success so far.
If the framework only takes a file name, then you have to pass it a file name. Which means the data must reside in the file system.
The portable answer is "write your data to a temporary file and pass the name of that".
On Unix, you might be able to use a named pipe and fork another thread to feed the data through the pipe...
But honestly, you are probably better off just using a temporary file. If you manage to open, read, and delete the file quickly enough, it most likely will never make it out to disk anyway, since the kernel will cache the data.
And if you are able to use a ramdisk (tmpfs), you can guarantee that everything happens in memory.
[edit]
One more thought. If you can modify your code base to operate on std::iostream instead of std::fstream, you can pass it a std::stringstream. They support all of the usual iostream operations on a memory buffer, including things like seeking.