Read the file with name filename, and put its content in a newly allocated buffer or map it with mmap() when available. In case of success set *bufptr to the read or mmapped buffer, and *size to the size in bytes of the buffer in *bufptr. Unlike mmap this function succeeds with zero sized files, in this case *bufptr will be set to NULL and *size will be set to 0. The returned buffer must be released with av_file_unmap().
Unmap or free the buffer bufptr created by av_file_map().
Wrapper to work around the lack of mkstemp() on mingw. Also, tries to create file in /tmp first, if possible. *prefix can be a character constant; *filename will be allocated internally. @return file descriptor of opened file (or negative value corresponding to an AVERROR code on error) and opened file name in **filename. @note On very old libcs it is necessary to set a secure umask before calling this, av_tempfile() can't call umask itself as it is used in libraries and could interfere with the calling application. @deprecated as fd numbers cannot be passed saftely between libs on some platforms