I know that zlib/miniz provides compressBound which returns a upper bound of deflate/compress size, according to plain-text size. That's convenient.
Is there a function for inflate (zlib/miniz) which return upper bound of inflate/decompress size? Or a simple formula determines it? like:
decompress size = compressed size * factor
Yes, but I don't think you will find it very useful. The upper limit is 1032 times the size of the input data.