Reads to EOF on the given gz-file pointer from the current position and writes the (uncompressed) results to standard output.
注: You may need to call gzrewind() to reset the file pointer to the beginning of the file if you have already written data to it.
提示: If you just want to dump the contents of a file to the output buffer, without first modifying it or seeking to a particular offset, you may want to use the readgzfile() function, which saves you the gzopen() call.
The gz-file pointer. It must be valid, and must point to a file successfully opened by gzopen().