(PHP 4, PHP 5, PHP 7)
Seek on a gz-file pointer
int gzseek ( resource $zp, int $offset [, int $whence = SEEK_SET ] )
Sets the file position indicator for the given file pointer to the given offset byte into the file stream. Equivalent to calling (in C) gzseek(zp, offset, SEEK_SET).
If the file is opened for reading, this function is emulated but can be extremely slow. If the file is opened for writing, only forward seeks