Rewind pointer positioning related issues

Rewind pointer positioning problem!
As if the rewind positioning pointer error what problem?
The code is as follows:
$fpstr = fopen ("Php://input", "RB");
... Slightly
$bin = Fread ($fpstr, 2); Read-only 2 bytes
... Slightly
Fseek ($fpstr, 0); Error here

We need to use $FPSTR resources again.
$realSize = Stream_copy_to_stream ($fpstr, $tmp); The newly created file is two bytes short

How to position the pointer at the beginning of the $FPSTR to make the file complete.

------Solution--------------------
$fpstr = fopen ("Php://input", "RB");

Php://input is the input stream
You can't do the positioning operation with convection.

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