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Hi!
 
With Lua 5.4 some of my old scripts stop working due to io.popen() refusing to support binary reading mode on Windows.
 
This is an example to illustrate the problem:
 
Lua 5.3.4  Copyright (C) 1994-2017 Lua.org, PUC-Rio
> io.popen('lua.exe -e"print(string.char(49,26,50))"', "r"):read"*a":byte(1,-1)
49
> io.popen('lua.exe -e"print(string.char(49,26,50))"', "rb"):read"*a":byte(1,-1)
49      26      50      13      10
 
Lua 5.4.2  Copyright (C) 1994-2020 Lua.org, PUC-Rio
> io.popen('lua.exe -e"print(string.char(49,26,50))"', "r"):read"*a":byte(1,-1)
49
> io.popen('lua.exe -e"print(string.char(49,26,50))"', "rb"):read"*a":byte(1,-1)
stdin:1: bad argument #2 to 'popen' (invalid mode)
stack traceback:
        [C]: in function 'io.popen'
        stdin:1: in main chunk
        [C]: in ?
 
Why does Lua 5.4 not allow me to read verbatim output of an external Windows process?