Pipe-through with NUL-delimited input

#!/usr/bin/env tclsh

set find_done 0
set find_path $env(HOME)

proc _pipe_chunk {ichan} {

  global find_done
  set chunk {}

  # Read a single character from $ichan.
  # See whether it's NUL.
  # If not, append it to $chunk.
  # Return $chunk when it's complete (NUL encountered).
  # Handle occurrence of EOF while doing this.

  while {true} {
    set char [read $ichan 1]
    if {[eof $ichan]} {
      close $ichan
      set find_done 1
      break
    } elseif {$char == "\0"} {
      puts $chunk
      break
    } else {
      set chunk ${chunk}${char}
    }
  }
}

set find_out [open "| find $find_path -type f -print0" r]
chan event $find_out readable [list _pipe_chunk $find_out]
#chan configure $find_out -buffering line

vwait $find_done