# Generate a Random string out of characters provided
# Version 20141208 Thomas Stokkeland (c) License GNU GPL v2
#
# Example:
#    !insertmacro GenerateRandomString "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRST1234567890" 15
#    pop $0
# Result is put on the stack
#
# Requirements:
#              ${rnd} - from http://nsis.sourceforge.net/Rnd
#
!Macro GenerateRandomString VALID_CHARS STRING_LENGTH
   # Preserve vars
   push $5
   push $6
   push $7
   push $8
   push $9
   # DetailPrint "GenerateRandomString: ${VALID_CHARS} : ${STRING_LENGTH}"
   StrCpy $5 ""
   GenerateRandomStringLoop:
      StrLen $8 ${VALID_CHARS} # Length of available chars
      IntOp $8 $8 - 1 # reduce by one to work as index for strcpy
      ${rnd} $9 0 $8 # Get a random number in range
      StrCpy $6 ${VALID_CHARS} 1 $9 # getting the next character
      StrCpy $5 $5$6 # adding to result string
      StrLen $8 $5 # Check if we have enough
      IntCmpU $8 ${STRING_LENGTH} 0 GenerateRandomStringLoop 0
   # restore vars and put our result on the stack
   pop $9
   pop $8
   pop $7
   pop $6
   push $5
   exch
   pop $5
!MacroEnd