From e5f4162b6178489181e3d7e7163ac12b7e0efc9d Mon Sep 17 00:00:00 2001
From: Julik Tarkhanov <me@julik.nl>
Date: Sun, 30 Dec 2018 17:56:22 +0100
Subject: Make Active Storage blob keys lowercase

Accommodate case-insensitive filesystems and database collations.
---
 .../lib/active_support/core_ext/securerandom.rb    | 26 +++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

(limited to 'activesupport/lib')

diff --git a/activesupport/lib/active_support/core_ext/securerandom.rb b/activesupport/lib/active_support/core_ext/securerandom.rb
index b4a491f5fd..ef812f7e1a 100644
--- a/activesupport/lib/active_support/core_ext/securerandom.rb
+++ b/activesupport/lib/active_support/core_ext/securerandom.rb
@@ -4,17 +4,18 @@ require "securerandom"
 
 module SecureRandom
   BASE58_ALPHABET = ("0".."9").to_a + ("A".."Z").to_a + ("a".."z").to_a - ["0", "O", "I", "l"]
+  BASE36_ALPHABET = ("0".."9").to_a + ("a".."z").to_a
+
   # SecureRandom.base58 generates a random base58 string.
   #
-  # The argument _n_ specifies the length, of the random string to be generated.
+  # The argument _n_ specifies the length of the random string to be generated.
   #
   # If _n_ is not specified or is +nil+, 16 is assumed. It may be larger in the future.
   #
-  # The result may contain alphanumeric characters except 0, O, I and l
+  # The result may contain alphanumeric characters except 0, O, I and l.
   #
   #   p SecureRandom.base58 # => "4kUgL2pdQMSCQtjE"
   #   p SecureRandom.base58(24) # => "77TMHrHJFvFDwodq8w7Ev2m7"
-  #
   def self.base58(n = 16)
     SecureRandom.random_bytes(n).unpack("C*").map do |byte|
       idx = byte % 64
@@ -22,4 +23,23 @@ module SecureRandom
       BASE58_ALPHABET[idx]
     end.join
   end
+
+  # SecureRandom.base36 generates a random base36 string in lowercase.
+  #
+  # The argument _n_ specifies the length of the random string to be generated.
+  #
+  # If _n_ is not specified or is +nil+, 16 is assumed. It may be larger in the future.
+  # This method can be used over +base58+ if a deterministic case key is necessary.
+  #
+  # The result will contain alphanumeric characters in lowercase.
+  #
+  #   p SecureRandom.base36 # => "4kugl2pdqmscqtje"
+  #   p SecureRandom.base36(24) # => "77tmhrhjfvfdwodq8w7ev2m7"
+  def self.base36(n = 16)
+    SecureRandom.random_bytes(n).unpack("C*").map do |byte|
+      idx = byte % 64
+      idx = SecureRandom.random_number(36) if idx >= 36
+      BASE36_ALPHABET[idx]
+    end.join
+  end
 end
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