nimble, uuid: generate UUIDs via std/sysrand, not pragmagic/uuids

configlet.nimble

@@ -23,15 +23,6 @@ requires "cligen#b962cf8bc0be847cbc1b4f77952775de765e9689"      # 1.5.19 (2021-0
 requires "jsony#2a2cc4331720b7695c8b66529dbfea6952727e7b"       # 1.1.3  (2022-01-03)
 requires "parsetoml#6e5e16179fa2db60f2f37d8b1af4128aaa9c8aaf"   # 0.7.1  (2023-08-06)
 requires "supersnappy#e4df8cb5468dd96fc5a4764028e20c8a3942f16a" # 2.1.3  (2022-06-12)
-requires "uuids#8cb8720b567c6bcb261bd1c0f7491bdb5209ad06"       # 0.1.11 (2021-01-15)
-# To make Nimble use the pinned `isaac` version, we must pin `isaac` after `uuids`
-# (which has `isaac` as a dependency).
-# Nimble still clones the latest `isaac` tag if there is no tag-versioned one
-# on-disk (e.g. at ~/.nimble/pkgs/isaac-0.1.3), and adds it to the path when
-# building, but (due to writing it later) the pinned version takes precedence.
-# Nimble will support lock files in the future, which should provide more robust
-# version pinning.
-requires "isaac#45a5cbbd54ff59ba3ed94242620c818b9aad1b5b"       # 0.1.3  (2017-11-16)
 
 task test, "Runs the test suite":
   exec "nim r ./tests/all_tests.nim"

src/create/approaches.nim

@@ -1,6 +1,6 @@
 import std/[os, strformat, strutils]
-import pkg/[jsony, uuids]
-import ".."/[helpers, sync/sync_common, types_track_config, types_approaches_config]
+import pkg/jsony
+import ".."/[helpers, sync/sync_common, types_track_config, types_approaches_config, uuid/uuid]
 
 func kebabToTitleCase(slug: Slug): string =
   result = newStringOfCap(slug.len)
@@ -44,7 +44,7 @@ proc createApproach*(approachSlug: Slug, exerciseSlug: Slug,
 
   if not approachExists:
     config.approaches.add ApproachConfig(
-      uuid: $genUUID(),
+      uuid: $genUuid(),
       slug: $approachSlug,
       title: title,
       blurb: "",

src/create/articles.nim

@@ -1,6 +1,6 @@
 import std/[os, strformat, strutils]
-import pkg/[jsony, uuids]
-import ".."/[helpers, sync/sync_common, types_track_config, types_articles_config]
+import pkg/jsony
+import ".."/[helpers, sync/sync_common, types_track_config, types_articles_config, uuid/uuid]
 
 func kebabToTitleCase(slug: Slug): string =
   result = newStringOfCap(slug.len)
@@ -40,7 +40,7 @@ proc createArticle*(articleSlug: Slug, exerciseSlug: Slug,
 
   if not articleExists:
     config.articles.add ArticleConfig(
-      uuid: $genUUID(),
+      uuid: $genUuid(),
       slug: $articleSlug,
       title: title,
       blurb: "",

src/uuid/uuid.nim

@@ -1,7 +1,30 @@
-import std/strformat
-import pkg/uuids
+import std/[strformat, sysrand]
 import ".."/logger
 
+type
+  Uuid* = array[16, byte]
+
+proc genUuid*: Uuid {.noinit.} =
+  ## Returns a version 4 UUID, using the system CSPRNG as the source of randomness.
+  if urandom(result):
+    result[6] = (result[6] and 0x0f) or 0x40 # Set version to 4
+    result[8] = (result[8] and 0x3f) or 0x80 # Set variant to 1
+  else:
+    stderr.writeLine "uuid: error: failed to generate UUID"
+    quit 1
+
+func `$`*(u: Uuid): string =
+  ## Returns the canonical string representation for the given UUID `u`.
+  result = newString(36)
+  result[8] = '-'
+  result[13] = '-'
+  result[18] = '-'
+  result[23] = '-'
+  for i, j in [0, 2, 4, 6, 9, 11, 14, 16, 19, 21, 24, 26, 28, 30, 32, 34]:
+    const hex = "0123456789abcdef"
+    result[j + 0] = hex[u[i] shr 4]
+    result[j + 1] = hex[u[i] and 0x0f]
+
 proc outputUuids(n: Positive) =
   ## Writes `n` version 4 UUIDs to stdout. Writes only 1000 UUIDs if `n` is
   ## greater than 1000.
@@ -12,7 +35,7 @@ proc outputUuids(n: Positive) =
   let numUuidsToGenerate = min(n, maxNumUuids)
   var s = newStringOfCap(numUuidsToGenerate * 37)
   for i in 1 .. numUuidsToGenerate:
-    s.add $genUUID()
+    s.add $genUuid()
     s.add '\n'
   stdout.write s
 

tests/test_uuid.nim

@@ -1,13 +1,19 @@
-import std/unittest
-import pkg/uuids
-import "."/lint/validators
+import std/[sets, strformat, strutils, unittest]
+import "."/[lint/validators, uuid/uuid]
 
 proc main =
-  suite "genUUID: returns a string that isUuidV4 says is valid":
-    test "1000 UUIDs":
-      for i in 1 .. 1000:
-        let uuid = $genUUID()
-        check isUuidV4(uuid)
+  suite "genUuid":
+    const n = 100_000
+    var uuids = initHashSet[Uuid](n)
+
+    test &"can generate {insertSep($n)} valid version 4 UUIDs":
+      for i in 1 .. n:
+        let uuid = genUuid()
+        check isUuidV4($uuid)
+        uuids.incl uuid
+
+    test "those UUIDs are distinct":
+      check uuids.len == n
 
 main()
 {.used.}