From 28bcc7fb2416ac5c9b0f0b24172416560b03797b Mon Sep 17 00:00:00 2001
From: Raito Bezarius <raito@lix.systems>
Date: Thu, 21 Aug 2025 14:36:10 +0000
Subject: [PATCH] =?UTF-8?q?Revert=20"libutil:=20use=20OS=E2=80=90provided?=
 =?UTF-8?q?=20entropy=20for=20temporary=20filenames"?=
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Revert submission 3850

Reason for revert: caused multiple regressions noticed in https://git.lix.systems/lix-project/lix/issues/975 and https://git.lix.systems/lix-project/lix/issues/966 (suspected).

Root cause analysis has not been done yet and this breaks Lix on Darwin on HEAD.

Reverted changes: /q/submissionid:3850

Change-Id: Icdbb89bbf031581250fbda3c9ab9095e7af10ec1
---
 lix/libutil/file-system.cc | 13 ++++---------
 lix/libutil/file-system.hh |  8 ++++----
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/lix/libutil/file-system.cc b/lix/libutil/file-system.cc
index 6a62e0dd1..4464fccf5 100644
--- a/lix/libutil/file-system.cc
+++ b/lix/libutil/file-system.cc
@@ -686,16 +686,11 @@ Path createTempSubdir(const Path & parent, const Path & prefix,
     }
 }
 
-Path makeTempPath(const Path & root, const Path & prefix)
+Path makeTempPath(const Path & root, const Path & suffix)
 {
-    static thread_local std::random_device generator{};
-    std::uniform_int_distribution<uint64_t> uniform_dist{};
-    const uint64_t entropy[2] = {uniform_dist(generator), uniform_dist(generator)};
-    const std::string unique = base32Encode(std::string_view(
-        reinterpret_cast<const char *>(entropy),
-        sizeof(entropy)
-    ));
-    return fmt("%s%s-%s", root, prefix, unique);
+    // start the counter at a random value to minimize issues with preexisting temp paths
+    static std::atomic_uint_fast32_t counter(std::random_device{}());
+    return fmt("%1%%2%-%3%-%4%", root, suffix, getpid(), counter.fetch_add(1, std::memory_order_relaxed));
 }
 
 Path makeTempSiblingPath(const Path & path)
diff --git a/lix/libutil/file-system.hh b/lix/libutil/file-system.hh
index fb8b93a80..cdcb61a65 100644
--- a/lix/libutil/file-system.hh
+++ b/lix/libutil/file-system.hh
@@ -311,12 +311,12 @@ Path createTempSubdir(const Path & parent, const Path & prefix = "nix",
     bool includePid = true, bool useGlobalCounter = true, mode_t mode = 0755);
 
 /**
- * Return temporary path constructed by appending to a root path.
+ * Return temporary path constructed by appending a suffix to a root path.
  *
- * The constructed path looks like `<root><prefix>-<unique>`. To create a
- * path nested in a directory, provide a root ending with `/`.
+ * The constructed path looks like `<root><suffix>-<pid>-<unique>`. To create a
+ * path nested in a directory, provide a suffix starting with `/`.
  */
-Path makeTempPath(const Path & root, const Path & prefix = ".tmp");
+Path makeTempPath(const Path & root, const Path & suffix = ".tmp");
 
 /**
  * Return temporary path in the same directory as a given path.