From 817e6885d9572012f133ed3f47a859c3e1df38c5 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 15 Apr 2026 07:44:55 +0000
Subject: [PATCH] Refactor toolExists to use direct Process execution for
 defense-in-depth

Replaced `toolExists` shell wrapper with a direct `Foundation.Process` execution of `/usr/bin/which` where `tool` is passed explicitly in the `arguments` array. Evaluates `process.terminationStatus == 0` after `process.waitUntilExit()`. Standard output/error is mapped to `FileHandle.nullDevice`.

Also documented findings in .jules/sentinel.md.

Co-authored-by: acebytes <2820910+acebytes@users.noreply.github.com>
---
 .jules/sentinel.md                          |  4 ++++
 Sources/Cacheout/Models/CacheCategory.swift | 19 +++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 .jules/sentinel.md

diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 0000000..dde8efc
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2024-04-15 - Command injection in CacheCategory probes
+**Vulnerability:** `CacheCategory.toolExists` passes user-supplied input to a shell via `/usr/bin/which \(tool)`, introducing command injection if the category allows dynamic inputs.
+**Learning:** Shell evaluation with string interpolation `\()` is unsafe. Passing dynamic inputs through `/bin/bash -c` risks evaluating shell operators.
+**Prevention:** Avoid shell evaluations where direct execution of `Process` with structured `arguments` is possible.
diff --git a/Sources/Cacheout/Models/CacheCategory.swift b/Sources/Cacheout/Models/CacheCategory.swift
index 7b3d942..c5ee6dc 100644
--- a/Sources/Cacheout/Models/CacheCategory.swift
+++ b/Sources/Cacheout/Models/CacheCategory.swift
@@ -186,8 +186,23 @@ struct CacheCategory: Identifiable, Hashable {
     }
 
     private func toolExists(_ tool: String) -> Bool {
-        let result = shell("/usr/bin/which \(tool)")
-        return result != nil && !result!.isEmpty
+        let process = Process()
+        process.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+        process.arguments = [tool]
+        process.standardOutput = FileHandle.nullDevice
+        process.standardError = FileHandle.nullDevice
+        process.environment = [
+            "PATH": "/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin",
+            "HOME": FileManager.default.homeDirectoryForCurrentUser.path
+        ]
+
+        do {
+            try process.run()
+            process.waitUntilExit()
+            return process.terminationStatus == 0
+        } catch {
+            return false
+        }
     }
 
     private func runProbe(_ command: String) -> String? {