[bug#55673] [PATCH v3] cache: Catch invalid 'last-expiry-cleanup'.

[zimoun]

Fixes <http://issues.guix.gnu.org/55638>.

* guix/cache.scm (maybe-remove-expired-cache-entries)[last-expiry-date]: Check
if the value is a valid integer.
* tests/cache.scm: Test it.
---
 guix/cache.scm  | 20 +++++++++++++++-----
 tests/cache.scm | 22 ++++++++++++++++++++++
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/guix/cache.scm b/guix/cache.scm
index 51009809bd..9727a9eb58 100644
--- a/guix/cache.scm
+++ b/guix/cache.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2020, 2021 Ludovic Courtès 
<ludo@gnu.org>
+;;; Copyright © 2022 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -17,9 +18,11 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (guix cache)
+  #:use-module ((guix utils) #:select (with-atomic-file-output))
   #:use-module (srfi srfi-19)
   #:use-module (srfi srfi-26)
   #:use-module (ice-9 match)
+  #:use-module ((ice-9 textual-ports) #:select (get-string-all))
   #:export (obsolete?
             delete-file*
             file-expiration-time
@@ -91,10 +94,17 @@ (define expiry-file
     (string-append cache "/last-expiry-cleanup"))
 
   (define last-expiry-date
-    (catch 'system-error
-      (lambda ()
-        (call-with-input-file expiry-file read))
-      (const 0)))
+    (let ((str (catch 'system-error
+                   (lambda ()
+                     (call-with-input-file expiry-file get-string-all))
+                   (const "0"))))
+      ;; Handle empty or corrupted 'expiry-file' when 'write' below is
+      ;; interrupted before being complete (e.g., SIGINT with C-c) or when
+      ;; the filesystem crashes.
+      (if (or (string-index str #\e)  ; Handle value out of range
+              (string-index str #\E)) ; (e.g., 1234567890 -> 12E4567890)
+       0
+       (or (string->number str) 0))))
 
   (when (obsolete? last-expiry-date now cleanup-period)
     (remove-expired-cache-entries (cache-entries cache)
@@ -103,7 +113,7 @@ (define last-expiry-date
                                   #:delete-entry delete-entry)
     (catch 'system-error
       (lambda ()
-        (call-with-output-file expiry-file
+        (with-atomic-file-output expiry-file
           (cute write (time-second now) <>)))
       (lambda args
         ;; ENOENT means CACHE does not exist.
diff --git a/tests/cache.scm b/tests/cache.scm
index 80b44d69aa..bd6fd64a22 100644
--- a/tests/cache.scm
+++ b/tests/cache.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2017, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2022 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -74,6 +75,27 @@ (define-syntax-rule (test-cache-cleanup cache exp ...)
       (lambda (port)
         (display 0 port)))))
 
+(test-equal "maybe-remove-expired-cache-entries, empty cache"
+  '("a" "b" "c")
+  (test-cache-cleanup cache
+    (call-with-output-file (string-append cache "/last-expiry-cleanup")
+      (lambda (port)
+        (display "" port)))))
+
+(test-equal "maybe-remove-expired-cache-entries, corrupted cache"
+  '("a" "b" "c")
+  (test-cache-cleanup cache
+    (call-with-output-file (string-append cache "/last-expiry-cleanup")
+      (lambda (port)
+        (display "1\"34657890" port)))))
+
+(test-equal "maybe-remove-expired-cache-entries, corrupted cache of out range"
+  '("a" "b" "c")
+  (test-cache-cleanup cache
+    (call-with-output-file (string-append cache "/last-expiry-cleanup")
+      (lambda (port)
+        (display "12E4567890" port)))))
+
 (test-end "cache")
 
 ;;; Local Variables:

base-commit: 38bf6c7d0cb588e8d4546db7d2e0bae2ec25183d
-- 
2.36.0