bug#30116: [PATCH] `substitute' crashes when file contains NUL characters (core-updates))

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

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From 9891e428eae0ed24e0d61862b3f5e298606b79eb Mon Sep 17 00:00:00 2001
From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Date: Sun, 14 Jan 2018 20:31:33 -0500
Subject: [PATCH] utils: Prevent substitute from crashing on files containing
 NUL chars.

Fixes issue #30116.

* guix/build/utils.scm (substitute): Add condition to skip lines containing
the NUL character.
---
 guix/build/utils.scm | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index 7391307c8..975f4e70a 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2013 Andreas Enge <andreas@enge.fr>
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2018 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -621,28 +622,35 @@ PROC as (PROC LINE MATCHES); PROC must return the line that will be written as
 a substitution of the original line.  Be careful about using '$' to match the
 end of a line; by itself it won't match the terminating newline of a line."
   (let ((rx+proc  (map (match-lambda
-                        (((? regexp? pattern) . proc)
-                         (cons pattern proc))
-                        ((pattern . proc)
-                         (cons (make-regexp pattern regexp/extended)
-                               proc)))
+                         (((? regexp? pattern) . proc)
+                          (cons pattern proc))
+                         ((pattern . proc)
+                          (cons (make-regexp pattern regexp/extended)
+                                proc)))
                        pattern+procs)))
     (with-atomic-file-replacement file
       (lambda (in out)
         (let loop ((line (read-line in 'concat)))
-          (if (eof-object? line)
-              #t
-              (let ((line (fold (lambda (r+p line)
-                                  (match r+p
-                                    ((regexp . proc)
-                                     (match (list-matches regexp line)
-                                       ((and m+ (_ _ ...))
-                                        (proc line m+))
-                                       (_ line)))))
-                                line
-                                rx+proc)))
-                (display line out)
-                (loop (read-line in 'concat)))))))))
+          (cond
+           ((eof-object? line)
+            #t)
+           ((string-contains line (make-string 1 #\nul))
+            ;; The regexp functions of the GNU C library (which Guile uses)
+            ;; cannot deal with NUL characters, so skip to the next line.
+            (format #t "skipping line with NUL characters: ~s\n" line)
+            (loop (read-line in 'concat)))
+           (else
+            (let ((line (fold (lambda (r+p line)
+                                (match r+p
+                                  ((regexp . proc)
+                                   (match (list-matches regexp line)
+                                     ((and m+ (_ _ ...))
+                                      (proc line m+))
+                                     (_ line)))))
+                              line
+                              rx+proc)))
+              (display line out)
+              (loop (read-line in 'concat))))))))))
 
 
 (define-syntax let-matches
-- 
2.15.1