gnu: less: Build fix for the Hurd.

* gnu/packages/patches/less-hurd-path-max.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/less.scm (less): Use it.

gnu/local.mk

@@ -1110,6 +1110,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/ldc-bootstrap-disable-tests.patch	\
   %D%/packages/patches/ldc-disable-phobos-tests.patch		\
   %D%/packages/patches/leela-zero-gtest.patch			\
+  %D%/packages/patches/less-hurd-path-max.patch			\
   %D%/packages/patches/liba52-enable-pic.patch			\
   %D%/packages/patches/liba52-link-with-libm.patch		\
   %D%/packages/patches/liba52-set-soname.patch			\

gnu/packages/less.scm

@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2012 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2019 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -19,6 +20,7 @@
 
 (define-module (gnu packages less)
   #:use-module (guix licenses)
+  #:use-module (gnu packages)
   #:use-module (gnu packages ncurses)
   #:use-module (guix packages)
   #:use-module (guix download)
@@ -35,6 +37,7 @@ (define-public less
                                  version ".tar.gz")
                   (string-append "http://www.greenwoodsoftware.com/less/less-"
                                  version ".tar.gz")))
+       (patches (search-patches "less-hurd-path-max.patch"))
        (sha256
         (base32 "0ggyjl3yzn7c450zk1rixi9ls6asdhgqynhk34zsd0ckhmsm45pz"))))
     (build-system gnu-build-system)

gnu/packages/patches/less-hurd-path-max.patch

@@ -0,0 +1,36 @@
+Avoid usage of PATH_MAX.
+
+Submitted to bug-less@gnu.org.
+
+From ef652341ed8b2c14ac40312ccd4ed329cb69fd0c Mon Sep 17 00:00:00 2001
+From: Jan Nieuwenhuizen <janneke@gnu.org>
+Date: Sat, 7 Mar 2020 14:57:19 +0100
+Subject: [PATCH] Avoid usage of PATH_MAX.
+
+* filename.c (lrealpath): Have realpath allocate the buffer.  Fixes
+compilation on the Hurd and avoids possible buffer overflow on other
+systems.
+---
+ filename.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/filename.c b/filename.c
+index e420837..faa71b0 100644
+--- a/filename.c
++++ b/filename.c
+@@ -795,9 +795,9 @@ lrealpath(path)
+ 	char *path;
+ {
+ #if HAVE_REALPATH
+-	char rpath[PATH_MAX];
+-	if (realpath(path, rpath) != NULL)
+-		return (save(rpath));
++	char *rpath = NULL;
++	if ((rpath = realpath(path, rpath)) != NULL)
++		return (rpath);
+ #endif
+ 	return (save(path));
+ }
+-- 
+2.24.0
+