package/can-utils: enable compilation on MMU-less systems

Systems that lack a MMU cannot use fork() to create the child process.
The added upstream patch does not compile the affected programs on
MMU-less systems.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/can-utils/0001-Don-t-compile-programs-using-fork-on-MMU-less-system.patch

@@ -0,0 +1,257 @@
+From 5ed3b4ded6cf3e4de6fc8c8739b84231b0285b0e Mon Sep 17 00:00:00 2001
+From: Dario Binacchi <dario.binacchi@amarulasolutions.com>
+Date: Fri, 5 May 2023 08:57:45 +0200
+Subject: [PATCH] Don't compile programs using fork() on MMU-less systems
+
+Systems that lack a MMU cannot use fork() to create the child process.
+The patch does not compile the affected programs on MMU-less systems.
+
+Co-developed-by: Marc Kleine-Budde <mkl@pengutronix.de>
+Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
+Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
+Upstream: https://github.com/linux-can/can-utils/commit/5ed3b4ded6cf3e4de6fc8c8739b84231b0285b0e
+---
+ CMakeLists.txt | 15 ++++++++++++---
+ GNUmakefile.am | 10 +++++++---
+ Makefile       | 16 +++++++++++++---
+ check_cc.sh    | 16 ++++++++++++++++
+ configure.ac   |  2 ++
+ fork_test.c    | 27 +++++++++++++++++++++++++++
+ 6 files changed, 77 insertions(+), 9 deletions(-)
+ create mode 100755 check_cc.sh
+ create mode 100644 fork_test.c
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 09ccd805de66..aee8ff7fca02 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -2,6 +2,7 @@ cmake_minimum_required(VERSION 3.3)
+ 
+ project(can-utils LANGUAGES C)
+ 
++include (CheckFunctionExists)
+ include (CheckSymbolExists)
+ include (GNUInstallDirs)
+ 
+@@ -25,12 +26,13 @@ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DSCM_TXTIME=SO_TXTIME")
+ include_directories (.)
+ include_directories (./include)
+ 
++check_function_exists(fork HAVE_FORK)
++
+ set(PROGRAMS_CANLIB
+     asc2log
+     canbusload
+     candump
+     cangen
+-    canlogserver
+     canplayer
+     cansend
+     cansequence
+@@ -39,6 +41,10 @@ set(PROGRAMS_CANLIB
+     slcanpty
+ )
+ 
++if(HAVE_FORK)
++    list(APPEND PROGRAMS_CANLIB canlogserver)
++endif()
++
+ set(PROGRAMS_J1939
+     j1939acd
+     j1939cat
+@@ -49,7 +55,6 @@ set(PROGRAMS_J1939
+ 
+ set(PROGRAMS
+     ${PROGRAMS_CANLIB}
+-    bcmserver
+     canfdtest
+     cangw
+     cansniffer
+@@ -57,13 +62,17 @@ set(PROGRAMS
+     isotpperf
+     isotprecv
+     isotpsend
+-    isotpserver
+     isotpsniffer
+     isotptun
+     slcan_attach
+     slcand
+ )
+ 
++if(HAVE_FORK)
++    list(APPEND PROGRAMS bcmserver)
++    list(APPEND PROGRAMS isotpserver)
++endif()
++
+ add_executable(can-calc-bit-timing
+     calc-bit-timing/can-calc-bit-timing.c
+ )
+diff --git a/GNUmakefile.am b/GNUmakefile.am
+index 5a7ad75f682e..e818754db3a4 100644
+--- a/GNUmakefile.am
++++ b/GNUmakefile.am
+@@ -75,14 +75,12 @@ EXTRA_DIST += \
+ 
+ bin_PROGRAMS = \
+ 	asc2log \
+-	bcmserver \
+ 	can-calc-bit-timing \
+ 	canbusload \
+ 	candump \
+ 	canfdtest \
+ 	cangen \
+ 	cangw \
+-	canlogserver \
+ 	canplayer \
+ 	cansend \
+ 	cansequence \
+@@ -91,7 +89,6 @@ bin_PROGRAMS = \
+ 	isotpperf \
+ 	isotprecv \
+ 	isotpsend \
+-	isotpserver \
+ 	isotpsniffer \
+ 	isotptun \
+ 	j1939acd \
+@@ -106,6 +103,13 @@ bin_PROGRAMS = \
+ 	slcanpty \
+ 	testj1939
+ 
++if HAVE_FORK
++bin_PROGRAMS += \
++	bcmserver \
++	canlogserver \
++	isotpserver
++endif
++
+ j1939acd_LDADD = libj1939.la
+ j1939cat_LDADD = libj1939.la
+ j1939spy_LDADD = libj1939.la
+diff --git a/Makefile b/Makefile
+index 29eef997b290..a26ff3d75e67 100644
+--- a/Makefile
++++ b/Makefile
+@@ -45,6 +45,8 @@ MAKEFLAGS := -k
+ 
+ CFLAGS := -O2 -Wall -Wno-parentheses
+ 
++HAVE_FORK := $(shell ./check_cc.sh "$(CC)" fork_test.c)
++
+ CPPFLAGS += \
+ 	-I. \
+ 	-Iinclude \
+@@ -66,10 +68,14 @@ PROGRAMS_ISOTP := \
+ 	isotpperf \
+ 	isotprecv \
+ 	isotpsend \
+-	isotpserver \
+ 	isotpsniffer \
+ 	isotptun
+ 
++ifeq ($(HAVE_FORK),1)
++PROGRAMS_ISOTP += \
++	isotpserver
++endif
++
+ PROGRAMS_J1939 := \
+ 	j1939acd \
+ 	j1939cat \
+@@ -87,14 +93,12 @@ PROGRAMS := \
+ 	$(PROGRAMS_J1939) \
+ 	$(PROGRAMS_SLCAN) \
+ 	asc2log \
+-	bcmserver \
+ 	can-calc-bit-timing \
+ 	canbusload \
+ 	candump \
+ 	canfdtest \
+ 	cangen \
+ 	cansequence \
+-	canlogserver \
+ 	canplayer \
+ 	cansend \
+ 	cansniffer \
+@@ -103,6 +107,12 @@ PROGRAMS := \
+ 	mcp251xfd-dump \
+ 	slcanpty
+ 
++ifeq ($(HAVE_FORK),1)
++PROGRAMS += \
++	canlogserver \
++	bcmserver
++endif
++
+ all: $(PROGRAMS)
+ 
+ clean:
+diff --git a/check_cc.sh b/check_cc.sh
+new file mode 100755
+index 000000000000..d85ad129da9d
+--- /dev/null
++++ b/check_cc.sh
+@@ -0,0 +1,16 @@
++#!/bin/sh
++# SPDX-License-Identifier: GPL-2.0-only
++# check_cc.sh - Helper to test userspace compilation support
++# Copyright (c) 2015 Andrew Lutomirski
++
++CC="$1"
++TESTPROG="$2"
++shift 2
++
++if [ -n "$CC" ] && $CC -o /dev/null "$TESTPROG" -O0 "$@"; then
++    echo 1
++else
++    echo 0
++fi
++
++exit 0
+diff --git a/configure.ac b/configure.ac
+index 5493c9c7ccdf..9bf62a5c6409 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -76,6 +76,8 @@ AC_CHECK_FUNCS([ \
+ 	strtoul \
+ ])
+ 
++AM_CONDITIONAL(HAVE_FORK, test "$ac_cv_func_fork_works" = "yes")
++
+ # glibc versions before 2.17 needs to link with -lrt for clock_nanosleep
+ AC_SEARCH_LIBS([clock_nanosleep], [rt])
+ 
+diff --git a/fork_test.c b/fork_test.c
+new file mode 100644
+index 000000000000..036692392483
+--- /dev/null
++++ b/fork_test.c
+@@ -0,0 +1,27 @@
++/* SPDX-License-Identifier: GPL-2.0-only */
++/*
++ * Copyright (C) 2023 Dario Binacchi <dario.binacchi@amarulasolutions.com>
++ *
++ * This program is free software; you can redistribute it and/or modify
++ * it under the terms of the version 2 of the GNU General Public License
++ * as published by the Free Software Foundation
++ *
++ * This program is distributed in the hope that it will be useful,
++ * but WITHOUT ANY WARRANTY; without even the implied warranty of
++ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
++ * GNU General Public License for more details.
++ *
++ * You should have received a copy of the GNU General Public License
++ * along with this program; if not, see <http://www.gnu.org/licenses/>.
++ */
++
++#include <stdio.h>
++#include <sys/types.h>
++#include <unistd.h>
++
++int main(int argc, char **argv)
++{
++	fork();
++
++	return 0;
++}
+-- 
+2.32.0
+

package/can-utils/Config.in

@@ -1,6 +1,5 @@
 config BR2_PACKAGE_CAN_UTILS
 	bool "can-utils"
-	depends on BR2_USE_MMU # fork()
 	help
 	  SocketCAN is a set of open source CAN drivers and a
 	  networking stack.