[v2,1/1] flex: Fix segfault of stage1flex when host has glibc 2.26 or newer

When the host uses glibc 2.26 or newer, Flex will try to use the
newly-introduced reallocarray() function, but as it would not define
_GNU_SOURCE a segmentation fault would occur later on due to the
compiler assumming that the function is implicitly defined.

This issue manifests itself due to a crash of "stage1flex" during the
Flex bootstrap:

  ./stage1flex   -o stage1scan.c ./scan.l
  make[2]: *** [Makefile:1725: stage1scan.c] Segmentation fault (core dumped)

This imports the patch from the upstream Git repository, and adds flags
in the .mk file to rebuild the Autotools scripts and support files. Due
to the latter, the patch to disable the documentation is changed so it
modifies the .am file instead.

Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>

---
Changes v1 -> v2:
  - Modify the patch to disable building the documentation so it changes
    Makefile.am instead of Makefile.in. This is needed because autoreconf
    is being used.
---
 ...-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch | 32 ++++++++++++++++++++
 package/flex/0001-flex-disable-documentation.patch | 23 --------------
 package/flex/0002-flex-disable-documentation.patch | 35 ++++++++++++++++++++++
 package/flex/flex.mk                               |  2 ++
 4 files changed, 69 insertions(+), 23 deletions(-)
 create mode 100644 package/flex/0001-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
 delete mode 100644 package/flex/0001-flex-disable-documentation.patch
 create mode 100644 package/flex/0002-flex-disable-documentation.patch

Hi Adrian,

On Wed, 2017-09-13 at 17:35 +0300, Adrian Perez de Castro wrote:
> When the host uses glibc 2.26 or newer, Flex will try to use the
> newly-introduced reallocarray() function, but as it would not define
> _GNU_SOURCE a segmentation fault would occur later on due to the
> compiler assumming that the function is implicitly defined.
> 
> This issue manifests itself due to a crash of "stage1flex" during the
> Flex bootstrap:
> 
>   ./stage1flex   -o stage1scan.c ./scan.l
>   make[2]: *** [Makefile:1725: stage1scan.c] Segmentation fault (core dumped)
> 
> This imports the patch from the upstream Git repository, and adds flags
> in the .mk file to rebuild the Autotools scripts and support files. Due
> to the latter, the patch to disable the documentation is changed so it
> modifies the .am file instead.
> 
> Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
> 
> ---
> Changes v1 -> v2:
>   - Modify the patch to disable building the documentation so it changes
>     Makefile.am instead of Makefile.in. This is needed because autoreconf
>     is being used.

I would prefer to have two seperate commits:
  1) changing the existing patch so autoreconf can be used
  2) adding the new patch

> ---
>  ...-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch | 32 ++++++++++++++++++++
>  package/flex/0001-flex-disable-documentation.patch | 23 --------------
>  package/flex/0002-flex-disable-documentation.patch | 35 ++++++++++++++++++++++
>  package/flex/flex.mk                               |  2 ++
>  4 files changed, 69 insertions(+), 23 deletions(-)
>  create mode 100644 package/flex/0001-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
>  delete mode 100644 package/flex/0001-flex-disable-documentation.patch
>  create mode 100644 package/flex/0002-flex-disable-documentation.patch
> 
> diff --git a/package/flex/0001-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch b/package/flex/0001-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
> new file mode 100644
> index 0000000000..2151a15fc6
> --- /dev/null
> +++ b/package/flex/0001-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
> @@ -0,0 +1,32 @@
> +From ffa886a580929f26fd5e5a40c9c5334955c48553 Mon Sep 17 00:00:00 2001
> +From: Explorer09 <explorer09@gmail.com>
> +Date: Mon, 4 Sep 2017 10:47:33 +0800
> +Subject: [PATCH] build: AC_USE_SYSTEM_EXTENSIONS in configure.ac.
> +
> +This would, e.g. define _GNU_SOURCE in config.h, enabling the
> +reallocarray() prototype in glibc 2.26+ on Linux systems with that
> +version of glibc.
> +
> +Fixes #241.

According to [1], please add:

Backported from: 24fd0551333e7eded87b64dd36062da3df2f6380

> +---
> + configure.ac | 2 ++
> + 1 file changed, 2 insertions(+)
> +
> +diff --git a/configure.ac b/configure.ac
> +index 55e774b..c879fe1 100644
> +--- a/configure.ac
> ++++ b/configure.ac
> +@@ -25,8 +25,10 @@
> + # autoconf requirements and initialization
> + 
> + AC_INIT([the fast lexical analyser generator],[2.6.4],[flex-help@lists.sourceforge.net],[flex])
> ++AC_PREREQ([2.60])
> + AC_CONFIG_SRCDIR([src/scan.l])
> + AC_CONFIG_AUX_DIR([build-aux])
> ++AC_USE_SYSTEM_EXTENSIONS
> + LT_INIT
> + AM_INIT_AUTOMAKE([1.11.3 -Wno-portability foreign check-news std-options dist-lzip parallel-tests subdir-objects])
> + AC_CONFIG_HEADER([src/config.h])
> +-- 
> +2.14.1
> +
> diff --git a/package/flex/0001-flex-disable-documentation.patch b/package/flex/0001-flex-disable-documentation.patch
> deleted file mode 100644
> index 68bec128ee..0000000000
> --- a/package/flex/0001-flex-disable-documentation.patch
> +++ /dev/null
> @@ -1,23 +0,0 @@
> -flex: disable documentation
> -
> -Since we prevent the flex binary to be built, we also need to prevent
> -the documentation to be built, otherwise it will fail like this:
> -
> -Making all in doc
> -make[2]: Entering directory '/br/output/build/flex-2.6.4/doc'
> -make[2]: *** No rule to make target '../src/flex', needed by 'flex.1'.
> -Stop.
> -
> -Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
> -
> -diff -rup a/Makefile.in b/Makefile.in
> ---- a/Makefile.in	2017-05-06 15:49:09.000000000 +0100
> -+++ b/Makefile.in	2017-05-10 14:35:20.152794902 +0100
> -@@ -450,7 +450,6 @@ EXTRA_DIST = \
> - 
> - SUBDIRS = \
> - 	src \
> --	doc \
> - 	examples \
> - 	po \
> - 	tests \
> diff --git a/package/flex/0002-flex-disable-documentation.patch b/package/flex/0002-flex-disable-documentation.patch
> new file mode 100644
> index 0000000000..a2e38d698a
> --- /dev/null
> +++ b/package/flex/0002-flex-disable-documentation.patch
> @@ -0,0 +1,35 @@
> +From a98443c6a72d5821d4e0152311e5c3eb4cdff25c Mon Sep 17 00:00:00 2001
> +From: Adrian Perez de Castro <aperez@igalia.com>
> +Date: Wed, 13 Sep 2017 17:26:48 +0300
> +Subject: [PATCH] flex: disable documentation
> +
> +Since we prevent the flex binary to be built, we also need to prevent
> +the documentation to be built, otherwise it will fail like this:
> +
> +Making all in doc
> +make[2]: Entering directory '/br/output/build/flex-2.6.4/doc'
> +make[2]: *** No rule to make target '../src/flex', needed by 'flex.1'.
> +Stop.
> +
> +Based on an patch by Vicente Olivert Riera <Vincent.Riera@imgtec.com>

Please add a URL where you got the patch from.

> +Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
> +---
> + Makefile.am | 1 -
> + 1 file changed, 1 deletion(-)
> +
> +diff --git a/Makefile.am b/Makefile.am
> +index 638c549..9db3420 100644
> +--- a/Makefile.am
> ++++ b/Makefile.am
> +@@ -43,7 +43,6 @@ EXTRA_DIST = \
> + 
> + SUBDIRS = \
> + 	src \
> +-	doc \
> + 	examples \
> + 	po \
> + 	tests \
> +-- 
> +2.14.1
> +
> diff --git a/package/flex/flex.mk b/package/flex/flex.mk
> index b78269952e..b84732d383 100644
> --- a/package/flex/flex.mk
> +++ b/package/flex/flex.mk
> @@ -11,6 +11,8 @@ FLEX_LICENSE = FLEX
>  FLEX_LICENSE_FILES = COPYING
>  FLEX_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES) host-m4
>  FLEX_CONF_ENV = ac_cv_path_M4=/usr/bin/m4
> +FLEX_AUTORECONF = YES
> +FLEX_GETTEXTIZE = YES

As the package also provides a host package, HOST_FLEX_AUTORECONF and
HOST_FLEX_GETTEXTIZE should be added.

Additionally, please add a comment why AUTORECONF and GETTEXTIZE are
necessary (because of patching configure.ac).

>  HOST_FLEX_DEPENDENCIES = host-m4
>  
>  define FLEX_DISABLE_PROGRAM

[1] https://buildroot.org/downloads/manual/manual.html#_integrating_pat
ches_found_on_the_web

On 13-09-17 16:35, Adrian Perez de Castro wrote:
> When the host uses glibc 2.26 or newer, Flex will try to use the
> newly-introduced reallocarray() function, but as it would not define
> _GNU_SOURCE a segmentation fault would occur later on due to the
> compiler assumming that the function is implicitly defined.
> 
> This issue manifests itself due to a crash of "stage1flex" during the
> Flex bootstrap:
> 
>   ./stage1flex   -o stage1scan.c ./scan.l
>   make[2]: *** [Makefile:1725: stage1scan.c] Segmentation fault (core dumped)
> 
> This imports the patch from the upstream Git repository, and adds flags
> in the .mk file to rebuild the Autotools scripts and support files. Due
> to the latter, the patch to disable the documentation is changed so it
> modifies the .am file instead.
> 
> Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>

 Applied to master, thanks.

 I did make a few changes though:

     - Add Adrian's Sob and upstream ref to new patch;
     - Keep patch 1 as patch 1;
     - Keep Vicente as author of path 1;
     - Add reason for autoreconf in a comment.

 I didn't follow Joerg's suggestion to separate into two patches, though it was
actually a good suggestion. I was just too lazy :-)

 Regards,
 Arnout