From 531316cc3f25db22d94310334dc8b61596dc263f Mon Sep 17 00:00:00 2001
From: Pino Toscano <ptoscano@redhat.com>
Date: Mon, 25 Sep 2017 14:29:47 +0200
Subject: [PATCH] build: improve and simplify distro detection

Add a --with-distro=ID argument for configure, so it is possible to
manually specify the distro to use for the packages (in case os-release
does not provide ID=.., or the ID is not recognized yet).

In the case when --with-distro is not set, keep doing the autodetection,
but using os-release only, i.e. dropping the checks for all the other
-release files -- since there is --with-distro, older distros with no
os-release can still be used.

RWMJ: Add documentation to guestfs-building(1).
---
 docs/guestfs-building.pod | 14 ++++++++++++++
 m4/guestfs_appliance.m4   | 44 +++++++++++++++++++-------------------------
 2 files changed, 33 insertions(+), 25 deletions(-)

diff --git a/docs/guestfs-building.pod b/docs/guestfs-building.pod
index ecc27f9d6..187da37be 100644
--- a/docs/guestfs-building.pod
+++ b/docs/guestfs-building.pod
@@ -648,6 +648,20 @@ Note that despite this setting, all backends are built into
 libguestfs, and you can override the backend at runtime by setting the
 C<$LIBGUESTFS_BACKEND> environment variable (or using API methods).
 
+=item B<--with-distro=REDHAT|DEBIAN|...>
+
+Libguestfs needs to know which Linux distro is in use so it can choose
+package names for the appliance correctly (see for example
+F<appliance/packagelist.in>).  It normally does this automatically.
+
+However if you can building or packaging libguestfs on a new distro
+then you can use I<--with-distro> to specify that the distro is
+similar to an existing one (eg. I<--with-distro=REDHAT> if the distro
+is a new Red Hat or CentOS derivative).
+
+Note that if your distro is completely new then it may still require
+upstream modifications.
+
 =item B<--with-extra=">I<distroname>=I<version>,libvirt,...B<">
 
 =item B<--with-extra="local">
diff --git a/m4/guestfs_appliance.m4 b/m4/guestfs_appliance.m4
index fbba3373f..4993f57a1 100644
--- a/m4/guestfs_appliance.m4
+++ b/m4/guestfs_appliance.m4
@@ -94,31 +94,25 @@ dnl names vary slightly across distros.  (See
 dnl appliance/packagelist.in, appliance/excludefiles.in,
 dnl appliance/hostfiles.in)
 AC_MSG_CHECKING([which Linux distro for package names])
-if test -f /etc/os-release; then
-    ( . /etc/os-release && echo $ID | tr '@<:@:lower:@:>@' '@<:@:upper:@:>@' ) >&AS_MESSAGE_LOG_FD
-    DISTRO="`. /etc/os-release && echo $ID | tr '@<:@:lower:@:>@' '@<:@:upper:@:>@'`"
-    AS_CASE([$DISTRO],
-            [FEDORA | RHEL | CENTOS],[DISTRO=REDHAT],
-            [OPENSUSE | SLED | SLES],[DISTRO=SUSE],
-            [ARCH],[DISTRO=ARCHLINUX])
-elif test -f /etc/debian_version; then
-    DISTRO=DEBIAN
-    if grep -q 'DISTRIB_ID=Ubuntu' /etc/lsb-release 2>&AS_MESSAGE_LOG_FD; then
-        DISTRO=UBUNTU
-    fi
-elif test -f /etc/arch-release; then
-    DISTRO=ARCHLINUX
-elif test -f /etc/SuSE-release; then
-    DISTRO=SUSE
-elif test -f /etc/frugalware-release; then
-    DISTRO=FRUGALWARE
-elif test -f /etc/mageia-release; then
-    DISTRO=MAGEIA
-else
-dnl fallback option
-    DISTRO=REDHAT
-fi
-AC_MSG_RESULT([$DISTRO])
+AC_ARG_WITH([distro],
+    [AS_HELP_STRING([--with-distro="DISTRO_ID"],
+                    [distro ID @<:@default=ID in /etc/os-release@:>@])],[
+        DISTRO="$withval"
+        AC_MSG_RESULT([$DISTRO (manually specified)])
+    ],[
+        if test -f /etc/os-release; then
+            ( . /etc/os-release && echo $ID | tr '@<:@:lower:@:>@' '@<:@:upper:@:>@' ) >&AS_MESSAGE_LOG_FD
+            DISTRO="`. /etc/os-release && echo $ID | tr '@<:@:lower:@:>@' '@<:@:upper:@:>@'`"
+            AS_CASE([$DISTRO],
+                    [FEDORA | RHEL | CENTOS],[DISTRO=REDHAT],
+                    [OPENSUSE | SLED | SLES],[DISTRO=SUSE],
+                    [ARCH],[DISTRO=ARCHLINUX])
+            AC_MSG_RESULT([$DISTRO (from /etc/os-release)])
+        else
+            AC_MSG_ERROR([/etc/os-release not available, please specify the distro using --with-distro=DISTRO])
+        fi
+    ]
+)
 AC_SUBST([DISTRO])
 
 dnl Add extra packages to the appliance.
-- 
2.13.2