Travis: also test on 32-bit Linux

When Git v2.9.1 was released, it had a bug that showed only on Windows
and on 32-bit systems: our assumption that `unsigned long` can hold
64-bit values turned out to be wrong.

This could have been caught earlier if we had a Continuous Testing
set up that includes a build and test run on 32-bit Linux.

Let's do this (and take care of the Windows build later). This patch
asks Travis CI to install a Docker image with 32-bit libraries and then
goes on to build and test Git using this 32-bit setup.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/ci/run-linux32-build.sh b/ci/run-linux32-build.sh
new file mode 100755
index 000000000..e30fb2cdd
--- /dev/null
+++ b/ci/run-linux32-build.sh
@@ -0,0 +1,30 @@
+#!/bin/sh
+#
+# Build and test Git in a 32-bit environment
+#
+# Usage:
+#   run-linux32-build.sh [host-user-id]
+#
+
+# Update packages to the latest available versions
+linux32 --32bit i386 sh -c '
+    apt update >/dev/null &&
+    apt install -y build-essential libcurl4-openssl-dev libssl-dev \
+	libexpat-dev gettext python >/dev/null
+' &&
+
+# If this script runs inside a docker container, then all commands are
+# usually executed as root. Consequently, the host user might not be
+# able to access the test output files.
+# If a host user id is given, then create a user "ci" with the host user
+# id to make everything accessible to the host user.
+HOST_UID=$1 &&
+CI_USER=$USER &&
+test -z $HOST_UID || (CI_USER="ci" && useradd -u $HOST_UID $CI_USER) &&
+
+# Build and test
+linux32 --32bit i386 su -m -l $CI_USER -c '
+    cd /usr/src/git &&
+    make --jobs=2 &&
+    make --quiet test
+'