Check code style as part of the CI tests

If checkpatch.pl detects any ERROR in the new patches, the Travis CI
build will fail.

Signed-off-by: Antonio Niño Díaz <antonio_nd@outlook.com>

.travis-checkpatch.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+echo "Checking code style..."
+
+# Return failure as soon as a command fails to execute
+
+set -e
+
+# Download checkpatch.pl and related files
+
+echo "Getting checkpatch.pl..."
+
+mkdir checkpatchdir
+
+wget https://raw.githubusercontent.com/torvalds/linux/master/scripts/checkpatch.pl
+mv checkpatch.pl checkpatchdir/checkpatch.pl
+chmod +x checkpatchdir/checkpatch.pl
+
+touch checkpatchdir/const_structs.checkpatch
+touch checkpatchdir/spelling.txt
+
+# Run checkpatch.pl on the new commits
+
+echo "Running checkpatch.pl..."
+
+fname=$(mktemp)
+rc=0
+
+git remote set-branches --add origin develop
+git fetch
+
+make CHECKPATCH=checkpatchdir/checkpatch.pl checkpatch > $fname
+
+cat $fname
+
+if grep "ERROR" $fname; then
+    # At least one error found
+    echo "Code style errors have been found!"
+    rc=1
+else
+    echo "No code style errors found, your patches are ready!"
+fi
+
+# Cleanup
+
+rm -rf checkpatchdir
+
+exit $rc

.travis.yml

@@ -10,5 +10,6 @@ compiler:
   - clang
   - gcc
 script:
+  - ./.travis-checkpatch.sh
   - cd test
   - ./run-tests.sh