CI: travis: new shellcheck-gitrange.bash

Travis passes $TRAVIS_COMMIT_RANGE to new shellcheck-gitrange.bash

Runs shellcheck only on files changed by the PR.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

Author: marc-hb

.travis.yml

@@ -0,0 +1,17 @@
+# bionic = 2018
+dist: bionic
+
+language: minimal
+
+git:
+  depth: false
+  quiet: true
+
+before_install:
+  - sudo apt-get -y install shellcheck
+
+jobs:
+  include:
+
+    - name: "shellcheck"
+      script: ./tools/shellcheck-gitrange.bash "${TRAVIS_COMMIT_RANGE}"

tools/shellcheck-gitrange.bash

@@ -0,0 +1,36 @@
+#!/bin/bash
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2018 Intel Corporation. All rights reserved.
+
+set -e
+
+# Sample usage:
+#
+#   $  shellcheck-gitrange.bash HEAD~5.. [ -f gcc ]
+
+main()
+{
+    # The rest of args is passed as is to shellcheck
+    local gitrange="$1"; shift
+
+    printf '%s checking range %s\n\n' "$0" "$gitrange"
+    # also a sanity check
+    git log --oneline "$gitrange" -- | cat # no pager
+
+    local fname ftype failed_files=0
+
+    # https://mywiki.wooledge.org/BashFAQ/001
+    while IFS=  read -r fname; do
+
+        ftype=$(file --brief --mime-type "$fname")
+        if  [ x'text/x-shellscript' = x"$ftype" ]; then
+            printf '\n\n  ----- shellcheck %s ----\n\n' "$fname"
+            shellcheck "$@" "$fname"  || : $((failed_files++))
+        fi
+
+    done < <(git diff --name-only --diff-filter=d "$gitrange" -- )
+
+    return $failed_files
+}
+
+main "$@"