.travis.yml: add a wrapped functions grepper script

.travis.yml

@@ -45,3 +45,22 @@ script:
   - CFLAGS="-Wformat -Wformat-security -Wextra -Wno-unused-parameter -Werror" make -j
   - (cd testcases && xvfb-run ./complete-run.pl --parallel=1 || (cat latest/complete-run.log; false))
   - clang-format-3.5 -i $(find . -name "*.[ch]" | tr '\n' ' ') && git diff --exit-code || (echo 'Code was not formatted using clang-format!'; false)
+  - |
+    funcs='malloc|calloc|realloc|strdup|strndup|asprintf|write'
+    cstring='"([^"\\]|\\.)*"'
+    cchar="'[^\\\\]'|'\\\\.[^']*'"
+    regex="^([^'\"]|${cstring}|${cchar})*\<(${funcs})\>"
+    detected=0
+    while IFS= read -r file; do
+        if { cpp -w -fpreprocessed "$file" || exit "$?"; } | grep -E -- "$regex"; then
+            echo "^ $file calls a function that has a safe counterpart."
+            detected=1
+        fi
+    done << EOF
+    $(find -name '*.c' -not -name safewrappers.c -not -name strndup.c)
+    EOF
+    if [ "$detected" -ne 0 ]; then
+        echo
+        echo "Calls of functions that have safe counterparts were detected."
+        exit 1
+    fi