Add error injection library

tests/run

@@ -31,6 +31,22 @@ if [ -z "$d" ]; then
     exit 0
 fi
 
+if [ -f $PWD/.libs/libinject_errors.so ]; then
+  # Do some simple error injection tests to check that we're handling
+  # I/O errors correctly.
+  (
+  jq=$PWD/jq
+  libinject=$PWD/.libs/libinject_errors.so
+  cd $d
+  LD_PRELOAD=$libinject $jq . /dev/null
+  touch fail_read
+  LD_PRELOAD=$libinject $jq . fail_read && exit 2
+  touch fail_close
+  LD_PRELOAD=$libinject $jq . fail_close && exit 2
+  true
+  )
+fi
+
 printf 'a\0b\nc\0d\ne' > $d/input
 $VALGRIND $Q ./jq -Rse '. == "a\u0000b\nc\u0000d\ne"' $d/input
 $VALGRIND $Q ./jq -Rne '[inputs] == ["a\u0000b", "c\u0000d", "e"]' $d/input