Re: [PATCH 29/29] t/test-lib: teach --chain-lint to detect broken &&-chains in subshells

[Elijah Newren]

On Tue, Jun 26, 2018 at 2:01 PM, Jeff King <p...@peff.net> wrote:
> On Tue, Jun 26, 2018 at 04:46:18PM -0400, Eric Sunshine wrote:

>> Some of these dangers can be de-thoothed during the linting phase by
>> defining do-nothing shell functions:
>>
>>     cp () { :; }
>>     mv () { :; }
>>     ln () { :; }
>>
>> That, at least, makes the scariest case ("rm") much less so.
>
> Now that's an interesting idea. We can't catch every dangerous action
> (notably ">" would be hard to override), but it should be pretty cheap
> to cover some obvious ones.
>
> -Peff

Crazy idea: maybe we could defang it a little more thoroughly with
something like the following (apologies in advance if gmail whitespace
damages this):

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 28315706be..7fda08a90a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -675,7 +675,7 @@ test_run_ () {
                trace=
                # 117 is magic because it is unlikely to match the exit
                # code of other programs
-               if test "OK-117" != "$(test_eval_ "(exit 117) &&
$1${LF}${LF}echo OK-\$?" 3>&1)"
+               if test "OK-117" != "$(test_eval_ "cd() { return 0; }
&& PATH=/dev/null && export PATH && (exit 117) && $1${LF}${LF}echo
OK-\$?" 3>&1)"
                then
                        error "bug in the test script: broken &&-chain
or run-away HERE-DOC: $1"
                fi