Fix teststr segfault when built with -ftrivial-auto-var-init

[dimakuv]

The apr test suite has a test error (segfault) when built with -ftrivial-auto-var-init=zero:

$ ./testall -v -q
testatomic : SUCCESS
testdir : SUCCESS
...
teststr             :  Segmentation fault

Debug stack trace:

(gdb) bt
#0 apr_strtok (str=str@entry=0x0, sep=sep@entry=0x43a429 " \t", last=last@entry=0x7fffffffe2d8) at strings/apr_strtok.c:35
#1 test_strtok (tc=0x7fffffffe380, data=<optimized out>) at test/teststr.c:81

Root cause analysis:

• apr/test/teststr.c

  Line 52 in e461da5

  NULL, /* but who cares if apr_strtok() segfaults? */

• apr/test/teststr.c

  Line 81 in e461da5

  retval1 = apr_strtok(str1, cases[curtc].sep, &state);

• The apr_strtok(str, sep, internal_state) function must not be called with str == NULL in the first invocation. However the test does exactly this, and this leads to an access to *internal_state, which is technically undefined (uninitialized pointer on the stack).
• Without -ftrivial-auto-var-init=zero, the *internal_state is benign by accident: the previous test case left the pointer-on-stack with some reasonable address. However, with -ftrivial-auto-var-init=zero, the *internal_state access fails because internal_state = NULL (auto-initialized to zero). So the whole test segfaults.

Reproducer

docker run -it amazonlinux:2023 /bin/bash

dnf install -y git vim make gcc14 autoconf libtool expat-devel
export CC=gcc14-gcc
export CFLAGS="$CFLAGS -ftrivial-auto-var-init=zero"

./buildconf
./configure
make -j
make test  # fails

cd test && ./testall -v -q  # to see the failure more clearly

Note that -ftrivial-auto-var-init=zero flag was introduced in GCC v12.

Testing the fix

$ cd test && ./testall -v -q
...
testsockopt         :  SUCCESS
teststr             :  SUCCESS  # <-- works now!
teststrnatcmp       :  SUCCESS
...

[notroj]

@dimakuv could you try adding another CI workflow to cover this compilation mode?

[dimakuv]

@notroj Looking at the current CI workflow (Linux example), I see that there are two knobs that the apr project uses:

1. "config", e.g. config: --enable-maintainer-mode
2. "notest-cflags", e.g. notest-cflags: -Werror

I cannot use the first knob, because there's no way to specify arbitrary compilation flags as inputs to the configure script (at least I don't see a way after inspecting ./configure --help).

I also cannot use the second knob (notest-cflags) because my PR fixes the test, and this knob applies only to non-test compilation units.

So the only option I see is to introduce a new variable cflags (similar to notest-cflags). This variable will be empty/undefined in all current workflows, and will be defined only in my new workflow. Smth like this:

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
@@ -87,10 +87,14 @@ jobs:
             notest-cflags: -Werror
             config: --enable-maintainer-mode --with-berkeley-db --with-dbm=db5
             config-output: APU_HAVE_DB
+          - name: Auto-var-init
+            os: ubuntu-latest  # requires gcc 12 or higher
+            cflags: -ftrivial-auto-var-init=zero
       fail-fast: false

     runs-on: ${{ matrix.os }}
     env:
+      CFLAGS: ${{ matrix.cflags }}
       NOTEST_CFLAGS: ${{ matrix.notest-cflags }}
     name: ${{ matrix.name }}
     steps:

Is the above what you would recommend to add?

[notroj]

because my PR fixes the test, and this knob applies only to non-test compilation units

NOTEST_CFLAGS specifies flags which aren't used during the configure run, they are used for all compilation including in test/

[dimakuv]

because my PR fixes the test, and this knob applies only to non-test compilation units

NOTEST_CFLAGS specifies flags which aren't used during the configure run, they are used for all compilation including in test/

Thanks, I didn't realize this (the name misled me, and I incorrectly read the comments about this envvar the first time).

Fixed now.

[notroj]

Perfect, thanks a lot!