[FFmpeg-devel] [PATCH v2] configure: fix symbol prefix detection

[epirat07 at gmail.com]

On 12 Sep 2024, at 8:03, Martin Storsjö wrote:

> On Wed, 11 Sep 2024, Marvin Scholz wrote:
>
>> The symbol prefix check would incorrectly detect a bogus prefix in circumstances where sanitizers
>> instrument the build, like when configuring with the clang-asan toolchain where it would detect the
>> prefix as __odr_asan_gen_, which is obviously wrong.
>>
>> To fix this, adjust the prefix detection to only detect a one-character prefix, which is the only case
>> that matters anywhere right now.
>> ---
>> configure | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/configure b/configure
>> index d3bd46f382a..7e84272b74b 100755
>> --- a/configure
>> +++ b/configure
>> @@ -6131,13 +6131,15 @@ enable_weak_pic() {
>> enabled pic && enable_weak_pic
>>
>> test_cc <<EOF || die "Symbol mangling check failed."
>> int ff_extern;
>> EOF
>> -sym=$($nm $TMPO | awk '/ff_extern/{ print substr($0, match($0, /[^ \t]*ff_extern/)) }')
>> +sym=$($nm $TMPO | awk '/[ \t]+[^ \t]{0,1}ff_extern/{ print substr($0, match($0, /[^ \t]{0,1}ff_extern$/)) }')
>> extern_prefix=${sym%%ff_extern*}
>
> Since we're checking for ff_extern$ in the substr match, would it be safest to include the $ in the initial ff_extern match as well? So if there's a _ff_extern$foo symbol listed first, that won't be matched?
>

Indeed, sent a v3 where this is fixed.

> // Martin
>
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