view auto/types/typedef @ 8018:5119c8150478

Fixed runtime handling of systems without EPOLLRDHUP support. In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP support in the kernel (but with EPOLLRDHUP in headers) was broken. Before the change, rev->available was never set to 0 unless ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP introduced in 6536:f7849bfb6d21 succeeded). After the change, rev->available might reach 0 on systems without runtime EPOLLRDHUP support, stopping further reading in ngx_readv_chain() and ngx_unix_recv(). And, if EOF happened to be already reported along with the last event, it is not reported again by epoll_wait(), leading to connection hangs and timeouts on such systems. This affects Linux kernels before 2.6.17 if nginx was compiled with newer headers, and, more importantly, emulation layers, such as DigitalOcean's App Platform's / gVisor's epoll emulation layer. Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author Marcus Ball <marcus.ball@live.com>
date Mon, 30 May 2022 02:38:07 +0300
parents e3faa5fb7772
children
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# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for $ngx_type ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_type

END

ngx_found=no

for ngx_try in $ngx_type $ngx_types
do

    cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <netinet/in.h>
$NGX_INCLUDE_INTTYPES_H

int main(void) {
    $ngx_try i = 0;
    return (int) i;
}

END

    ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
              -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs"

    eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

    if [ -x $NGX_AUTOTEST ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo " found"
            ngx_found=yes
        else
            echo ", $ngx_try used"
            ngx_found=$ngx_try
        fi
    fi

    if [ $ngx_found = no ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo $ngx_n " $ngx_try not found$ngx_c"
        else
            echo $ngx_n ", $ngx_try not found$ngx_c"
        fi

        echo "----------"    >> $NGX_AUTOCONF_ERR
        cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
        echo $ngx_test       >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
    fi

    rm -rf $NGX_AUTOTEST*

    if [ $ngx_found != no ]; then
        break
    fi
done

if [ $ngx_found = no ]; then
    echo
    echo "$0: error: can not define $ngx_type"

    exit 1
fi

if [ $ngx_found != yes ]; then
    echo "typedef $ngx_found  $ngx_type;"   >> $NGX_AUTO_CONFIG_H
fi