The following is enough to reproduce the problem:

<?php
echo curl_version();
/*
$ch = curl_init ("http://www.php.net/");

$fp = fopen ("php_homepage.txt", "w");

curl_setopt ($ch, CURLOPT_INFILE, $fp);
curl_setopt ($ch, CURLOPT_HEADER, 0);

curl_exec ($ch);
curl_close ($ch);
fclose ($fp);
*/
?>

As it is, the curl_version is correctly output to the browser, but if you just uncomment the curl_init() line, httpd crashes and in the error_log you see a Segmentation Fault (no data is output to the browser).

I get the error with curl 7.2.1, 7.2, 7.1.1, 7.1, and also on a RedHat 6.1 system.

I'm using the 'optimized' version of php.ini, but I don't think it is relevant.

My PHP 4.0.2 configure line is:

./configure --prefix=/opt/www --mandir=/usr/man \
--with-config-file-path=/opt/www/conf --disable-debug \
--enable-safe-mode --with-exec-dir=/opt/www/php/bin \
--enable-track-vars --enable-magic-quotes \
--with-apxs=/opt/www/bin/apxs --enable-bcmath \
--with-cpdflib=/opt/ClibPDF --with-jpeg-dir=/opt/jpeg \
--with-tiff-dir=/opt/tiff --enable-ftp --with-gd \
--with-mysql=/opt/mysql --with-mm=/opt/mm \
--enable-sysvsem --enable-sysvshm --enable-wddx \
--enable-xml --enable-calendar --with-zlib=/opt/zlib \
--enable-inline-optimization --with-ttf --with-readline \
--with-curl=/opt/curl

I've run PHP 4.x with this setup with no problems for the last few months, and simply added the last option a couple of days ago since the curl functions could be very useful for me at work.

I can't generate a gdb backtrace right now (after all, I think the problem can be easily reproduced), but if needed I can manage to send it.