Calling gzopen in a php4 shell script causes a segmentation fault.  Here is a backtrace that I generated:

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warning: core file may not match specified executable file.
Core was generated by `php4 -q ./weblog_traffic.php -d 20000723 -n dealnews.com -l /www/logs/dealnews/'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /usr/lib/libgdbm.so.2...done.
Reading symbols from /lib/libpam.so.0...done.
Reading symbols from /lib/libdl.so.2...done.
Reading symbols from /usr/lib/libz.so.1...done.
Reading symbols from /lib/libresolv.so.2...done.
Reading symbols from /lib/libm.so.6...done.
Reading symbols from /lib/libcrypt.so.1...done.
Reading symbols from /lib/libnsl.so.1...done.
Reading symbols from /lib/libc.so.6...done.
Reading symbols from /lib/ld-linux.so.2...done.
Reading symbols from /lib/libnss_files.so.2...done.
Reading symbols from /usr/lib/gconv/ISO8859-1.so...done.
#0  0x80614c8 in php_fopen_url_wrapper (path=0x819715c "/www/logs/dealnews/weblogs//20000723_access.log.gz", mode=0x8161b7c "r", 
    options=4, issock=0x0, socketd=0x0, opened_path=0x0) at fopen-wrappers.c:1014
1014                    *issock = 0;
(gdb) bt
#0  0x80614c8 in php_fopen_url_wrapper (path=0x819715c "/www/logs/dealnews/weblogs//20000723_access.log.gz", mode=0x8161b7c "r", 
    options=4, issock=0x0, socketd=0x0, opened_path=0x0) at fopen-wrappers.c:1014
#1  0x8060190 in php_fopen_wrapper (path=0x819715c "/www/logs/dealnews/weblogs//20000723_access.log.gz", mode=0x8161b7c "r", 
    options=4, issock=0x0, socketd=0x0, opened_path=0x0) at fopen-wrappers.c:259
#2  0x80af941 in php_gzopen_wrapper (path=0x819715c "/www/logs/dealnews/weblogs//20000723_access.log.gz", mode=0x8161b7c "r", 
    options=4) at zlib.c:157
#3  0x80afeae in php_if_gzopen (ht=2, return_value=0x8188664, this_ptr=0x0, return_value_used=1) at zlib.c:254
#4  0x80dfbdc in execute (op_array=0x812f534) at ./zend_execute.c:1558
#5  0x805e05b in php_execute_script (primary_file=0xbffffa94) at main.c:1168
#6  0x805caa9 in main (argc=9, argv=0xbffffaf4) at cgi_main.c:664