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 Topic: Undefined references in Apache user-written module |
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DrKlahn
Joined: 25 Jan 2019
Posts: 3
Location: USA
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 Posted: Fri 25 Jan '19 21:48 Post subject: Undefined references in Apache user-written module |
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(This has also been posted on Stack Exchange but with only 2 views, results there are not promising so far.)
I have some undefined reference errors in an Apache module. I've cut the source code down to a minimum that reproduced the error. Below is the source for "mod_test.c" ...
| Code: | #include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_protocol.h"
#include "http_core.h"
#include "http_main.h"
#include "http_log.h"
#include "ap_mpm.h"
#include "apr_strings.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netdb.h>
module AP_MODULE_DECLARE_DATA test_module;
static int test_handler(request_rec *r);
static int test_init(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s);
/* Structure containing state information for the module */
typedef struct {
} ns_mod_config;
static int ns_typematch(request_rec *r) {
ns_mod_config *ns_scfg = ap_get_module_config(r->server->module_config,
&test_module);
core_request_config *creq_cfg;
creq_cfg = ap_get_core_module_config(r->request_config);
return 0;
}
module AP_MODULE_DECLARE_DATA test_module = {
STANDARD20_MODULE_STUFF,NULL,NULL,NULL,NULL,NULL,NULL};
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I am using a more-or-less standard Makefile for compiling the module (the install option was removed as this is a test to demonstrate the problem.)
| Code: | APXS=/usr/local/apache2/bin/apxs
APXS_OPTS=-Wc, -Wc,-DDST_CLASS=3
SRC=src/mod_test.c
OBJ=src/.libs/mod_test.so
$(OBJ): $(SRC)
@echo
$(APXS) $(APXS_OPTS) -c $(SRC)
@echo
@echo write '"make install"' to install module
@echo
clean:
rm -f src/.libs/*
rm -f src/*.o
rm -f src/*.lo
rm -f src/*.la
rm -f src/*.slo
rmdir src/.libs
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The compile fails as follows:
| Code: | /usr/local/apache2/bin/apxs -Wc, -Wc,-DDST_CLASS=3 -c src/mod_test.c
/usr/local/apache2/build/libtool --silent --mode=compile gcc -prefer-pic -DLINUX -D_REENTRANT -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -g -O2 -pthread -I/usr/local/apache2/include -I/usr/local/apache2/include -I/usr/local/apache2/include -DDST_CLASS=3 -c -o src/mod_test.lo src/mod_test.c && touch src/mod_test.slo
src/mod_test.c: In function âns_typematchâ:
src/mod_test.c:34:3: error: unknown type name âcore_request_configâ
core_request_config *creq_cfg;
^~~~~~~~~~~~~~~~~~~
src/mod_test.c:35:14: warning: implicit declaration of function âap_get_core_module_configâ [-Wimplicit-function-declaration]
creq_cfg = ap_get_core_module_config(r->request_config);
^~~~~~~~~~~~~~~~~~~~~~~~~
src/mod_test.c:35:12: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
creq_cfg = ap_get_core_module_config(r->request_config);
^
apxs:Error: Command failed with rc=65536
.
Makefile:23: recipe for target 'src/.libs/mod_test.so' failed
make: *** [src/.libs/mod_test.so] Error 1
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I am not sure how this can occur.
http_core.h is present in /usr/local/apache2/include and examining it shows that it does include the definitions claimed missing by the compiler.
Six other modules on the same system compile without errors, though none of them use this specific code to reference the core data structures.
Help will be gratefully received. |
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Jan-E
Joined: 09 Mar 2012
Posts: 1266
Location: Amsterdam, NL, EU
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DrKlahn
Joined: 25 Jan 2019
Posts: 3
Location: USA
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| Posted: Sat 26 Jan '19 19:12 Post subject: |
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| Thanks providing that citation. This confirms that the code looks OK, as it appears to have no significant different from the code that I am using. |
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DrKlahn
Joined: 25 Jan 2019
Posts: 3
Location: USA
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| Posted: Sun 27 Jan '19 23:06 Post subject: |
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After posting to the Apache modules mailing list, it develops that the problem is in two parts.
1. Defining CORE_PRIVATE is required under Apache 2.2 to have access to the core data structures.
2. ap_get_core_module_config is an Apache 2.4 construct. |
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