[users@httpd] Erasing HTTPD library global variables before reinitialize server

[Ishay Lavi <Is...@audiocodes.com>]

Hello!

I build my application vs. libhttpd (Apache) library  (for adding HTTP server abilities), during application running it required to shutting down and then (after some time) to start this (HTTP) server again.
The procedure I used to initialize/shutting down this server is same as used in the Apache httpd project “main.c” file with one difference, I set back the 'apr_app_init_complete' (defined at 'start.c' file) global variable (again 'erasing global variables' issue) to zero (cause server to read again the CLI 'argc'/'argv' argument).

The problem occur in the 2nd  running, exception occur.
I debug it and I see that this issue caused by global (static) variables that initialized and doesn’t erased after 1st server running.

Specifically I saw it for the ‘hooks’ ( “static struct { members } _hooks;”) global variable that defined at the ‘apr_hooks.h’ file, for the 1st running it’s fields set to ‘NULL’ value, but at 2nd it keep illegal addresses from the 1st running.



Location for this acceptation:
          APR_DECLARE(void *) apr_array_push(apr_array_header_t *arr)
          {
here==>       if (arr->nelts == arr->nalloc) {
                  int new_size = (arr->nalloc <= 0) ? 1 : arr->nalloc * 2;
                  char *new_data;

                  new_data = apr_palloc(arr->pool, arr->elt_size * new_size);
          .
          .
          .
          }


Call Stack for this exception:
>       libapr-1.dll!apr_array_push(apr_array_header_t * arr=0x046299c0)  Line 109 + 0x6 bytes  C
        libhttpd.dll!ap_hook_create_connection(conn_rec * (apr_pool_t *, server_rec *, apr_socket_t *, long, void *, apr_bucket_alloc_t *)* pf=0x6ff0c430, const char * const * aszPre=0x00000000, const char * const * aszSucc=0x00000000, int nOrder=30)  Line 42 + 0x41 bytes        C
        libhttpd.dll!register_hooks(apr_pool_t * p=0x043905b0)  Line 3988       C
        libhttpd.dll!ap_register_hooks(module_struct * m=0x6ff47928, apr_pool_t * p=0x043905b0)  Line 427 + 0xc bytes   C
        libhttpd.dll!ap_add_module(module_struct * m=0x6ff47928, apr_pool_t * p=0x043905b0)  Line 554   C
        libhttpd.dll!ap_setup_prelinked_modules(process_rec * process=0x0438f5c8)  Line 697 + 0x12 bytes        C


NOTE: The called to apr_array_push() procedure added using the 'APR_IMPLEMENT_EXTERNAL_HOOK_BASE' macro (defined at 'apr_hooks.h' file).
/** macro to implement the hook */
#define APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf,const char * const *aszPre, \
                                      const char * const *aszSucc,int nOrder) \
    { \
    ns##_LINK_##name##_t *pHook; \
    if(!_hooks.link_##name) \
        { \
        _hooks.link_##name=apr_array_make(apr_hook_global_pool,1,sizeof(ns##_LINK_##name##_t)); \
        apr_hook_sort_register(#name,&_hooks.link_##name); \
        } \
    pHook=apr_array_push(_hooks.link_##name); \
.
.
.
}




I use:
------
HTTPD version: httpd-2.2.13-win32-src
Platform: Windows, build with VC2005

Any suggestion?



P.S
I run it with the CLI -X (single process) option,
I use the 'SIGNAL_PARENT_SHUTDOWN' signal (e.g. "ap_signal_parent(SIGNAL_PARENT_SHUTDOWN)") for terminate this (httpd) server.



Thanks,

Ishay Lavi
Software Engineer
Web:   www.audiocodes.com
Email: ishay.lavi@audiocodes.com




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