Re: Reading post parameters from apache request

[Yoichi Kawasaki]

2009/11/21 Sorin Manolache :
> On Fri, Nov 20, 2009 at 22:01, pranil dasika  wrote:
>> Hi,
>>
>> I am trying to write a custom module where I need to read post parameters
>> from the request. I guess apreq library is relevant to this but could not
>> find any substantial examples or documents.
>> Is there any other way to read the params other than apreq. Any pseudocode/
>> examples will be appreciated.
>>
>> Thanks,
>> Pranil
>>
>
> Here you have an example. It is not optimal, you could, for example,
> take the brigade creation out of the loop and clean the brigade at the
> end of each iteration, after you extracted the data.
>
> apr_bucket_brigade *bb;
> do {
>   bb = apr_brigade_create(req->pool, req->connection->bucket_alloc);
>   if (0 == bb)
>        // error
>   if (APR_SUCCESS != ap_get_brigade(req->input_filters, bb,
> AP_MODE_READBYTES, APR_BLOCK_READ, 9216))
>        // error
>   extract data from bb;
> } while (EOS not yet encountered in bb);
>
>
> S
>


Hi

I  have an another example. I read post parameters in the source code below:

http://github.com/yokawasa/mod_akismet/blob/master/mod_akismet.c#L647
line: 647 - 705

hope this helps you.

Yoichi

-- 
Yoichi Kawasaki 

Re: maintaining sessions among multiple processes

[Yoichi Kawasaki]

>
> i find your book to be one of the most enlightening ones written in
> recent years, but i haven't found the answers to my question in there.
> the closest you get to touching the subject is perhaps the section on
> "session management with SQL", which as jim jagielski also points out,
> might be the way forward. it's just that my session objects contains
> objects of unknown types so i don't know how to store them in a
> traditional rdbms. maybe i can figure out a way to convert them to
> blobs if you tell me that there is no way to do what i originally
> suggested: interfere with the request dispatching in apache.
>

why don't you serizlie the session objects and store them in rdmbs,
memcached, etc?
I use the term "seralize" and "deserialize" to mean the deconstruction
of "sessionObject"
to  a sequence of bytes, and reverse construction from a sequece of
bytes to "sessionObject"
respectively.
for serialization, you can use any famouse libraries like
"boost::serialization"
or create a converter that can achive this kind of thing by yourself
if the structure of
"sessionObject" is simple enough.

Yoichi

-- 
Yoichi Kawasaki 

Re: apr_global_mutex_lock() failing with "permission denied"

[Yoichi Kawasaki]

Hi Elison.

2009/3/21 Elison Smith :
> I am using shared memory to share some data between my module instances in
> Apache child processes, and apr_global_mutex_t  to achieve
> mutually-exclusive reads and writes.
>
> In a post_config_hook, I create the mutex using apr_global_mutex_create()
> and then reopen it inside each child process by calling
> apr_global_mutex_child_init() inside a child_init hook.
>
> However, when I try to grab the lock inside a child, the operation fails
> with a "permission denied". For the lock file, I  am using "/tmp/tmp" which
> is a file writeable by all.
>
> Any clues?
>


the platform on which your module runs is unix?

There should be such a permission problem if the parent process
starts as root while child processes as user/group that you
specify in apache configuration file.

In that case, use unixd_set_global_mutex_perms in child_init hook,
after apr_global_mutex_create just like this below:

** code snippet from mod_rewrite.c
-

#ifdef AP_NEED_SET_MUTEX_PERMS
#include "unixd.h"
#endif
...

/* create the lockfile */
rc = apr_global_mutex_create(&rewrite_mapr_lock_acquire, lockname,
 APR_LOCK_DEFAULT, p);
if (rc != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_CRIT, rc, s,
 "mod_rewrite: Parent could not create RewriteLock "
 "file %s", lockname);
return rc;
}

#ifdef AP_NEED_SET_MUTEX_PERMS
rc = unixd_set_global_mutex_perms(rewrite_mapr_lock_acquire);
if (rc != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_CRIT, rc, s,
 "mod_rewrite: Parent could not set permissions "
 "on RewriteLock; check User and Group directives");
return rc;
}
#endif
-

you should also see unixd.h  (/path-to-apache/include/unixd.h)
-
/**
 * One of the functions to set mutex permissions should be called in
 * the parent process on platforms that switch identity when the
 * server is started as root.
 * If the child init logic is performed before switching identity
 * (e.g., MPM setup for an accept mutex), it should only be called
 * for SysV semaphores.  Otherwise, it is safe to call it for all
 * mutex types.
 */
AP_DECLARE(apr_status_t) unixd_set_proc_mutex_perms(apr_proc_mutex_t *pmutex);
AP_DECLARE(apr_status_t)
unixd_set_global_mutex_perms(apr_global_mutex_t *gmutex);
AP_DECLARE(apr_status_t) unixd_accept(void **accepted, ap_listen_rec
*lr, apr_pool_t *ptrans);
-

good luck!

Yoichi



-- 
-- 
Yoichi Kawasaki