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From Hoang-Vu Dang <>
Subject Re: ap_log_rerror limit size
Date Wed, 13 Mar 2013 15:40:50 GMT
I traced this into the Apache source code (ver 2.4.4). It looks like the 
error message string is really limited by the size of 8KB.

This line is in server/log.c:1097

static void log_error_core(const char *file, int line, int module_index,
                            int level,
                            apr_status_t status, const server_rec *s,
                            const conn_rec *c,
                            const request_rec *r, apr_pool_t *pool,
                            const char *fmt, va_list args)
     char errstr[MAX_STRING_LEN];

And MAX_STRING_LEN is defined in include/httpd.h:298

/** The default string length */

/** The length of a Huge string */
#define HUGE_STRING_LEN 8192

I tried to increase this value, recompile, and apparently I got a longer 
Please correct me if I am wrong... If this is true then can anyone tell 
me why this "HUGE_STRING_LEN" value is a hard-coded value but not a 
configurable option ?

Cheers, Vu

On 03/13/2013 11:16 AM, Eric Covener wrote:
> On Wed, Mar 13, 2013 at 6:01 AM, Hoang Vu Dang <> wrote:
>> Hi guys,
>> Is there any limit of the size of a message log entry? How to control this ?
>> I did this:
>> ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, f->r,
>>                  "%s", buffer);
>> And the buffer was truncated on the error log. I check the strlen of the buffer and
it was about 320K, and I got only around: ~ 8KB
> If it's more than PIPE_BUF, it won't be atomic and can be interleaved
> with other entries.  Are you sure it's truncated and not just spread
> out?

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