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From: Simon Walter <simon@gikaku.com>
Message-ID: <3f301b2d-e737-139b-1a0c-118c24937049@gikaku.com>
Date: Mon, 1 Jan 2018 23:21:53 +0900
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Subject: Re: [users@httpd] apr_bucket_split data remains
archived-at: Mon, 01 Jan 2018 14:22:06 -0000

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On 01/01/2018 10:44 PM, Eric Covener wrote:
> On Mon, Jan 1, 2018 at 8:37 AM, Simon Walter <simon@gikaku.com> wrote:
>> I am interested in how apr_bucket_split(e, point) works.
>>
>> It seems that after splitting e, it still contains everything after
>> point. Only when flattened is this data "removed" from e.
>>
>> If that is correct, then is it also correct to assume that I would need
>> to use apr_bucket_read with snprintf and make a copy of the data in
>> order to display it accurately?
>>
>> Is there another way to show the contents of buckets after they've been
>> split/manipulated?
>>
>> I need to flatten the brigade (or flush it to a socket? that's a
>> different question), but for debugging purposes, to check my logic, I am
>> trying to see the contents of individual buckets.
>>
> 
> I don't think that's right. For example mod_substitute does this to
> remove the pattern that matched from the input:
> 
> #define SEDRMPATBCKT(b, offset, tmp_b, patlen) do {  \
>     apr_bucket_split(b, offset);                     \
>     tmp_b = APR_BUCKET_NEXT(b);                      \
>     apr_bucket_split(tmp_b, patlen);                 \
>     b = APR_BUCKET_NEXT(tmp_b);                      \
>     apr_bucket_delete(tmp_b);                        \
> } while (0)
> 
> 
> The dump_brigade macro in .gdbinit in the source tree will help here.
> You can also use the code there to add your own trace.
> 

I see such code as the example you gave in various places. However, this
bit of code (attached) shows me that I cannot simply printf the data.
Again, I am probably doing something wrong.

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#include <stdlib.h>
#include <linux/limits.h>
#include <apr-1.0/apr_buckets.h>

int main(int ArgCount, char * Arg[])
{
    apr_initialize();
    atexit(apr_terminate);
   =20
    apr_pool_t * Pool;
    apr_pool_create(&Pool, NULL);
    apr_bucket_alloc_t * BucketAlloc =3D apr_bucket_alloc_create(Pool);
    apr_bucket_brigade * Brigade =3D apr_brigade_create(Pool, BucketAlloc=
);
   =20
    char * String0 =3D "_ASCII_String0_!";
    apr_bucket * Bucket0 =3D apr_bucket_immortal_create(String0, strlen(S=
tring0), BucketAlloc);
    APR_BRIGADE_INSERT_TAIL(Brigade, Bucket0);
   =20
    char * String1 =3D "_ASCII_String1_!";
    apr_bucket * Bucket1 =3D apr_bucket_immortal_create(String1, strlen(S=
tring1), BucketAlloc);
    APR_BRIGADE_INSERT_TAIL(Brigade, Bucket1);
   =20
    char * String2 =3D "_ASCII_String2_!";
    apr_bucket * Bucket2 =3D apr_bucket_immortal_create(String2, strlen(S=
tring2), BucketAlloc);
    APR_BRIGADE_INSERT_TAIL(Brigade, Bucket2);
   =20
    char * String3 =3D "_ASCII_String3_!";
    apr_bucket * Bucket3 =3D apr_bucket_immortal_create(String3, strlen(S=
tring3), BucketAlloc);
    APR_BRIGADE_INSERT_TAIL(Brigade, Bucket3);
   =20
    apr_bucket * Index;
    apr_bucket * NextBucket;
    apr_bucket * PrevBucket;
   =20
    const char * TestBuffer =3D NULL;
    int Marker =3D 0;
    size_t Length =3D 0;
   =20
    for (Index =3D APR_BRIGADE_FIRST(Brigade); Index !=3D APR_BRIGADE_SEN=
TINEL(Brigade); Index =3D APR_BUCKET_NEXT(Index))
    {
        printf("Marker: %d\n", Marker);
        if (Marker =3D=3D 1)
        {
            char * String4 =3D "_ASCII_String4_!";
            apr_bucket * Bucket4 =3D apr_bucket_immortal_create(String4, =
strlen(String4), BucketAlloc);
           =20
            apr_bucket_split(Index, 1);
            APR_BUCKET_INSERT_AFTER(Index, Bucket4);
        }
       =20
        TestBuffer =3D NULL;
        Length =3D 0;
        if (apr_bucket_read(Index, &TestBuffer, &Length, APR_BLOCK_READ) =
=3D=3D APR_SUCCESS)
        {
            printf("CurrBucket: %s\n", TestBuffer);
            printf("Length: %zu\n", Length);
        }
       =20
        NextBucket =3D APR_BUCKET_NEXT(Index);
        TestBuffer =3D NULL;
        Length =3D 0;
        if (NextBucket !=3D APR_BRIGADE_SENTINEL(Brigade) &&
            apr_bucket_read(NextBucket, &TestBuffer, &Length, APR_BLOCK_R=
EAD) =3D=3D APR_SUCCESS)
        {
            printf("NextBucket: %s\n", TestBuffer);
            printf("Length: %zu\n", Length);
        }
       =20
        PrevBucket =3D APR_BUCKET_PREV(Index);
        TestBuffer =3D NULL;
        if (PrevBucket !=3D APR_BRIGADE_SENTINEL(Brigade) &&
            apr_bucket_read(PrevBucket, &TestBuffer, &Length, APR_BLOCK_R=
EAD) =3D=3D APR_SUCCESS)
        {
            printf("PrevBucket: %s\n", TestBuffer);
            printf("Length: %zu\n", Length);
        }
        Marker++;
    }
   =20
    char * Output =3D NULL;
    apr_size_t OutputLength;
    apr_brigade_pflatten(Brigade, &Output, &OutputLength, Pool);
   =20
    printf("output: %s\n", Output);
   =20
    apr_pool_destroy(Pool);
}


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