[prev in list] [next in list] [prev in thread] [next in thread] 

List:       rpm-devel
Subject:    Re: rpm API available ?
From:       Jeff Johnson <n3npq () mac ! com>
Date:       2009-04-27 9:54:23
Message-ID: B0114ECD-FB10-4216-BA9E-83274B4F630D () mac ! com
[Download RAW message or body]


On Apr 27, 2009, at 5:25 AM, Sven Luther wrote:

> On Wed, Apr 15, 2009 at 03:13:17PM -0400, Jeff Johnson wrote:
>>>>      msg = NULL;
>>>>      rc = rpmpkgRead(item, fd, &sigh, &msg);
>>>>      switch (rc) {
>>>>      default:
>>>>          rpmlog(RPMLOG_ERR, "%s: %s: %s", fn, item,
>>>>              (msg && *msg ? msg : _("read failed\n")));
>>>>          msg = _free(msg);
>>>>          goto exit;
>>>>          /*@notreached@*/ break;
>>>>      case RPMRC_OK:
>>>>          if (sigh == NULL) {
>>>>              rpmlog(RPMLOG_ERR, _("%s: No signature available\n"),
>>>> fn);
>>>>              rc = RPMRC_FAIL;
>>>>              goto exit;
>>>>          }
>>>>          break;
>>>>      }
>>>>      msg = _free(msg);
>>>>  }
>>>>
>
> Hi Jeff, ...
>
> I continued working on this, tryign to read the headers with the
> following code :
>
>        msg = NULL;
>        rc = rpmpkgRead(header_item, rpm_handler, &headers, &msg);
>        switch (rc) {
>                case RPMRC_OK:
>                        if (headers == NULL) {
>                                rpmlog(RPMLOG_ERR, "%s: No signature  
> available\n", header_item);
>                                rc = RPMRC_FAIL;
>                                goto error_open;
>                        }
>                        break;
>                default:
>                        rpmlog(RPMLOG_ERR, "%s: %s", header_item,  
> (msg && *msg ? msg : "read failed\n"));
>                        msg = _free(msg);
>                        goto error_open;
>                        /*@notreached@*/ break;
>        }
>        msg = _free(msg);
>
>        size = rpmpkgSizeof(header_item, headers);

Try
	size_t size = headerSizeof(header_item);
(if necessary) for headers; the lead is always 96b.

>
>        printf ("Header size is %d\n", size);
>

Likely should be cast to int ...

>        hi = headerInit (headers);
>
>        rc = headerNext (hi, he, 0);
>        switch (rc) {
>                case RPMRC_OK:
>                        if (he == NULL) {
>                                rpmlog(RPMLOG_ERR, "Header: No tag  
> available\n");
>                                rc = RPMRC_FAIL;
>                                goto error_open;
>                        }
>                        break;
>                default:
>                        rpmlog(RPMLOG_ERR, "No header available, %d 
> \n", rc);
>                        goto error_open;
>                        /*@notreached@*/ break;
>        }
>
>        printf ("Header is of tag %d, data type %d of size %d, index  
> %d (%d/%d/%d)\n",
>                he->tag, he->t, he->c, he->ix, he->freeData, he- 
> >avail, he->append);
>

Note the bit fields in the HE_t.

For reading content tags, only he->tag, he->t, he->p.ptr,
and he->c are likely of any interest.

(aside)
There's something called a "header extension tag", which
is basically a transform applied to header tags, that
uses the other fields. But you should see only content
tags from headerNext() iirc.

You can use tagName(he->tag) to convert the tagno to a readable string.

>        hi = headerFini (hi);
>
> But that fails to work, as i get :
>
> Header size is -1267349847
> error: No header available, 1
>
> so, headernext returns with RPMRC_NOTFOUND, which seems strange, i  
> guess i somehow messed up the pointer stuff.
>

The rpmRC return codes are overloaded, so I can't instantly tell
what RPMRC_NOTFOUND means. In general RPMRC_NOTFOUND is used
for failing searches or magic mis-matches.

Note that digests/signatures are being verified on headers while being  
read.

You can probably track the code flow if you do the equivalent of -vv:

	rpmSetVerbosity(RPMLOG_DEBUG);

There's also pkgio specific debugging if you do
	extern _pkgio_debug;

If I can see -vv output, I might be able to help more.

73 de Jeff
______________________________________________________________________
RPM Package Manager                                    http://rpm5.org
Developer Communication List                        rpm-devel@rpm5.org
[prev in list] [next in list] [prev in thread] [next in thread]