Re: RPM C API (and other fun acronyms)

[Jeff Johnson <n3npq jbj gmail com>]

On Sep 19, 2006, at 4:13 PM, R. Tyler Ballance wrote:

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> > Are you talking about package files or installed packages from the
> > local RPMDB?  The procedure is different for each one, but once you
> > have a "Header" object for the package in question, use something  
> > like
> > this to get the name, version, etc.:
> >
> >     char *N, *E, *V, *R, *A;

Note that headerNEVRA() does not actually return the Epoch:.

> >     E = NULL;
> >     headerNEVRA(hdr, (const char **) &N, (const char **) &E,  
> > (const char **) &V, (const char **) &R,
> >                 (const char **) &A);
> >     printf("Package:  %s (%s:%s-%s) for %s\n", N, ((E)?(E):("0")),  
> > V, R, A);
> >     headerFreeData(N, RPM_STRING_TYPE);
> >     headerFreeData(E, RPM_STRING_TYPE);
> >     headerFreeData(V, RPM_STRING_TYPE);
> >     headerFreeData(R, RPM_STRING_TYPE);
> >     headerFreeData(A, RPM_STRING_TYPE);
>
> NEVRA, now I get it :) That is what I was looking for. However,  
> your snippets combined with Jeff's snippets don't work:

Hint: Using data structures other than Header is recommended, headers  
are way too bloaty
to be used as the primary data structure for rpm (or anything using  
rpmlib).

E.g.
	ds = rpmdsThis(h, RPMTAG_PROVIDENAME, RPMSENSE_EQUAL);
        fprintf(stdout, "%s\n", rpmdsDNEVR(ds)+2);
	ds = rpmdsFree(ds);
is perhaps terser (but lacks the arch, and os, and ...).

headerSprintf() is the fastest and most convenient if you want  
strings from headers.

hth

73 de Jeff