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<TITLE>Maximum RPM (RPM):A Guide to the RPM Library API:EarthWeb Inc.-</TITLE>
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<!-- ISBN=0672311054 //-->
<!-- TITLE=Maximum RPM (RPM)//-->
<!-- AUTHOR=Edward Bailey//-->
<!-- PUBLISHER=Macmillan Computer Publishing//-->
<!-- IMPRINT=Sams//-->
<!-- CHAPTER=21 //-->
<!-- PAGES=0305-0336 //-->
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<P><CENTER>
<a href="0305-0309.html">Previous</A> | <a href="../ewtoc.html">Table of Contents</A> | <a href="0314-0317.html">Next</A>
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<A NAME="PAGENUM-310"><P>Page 310</P></A>
<P>The building argument should be set to 1 only if a package is being built when this function
is called. Since most rpmlib-based applications will probably not duplicate RPM's
package-building capabilities, building should normally be set to
0.
</P>
<H4><A NAME="ch21_ 16">
21.2.4.2. rpmGetOsName()—Return Operating System Name
</A></H4>
<P>This function returns the name of the operating system, as determined by
rpmlib's normal rpmrc file processing:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
char *rpmGetOsName(void);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 17">
21.2.4.3. rpmGetArchName()—Return Architecture Name
</A></H4>
<P>This function returns the name of the architecture, as determined by rpmlib's normal
rpmrc file processing:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
char *rpmGetArchName(void);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 18">
21.2.4.4. rpmShowRC()—Print All rpmrc-Derived Variables
</A></H4>
<P>This function writes all variable names and their values
to the file f. It always returns 0:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmShowRC(FILE *f);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 19">
21.2.4.5. rpmArchScore()—Return Architecture Compatibility Score
</A></H4>
<P>This function returns the level of compatibility between the architecture whose name is
specified in arch and the current architecture. Returns
0 if the two architectures are incompatible. The smaller the number returned, the more compatible the two architectures are:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmArchScore(char * arch);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 20">
21.2.4.6. rpmOsScore()—Return Operating System Compatibility Score
</A></H4>
<P>This function returns the level of compatibility between the operating system whose name
is specified in os and the current operating system.
Returns 0 if the two operating systems are incompatible. The smaller the number returned, the more compatible the two operating
systems are:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmOsScore(char * os);
</PRE>
<!-- END CODE SNIP //--><A NAME="PAGENUM-311"><P>Page 311</P></A>
<H4>
21.2.5. RPM Database Manipulation
</H4>
<P>The functions in this section perform the basic operations on the RPM database. This
includes opening and closing the database, as well as creating the database. A function also exists to
rebuild a database that has been corrupted.
</P>
<P>Every function that accesses the RPM database in some fashion makes use of the
rpmdb structure. This structure is used as a handle to refer to a particular RPM database.
</P>
<H4><A NAME="ch21_ 21">
21.2.5.1. rpmdbOpen()—Open RPM Database
</A></H4>
<P>This function opens the RPM database located in
RPMVAR_DBPATH, returning the rpmdb structure dbp. If
root is specified, it is prepended to
RPMVAR_DBPATH prior to opening. The mode and perms parameters are identical to
open(2)'s flags and mode parameters, respectively:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmdbOpen(char * root,
rpmdb * dbp,
int mode,
int perms);
</PRE>
<!-- END CODE SNIP //-->
<P>The function returns 1 on error, and 0 on success.
</P>
<H4><A NAME="ch21_ 22">
21.2.5.2. rpmdbClose()—Close RPM Database
</A></H4>
<P>This function closes the RPM database specified by the
rpmdb structure db. The db structure is also freed:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
void rpmdbClose(rpmdb db);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 23">
21.2.5.3. rpmdbInit()—Create RPM Database
</A></H4>
<P>This function creates a new RPM database to be located in
RPMVAR_DBPATH. If the database already exists, it is left unchanged. If
root is specified, it is prepended to
RPMVAR_DBPATH prior to creation. The perms parameter is identical to
open(2)'s mode parameter:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmdbInit(char * root,
int perms);
</PRE>
<!-- END CODE SNIP //-->
<P>The function returns 1 on error, and 0 on success.
</P>
<A NAME="PAGENUM-312"><P>Page 312</P></A>
<H4><A NAME="ch21_ 24">
21.2.5.4. rpmdbRebuild()—Rebuild RPM Database
</A></H4>
<P>This function rebuilds the RPM database located in
RPMVAR_DBPATH. If root is specified, it is prepended to
RPMVAR_DBPATH prior to rebuilding:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
int rpmdbRebuild(char * root);
</PRE>
<!-- END CODE SNIP //-->
<P>The function returns 1 on error, and 0 on success.
</P>
<H4><A NAME="ch21_ 25">
21.2.6. RPM Database Traversal
</A></H4>
<P>The following functions are used to traverse the RPM database. Also described in this
section is a function to retrieve a database record by its record number.
</P>
<P>Note that database records are returned in the form of a
Header structure. This data structure is widely used throughout rpmlib. We will discuss more header-related functions in
sections 21.2.13 and 21.2.14.
</P>
<H4><A NAME="ch21_ 26">
21.2.6.1. rpmdbFirstRecNum()—Begin RPM Database Traversal
</A></H4>
<P>This function returns the record number of the first record
in the database specified by db:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
unsigned int rpmdbFirstRecNum(rpmdb db);
</PRE>
<!-- END CODE SNIP //-->
<P>On error, it returns 0.
</P>
<H4><A NAME="ch21_ 27">
21.2.6.2. rpmdbNextRecNum()—Traverse to Next RPM Database Record
</A></H4>
<P>This function returns the record number of the record following the
record number passed in lastOffset, in the database specified by
db:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
unsigned int rpmdbNextRecNum(rpmdb db,
unsigned int lastOffset);
</PRE>
<!-- END CODE SNIP //-->
<P>On error, this function returns 0.
</P>
<H4><A NAME="ch21_ 28">
21.2.6.3. rpmdbGetRecord()—Return Record from RPM Database
</A></H4>
<P>This function returns the record at the record number specified by
offset from the database specified by db:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
Header rpmdbGetRecord(rpmdb db,
unsigned int offset);
</PRE>
<!-- END CODE SNIP //-->
<P>This function returns NULL on error.
</P>
<A NAME="PAGENUM-313"><P>Page 313</P></A>
<H4><A NAME="ch21_ 29">
21.2.7. RPM Database Search
</A></H4>
<P>The functions in this section search the various parts of the RPM database. They all return
a structure of type dbiIndexSet, which contains the records that match the search term. Here
is the definition of the structure, as found in
<rpm/dbindex.h>:
</P>
<!-- CODE SNIP //-->
<PRE>
typedef struct {
dbiIndexRecord * recs;
int count;
} dbiIndexSet;
</PRE>
<!-- END CODE SNIP //-->
<P>Each dbiIndexRecord is also defined in
<rpm/dbindex.h>, as follows:
</P>
<!-- CODE SNIP //-->
<PRE>
typedef struct {
unsigned int recOffset;
unsigned int fileNumber;
} dbiIndexRecord;
</PRE>
<!-- END CODE SNIP //-->
<P>The recOffset element is the offset of the record from the start of the database file.
The fileNumber element is only used by
rpmdbFindByFile().
</P>
<P>Keep in mind that the rpmdbFindxxx() search functions each return
dbiIndexSet structures, which must be freed with
dbiFreeIndexRecord() when no longer needed.
</P>
<H4><A NAME="ch21_ 30">
21.2.7.1. dbiFreeIndexRecord()—Free Database Index
</A></H4>
<P>This function frees the database index set specified by
set:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
#include <rpm/dbindex.h>
void dbiFreeIndexRecord(dbiIndexSet set);
</PRE>
<!-- END CODE SNIP //-->
<H4><A NAME="ch21_ 31">
21.2.7.2. rpmdbFindByFile()—Search RPM Database by File
</A></H4>
<P>This function searches the RPM database specified by
db for the package that owns the file specified by
filespec. It returns matching records in matches:
</P>
<!-- CODE SNIP //-->
<PRE>
#include <rpm/rpmlib.h>
#include <rpm/dbindex.h>
int rpmdbFindByFile(rpmdb db,
char * filespec,
dbiIndexSet * matches);
</PRE>
<!-- END CODE SNIP //-->
<P>This function returns the following status values:
</P>
<BLOCKQUOTE>
-1—An error occurred while reading a database record.<BR>
0—The search completed normally.<BR>
1—The search term was not found.<BR>
</BLOCKQUOTE>
<P><CENTER>
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