9 libsolv-pool - Libsolv's pool object
16 A no-purpose pointer free to use for the library user. Freeing the pool
17 simply discards the pointer.
20 The pool of unified strings.
23 The pool of unified relation dependencies.
26 Number of allocated relation dependencies.
29 The array of repository pointers, indexed by repository Id.
32 Number of allocated repository array elements, i.e. the size
36 Number of used (i.e. non-zero) repository array elements.
39 Pointer to the repo holding the installed packages. You are free to read
40 this attribute, but you should use pool_set_installed() if you want to
43 *Solvable *solvables*::
44 The array of Solvable objects.
47 Number of Solvable objects, i.e. the size of the solvables array. Note
48 that the array may contain freed solvables, in that case the repo pointer
49 of the solvable will be zero.
52 The distribution type of your system, e.g. DISTTYPE_DEB. You are free to
53 read this attribute, but you should use pool_setdisttype() if you want to
56 *Id *whatprovidesdata*::
57 Multi-purpose Id storage holding zero terminated arrays of Ids.
58 pool_whatprovides() returns an offset into this data.
61 Optional bitmap that can make the library ignore solvables. If a bitmap is
62 set, only solvables that have a set bit in the bitmap at their Id are
66 A mask that defines which debug events should be reported.
67 pool_setdebuglevel() sets this mask.
70 An object storing some position in the repository data. Functions like
71 dataiterator_set_pos() set this object, accessing data with a pseudo
72 solvable Id of SOLVID_POS uses it.
75 A queue where fixed solver jobs can be stored. This jobs are automatically
76 added when solver_solve() is called, they are useful to store configuration
77 data like which packages should be multiversion installed.
79 Creation and Destruction
80 ------------------------
84 Create a new instance of a pool.
86 void pool_free(Pool *pool);
88 Free a pool and all of the data it contains, e.g. the solvables,
89 repositories, strings.
92 Debugging and error reporting
93 -----------------------------
98 Report the error and call ``exit(1)'' afterwards. You cannot mask this
99 level. Reports to stderr instead of stdout.
102 Used to report errors. Reports to stderr instead of stdout.
105 Used to report warnings.
108 Used to report statistical data.
110 *SOLV_DEBUG_RULE_CREATION*::
111 Used to report information about the solver's creation of rules.
113 *SOLV_DEBUG_PROPAGATE*::
114 Used to report information about the solver's unit rule propagation
117 *SOLV_DEBUG_ANALYZE*::
118 Used to report information about the solver's learnt rule generation
121 *SOLV_DEBUG_UNSOLVABLE*::
122 Used to report information about the solver dealing with conflicting
125 *SOLV_DEBUG_SOLUTIONS*::
126 Used to report information about the solver creating solutions to solve
129 *SOLV_DEBUG_POLICY*::
130 Used to report information about the solver searching for an optimal
133 *SOLV_DEBUG_RESULT*::
134 Used by the debug functions to output results.
137 Used to report information about the job rule generation process.
139 *SOLV_DEBUG_SOLVER*::
140 Used to report information about what the solver is currently
143 *SOLV_DEBUG_TRANSACTION*::
144 Used to report information about the transaction generation and
147 *SOLV_DEBUG_TO_STDERR*::
148 Write debug messages to stderr instead of stdout.
152 void pool_debug(Pool *pool, int type, const char *format, ...);
154 Report a message of the type _type_. You can filter debug messages by
155 setting a debug mask.
157 void pool_setdebuglevel(Pool *pool, int level);
159 Set a predefined debug mask. A higher level generally means more bits in
160 the mask are set, thus more messages are printed.
162 void pool_setdebugmask(Pool *pool, int mask);
164 Set the debug mask to filter debug messages.
166 int pool_error(Pool *pool, int ret, const char *format, ...);
168 Set the pool's error string. The _ret_ value is simply used as a
169 return value of the function so that you can write code like
170 +return pool_error(...);+. If the debug mask contains the *SOLV_ERROR*
171 bit, pool_debug() is also called with the message and type *SOLV_ERROR*.
173 extern char *pool_errstr(Pool *pool);
175 Return the current error string stored in the pool. Like with the libc's
176 errno value, the string is only meaningful after a function returned an
179 void pool_setdebugcallback(Pool *pool, void (*debugcallback)(Pool *, void *data, int type, const char *str), void *debugcallbackdata);
181 Set a custom debug callback function. Instead of writing to stdout or
182 stderr, the callback function will be called.
191 Used for systems with use rpm as low level package manager.
194 Used for systems with use dpkg as low level package manager.
197 Used for systems with use the arch linux package manager.
200 Used for systems with use haiku packages.
202 *POOL_FLAG_PROMOTEEPOCH*::
203 Promote the epoch of the providing dependency to the requesting
204 dependency if it does not contain an epoch. Used at some time
205 in old rpm versions, modern systems should never need this.
207 *POOL_FLAG_FORBIDSELFCONFLICTS*::
208 Disallow the installation of packages that conflict with themselves.
209 Debian always allows self-conflicting packages, rpm used to forbid
210 them but switched to also allowing them recently.
212 *POOL_FLAG_OBSOLETEUSESPROVIDES*::
213 Make obsolete type dependency match against provides instead of
214 just the name and version of packages. Very old versions of rpm
215 used the name/version, then it got switched to provides and later
216 switched back again to just name/version.
218 *POOL_FLAG_IMPLICITOBSOLETEUSESPROVIDES*::
219 An implicit obsoletes is the internal mechanism to remove the
220 old package on an update. The default is to remove all packages
221 with the same name, rpm-5 switched to also removing packages
222 providing the same name.
224 *POOL_FLAG_OBSOLETEUSESCOLORS*::
225 Rpm's multilib implementation (used in RedHat and Fedora)
226 distinguishes between 32bit and 64bit packages (the terminology
227 is that they have a different color). If obsoleteusescolors is
228 set, packages with different colors will not obsolete each other.
230 *POOL_FLAG_IMPLICITOBSOLETEUSESCOLORS*::
231 Same as POOL_FLAG_OBSOLETEUSESCOLORS, but used to find out if
232 packages of the same name can be installed in parallel. For
233 current Fedora systems, POOL_FLAG_OBSOLETEUSESCOLORS should be
234 false and POOL_FLAG_IMPLICITOBSOLETEUSESCOLORS should be true
235 (this is the default if FEDORA is defined when libsolv is
238 *POOL_FLAG_NOINSTALLEDOBSOLETES*::
239 New versions of rpm consider the obsoletes of installed packages
240 when checking for dependency, thus you may not install a package
241 that is obsoleted by some other installed package, unless you
242 also erase the other package.
244 *POOL_FLAG_HAVEDISTEPOCH*::
245 Mandriva added a new field called distepoch that gets checked in
246 version comparison if the epoch/version/release of two packages
249 *POOL_FLAG_NOOBSOLETESMULTIVERSION*::
250 If a package is installed in multiversionmode, rpm used to ignore
251 both the implicit obsoletes and the obsolete dependency of a
252 package. This was changed to ignoring just the implicit obsoletes,
253 thus you may install multiple versions of the same name, but
254 obsoleted packages still get removed.
256 *POOL_FLAG_ADDFILEPROVIDESFILTERED*::
257 Make the addfileprovides method only add files from the standard
258 locations (i.e. the ``bin'' and ``etc'' directories). This is
259 useful if you have only few packages that use non-standard file
260 dependencies, but you still wand the fast speed that addfileprovides()
265 int pool_setdisttype(Pool *pool, int disttype);
267 Set the package type of your system. The disttype is used for example
268 to define package comparison semantics. Libsolv's default disttype
269 should match the package manager of your system, so you only need to
270 use this function if you want to use the library to solve packaging
271 problems for different systems. The Function returns the old
272 disttype on success, and -1 if the new disttype is not supported.
274 int pool_set_flag(Pool *pool, int flag, int value);
276 Set a flag to a new value. Returns the old value of the flag.
278 int pool_get_flag(Pool *pool, int flag);
280 Get the value of a pool flag. See the constants section about the meaning
283 void pool_set_rootdir(Pool *pool, const char *rootdir);
285 Set a specific root directory. Some library functions support a flag that
286 tells the function to prepend the rootdir to file and directory names.
288 const char *pool_get_rootdir(Pool *pool);
290 Return the current value of the root directory.
292 char *pool_prepend_rootdir(Pool *pool, const char *dir);
294 Prepend the root directory to the _dir_ argument string. The returned
295 string has been newly allocated and needs to be freed after use.
297 char *pool_prepend_rootdir_tmp(Pool *pool, const char *dir);
299 Same as pool_prepend_rootdir, but uses the pool's temporary space for
302 void pool_set_installed(Pool *pool, Repo *repo);
304 Set which repository should be treated as the ``installed'' repository,
305 i.e. the one that holds information about the installed packages.
307 void pool_set_languages(Pool *pool, const char **languages, int nlanguages);
309 Set the language of your system. The library provides lookup functions that
310 return localized strings, for example for package descriptions. You can
311 set an array of languages to provide a fallback mechanism if one language
314 void pool_setarch(Pool *pool, const char *arch);
316 Set the architecture of your system. The architecture is used to determine
317 which packages are installable and which packages cannot be installed.
318 The _arch_ argument is normally the ``machine'' value of the ``uname''
321 void pool_setarchpolicy(Pool *, const char *);
323 Set the architecture policy for your system. This is the general version
324 of pool_setarch (in fact pool_setarch calls pool_setarchpolicy internally).
325 See the section about architecture policies for more information.
327 void pool_addvendorclass(Pool *pool, const char **vendorclass);
329 Add a new vendor equivalence class to the system. A vendor equivalence class
330 defines if an installed package of one vendor can be replaced by a package
331 coming from a different vendor. The _vendorclass_ argument must be a
332 NULL terminated array of strings. See the section about vendor policies for
335 void pool_setvendorclasses(Pool *pool, const char **vendorclasses);
337 Set all allowed vendor equivalences. The vendorclasses argument must be an
338 NULL terminated array consisting of all allowed classes concatenated.
339 Each class itself must be NULL terminated, thus the last class ends with
340 two NULL elements, one to finish the class and one to finish the list
343 void pool_set_custom_vendorcheck(Pool *pool, int (*vendorcheck)(Pool *, Solvable *, Solvable *));
345 Define a custom vendor check mechanism. You can use this if libsolv's
346 internal vendor equivalence class mechanism does not match your needs.
348 void pool_setloadcallback(Pool *pool, int (*cb)(Pool *, Repodata *, void *), void *loadcbdata);
350 Define a callback function that gets called when repository metadata needs
351 to be loaded on demand. See the section about on demand loading in the
352 libsolv-repodata manual.
354 void pool_setnamespacecallback(Pool *pool, Id (*cb)(Pool *, void *, Id, Id), void *nscbdata);
356 Define a callback function to implement custom namespace support. See the
357 section about namespace dependencies.
365 The Id of the empty string, it is always Id 1.
368 Represents a ``<'' relation.
371 Represents a ``='' relation.
374 Represents a ``>'' relation. You can use combinations of REL_GT, REL_EQ,
375 and REL_LT or-ed together to create any relation you like.
378 A boolean AND operation, the ``name'' and ``evr'' parts of the relation can
379 be two sub-dependencies. Packages must match both parts of the dependency.
382 A boolean OR operation, the ``name'' and ``evr'' parts of the relation can
383 be two sub-dependencies. Packages can match any part of the dependency.
386 Like REL_AND, but packages mast match both dependencies simultaneously. See
387 the section about boolean dependencies about more information.
390 A special namespace relation. See the section about namespace dependencies
391 for more information.
394 A architecture filter dependency. The ``name'' part of the relation is a
395 sub-dependency, the ``evr'' part is the Id of an architecture that the
396 matching packages must have (note that this is an exact match ignoring
397 architecture policies).
400 An internal file conflict dependency used to represent file conflicts. See
401 the pool_add_fileconflicts_deps() function.
404 A conditional dependency, the ``name'' sub-dependency is only considered if
405 the ``evr'' sub-dependency is fulfilled. See the section about boolean
406 dependencies about more information.
409 A compat dependency used in Haiku to represent version ranges. The
410 ``name'' part is the actual version, the ``evr'' part is the backwards
411 compatibility version.
414 Id pool_str2id(Pool *pool, const char *str, int create);
416 Add a string to the pool of unified strings, returning the Id of the string.
417 If _create_ is zero, new strings will not be added to the pool, instead
420 Id pool_strn2id(Pool *pool, const char *str, unsigned int len, int create);
422 Same as pool_str2id, but only _len_ characters of the string are used. This
423 can be used to add substrings to the pool.
425 Id pool_rel2id(Pool *pool, Id name, Id evr, int flags, int create);
427 Create a relational dependency from to other dependencies, _name_ and _evr_,
428 and a _flag_. See the *REL_* constants for the supported flags. As with
429 pool_str2id, _create_ defines if new dependencies will get added or Id zero
430 will be returned instead.
432 Id pool_id2langid(Pool *pool, Id id, const char *lang, int create);
434 Attach a language suffix to a string Id. This function can be used to
435 create language keyname Ids from keynames, it is functional equivalent
436 to converting the _id_ argument to a string, adding a ``:'' character
437 and the _lang_ argument to the string and then converting the result back
440 const char *pool_id2str(const Pool *pool, Id id);
442 Convert an Id back into a string. If the Id is a relational Id, the
443 ``name'' part will be converted instead.
445 const char *pool_id2rel(const Pool *pool, Id id);
447 Return the relation string of a relational Id. Returns an empty string if
448 the passed Id is not a relation.
450 const char *pool_id2evr(const Pool *pool, Id id);
452 Return the ``evr'' part of a relational Id as string. Returns an empty
453 string if the passed Id is not a relation.
455 const char *pool_dep2str(Pool *pool, Id id);
457 Convert an Id back into a string. If the passed Id belongs to a relation,
458 a string representing the relation is returned. Note that in that case
459 the string is allocated on the pool's temporary space.
461 void pool_freeidhashes(Pool *pool);
463 Free the hashes used to unify strings and relations. You can use this
464 function to save memory if you know that you will no longer create new
465 strings and relations.
471 Solvable *pool_id2solvable(const Pool *pool, Id p);
473 Convert a solvable Id into a pointer to the solvable data. Note that the
474 pointer may become invalid if new solvables are created or old solvables
475 deleted, because the array storing all solvables may get reallocated.
477 const char *pool_solvid2str(Pool *pool, Id p);
479 Return a string representing the solvable with the Id _p_. The string will
480 be some canonical representation of the solvable, usually a combination of
481 the name, the version, and the architecture.
483 const char *pool_solvable2str(Pool *pool, Solvable *s);
485 Same as pool_solvid2str, but instead of the Id, a pointer to the solvable
494 Compare all parts of the version, treat missing parts as empty strings.
496 *EVRCMP_MATCH_RELEASE*::
497 A special mode for rpm version string matching. If a version misses a
498 release part, it matches all releases. In that case the special values
499 ``-2'' and ``2'' are returned, depending on which of the two versions
500 did not have a release part.
503 A generic match, missing parts always match.
505 *EVRCMP_COMPARE_EVONLY*::
506 Only compare the epoch and the version parts, ignore the release part.
509 int pool_evrcmp(const Pool *pool, Id evr1id, Id evr2id, int mode);
511 Compare two version Ids, return -1 if the first version is less then the
512 second version, 0 if they are identical, and 1 if the first version is
513 bigger than the second one.
515 int pool_evrcmp_str(const Pool *pool, const char *evr1, const char *evr2, int mode);
517 Same as pool_evrcmp(), but uses strings instead of Ids.
519 int pool_evrmatch(const Pool *pool, Id evrid, const char *epoch, const char *version, const char *release);
521 Match a version Id against an epoch, a version and a release string. Passing
522 NULL means that the part should match everything.
524 int pool_match_dep(Pool *pool, Id d1, Id d2);
526 Returns ``1'' if the dependency _d1_ (the provider) is matched by the
527 dependency _d2_, otherwise ``0'' is returned. For two dependencies to
528 match, both the ``name'' parts must match and the version range described
529 by the ``evr'' parts must overlap.
531 int pool_match_nevr(Pool *pool, Solvable *s, Id d);
533 Like pool_match_dep, but the provider is the "self-provides" dependency
534 of the Solvable _s_, i.e. the dependency ``s->name = s->evr''.
539 void pool_createwhatprovides(Pool *pool);
541 Create a index that maps dependency Ids to sets of packages that provide the
544 void pool_freewhatprovides(Pool *pool);
546 Free the whatprovides index to save memory.
548 Id pool_whatprovides(Pool *pool, Id d);
550 Return an offset into the Pool's whatprovidesdata array. The solvables with
551 the Ids stored starting at that offset provide the dependency _d_. The
552 solvable list is zero terminated.
554 Id *pool_whatprovides_ptr(Pool *pool, Id d);
556 Instead of returning the offset, return the pointer to the Ids stored at
557 that offset. Note that this pointer has a very limit validity time, as any
558 call that adds new values to the whatprovidesdata area may reallocate the
561 Id pool_queuetowhatprovides(Pool *pool, Queue *q);
563 Add the contents of the Queue _q_ to the end of the whatprovidesdata array,
564 returning the offset into the array.
566 void pool_addfileprovides(Pool *pool);
568 Some package managers like rpm allow dependencies on files contained in
569 other packages. To allow libsolv to deal with those dependencies in an
570 efficient way, you need to call the addfileprovides method after creating
571 and reading all repositories. This method will scan all dependency for file
572 names and than scan all packages for matching files. If a filename has been
573 matched, it will be added to the provides list of the corresponding
576 void pool_addfileprovides_queue(Pool *pool, Queue *idq, Queue *idqinst);
578 Same as pool_addfileprovides, but the added Ids are returned in two Queues,
579 _idq_ for all repositories except the one containing the ``installed''
580 packages, _idqinst_ for the latter one. This information can be stored in
581 the meta section of the repositories to speed up the next time the
582 repository is loaded and addfileprovides is called
584 void pool_flush_namespaceproviders(Pool *pool, Id ns, Id evr);
586 Clear the cache of the providers for namespace dependencies matching
587 namespace _ns_. If the _evr_ argument is non-zero, the namespace dependency
588 for exactly that dependency is cleared, otherwise all matching namespace
589 dependencies are cleared. See the section about Namespace dependencies
590 for further information.
592 void pool_add_fileconflicts_deps(Pool *pool, Queue *conflicts);
594 Some package managers like rpm report conflicts when a package installation
595 overwrites a file of another installed package with different content. As
596 file content information is not stored in the repository metadata, those
597 conflicts can only be detected after the packages are downloaded. Libsolv
598 provides a function to check for such conflicts, pool_findfileconflicts().
599 If conflicts are found, they can be added as special *REL_FILECONFLICT*
600 provides dependencies, so that the solver will know about the conflict when
606 char *pool_alloctmpspace(Pool *pool, int len);
608 Allocate space on the pool's temporary space area. This space has a limited
609 lifetime, it will be automatically freed after a fixed amount (currently
610 16) of other pool_alloctmpspace() calls are done.
612 void pool_freetmpspace(Pool *pool, const char *space);
614 Give the space allocated with pool_alloctmpspace back to the system. You
615 do not have to use this function, as the space is automatically reclaimed,
616 but it can be useful to extend the lifetime of other pointers to the pool's
617 temporary space area.
619 const char *pool_bin2hex(Pool *pool, const unsigned char *buf, int len);
621 Convert some binary data to hexadecimal, returning a string allocated in
622 the pool's temporary space area.
624 char *pool_tmpjoin(Pool *pool, const char *str1, const char *str2, const char *str3);
626 Join three strings and return the result in the pool's temporary space
627 area. You can use NULL arguments if you just want to join less strings.
629 char *pool_tmpappend(Pool *pool, const char *str1, const char *str2, const char *str3);
631 Like pool_tmpjoin(), but if the first argument is the last allocated space
632 in the pool's temporary space area, it will be replaced with the result of
633 the join and no new temporary space slot will be used. Thus you can join
634 more then three strings by a combination of one pool_tmpjoin() and multiple
635 pool_tmpappend() calls. Note that the _str1_ pointer is no longer usable
644 Use the data position stored in the pool for the lookup instead of looking
645 up the data of a solvable.
648 Use the data stored in the meta section of a repository (or repodata
649 area) instead of looking up the data of a solvable. This constant does
650 not work for the pool's lookup functions, use it for the repo's or
651 repodata's lookup functions instead. It's just listed for completeness.
654 const char *pool_lookup_str(Pool *pool, Id solvid, Id keyname);
656 Return the string value stored under the attribute _keyname_ in solvable
659 unsigned long long pool_lookup_num(Pool *pool, Id solvid, Id keyname, unsigned long long notfound);
661 Return the 64bit unsigned number stored under the attribute _keyname_ in
662 solvable _solvid_. If no such number is found, the value of the _notfound_
663 argument is returned instead.
665 Id pool_lookup_id(Pool *pool, Id solvid, Id keyname);
667 Return the Id stored under the attribute _keyname_ in solvable _solvid_.
669 int pool_lookup_idarray(Pool *pool, Id solvid, Id keyname, Queue *q);
671 Fill the queue _q_ with the content of the Id array stored under the
672 attribute _keyname_ in solvable _solvid_. Returns ``1'' if an array was
673 found, otherwise the queue will be empty and ``0'' will be returned.
675 int pool_lookup_void(Pool *pool, Id solvid, Id keyname);
677 Returns ``1'' if a void value is stored under the attribute _keyname_ in
678 solvable _solvid_, otherwise ``0''.
680 const char *pool_lookup_checksum(Pool *pool, Id solvid, Id keyname, Id *typep);
682 Return the checksum that is stored under the attribute _keyname_ in
683 solvable _solvid_. The type of the checksum will be returned over the
684 _typep_ pointer. If no such checksum is found, NULL will be returned and
685 the type will be set to zero. Note that the result is stored in the Pool's
686 temporary space area.
688 const unsigned char *pool_lookup_bin_checksum(Pool *pool, Id solvid, Id keyname, Id *typep);
690 Return the checksum that is stored under the attribute _keyname_ in
691 solvable _solvid_. Returns the checksum as binary data, you can use the
692 returned type to calculate the length of the checksum. No temporary space
695 const char *pool_lookup_deltalocation(Pool *pool, Id solvid, unsigned int *medianrp);
697 This is a utility lookup function to return the delta location for a delta
698 rpm. As solvables cannot store deltas, you have to use SOLVID_POS as
699 argument and set the Pool's datapos pointer to point to valid delta rpm
702 void pool_search(Pool *pool, Id solvid, Id keyname, const char *match, int flags, int (*callback)(void *cbdata, Solvable *s, Repodata *data, Repokey *key, KeyValue *kv), void *cbdata);
704 Perform a search on all data stored in the pool. You can limit the search
705 area by using the _solvid_ and _keyname_ arguments. The values can be
706 optionally matched against the _match_ argument, use NULL if you do not
707 want this matching. See the Dataiterator manpage about the possible matches
708 modes and the _flags_ argument. For all (matching) values, the callback
709 function is called with the _cbdata_ callback argument and the data
710 describing the value.
713 Job and Selection functions
714 ---------------------------
715 A Job consists of two Ids, _how_ and _what_. The _how_ part describes the
716 action, the job flags, and the selection method while the _what_ part is
717 in input for the selection. A Selection is a queue consisting of multiple
718 jobs (thus the number of elements in the queue must be a multiple of two).
719 See the Solver manpage for more information about jobs.
721 const char *pool_job2str(Pool *pool, Id how, Id what, Id flagmask);
723 Convert a job into a string. Useful for debugging purposes. The _flagmask_
724 can be used to mask the flags of the job, use ``0'' if you do not want to
725 see such flags, ``-1'' to see all flags, or a combination of the flags
728 void pool_job2solvables(Pool *pool, Queue *pkgs, Id how, Id what);
730 Return a list of solvables that the specified job selects.
732 int pool_isemptyupdatejob(Pool *pool, Id how, Id what);
734 Return ``1'' if the job is an update job that does not work with any
735 installed package, i.e. the job is basically a no-op. You can use this
736 to turn no-op update jobs into install jobs (as done by package managers
739 const char *pool_selection2str(Pool *pool, Queue *selection, Id flagmask);
741 Convert a selection into a string. Useful for debugging purposes. See the
742 pool_job2str() function for the _flagmask_ argument.
747 void pool_freeallrepos(Pool *pool, int reuseids);
749 Free all repos from the pool (including all solvables). If _reuseids_ is
750 true, all Ids of the solvables are free to be reused the next time
751 solvables are created.
753 void pool_clear_pos(Pool *pool);
755 Clear the data position stored in the pool.
758 Architecture Policies
759 ---------------------
760 An architecture policy defines a list of architectures that can be
761 installed on the system, and also the relationship between them (i.e. the
762 ordering). Architectures can be delimited with three different characters:
765 No relationship between the architectures. A package of one architecture
766 can not be replaced with one of the other architecture.
769 The first architecture is better than the second one. An installed package
770 of the second architecture may be replaced with one from the first
771 architecture and vice versa. The solver will select the better architecture
772 if the versions are the same.
775 The two architectures are freely exchangeable. Used to define aliases
778 An example would be \'+x86_64:i686=athlon>i586+'. This means that x86_64
779 packages can only be replaced by other x86_64 packages, i686 packages
780 can be replaced by i686 and i586 packages (but i686 packages will be
781 preferred) and athlon is another name for the i686 architecture.
783 You can turn off the architecture replacement checks with the Solver's
784 SOLVER_FLAG_ALLOW_ARCHCHANGE flag.
788 Different vendors often compile packages with different features, so
789 Libsolv only replace installed packages of one vendor with packages coming
790 from the same vendor. Also, while the version of a package is normally
791 defined by the upstream project, the release part of the version is
792 set by the vendor's package maintainer, so it's not meaningful to
793 do version comparisons for packages coming from different vendors.
795 Vendor in this case means the SOLVABLE_VENDOR string stored in each
796 solvable. Sometimes a vendor changes names, or multiple vendors form a
797 group that coordinate their package building, so libsolv offers a way
798 to define that a group of vendors are compatible. You do that be
799 defining vendor equivalence classes, packages from a vendor from
800 one class may be replaced with packages from all the other vendors
803 There can be multiple equivalence classes, the set of allowed vendor
804 changes for an installed package is calculated by building the union
805 of all of the equivalence classes the vendor of the installed package
808 You can turn off the architecture replacement checks with the Solver's
809 SOLVER_FLAG_ALLOW_VENDORCHANGE flag.
814 Boolean Dependencies allow to build complex expressions from simple
815 dependencies. While rpm does not support boolean expressions in
816 dependencies and debian only allows an "OR" expression, libsolv
817 allows arbitrary complex expressions. The following basic types
821 The expression is true if either the first dependency or the second
822 one is true. This is useful for package dependencies like ``Requires'',
823 where you can specify that either one of the packages need to be
827 The expression is true if both dependencies are true. The packages
828 fulfilling the dependencies may be different, i.e.
829 ``Supplements: perl AND python'' is true if both a package providing
830 perl and a package providing python are installed. The solver currently
831 only supports REL_AND in Supplements/Enhances dependencies, in other
832 types of dependencies it gets treated as REL_WITH.
835 The expression is true if both dependencies are true and are fulfilled by
836 the same package. Thus ``Supplements: perl AND python'' would only be true
837 if a package is installed that provides both dependencies (some kind
838 of multi-language interpreter).
841 The expression is true if the first dependency is true or the second
842 dependency is false. Libsolv currently does not support this type of
843 dependency in the solver code.
845 Each sub-dependency of a boolean dependency can in turn be a boolean
846 dependency, so you can chain them to create complex dependencies.
849 Namespace Dependencies
850 ----------------------
851 Namespace dependencies can be used to implement dependencies on
852 attributes external to libsolv. An example would be a dependency
853 on the language set by the user. This types of dependencies are
854 usually only used for ``Conflicts'' or ``Supplements'' dependencies,
855 as the underlying package manager does not know how to deal with
858 If the library needs to evaluate a namespace dependency, it calls
859 the namespace callback function set in the pool. The callback
860 function can return a set of packages that ``provide'' the
861 dependency. If the dependency is provided by the system, the
862 returned set should consist of just the system solvable (Solvable
865 The returned set of packages must be returned as offset into
866 the whatprovidesdata array. You can use the pool_queuetowhatprovides
867 function to convert a queue into such an offset. To ease programming
868 the callback function, the return values ``0'' and ``1'' are not
869 interpreted as an offset. ``0'' means that no package is in the
870 return set, ``1'' means that just the system solvable is in the set.
872 The returned set is cached, so that for each namespace dependency
873 the callback is just called once. If you need to flush the cache (maybe
874 because the user has selected a different language), use the
875 pool_flush_namespaceproviders() function.
880 Michael Schroeder <mls@suse.de>