Complete rework of package accessor logic

Hopefully we've finally arrived at package handling nirvana, or at least
this commit will get us a heck of a lot closer. The former method of getting
the depends list for a package was the following:

1. call alpm_pkg_get_depends()
2. this method would check if the package came from the cache
3. if so, ensure our cache level is correct, otherwise call db_load
4. finally return the depends list

Why did this suck? Because getting the depends list from the package
shouldn't care about whether the package was loaded from a file, from the
'package cache', or some other system which we can't even use because the
damn thing is so complicated. It should just return the depends list.

So what does this commit change? It adds a pointer to a struct of function
pointers to every package for all of these 'package operations'  as I've
decided to call them (I know, sounds completely straightforward, right?). So
now when we call an alpm_pkg_get-* function, we don't do any of the cache
logic or anything else there- we let the actual backend handle it by
delegating all work to the method at pkg->ops->get_depends.

Now that be_package has achieved equal status with be_files, we can treat
packages from these completely different load points differently. We know a
package loaded from a zip file will have all of its fields populated, so
we can set up all its accessor functions to be direct accessors. On the
other hand, the packages loaded from the local and sync DBs are not always
fully-loaded, so their accessor functions are routed through the same logic
as before.

Net result? More code. However, this code now make it roughly 52 times
easier to open the door to something like a read-only tar.gz database
backend.

Are you still reading? I'm impressed. Looking at the patch will probably be
clearer than this long-winded explanation.

Signed-off-by: Dan McGee <dan@archlinux.org>
[Allan: rebase and adjust]
Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 93 insertions, 81 deletions

diff --git a/lib/libalpm/package.c b/lib/libalpm/package.c
index d30e6138..4f7cc2db 100644
--- a/lib/libalpm/package.c
+++ b/lib/libalpm/package.c
@@ -99,176 +99,187 @@ int SYMEXPORT alpm_pkg_checkmd5sum(pmpkg_t *pkg)
 	return(retval);
 }
 
-#define LAZY_LOAD(info, errret) \
-	do { \
-	ALPM_LOG_FUNC; \
-	ASSERT(handle != NULL, return(errret)); \
-	ASSERT(pkg != NULL, return(errret)); \
-	if(pkg->origin != PKG_FROM_FILE && !(pkg->infolevel & info)) { \
-		_alpm_db_read(pkg->origin_data.db, pkg, info); \
-	} \
-	} while(0)
-
+/* Default package accessor functions. These will get overridden by any
+ * backend logic that needs lazy access, such as the local database through
+ * a lazy-laod cache. However, the defaults will work just fine for fully-
+ * populated package structures. */
+const char *_pkg_get_filename(pmpkg_t *pkg)    { return pkg->filename; }
+const char *_pkg_get_name(pmpkg_t *pkg)        { return pkg->name; }
+const char *_pkg_get_version(pmpkg_t *pkg)     { return pkg->version; }
+const char *_pkg_get_desc(pmpkg_t *pkg)        { return pkg->desc; }
+const char *_pkg_get_url(pmpkg_t *pkg)         { return pkg->url; }
+time_t _pkg_get_builddate(pmpkg_t *pkg)        { return pkg->builddate; }
+time_t _pkg_get_installdate(pmpkg_t *pkg)      { return pkg->installdate; }
+const char *_pkg_get_packager(pmpkg_t *pkg)    { return pkg->packager; }
+const char *_pkg_get_md5sum(pmpkg_t *pkg)      { return pkg->md5sum; }
+const char *_pkg_get_arch(pmpkg_t *pkg)        { return pkg->arch; }
+off_t _pkg_get_size(pmpkg_t *pkg)              { return pkg->size; }
+off_t _pkg_get_isize(pmpkg_t *pkg)             { return pkg->isize; }
+pmpkgreason_t _pkg_get_reason(pmpkg_t *pkg)    { return pkg->reason; }
+int _pkg_has_force(pmpkg_t *pkg)               { return pkg->force; }
+
+alpm_list_t *_pkg_get_licenses(pmpkg_t *pkg)   { return pkg->licenses; }
+alpm_list_t *_pkg_get_groups(pmpkg_t *pkg)     { return pkg->groups; }
+alpm_list_t *_pkg_get_depends(pmpkg_t *pkg)    { return pkg->depends; }
+alpm_list_t *_pkg_get_optdepends(pmpkg_t *pkg) { return pkg->optdepends; }
+alpm_list_t *_pkg_get_conflicts(pmpkg_t *pkg)  { return pkg->conflicts; }
+alpm_list_t *_pkg_get_provides(pmpkg_t *pkg)   { return pkg->provides; }
+alpm_list_t *_pkg_get_replaces(pmpkg_t *pkg)   { return pkg->replaces; }
+alpm_list_t *_pkg_get_deltas(pmpkg_t *pkg)     { return pkg->deltas; }
+alpm_list_t *_pkg_get_files(pmpkg_t *pkg)      { return pkg->files; }
+alpm_list_t *_pkg_get_backup(pmpkg_t *pkg)     { return pkg->backup; }
+
+/** The standard package operations struct. Get fields directly from the
+ * struct itself with no abstraction layer or any type of lazy loading.
+ */
+struct pkg_operations default_pkg_ops = {
+	.get_filename    = _pkg_get_filename,
+	.get_name        = _pkg_get_name,
+	.get_version     = _pkg_get_version,
+	.get_desc        = _pkg_get_desc,
+	.get_url         = _pkg_get_url,
+	.get_builddate   = _pkg_get_builddate,
+	.get_installdate = _pkg_get_installdate,
+	.get_packager    = _pkg_get_packager,
+	.get_md5sum      = _pkg_get_md5sum,
+	.get_arch        = _pkg_get_arch,
+	.get_size        = _pkg_get_size,
+	.get_isize       = _pkg_get_isize,
+	.get_reason      = _pkg_get_reason,
+	.has_force       = _pkg_has_force,
+	.get_licenses    = _pkg_get_licenses,
+	.get_groups      = _pkg_get_groups,
+	.get_depends     = _pkg_get_depends,
+	.get_optdepends  = _pkg_get_optdepends,
+	.get_conflicts   = _pkg_get_conflicts,
+	.get_provides    = _pkg_get_provides,
+	.get_replaces    = _pkg_get_replaces,
+	.get_deltas      = _pkg_get_deltas,
+	.get_files       = _pkg_get_files,
+	.get_backup      = _pkg_get_backup,
+};
+
+/* Public functions for getting package information. These functions
+ * delegate the hard work to the function callbacks attached to each
+ * package, which depend on where the package was loaded from. */
 const char SYMEXPORT *alpm_pkg_get_filename(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->filename;
+	return pkg->ops->get_filename(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_name(pmpkg_t *pkg)
 {
-	ASSERT(pkg != NULL, return(NULL));
-	return pkg->name;
+	return pkg->ops->get_name(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_version(pmpkg_t *pkg)
 {
-	ASSERT(pkg != NULL, return(NULL));
-	return pkg->version;
+	return pkg->ops->get_version(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_desc(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->desc;
+	return pkg->ops->get_desc(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_url(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->url;
+	return pkg->ops->get_url(pkg);
 }
 
 time_t SYMEXPORT alpm_pkg_get_builddate(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, 0);
-	return pkg->builddate;
+	return pkg->ops->get_builddate(pkg);
 }
 
 time_t SYMEXPORT alpm_pkg_get_installdate(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, 0);
-	return pkg->installdate;
+	return pkg->ops->get_installdate(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_packager(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->packager;
+	return pkg->ops->get_packager(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_md5sum(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->md5sum;
+	return pkg->ops->get_md5sum(pkg);
 }
 
 const char SYMEXPORT *alpm_pkg_get_arch(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->arch;
+	return pkg->ops->get_arch(pkg);
 }
 
 off_t SYMEXPORT alpm_pkg_get_size(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, -1);
-	return pkg->size;
+	return pkg->ops->get_size(pkg);
 }
 
 off_t SYMEXPORT alpm_pkg_get_isize(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, -1);
-	return pkg->isize;
+	return pkg->ops->get_isize(pkg);
 }
 
 pmpkgreason_t SYMEXPORT alpm_pkg_get_reason(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, -1);
-	return pkg->reason;
+	return pkg->ops->get_reason(pkg);
 }
 
-alpm_list_t SYMEXPORT *alpm_pkg_get_licenses(pmpkg_t *pkg)
+int SYMEXPORT alpm_pkg_has_force(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->licenses;
+	return pkg->ops->has_force(pkg);
 }
 
-alpm_list_t SYMEXPORT *alpm_pkg_get_groups(pmpkg_t *pkg)
+alpm_list_t SYMEXPORT *alpm_pkg_get_licenses(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->groups;
+	return pkg->ops->get_licenses(pkg);
 }
 
-int SYMEXPORT alpm_pkg_has_force(pmpkg_t *pkg)
+alpm_list_t SYMEXPORT *alpm_pkg_get_groups(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, -1);
-	return pkg->force;
+	return pkg->ops->get_groups(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_depends(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DEPENDS, NULL);
-	return pkg->depends;
+	return pkg->ops->get_depends(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_optdepends(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DEPENDS, NULL);
-	return pkg->optdepends;
+	return pkg->ops->get_optdepends(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_conflicts(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DEPENDS, NULL);
-	return pkg->conflicts;
+	return pkg->ops->get_conflicts(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_provides(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DEPENDS, NULL);
-	return pkg->provides;
+	return pkg->ops->get_provides(pkg);
 }
 
-alpm_list_t SYMEXPORT *alpm_pkg_get_deltas(pmpkg_t *pkg)
+alpm_list_t SYMEXPORT *alpm_pkg_get_replaces(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DELTAS, NULL);
-	return pkg->deltas;
+	return pkg->ops->get_replaces(pkg);
 }
 
-alpm_list_t SYMEXPORT *alpm_pkg_get_replaces(pmpkg_t *pkg)
+alpm_list_t SYMEXPORT *alpm_pkg_get_deltas(pmpkg_t *pkg)
 {
-	LAZY_LOAD(INFRQ_DESC, NULL);
-	return pkg->replaces;
+	return pkg->ops->get_deltas(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_files(pmpkg_t *pkg)
 {
-	ALPM_LOG_FUNC;
-
-	/* Sanity checks */
-	ASSERT(handle != NULL, return(NULL));
-	ASSERT(pkg != NULL, return(NULL));
-
-	if(pkg->origin == PKG_FROM_LOCALDB
-		 && !(pkg->infolevel & INFRQ_FILES)) {
-		_alpm_db_read(pkg->origin_data.db, pkg, INFRQ_FILES);
-	}
-	return pkg->files;
+	return pkg->ops->get_files(pkg);
 }
 
 alpm_list_t SYMEXPORT *alpm_pkg_get_backup(pmpkg_t *pkg)
 {
-	ALPM_LOG_FUNC;
-
-	/* Sanity checks */
-	ASSERT(handle != NULL, return(NULL));
-	ASSERT(pkg != NULL, return(NULL));
-
-	if(pkg->origin == PKG_FROM_LOCALDB
-		 && !(pkg->infolevel & INFRQ_FILES)) {
-		_alpm_db_read(pkg->origin_data.db, pkg, INFRQ_FILES);
-	}
-	return pkg->backup;
+	return pkg->ops->get_backup(pkg);
 }
 
 pmdb_t SYMEXPORT *alpm_pkg_get_db(pmpkg_t *pkg)
@@ -517,6 +528,7 @@ pmpkg_t *_alpm_pkg_dup(pmpkg_t *pkg)
 
 	/* internal */
 	newpkg->origin = pkg->origin;
+	newpkg->ops = pkg->ops;
 	if(newpkg->origin == PKG_FROM_FILE) {
 		newpkg->origin_data.file = strdup(pkg->origin_data.file);
 	} else {