solver, db: implement repository pinning

Improves /etc/apk/repositories format so you can say:
http://nl.alpinelinux.org/alpine/v2.3/main
@edge http://nl.alpinelinux.org/alpine/edge/main
@testing http://nl.alpinelinux.org/alpine/edge/testing

After which you can pin dependencies to these tags using:
 apk add stableapp newapp@edge bleedingapp@testing

Apk will now by default only use the untagged repositories,
but adding a tag to specific dependency:
 1. will prefer that tag for the name
 2. allowing pulling in dependencies from that tag (though,
    it prefers untagged packages to satisfy deps if possible)

fixes #575

17 files changed, 182 insertions, 54 deletions

diff --git a/src/apk_database.h b/src/apk_database.h
index d7c4f5b..e5d28f4 100644
--- a/src/apk_database.h
+++ b/src/apk_database.h
@@ -115,10 +115,15 @@ struct apk_db_options {
 	struct list_head repository_list;
 };
 
+struct apk_repository_tag {
+	unsigned int allowed_repos;
+	apk_blob_t *name;
+};
+
 struct apk_database {
 	char *root;
 	int root_fd, lock_fd, cache_fd, cachetmp_fd, keys_fd;
-	unsigned num_repos;
+	unsigned num_repos, num_repo_tags;
 	const char *cache_dir;
 	char *cache_remount_dir;
 	apk_blob_t *arch;
@@ -131,6 +136,7 @@ struct apk_database {
 	struct apk_dependency_array *world;
 	struct apk_string_array *protected_paths;
 	struct apk_repository repos[APK_MAX_REPOS];
+	struct apk_repository_tag repo_tags[APK_MAX_REPOS];
 	struct apk_id_cache id_cache;
 
 	struct {
@@ -158,6 +164,7 @@ typedef union apk_database_or_void {
 
 struct apk_name *apk_db_get_name(struct apk_database *db, apk_blob_t name);
 struct apk_name *apk_db_query_name(struct apk_database *db, apk_blob_t name);
+int apk_db_get_tag_id(struct apk_database *db, apk_blob_t tag);
 struct apk_db_dir *apk_db_dir_query(struct apk_database *db,
 				    apk_blob_t name);
 struct apk_db_file *apk_db_file_query(struct apk_database *db,
diff --git a/src/apk_package.h b/src/apk_package.h
index c68fef7..a241a67 100644
--- a/src/apk_package.h
+++ b/src/apk_package.h
@@ -59,6 +59,7 @@ struct apk_sign_ctx {
 struct apk_dependency {
 	struct apk_name *name;
 	apk_blob_t *version;
+	unsigned short repository_tag;
 	unsigned optional : 1;
 	unsigned result_mask : 3;
 };
@@ -120,12 +121,13 @@ void apk_dep_from_pkg(struct apk_dependency *dep, struct apk_database *db,
 		      struct apk_package *pkg);
 int apk_dep_is_satisfied(struct apk_dependency *dep, struct apk_package *pkg);
 
-void apk_blob_push_dep(apk_blob_t *to, struct apk_dependency *dep);
-void apk_blob_push_deps(apk_blob_t *to, struct apk_dependency_array *deps);
+void apk_blob_push_dep(apk_blob_t *to, struct apk_database *, struct apk_dependency *dep);
+void apk_blob_push_deps(apk_blob_t *to, struct apk_database *, struct apk_dependency_array *deps);
 void apk_blob_pull_dep(apk_blob_t *from, struct apk_database *, struct apk_dependency *);
 void apk_blob_pull_deps(apk_blob_t *from, struct apk_database *, struct apk_dependency_array **);
 
-int apk_deps_write(struct apk_dependency_array *deps, struct apk_ostream *os);
+int apk_deps_write(struct apk_database *db, struct apk_dependency_array *deps,
+		   struct apk_ostream *os);
 
 int apk_deps_add(struct apk_dependency_array **depends,
 		 struct apk_dependency *dep);
diff --git a/src/blob.c b/src/blob.c
index aaaa377..8cf4076 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -44,8 +44,10 @@ int apk_blob_spn(apk_blob_t blob, const char *accept, apk_blob_t *l, apk_blob_t
 
 	for (i = 0; i < blob.len; i++) {
 		if (strchr(accept, blob.ptr[i]) == NULL) {
-			*l = APK_BLOB_PTR_LEN(blob.ptr, i);
-			*r = APK_BLOB_PTR_LEN(blob.ptr+i, blob.len-i);
+			if (l != NULL)
+				*l = APK_BLOB_PTR_LEN(blob.ptr, i);
+			if (r != NULL)
+				*r = APK_BLOB_PTR_LEN(blob.ptr+i, blob.len-i);
 			return 1;
 		}
 	}
@@ -58,8 +60,10 @@ int apk_blob_cspn(apk_blob_t blob, const char *reject, apk_blob_t *l, apk_blob_t
 
 	for (i = 0; i < blob.len; i++) {
 		if (strchr(reject, blob.ptr[i]) != NULL) {
-			*l = APK_BLOB_PTR_LEN(blob.ptr, i);
-			*r = APK_BLOB_PTR_LEN(blob.ptr+i, blob.len-i);
+			if (l != NULL)
+				*l = APK_BLOB_PTR_LEN(blob.ptr, i);
+			if (r != NULL)
+				*r = APK_BLOB_PTR_LEN(blob.ptr+i, blob.len-i);
 			return 1;
 		}
 	}
diff --git a/src/database.c b/src/database.c
index 482f406..8eaba6c 100644
--- a/src/database.c
+++ b/src/database.c
@@ -713,7 +713,7 @@ static int apk_db_write_fdb(struct apk_database *db, struct apk_ostream *os)
 
 		if (ipkg->replaces->num) {
 			apk_blob_push_blob(&bbuf, APK_BLOB_STR("r:"));
-			apk_blob_push_deps(&bbuf, ipkg->replaces);
+			apk_blob_push_deps(&bbuf, db, ipkg->replaces);
 			apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
 		}
 		if (ipkg->replaces_priority) {
@@ -1156,6 +1156,9 @@ int apk_db_open(struct apk_database *db, struct apk_db_options *dbopts)
 	apk_string_array_init(&db->protected_paths);
 	db->permanent = 1;
 
+	/* Get first repository tag (the NULL tag) */
+	apk_db_get_tag_id(db, APK_BLOB_NULL);
+
 	if (dbopts->root && dbopts->arch) {
 		db->arch = apk_blob_atomize(APK_BLOB_STR(dbopts->arch));
 	} else {
@@ -1351,7 +1354,7 @@ int apk_db_write_config(struct apk_database *db)
 	if (os == NULL)
 		return -1;
 
-	apk_deps_write(db->world, os);
+	apk_deps_write(db, db->world, os);
 	os->write(os, "\n", 1);
 	r = os->close(os);
 	if (r < 0)
@@ -1443,6 +1446,25 @@ void apk_db_close(struct apk_database *db)
 	}
 }
 
+int apk_db_get_tag_id(struct apk_database *db, apk_blob_t tag)
+{
+	apk_blob_t *b = apk_blob_atomize_dup(tag);
+	int i;
+
+	for (i = 0; i < db->num_repo_tags; i++) {
+		if (db->repo_tags[i].name == b)
+			return i;
+	}
+	if (i < ARRAY_SIZE(db->repo_tags)) {
+		db->num_repo_tags++;
+		db->repo_tags[i] = (struct apk_repository_tag) {
+			.name = b
+		};
+		return i;
+	}
+	return -1;
+}
+
 static int fire_triggers(apk_hash_item item, void *ctx)
 {
 	struct apk_database *db = (struct apk_database *) ctx;
@@ -1696,30 +1718,38 @@ int apk_db_index_read_file(struct apk_database *db, const char *file, int repo)
 	return load_index(db, apk_bstream_from_file(AT_FDCWD, file), targz, repo);
 }
 
-int apk_db_add_repository(apk_database_t _db, apk_blob_t repository)
+int apk_db_add_repository(apk_database_t _db, apk_blob_t _repository)
 {
 	struct apk_database *db = _db.db;
 	struct apk_bstream *bs = NULL;
 	struct apk_repository *repo;
-	int r, targz = 1;
+	apk_blob_t brepo, btag;
+	int r, targz = 1, tag_id = 0;
 	char buf[PATH_MAX];
 
-	if (repository.ptr == NULL || repository.len == 0 ||
-	    *repository.ptr == '#')
-		return 0;
-
 	if (db->num_repos >= APK_MAX_REPOS)
 		return -1;
 
-	r = db->num_repos++;
+	brepo = _repository;
+	btag = APK_BLOB_NULL;
+	if (brepo.ptr == NULL || brepo.len == 0 || *brepo.ptr == '#')
+		return 0;
 
+	if (brepo.ptr[0] == '@') {
+		apk_blob_pull_char(&brepo, '@');
+		apk_blob_cspn(brepo, ": ", &btag, &brepo);
+		apk_blob_spn(brepo, ": ", NULL, &brepo);
+		tag_id = apk_db_get_tag_id(db, btag);
+	}
+
+	r = db->num_repos++;
 	repo = &db->repos[r];
 	*repo = (struct apk_repository) {
-		.url = apk_blob_cstr(repository),
+		.url = apk_blob_cstr(brepo),
 	};
 
 	if (apk_url_local_file(repo->url) == NULL) {
-		apk_blob_checksum(repository, apk_checksum_default(), &repo->csum);
+		apk_blob_checksum(brepo, apk_checksum_default(), &repo->csum);
 
 		if (apk_flags & APK_UPDATE_CACHE)
 			apk_repository_update(db, repo);
@@ -1730,6 +1760,7 @@ int apk_db_add_repository(apk_database_t _db, apk_blob_t repository)
 		db->local_repos |= BIT(r);
 		bs = apk_repo_file_open(repo, db->arch, apkindex_tar_gz, buf, sizeof(buf));
 	}
+	db->repo_tags[tag_id].allowed_repos |= BIT(r);
 	if (bs == NULL) {
 		apk_warning("%s: index failed to open", buf);
 		return 0;
diff --git a/src/info.c b/src/info.c
index b45eba5..b90fa1a 100644
--- a/src/info.c
+++ b/src/info.c
@@ -18,6 +18,7 @@
 #include "apk_print.h"
 
 struct info_ctx {
+	struct apk_database *db;
 	int (*action)(struct info_ctx *ctx, struct apk_database *db,
 		      int argc, char **argv);
 	int subaction_mask;
@@ -130,7 +131,7 @@ static int info_who_owns(struct info_ctx *ctx, struct apk_database *db,
 		struct apk_ostream *os;
 
 		os = apk_ostream_to_fd(STDOUT_FILENO);
-		apk_deps_write(deps, os);
+		apk_deps_write(db, deps, os);
 		os->write(os, "\n", 1);
 		os->close(os);
 	}
@@ -139,7 +140,7 @@ static int info_who_owns(struct info_ctx *ctx, struct apk_database *db,
 	return r;
 }
 
-static void info_print_description(struct apk_package *pkg)
+static void info_print_description(struct apk_database *db, struct apk_package *pkg)
 {
 	if (apk_verbosity > 1)
 		printf("%s: %s", pkg->name->name, pkg->description);
@@ -149,7 +150,7 @@ static void info_print_description(struct apk_package *pkg)
 		       pkg->description);
 }
 
-static void info_print_url(struct apk_package *pkg)
+static void info_print_url(struct apk_database *db, struct apk_package *pkg)
 {
 	if (apk_verbosity > 1)
 		printf("%s: %s", pkg->name->name, pkg->url);
@@ -159,7 +160,7 @@ static void info_print_url(struct apk_package *pkg)
 		       pkg->url);
 }
 
-static void info_print_size(struct apk_package *pkg)
+static void info_print_size(struct apk_database *db, struct apk_package *pkg)
 {
 	if (apk_verbosity > 1)
 		printf("%s: %zu", pkg->name->name, pkg->installed_size);
@@ -169,7 +170,7 @@ static void info_print_size(struct apk_package *pkg)
 		       pkg->installed_size);
 }
 
-static void info_print_depends(struct apk_package *pkg)
+static void info_print_depends(struct apk_database *db, struct apk_package *pkg)
 {
 	apk_blob_t separator = APK_BLOB_STR(apk_verbosity > 1 ? " " : "\n");
 	char dep[256];
@@ -182,14 +183,14 @@ static void info_print_depends(struct apk_package *pkg)
 		printf("%s: ", pkg->name->name);
 	for (i = 0; i < pkg->depends->num; i++) {
 		apk_blob_t b = APK_BLOB_BUF(dep);
-		apk_blob_push_dep(&b, &pkg->depends->item[i]);
+		apk_blob_push_dep(&b, db, &pkg->depends->item[i]);
 		apk_blob_push_blob(&b, separator);
 		b = apk_blob_pushed(APK_BLOB_BUF(dep), b);
 		fwrite(b.ptr, b.len, 1, stdout);
 	}
 }
 
-static void info_print_required_by(struct apk_package *pkg)
+static void info_print_required_by(struct apk_database *db, struct apk_package *pkg)
 {
 	int i, j, k;
 	char *separator = apk_verbosity > 1 ? " " : "\n";
@@ -221,7 +222,7 @@ static void info_print_required_by(struct apk_package *pkg)
 	}
 }
 
-static void info_print_install_if(struct apk_package *pkg)
+static void info_print_install_if(struct apk_database *db, struct apk_package *pkg)
 {
 	apk_blob_t separator = APK_BLOB_STR(apk_verbosity > 1 ? " " : "\n");
 	char dep[256];
@@ -234,14 +235,14 @@ static void info_print_install_if(struct apk_package *pkg)
 		printf("%s: ", pkg->name->name);
 	for (i = 0; i < pkg->install_if->num; i++) {
 		apk_blob_t b = APK_BLOB_BUF(dep);
-		apk_blob_push_dep(&b, &pkg->install_if->item[i]);
+		apk_blob_push_dep(&b, db, &pkg->install_if->item[i]);
 		apk_blob_push_blob(&b, separator);
 		b = apk_blob_pushed(APK_BLOB_BUF(dep), b);
 		fwrite(b.ptr, b.len, 1, stdout);
 	}
 }
 
-static void info_print_rinstall_if(struct apk_package *pkg)
+static void info_print_rinstall_if(struct apk_database *db, struct apk_package *pkg)
 {
 	int i, j, k;
 	char *separator = apk_verbosity > 1 ? " " : "\n";
@@ -273,7 +274,7 @@ static void info_print_rinstall_if(struct apk_package *pkg)
 	}
 }
 
-static void info_print_contents(struct apk_package *pkg)
+static void info_print_contents(struct apk_database *db, struct apk_package *pkg)
 {
 	struct apk_installed_package *ipkg = pkg->ipkg;
 	struct apk_db_dir_instance *diri;
@@ -295,7 +296,7 @@ static void info_print_contents(struct apk_package *pkg)
 	}
 }
 
-static void info_print_triggers(struct apk_package *pkg)
+static void info_print_triggers(struct apk_database *db, struct apk_package *pkg)
 {
 	struct apk_installed_package *ipkg = pkg->ipkg;
 	int i;
@@ -311,7 +312,7 @@ static void info_print_triggers(struct apk_package *pkg)
 	}
 }
 
-static void info_print_replaces(struct apk_package *pkg)
+static void info_print_replaces(struct apk_database *db, struct apk_package *pkg)
 {
 	apk_blob_t separator = APK_BLOB_STR(apk_verbosity > 1 ? " " : "\n");
 	char dep[256];
@@ -324,7 +325,7 @@ static void info_print_replaces(struct apk_package *pkg)
 		printf("%s: ", pkg->name->name);
 	for (i = 0; i < pkg->ipkg->replaces->num; i++) {
 		apk_blob_t b = APK_BLOB_BUF(dep);
-		apk_blob_push_dep(&b, &pkg->ipkg->replaces->item[i]);
+		apk_blob_push_dep(&b, db, &pkg->ipkg->replaces->item[i]);
 		apk_blob_push_blob(&b, separator);
 		b = apk_blob_pushed(APK_BLOB_BUF(dep), b);
 		fwrite(b.ptr, b.len, 1, stdout);
@@ -333,7 +334,7 @@ static void info_print_replaces(struct apk_package *pkg)
 
 static void info_subaction(struct info_ctx *ctx, struct apk_package *pkg)
 {
-	typedef void (*subaction_t)(struct apk_package *);
+	typedef void (*subaction_t)(struct apk_database *, struct apk_package *);
 	static subaction_t subactions[] = {
 		info_print_description,
 		info_print_url,
@@ -358,7 +359,7 @@ static void info_subaction(struct info_ctx *ctx, struct apk_package *pkg)
 		if (pkg->ipkg == NULL && (BIT(i) & requireipkg))
 			continue;
 
-		subactions[i](pkg);
+		subactions[i](ctx->db, pkg);
 		puts("");
 	}
 }
@@ -437,6 +438,7 @@ static int info_main(void *ctx, struct apk_database *db, int argc, char **argv)
 {
 	struct info_ctx *ictx = (struct info_ctx *) ctx;
 
+	ictx->db = db;
 	if (ictx->action != NULL)
 		return ictx->action(ictx, db, argc, argv);
 
diff --git a/src/package.c b/src/package.c
index 3886d82..1c7bd2d 100644
--- a/src/package.c
+++ b/src/package.c
@@ -194,8 +194,8 @@ struct parse_depend_ctx {
 void apk_blob_pull_dep(apk_blob_t *b, struct apk_database *db, struct apk_dependency *dep)
 {
 	struct apk_name *name;
-	apk_blob_t bname, bop, bver = APK_BLOB_NULL;
-	int mask = APK_DEPMASK_REQUIRE, optional = 0;
+	apk_blob_t bname, bop, bver = APK_BLOB_NULL, btag;
+	int mask = APK_DEPMASK_REQUIRE, optional = 0, tag = 0;
 	size_t len;
 
 	/* [!]name[<,<=,=,>=,>]ver */
@@ -239,6 +239,9 @@ void apk_blob_pull_dep(apk_blob_t *b, struct apk_database *db, struct apk_depend
 	b->ptr += len;
 	b->len -= len;
 
+	if (apk_blob_split(bname, APK_BLOB_STR("@"), &bname, &btag))
+		tag = apk_db_get_tag_id(db, btag);
+
 	name = apk_db_get_name(db, bname);
 	if (name == NULL)
 		goto fail;
@@ -249,6 +252,7 @@ void apk_blob_pull_dep(apk_blob_t *b, struct apk_database *db, struct apk_depend
 	*dep = (struct apk_dependency){
 		.name = name,
 		.version = apk_blob_atomize_dup(bver),
+		.repository_tag = tag,
 		.result_mask = mask,
 		.optional = optional,
 	};
@@ -325,7 +329,7 @@ void apk_blob_pull_deps(apk_blob_t *b, struct apk_database *db, struct apk_depen
 	apk_blob_for_each_segment(*b, " ", parse_depend, &ctx);
 }
 
-void apk_blob_push_dep(apk_blob_t *to, struct apk_dependency *dep)
+void apk_blob_push_dep(apk_blob_t *to, struct apk_database *db, struct apk_dependency *dep)
 {
 	int result_mask = dep->result_mask;
 
@@ -335,14 +339,17 @@ void apk_blob_push_dep(apk_blob_t *to, struct apk_dependency *dep)
 	}
 
 	apk_blob_push_blob(to, APK_BLOB_STR(dep->name->name));
-
 	if (!APK_BLOB_IS_NULL(*dep->version)) {
 		apk_blob_push_blob(to, APK_BLOB_STR(apk_version_op_string(dep->result_mask)));
 		apk_blob_push_blob(to, *dep->version);
 	}
+	if (dep->repository_tag && db != NULL) {
+		apk_blob_push_blob(to, APK_BLOB_PTR_LEN("@", 1));
+		apk_blob_push_blob(to, *db->repo_tags[dep->repository_tag].name);
+	}
 }
 
-void apk_blob_push_deps(apk_blob_t *to, struct apk_dependency_array *deps)
+void apk_blob_push_deps(apk_blob_t *to, struct apk_database *db, struct apk_dependency_array *deps)
 {
 	int i;
 
@@ -352,11 +359,11 @@ void apk_blob_push_deps(apk_blob_t *to, struct apk_dependency_array *deps)
 	for (i = 0; i < deps->num; i++) {
 		if (i)
 			apk_blob_push_blob(to, APK_BLOB_PTR_LEN(" ", 1));
-		apk_blob_push_dep(to, &deps->item[i]);
+		apk_blob_push_dep(to, db, &deps->item[i]);
 	}
 }
 
-int apk_deps_write(struct apk_dependency_array *deps, struct apk_ostream *os)
+int apk_deps_write(struct apk_database *db, struct apk_dependency_array *deps, struct apk_ostream *os)
 {
 	apk_blob_t blob;
 	char tmp[256];
@@ -369,7 +376,7 @@ int apk_deps_write(struct apk_dependency_array *deps, struct apk_ostream *os)
 		blob = APK_BLOB_BUF(tmp);
 		if (i)
 			apk_blob_push_blob(&blob, APK_BLOB_PTR_LEN(" ", 1));
-		apk_blob_push_dep(&blob, &deps->item[i]);
+		apk_blob_push_dep(&blob, db, &deps->item[i]);
 
 		blob = apk_blob_pushed(APK_BLOB_BUF(tmp), blob);
 		if (APK_BLOB_IS_NULL(blob) || 
@@ -998,7 +1005,7 @@ static int write_depends(struct apk_ostream *os, const char *field,
 
 	if (os->write(os, field, 2) != 2)
 		return -1;
-	r = apk_deps_write(deps, os);
+	r = apk_deps_write(NULL, deps, os);
 	if (r < 0)
 		return r;
 	if (os->write(os, "\n", 1) != 1)
diff --git a/src/solver.c b/src/solver.c
index d277bc5..8718423 100644
--- a/src/solver.c
+++ b/src/solver.c
@@ -47,6 +47,7 @@ struct apk_name_state {
 	struct list_head unsolved_list;
 	struct apk_name *name;
 	struct apk_package *chosen;
+	unsigned int allowed_repos, preferred_repos;
 	unsigned short requirers;
 	unsigned short install_ifs;
 
@@ -280,9 +281,18 @@ static void foreach_dependency(struct apk_solver_state *ss, struct apk_dependenc
 }
 
 static int compare_package_preference(unsigned short solver_flags,
+				      unsigned int preferred_repos,
 				      struct apk_package *pkgA,
 				      struct apk_package *pkgB)
 {
+	/* preferred repository pinning */
+	if ((pkgA->ipkg || (pkgA->repos & preferred_repos)) &&
+	    !(pkgB->ipkg || (pkgB->repos & preferred_repos)))
+		return 1;
+	if ((pkgB->ipkg || (pkgB->repos & preferred_repos)) &&
+	    !(pkgA->ipkg || (pkgA->repos & preferred_repos)))
+		return -1;
+
 	if (solver_flags & APK_SOLVERF_AVAILABLE) {
 		if (pkgA->repos != 0 && pkgB->repos == 0)
 			return 1;
@@ -320,6 +330,7 @@ static int get_preference(struct apk_solver_state *ss,
 	unsigned short name_flags = ns->solver_flags_local
 		| ns->solver_flags_inherited
 		| ss->solver_flags;
+	unsigned int preferred_repos = ns->preferred_repos | ss->db->repo_tags[0].allowed_repos;
 	unsigned short preference = 0;
 	int i;
 
@@ -330,7 +341,9 @@ static int get_preference(struct apk_solver_state *ss,
 		if (pkg0 == pkg || ps0 == NULL)
 			continue;
 
-		if (compare_package_preference(name_flags, pkg, pkg0) < 0) {
+		if (compare_package_preference(name_flags,
+					       preferred_repos,
+					       pkg, pkg0) < 0) {
 			if (installable_only) {
 				if (ss->topology_position > pkg0->topology_hard &&
 				    !(ps0->flags & APK_PKGSTF_DECIDED))
@@ -364,6 +377,7 @@ static int update_name_state(struct apk_solver_state *ss, struct apk_name *name)
 	struct apk_name_state *ns = name_to_ns(name);
 	struct apk_package *best_pkg = NULL;
 	unsigned int best_topology = 0;
+	unsigned int allowed_repos = ns->allowed_repos | ss->db->repo_tags[0].allowed_repos;
 	int i, options = 0, skipped_options = 0;
 
 	for (i = 0; i < name->pkgs->num; i++) {
@@ -372,6 +386,7 @@ static int update_name_state(struct apk_solver_state *ss, struct apk_name *name)
 
 		if (ps0 == NULL ||
 		    pkg0->topology_hard >= ss->topology_position ||
+		    ((pkg0->repos != 0) && (pkg0->ipkg == NULL) && !(pkg0->repos & allowed_repos)) ||
 		    (ps0->flags & APK_PKGSTF_DECIDED))
 			continue;
 
@@ -571,6 +586,7 @@ static void inherit_name_state(struct apk_name *to, struct apk_name *from)
 	tns->solver_flags_inherited |=
 		fns->solver_flags_inherited |
 		(fns->solver_flags_local & fns->solver_flags_local_mask);
+	tns->allowed_repos |= fns->allowed_repos;
 }
 
 static void inherit_name_state_wrapper(struct apk_package *rdepend, void *ctx)
@@ -587,6 +603,8 @@ static int has_inherited_state(struct apk_name *name)
 		return 0;
 	if (ns->solver_flags_inherited || (ns->solver_flags_local & ns->solver_flags_local_mask))
 		return 1;
+	if (ns->allowed_repos)
+		return 1;
 	return 0;
 }
 
@@ -595,6 +613,7 @@ static void recalculate_inherted_name_state(struct apk_name *name)
 	struct apk_name_state *ns = name_to_ns(name);
 
 	ns->solver_flags_inherited = 0;
+	ns->allowed_repos = 0;
 	foreach_locked_reverse_dependency(name, inherit_name_state_wrapper, name);
 }
 
@@ -614,6 +633,16 @@ static void apply_constraint(struct apk_solver_state *ss, struct apk_dependency
 		return;
 	}
 
+	if (dep->repository_tag) {
+		unsigned int allowed_repos;
+
+		dbg_printf("%s: enabling repository tag %d\n",
+			   dep->name->name, dep->repository_tag);
+		allowed_repos = ss->db->repo_tags[dep->repository_tag].allowed_repos;
+		ns->allowed_repos |= allowed_repos;
+		ns->preferred_repos |= allowed_repos;
+	}
+
 	for (i = 0; i < name->pkgs->num; i++) {
 		struct apk_package *pkg0 = name->pkgs->item[i];
 		struct apk_package_state *ps0 = pkg_to_ps(pkg0);
@@ -1256,7 +1285,7 @@ all_done:
 	return r;
 }
 
-static void print_dep_errors(char *label, struct apk_dependency_array *deps)
+static void print_dep_errors(struct apk_database *db, char *label, struct apk_dependency_array *deps)
 {
 	int i, print_label = 1;
 	char buf[256];
@@ -1276,7 +1305,7 @@ static void print_dep_errors(char *label, struct apk_dependency_array *deps)
 			indent.indent = indent.x + 1;
 		}
 		p = APK_BLOB_BUF(buf);
-		apk_blob_push_dep(&p, dep);
+		apk_blob_push_dep(&p, db, dep);
 		p = apk_blob_pushed(APK_BLOB_BUF(buf), p);
 		apk_print_indented(&indent, p);
 	}
@@ -1298,12 +1327,12 @@ void apk_solver_print_errors(struct apk_database *db,
 		pkg->name->state_ptr = pkg;
 	}
 
-	print_dep_errors("world", world);
+	print_dep_errors(db, "world", world);
 	for (i = 0; i < solution->num; i++) {
 		struct apk_package *pkg = solution->item[i];
 		char pkgtext[256];
 		snprintf(pkgtext, sizeof(pkgtext), PKG_VER_FMT, PKG_VER_PRINTF(solution->item[i]));
-		print_dep_errors(pkgtext, pkg->depends);
+		print_dep_errors(db, pkgtext, pkg->depends);
 	}
 }
 
diff --git a/src/test.c b/src/test.c
index 9fc3e1f..29ee789 100644
--- a/src/test.c
+++ b/src/test.c
@@ -91,7 +91,7 @@ static inline void print_change(struct apk_package *oldpkg,
 	}
 }
 
-static void print_dep_errors(char *label, struct apk_dependency_array *deps)
+static void print_dep_errors(struct apk_database *db, char *label, struct apk_dependency_array *deps)
 {
 	int i, print_label = 1;
 	char buf[256];
@@ -110,7 +110,7 @@ static void print_dep_errors(char *label, struct apk_dependency_array *deps)
 		} else {
 			printf(" ");
 		}
-		apk_blob_push_dep(&p, dep);
+		apk_blob_push_dep(&p, db, dep);
 		p = apk_blob_pushed(APK_BLOB_BUF(buf), p);
 		fwrite(p.ptr, p.len, 1, stdout);
 	}
@@ -131,12 +131,12 @@ static void print_errors_in_solution(struct apk_database *db, int unsatisfiable,
 		pkg->name->state_ptr = pkg;
 	}
 
-	print_dep_errors("world", db->world);
+	print_dep_errors(db, "world", db->world);
 	for (i = 0; i < solution->num; i++) {
 		struct apk_package *pkg = solution->item[i];
 		char pkgtext[256];
 		snprintf(pkgtext, sizeof(pkgtext), PKG_VER_FMT, PKG_VER_PRINTF(solution->item[i]));
-		print_dep_errors(pkgtext, pkg->depends);
+		print_dep_errors(db, pkgtext, pkg->depends);
 	}
 
 }
@@ -153,6 +153,8 @@ static int test_main(void *pctx, struct apk_database *db, int argc, char **argv)
 	if (argc != 1)
 		return -EINVAL;
 
+	apk_db_get_tag_id(db, APK_BLOB_STR("testing"));
+
 	/* load installed db */
 	if (ctx->installed_db != NULL) {
 		bs = apk_bstream_from_file(AT_FDCWD, ctx->installed_db);
@@ -165,9 +167,16 @@ static int test_main(void *pctx, struct apk_database *db, int argc, char **argv)
 	/* load additional indexes */
 	if (ctx->repos) {
 		for (i = 0; i < ctx->repos->num; i++) {
-			bs = apk_bstream_from_file(AT_FDCWD, ctx->repos->item[i]);
+			char *fn = ctx->repos->item[i];
+			int repo = 0;
+			if (fn[0] == '+') {
+				fn++;
+				repo = 1;
+			}
+			bs = apk_bstream_from_file(AT_FDCWD, fn);
 			if (bs != NULL) {
 				apk_db_index_read(db, bs, i);
+				db->repo_tags[repo].allowed_repos |= BIT(i);
 				bs->close(bs, NULL);
 			}
 		}
diff --git a/test/pinning.repo b/test/pinning.repo
new file mode 100644
index 0000000..c41ddf7
--- /dev/null
+++ b/test/pinning.repo
@@ -0,0 +1,20 @@
+C:Q1eVpkasfqZAukAXFYbgwt4xffZWU=
+P:a
+V:3
+S:1
+I:1
+D:b
+
+C:Q1hdUpqRv5mYgJEqW52UmVsv23ysE=
+P:b
+V:3
+S:1
+I:1
+
+C:Q1eVpkasfqZAukAXFYbg324xAt4WU=
+P:c
+V:3
+S:1
+I:1
+D:a>=3
+
diff --git a/test/pinning1.expect b/test/pinning1.expect
new file mode 100644
index 0000000..81756fe
--- /dev/null
+++ b/test/pinning1.expect
@@ -0,0 +1,2 @@
+Installing b (2)
+Installing a (2)
diff --git a/test/pinning1.test b/test/pinning1.test
new file mode 100644
index 0000000..4396875
--- /dev/null
+++ b/test/pinning1.test
@@ -0,0 +1,2 @@
+--raw-repository basic.repo --raw-repository +pinning.repo
+a
diff --git a/test/pinning2.expect b/test/pinning2.expect
new file mode 100644
index 0000000..cce6084
--- /dev/null
+++ b/test/pinning2.expect
@@ -0,0 +1,2 @@
+Installing b (2)
+Installing a (3)
diff --git a/test/pinning2.test b/test/pinning2.test
new file mode 100644
index 0000000..69d4f79
--- /dev/null
+++ b/test/pinning2.test
@@ -0,0 +1,2 @@
+--raw-repository basic.repo --raw-repository +pinning.repo
+a@testing
diff --git a/test/pinning3.expect b/test/pinning3.expect
new file mode 100644
index 0000000..a2b2fca
--- /dev/null
+++ b/test/pinning3.expect
@@ -0,0 +1,2 @@
+Installing b (3)
+Installing a (3)
diff --git a/test/pinning3.test b/test/pinning3.test
new file mode 100644
index 0000000..220f128
--- /dev/null
+++ b/test/pinning3.test
@@ -0,0 +1,2 @@
+--raw-repository basic.repo --raw-repository +pinning.repo
+a@testing b@testing
diff --git a/test/pinning4.expect b/test/pinning4.expect
new file mode 100644
index 0000000..5a03102
--- /dev/null
+++ b/test/pinning4.expect
@@ -0,0 +1,3 @@
+Installing b (2)
+Installing a (3)
+Installing c (3)
diff --git a/test/pinning4.test b/test/pinning4.test
new file mode 100644
index 0000000..4bf8d38
--- /dev/null
+++ b/test/pinning4.test
@@ -0,0 +1,2 @@
+--raw-repository basic.repo --raw-repository +pinning.repo
+c@testing