libxbps: introduce the concept of "soft replace"; see the NEWS file.

lib/package_remove.c

@@ -264,7 +264,8 @@ xbps_remove_pkg_files(prop_dictionary_t dict,
 }
 
 int
-xbps_remove_pkg(const char *pkgname, const char *version, bool update)
+xbps_remove_pkg(const char *pkgname, const char *version, bool update,
+		bool soft_replace)
 {
 	struct xbps_handle *xhp;
 	prop_dictionary_t pkgd = NULL;
@@ -343,6 +344,13 @@ xbps_remove_pkg(const char *pkgname, const char *version, bool update)
 		free(pkgver);
 		free(buf);
 		return xbps_requiredby_pkg_remove(pkgname);
+	} else if (soft_replace) {
+		/*
+		 * Soft replace a package. Do not remove its files, but
+		 * execute PURGE action, remove metadata files and unregister
+		 * from pkgdb.
+		 */
+		goto softreplace;
 	}
 
 	pkgd = xbps_dictionary_from_metadata_plist(pkgname, XBPS_PKGFILES);
@@ -383,6 +391,8 @@ xbps_remove_pkg(const char *pkgname, const char *version, bool update)
 		    pkgver, strerror(rv));
 		goto out;
 	}
+
+softreplace:
 	/*
 	 * Set package state to "half-removed".
 	 */

lib/transaction_commit.c

@@ -190,7 +190,7 @@ xbps_transaction_commit(void)
 	size_t i;
 	const char *pkgname, *version, *pkgver, *tract;
 	int rv = 0;
-	bool update, install;
+	bool update, install, sr;
 
 	assert(prop_object_type(xhp->transd) == PROP_TYPE_DICTIONARY);
 
@@ -234,12 +234,14 @@ xbps_transaction_commit(void)
 
 		if (strcmp(tract, "remove") == 0) {
 			update = false;
+			sr = false;
 			/*
 			 * Remove package.
 			 */
 			prop_dictionary_get_bool(obj, "remove-and-update",
 			    &update);
-			rv = xbps_remove_pkg(pkgname, version, update);
+			prop_dictionary_get_bool(obj, "softreplace", &sr);
+			rv = xbps_remove_pkg(pkgname, version, update, sr);
 			if (rv != 0)
 				goto out;
 		} else if (strcmp(tract, "configure") == 0) {
@@ -265,7 +267,8 @@ xbps_transaction_commit(void)
 				 */
 				xbps_set_cb_state(XBPS_STATE_UPDATE, 0,
 				    pkgname, version, NULL);
-				rv = xbps_remove_pkg(pkgname, version, true);
+				rv = xbps_remove_pkg(pkgname, version,
+						     true, false);
 				if (rv != 0) {
 					xbps_set_cb_state(
 					    XBPS_STATE_UPDATE_FAIL,

lib/transaction_package_replace.c

@@ -40,7 +40,7 @@ xbps_transaction_package_replace(prop_dictionary_t transd)
 	prop_object_t obj;
 	prop_object_iterator_t iter;
 	const char *pattern, *pkgname, *curpkgname, *pkgver, *curpkgver;
-	bool instd_auto;
+	bool instd_auto, sr;
 	size_t idx;
 
 	assert(prop_object_type(transd) == PROP_TYPE_DICTIONARY);
@@ -141,6 +141,22 @@ xbps_transaction_package_replace(prop_dictionary_t transd)
 				prop_dictionary_set_bool(pkg_repod,
 				    "automatic-install", instd_auto);
 			}
+			/*
+			 * Copy requiredby and automatic-install objects
+			 * from replaced package into pkg's dictionary
+			 * for "softreplace" packages.
+			 */
+			sr = false;
+			prop_dictionary_get_bool(pkg_repod, "softreplace", &sr);
+			if (sr) {
+				if (instd_reqby &&
+				    prop_array_count(instd_reqby)) {
+					prop_dictionary_set(pkg_repod,
+					    "requiredby", instd_reqby);
+				}
+				prop_dictionary_set_bool(pkg_repod,
+				    "automatic-install", instd_auto);
+			}
 			/*
 			 * Add package dictionary into the transaction and mark
 			 * it as to be "removed".