lib/transaction_{revdeps,prepare}.c: try to update packages if necessary

`xbps_transaction_revdeps` will now try to add updates for packages to the
transaction if the dependency is not satisified anymore due to a package
install/update.

`xbps_transaction_prepare` will now check the return value of
`xbps_transaction_revdeps` and repeat the dependency resolution,
until `xbps_transaction_revdeps` returns 0, which means that it didn't
add any new packages to the transaction.

include/xbps_api_impl.h

@@ -127,7 +127,7 @@ xbps_dictionary_t HIDDEN xbps_find_pkg_in_array(xbps_array_t, const char *,
 		const char *);
 xbps_dictionary_t HIDDEN xbps_find_virtualpkg_in_array(struct xbps_handle *,
 		xbps_array_t, const char *, const char *);
-void HIDDEN xbps_transaction_revdeps(struct xbps_handle *, xbps_array_t);
+int HIDDEN xbps_transaction_revdeps(struct xbps_handle *, xbps_array_t);
 bool HIDDEN xbps_transaction_shlibs(struct xbps_handle *, xbps_array_t,
 		xbps_array_t);
 int HIDDEN xbps_transaction_init(struct xbps_handle *);

lib/transaction_prepare.c

@@ -272,11 +272,13 @@ xbps_transaction_init(struct xbps_handle *xhp)
 	return 0;
 }
 
+#define MAX_REPEAT 512
+
 int
 xbps_transaction_prepare(struct xbps_handle *xhp)
 {
 	xbps_array_t array, pkgs, edges;
-	unsigned int i, cnt;
+	unsigned int i, j, cnt;
 	int rv = 0;
 
 	if ((rv = xbps_transaction_init(xhp)) != 0)
@@ -285,6 +287,7 @@ xbps_transaction_prepare(struct xbps_handle *xhp)
 	if (xhp->transd == NULL)
 		return ENXIO;
 
+	for (j = 0; j < MAX_REPEAT; j++) {
 		/*
 		 * Collect dependencies for pkgs in transaction.
 		 */
@@ -335,10 +338,28 @@ xbps_transaction_prepare(struct xbps_handle *xhp)
 			xhp->transd = NULL;
 			return rv;
 		}
+		/*
+		 * Check reverse dependencies.
+		 */
+		if ((rv = xbps_transaction_revdeps(xhp, pkgs)) == 0)
+			break;
+		if (rv != EAGAIN)
+			return rv;
+	}
+	/*
+	 * Repeated too many times.
+	 */
+	if (j == MAX_REPEAT) {
+		xbps_dbg_printf(xhp, "[trans] aborted due to too many repetitions"
+		    " while resolving dependencies!\n");
+		return ELOOP;
+	} else {
+		xbps_dbg_printf(xhp, "[trans] resolved dependencies in"
+		    " %d repetitions.\n", j);
+	}
 	/*
 	 * If there are missing deps or revdeps bail out.
 	 */
-	xbps_transaction_revdeps(xhp, pkgs);
 	array = xbps_dictionary_get(xhp->transd, "missing_deps");
 	if (xbps_array_count(array)) {
 		if (xhp->flags & XBPS_FLAG_FORCE_REMOVE_REVDEPS) {

lib/transaction_revdeps.c

@@ -101,10 +101,21 @@ broken_pkg(xbps_array_t mdeps, const char *dep, const char *pkg, const char *tra
 	free(str);
 }
 
-void HIDDEN
+static int
+update_pkg(struct xbps_handle *xhp, const char *pkg)
+{
+	int rv = 0;
+	rv = xbps_transaction_update_pkg(xhp, pkg);
+	if (rv == EEXIST)
+		return 0;
+	return rv;
+}
+
+int HIDDEN
 xbps_transaction_revdeps(struct xbps_handle *xhp, xbps_array_t pkgs)
 {
 	xbps_array_t mdeps;
+	int updated = 0;
 
 	mdeps = xbps_dictionary_get(xhp->transd, "missing_deps");
 
@@ -235,9 +246,17 @@ xbps_transaction_revdeps(struct xbps_handle *xhp, xbps_array_t pkgs)
 				free(pkgname);
 				continue;
 			}
+			if (update_pkg(xhp, pkgname) == 0) {
+				updated++;
+				free(pkgname);
+				continue;
+			}
 			free(pkgname);
 			broken_pkg(mdeps, curpkgver, pkgver, tract);
 		}
 
 	}
+	if (updated > 0)
+		return EAGAIN;
+	return 0;
 }