From 9176e800dbcb2636a2f24411eafc3c800e3455bd Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 12 Nov 2020 08:40:11 -0500 Subject: keyval: introduce keyval_merge This patch introduces a function that merges two keyval-produced (or keyval-like) QDicts. It can be used to emulate the behavior of .merge_lists = true QemuOpts groups, merging -readconfig sections and command-line options in a single QDict, and also to implement -set. Signed-off-by: Paolo Bonzini --- include/qemu/option.h | 1 + tests/unit/test-keyval.c | 58 +++++++++++++++++++++++++++++++++++ util/keyval.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 139 insertions(+) diff --git a/include/qemu/option.h b/include/qemu/option.h index f73e0dc..d89c661 100644 --- a/include/qemu/option.h +++ b/include/qemu/option.h @@ -149,5 +149,6 @@ QemuOptsList *qemu_opts_append(QemuOptsList *dst, QemuOptsList *list); QDict *keyval_parse(const char *params, const char *implied_key, bool *help, Error **errp); +void keyval_merge(QDict *old, const QDict *new, Error **errp); #endif diff --git a/tests/unit/test-keyval.c b/tests/unit/test-keyval.c index e20c07c..af0581a 100644 --- a/tests/unit/test-keyval.c +++ b/tests/unit/test-keyval.c @@ -747,6 +747,61 @@ static void test_keyval_visit_any(void) visit_free(v); } +static void test_keyval_merge_dict(void) +{ + QDict *first = keyval_parse("opt1=abc,opt2.sub1=def,opt2.sub2=ghi,opt3=xyz", + NULL, NULL, &error_abort); + QDict *second = keyval_parse("opt1=ABC,opt2.sub2=GHI,opt2.sub3=JKL", + NULL, NULL, &error_abort); + QDict *combined = keyval_parse("opt1=ABC,opt2.sub1=def,opt2.sub2=GHI,opt2.sub3=JKL,opt3=xyz", + NULL, NULL, &error_abort); + Error *err = NULL; + + keyval_merge(first, second, &err); + g_assert(!err); + g_assert(qobject_is_equal(QOBJECT(combined), QOBJECT(first))); + qobject_unref(first); + qobject_unref(second); + qobject_unref(combined); +} + +static void test_keyval_merge_list(void) +{ + QDict *first = keyval_parse("opt1.0=abc,opt2.0=xyz", + NULL, NULL, &error_abort); + QDict *second = keyval_parse("opt1.0=def", + NULL, NULL, &error_abort); + QDict *combined = keyval_parse("opt1.0=abc,opt1.1=def,opt2.0=xyz", + NULL, NULL, &error_abort); + Error *err = NULL; + + keyval_merge(first, second, &err); + g_assert(!err); + g_assert(qobject_is_equal(QOBJECT(combined), QOBJECT(first))); + qobject_unref(first); + qobject_unref(second); + qobject_unref(combined); +} + +static void test_keyval_merge_conflict(void) +{ + QDict *first = keyval_parse("opt2=ABC", + NULL, NULL, &error_abort); + QDict *second = keyval_parse("opt2.sub1=def,opt2.sub2=ghi", + NULL, NULL, &error_abort); + QDict *third = qdict_clone_shallow(first); + Error *err = NULL; + + keyval_merge(first, second, &err); + error_free_or_abort(&err); + keyval_merge(second, third, &err); + error_free_or_abort(&err); + + qobject_unref(first); + qobject_unref(second); + qobject_unref(third); +} + int main(int argc, char *argv[]) { g_test_init(&argc, &argv, NULL); @@ -760,6 +815,9 @@ int main(int argc, char *argv[]) g_test_add_func("/keyval/visit/optional", test_keyval_visit_optional); g_test_add_func("/keyval/visit/alternate", test_keyval_visit_alternate); g_test_add_func("/keyval/visit/any", test_keyval_visit_any); + g_test_add_func("/keyval/merge/dict", test_keyval_merge_dict); + g_test_add_func("/keyval/merge/list", test_keyval_merge_list); + g_test_add_func("/keyval/merge/conflict", test_keyval_merge_conflict); g_test_run(); return 0; } diff --git a/util/keyval.c b/util/keyval.c index be34928..9bc3806 100644 --- a/util/keyval.c +++ b/util/keyval.c @@ -311,6 +311,86 @@ static char *reassemble_key(GSList *key) } /* + * Recursive worker for keyval_merge. + * + * @str is the path that led to the * current dictionary (to be used for + * error messages). It is modified internally but restored before the + * function returns. + */ +static void keyval_do_merge(QDict *dest, const QDict *merged, GString *str, Error **errp) +{ + size_t save_len = str->len; + const QDictEntry *ent; + QObject *old_value; + + for (ent = qdict_first(merged); ent; ent = qdict_next(merged, ent)) { + old_value = qdict_get(dest, ent->key); + if (old_value) { + if (qobject_type(old_value) != qobject_type(ent->value)) { + error_setg(errp, "Parameter '%s%s' used inconsistently", + str->str, ent->key); + return; + } else if (qobject_type(ent->value) == QTYPE_QDICT) { + /* Merge sub-dictionaries. */ + g_string_append(str, ent->key); + g_string_append_c(str, '.'); + keyval_do_merge(qobject_to(QDict, old_value), + qobject_to(QDict, ent->value), + str, errp); + g_string_truncate(str, save_len); + continue; + } else if (qobject_type(ent->value) == QTYPE_QLIST) { + /* Append to old list. */ + QList *old = qobject_to(QList, old_value); + QList *new = qobject_to(QList, ent->value); + const QListEntry *item; + QLIST_FOREACH_ENTRY(new, item) { + qobject_ref(item->value); + qlist_append_obj(old, item->value); + } + continue; + } else { + assert(qobject_type(ent->value) == QTYPE_QSTRING); + } + } + + qobject_ref(ent->value); + qdict_put_obj(dest, ent->key, ent->value); + } +} + +/* Merge the @merged dictionary into @dest. + * + * The dictionaries are expected to be returned by the keyval parser, and + * therefore the only expected scalar type is the string. In case the same + * path is present in both @dest and @merged, the semantics are as follows: + * + * - lists are concatenated + * + * - dictionaries are merged recursively + * + * - for scalar values, @merged wins + * + * In case an error is reported, @dest may already have been modified. + * + * This function can be used to implement semantics analogous to QemuOpts's + * .merge_lists = true case, or to implement -set for options backed by QDicts. + * + * Note: while QemuOpts is commonly used so that repeated keys overwrite + * ("last one wins"), it can also be used so that repeated keys build up + * a list. keyval_merge() can only be used when the options' semantics are + * the former, not the latter. + */ +void keyval_merge(QDict *dest, const QDict *merged, Error **errp) +{ + GString *str; + + str = g_string_new(""); + keyval_do_merge(dest, merged, str, errp); + g_string_free(str, TRUE); +} + +/* * Listify @cur recursively. * Replace QDicts whose keys are all valid list indexes by QLists. * @key_of_cur is the list of key fragments leading up to @cur. -- cgit v1.1