Commit 15c2f669 authored by Eric Blake's avatar Eric Blake Committed by Markus Armbruster
Browse files

qapi: Split visit_end_struct() into pieces 



As mentioned in previous patches, we want to call visit_end_struct()
functions unconditionally, so that visitors can release resources
tied up since the matching visit_start_struct() without also having
to worry about error priority if more than one error occurs.

Even though error_propagate() can be safely used to ignore a second
error during cleanup caused by a first error, it is simpler if the
cleanup cannot set an error.  So, split out the error checking
portion (basically, input visitors checking for unvisited keys) into
a new function visit_check_struct(), which can be safely skipped if
any earlier errors are encountered, and leave the cleanup portion
(which never fails, but must be called unconditionally if
visit_start_struct() succeeded) in visit_end_struct().

Generated code in qapi-visit.c has diffs resembling:

|@@ -59,10 +59,12 @@ void visit_type_ACPIOSTInfo(Visitor *v,
|         goto out_obj;
|     }
|     visit_type_ACPIOSTInfo_members(v, obj, &err);
|-    error_propagate(errp, err);
|-    err = NULL;
|+    if (err) {
|+        goto out_obj;
|+    }
|+    visit_check_struct(v, &err);
| out_obj:
|-    visit_end_struct(v, &err);
|+    visit_end_struct(v);
| out:

and in qapi-event.c:

@@ -47,7 +47,10 @@ void qapi_event_send_acpi_device_ost(ACP
|         goto out;
|     }
|     visit_type_q_obj_ACPI_DEVICE_OST_arg_members(v, &param, &err);
|-    visit_end_struct(v, err ? NULL : &err);
|+    if (!err) {
|+        visit_check_struct(v, &err);
|+    }
|+    visit_end_struct(v);
|     if (err) {
|         goto out;

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-20-git-send-email-eblake@redhat.com>
[Conflict with a doc fixup resolved]
Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
parent 56a6f02b

block/crypto.c

+8 −6
Original line number Diff line number Diff line
@@ -196,7 +196,6 @@ block_crypto_open_opts_init(QCryptoBlockFormat format, 
    OptsVisitor *ov;

    QCryptoBlockOpenOptions *ret = NULL;

    Error *local_err = NULL;

    Error *end_err = NULL;



    ret = g_new0(QCryptoBlockOpenOptions, 1);

    ret->format = format;
@@ -219,9 +218,11 @@ block_crypto_open_opts_init(QCryptoBlockFormat format, 
        error_setg(&local_err, "Unsupported block format %d", format);

        break;

    }

    if (!local_err) {

        visit_check_struct(opts_get_visitor(ov), &local_err);

    }



    visit_end_struct(opts_get_visitor(ov), &end_err);

    error_propagate(&local_err, end_err);

    visit_end_struct(opts_get_visitor(ov));



 out:

    if (local_err) {
@@ -242,7 +243,6 @@ block_crypto_create_opts_init(QCryptoBlockFormat format, 
    OptsVisitor *ov;

    QCryptoBlockCreateOptions *ret = NULL;

    Error *local_err = NULL;

    Error *end_err = NULL;



    ret = g_new0(QCryptoBlockCreateOptions, 1);

    ret->format = format;
@@ -265,9 +265,11 @@ block_crypto_create_opts_init(QCryptoBlockFormat format, 
        error_setg(&local_err, "Unsupported block format %d", format);

        break;

    }

    if (!local_err) {

        visit_check_struct(opts_get_visitor(ov), &local_err);

    }



    visit_end_struct(opts_get_visitor(ov), &end_err);

    error_propagate(&local_err, end_err);

    visit_end_struct(opts_get_visitor(ov));



 out:

    if (local_err) {

docs/qapi-code-gen.txt

+10 −5
Original line number Diff line number Diff line
@@ -899,10 +899,12 @@ Example: 
            goto out_obj;

        }

        visit_type_UserDefOne_members(v, *obj, &err);

        error_propagate(errp, err);

        err = NULL;

        if (err) {

            goto out_obj;

        }

        visit_check_struct(v, &err);

    out_obj:

        visit_end_struct(v, &err);

        visit_end_struct(v);

    out:

        error_propagate(errp, err);

    }
@@ -1007,7 +1009,10 @@ Example: 
            goto out;

        }

        visit_type_UserDefOneList(v, "arg1", &arg1, &err);

        visit_end_struct(v, err ? NULL : &err);

        if (!err) {

            visit_check_struct(v, &err);

        }

        visit_end_struct(v);

        if (err) {

            goto out;

        }
@@ -1026,7 +1031,7 @@ Example: 
        v = qapi_dealloc_get_visitor(qdv);

        visit_start_struct(v, NULL, NULL, 0, NULL);

        visit_type_UserDefOneList(v, "arg1", &arg1, NULL);

        visit_end_struct(v, NULL);

        visit_end_struct(v);

        qapi_dealloc_visitor_cleanup(qdv);

    }

hw/ppc/spapr_drc.c

+2 −1
Original line number Diff line number Diff line
@@ -297,7 +297,8 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name, 
        case FDT_END_NODE:

            /* shouldn't ever see an FDT_END_NODE before FDT_BEGIN_NODE */

            g_assert(fdt_depth > 0);

            visit_end_struct(v, &err);

            visit_check_struct(v, &err);

            visit_end_struct(v);

            if (err) {

                error_propagate(errp, err);

                return;

hw/virtio/virtio-balloon.c

+8 −7
Original line number Diff line number Diff line
@@ -138,17 +138,18 @@ static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name, 
    for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {

        visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err);

        if (err) {

            break;

            goto out_nested;

        }

    }

    error_propagate(errp, err);

    err = NULL;

    visit_end_struct(v, &err);

    visit_check_struct(v, &err);

out_nested:

    visit_end_struct(v);



    if (!err) {

        visit_check_struct(v, &err);

    }

out_end:

    error_propagate(errp, err);

    err = NULL;

    visit_end_struct(v, &err);

    visit_end_struct(v);

out:

    error_propagate(errp, err);

}

include/qapi/visitor-impl.h

+4 −1
Original line number Diff line number Diff line
@@ -43,8 +43,11 @@ struct Visitor 
    void (*start_struct)(Visitor *v, const char *name, void **obj,

                         size_t size, Error **errp);



    /* Optional; intended for input visitors */

    void (*check_struct)(Visitor *v, Error **errp);



    /* Must be set to visit structs */

    void (*end_struct)(Visitor *v, Error **errp);

    void (*end_struct)(Visitor *v);



    /* Must be set */

    void (*start_list)(Visitor *v, const char *name, Error **errp);