nbd: Use ERRP_GUARD()

If we want to check error after errp-function call, we need to
introduce local_err and then propagate it to errp. Instead, use
the ERRP_GUARD() macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_GUARD() leaves errp as is if it's not NULL or
   &error_fatal, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_GUARD() macro.
Otherwise, this info will not be added when errp == &error_fatal
(the program will exit prior to the error_append_hint() or
error_prepend() call).  Fix several such cases, e.g. in nbd_read().

This commit is generated by command

    sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
        MAINTAINERS | \
    xargs git ls-files | grep '\.[hc]$' | \
    xargs spatch \
        --sp-file scripts/coccinelle/errp-guard.cocci \
        --macro-file scripts/cocci-macro-file.h \
        --in-place --no-show-diff --max-width 80

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-8-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci.  Commit message
tweaked again.]

2 files changed, 10 insertions, 0 deletions

diff --git a/nbd/client.c b/nbd/client.c
index ba17310..0c2db4b 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -68,6 +68,7 @@ static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
                                    uint32_t len, const char *data,
                                    Error **errp)
 {
+    ERRP_GUARD();
     NBDOption req;
     QEMU_BUILD_BUG_ON(sizeof(req) != 16);
 
@@ -153,6 +154,7 @@ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
 static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
                                 bool strict, Error **errp)
 {
+    ERRP_GUARD();
     g_autofree char *msg = NULL;
 
     if (!(reply->type & (1 << 31))) {
@@ -337,6 +339,7 @@ static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
 static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
                               NBDExportInfo *info, Error **errp)
 {
+    ERRP_GUARD();
     NBDOptionReply reply;
     uint32_t len = strlen(info->name);
     uint16_t type;
@@ -882,6 +885,7 @@ static int nbd_start_negotiate(AioContext *aio_context, QIOChannel *ioc,
                                bool structured_reply, bool *zeroes,
                                Error **errp)
 {
+    ERRP_GUARD();
     uint64_t magic;
 
     trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>");
@@ -1017,6 +1021,7 @@ int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc,
                           const char *hostname, QIOChannel **outioc,
                           NBDExportInfo *info, Error **errp)
 {
+    ERRP_GUARD();
     int result;
     bool zeroes;
     bool base_allocation = info->base_allocation;
diff --git a/nbd/server.c b/nbd/server.c
index 20754e9..5357f58 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -211,6 +211,7 @@ static int GCC_FMT_ATTR(4, 0)
 nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type,
                             Error **errp, const char *fmt, va_list va)
 {
+    ERRP_GUARD();
     g_autofree char *msg = NULL;
     int ret;
     size_t len;
@@ -382,6 +383,7 @@ static int nbd_opt_read_name(NBDClient *client, char **name, uint32_t *length,
 static int nbd_negotiate_send_rep_list(NBDClient *client, NBDExport *exp,
                                        Error **errp)
 {
+    ERRP_GUARD();
     size_t name_len, desc_len;
     uint32_t len;
     const char *name = exp->name ? exp->name : "";
@@ -445,6 +447,7 @@ static void nbd_check_meta_export(NBDClient *client)
 static int nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes,
                                             Error **errp)
 {
+    ERRP_GUARD();
     g_autofree char *name = NULL;
     char buf[NBD_REPLY_EXPORT_NAME_SIZE] = "";
     size_t len;
@@ -1289,6 +1292,7 @@ static int nbd_negotiate_options(NBDClient *client, Error **errp)
  */
 static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
 {
+    ERRP_GUARD();
     char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = "";
     int ret;
 
@@ -1663,6 +1667,7 @@ void nbd_export_close(NBDExport *exp)
 
 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
 {
+    ERRP_GUARD();
     if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) {
         nbd_export_close(exp);
         return;