[RFC v5 084/126] SLIRP: introduce ERRP_AUTO_PROPAGATE

[Vladimir Sementsov-Ogievskiy]

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

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

This commit (together with its neighbors) was generated by

for f in $(git grep -l errp \*.[ch]); do \
    spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
    --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; \
done;

then fix a bit of compilation problems: coccinelle for some reason
leaves several
f() {
    ...
    goto out;
    ...
    out:
}
patterns, with "out:" at function end.

then
./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"

(auto-msg was a file with this commit message)

Still, for backporting it may be more comfortable to use only the first
command and then do one huge commit.

Reported-by: Kevin Wolf <address@hidden>
Reported-by: Greg Kurz <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 net/slirp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/slirp.c b/net/slirp.c
index c4334ee876..cbde9ba2a9 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -941,6 +941,7 @@ static ssize_t guestfwd_write(const void *buf, size_t len, 
void *chr)
 
 static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     /* TODO: IPv6 */
     struct in_addr server = { .s_addr = 0 };
     struct GuestFwd *fwd;
@@ -979,7 +980,6 @@ static int slirp_guestfwd(SlirpState *s, const char 
*config_str, Error **errp)
             return -1;
         }
     } else {
-        Error *err = NULL;
         /*
          * FIXME: sure we want to support implicit
          * muxed monitors here?
@@ -993,9 +993,8 @@ static int slirp_guestfwd(SlirpState *s, const char 
*config_str, Error **errp)
         }
 
         fwd = g_new(struct GuestFwd, 1);
-        qemu_chr_fe_init(&fwd->hd, chr, &err);
-        if (err) {
-            error_propagate(errp, err);
+        qemu_chr_fe_init(&fwd->hd, chr, errp);
+        if (*errp) {
             object_unparent(OBJECT(chr));
             g_free(fwd);
             return -1;
-- 
2.21.0