qemu-img: Suppress unhelpful extra errors in convert, amend

img_convert() and img_amend() use qemu_opts_do_parse(), which reports
errors with qerror_report_err().  Its error messages aren't helpful
here, the caller reports one that actually makes sense.  Reproducer:

    $ qemu-img convert -o backing_format=raw in.img out.img
    qemu-img: Invalid parameter 'backing_format'
    qemu-img: Invalid options for file format 'raw'

To fix, propagate errors through qemu_opts_do_parse().  This lifts the
error reporting into callers.  Drop it from img_convert() and
img_amend(), keep it in qemu_chr_parse_compat(), bdrv_img_create().

Since I'm touching qemu_opts_do_parse() anyway, write a function
comment for it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/qemu-char.c b/qemu-char.c
index 3ed46ee..a405d76 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -3379,8 +3379,11 @@ QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
         qemu_opt_set(opts, "host", host, &error_abort);
         qemu_opt_set(opts, "port", port, &error_abort);
         if (p[pos] == ',') {
-            if (qemu_opts_do_parse(opts, p+pos+1, NULL) != 0)
+            qemu_opts_do_parse(opts, p+pos+1, NULL, &local_err);
+            if (local_err) {
+                error_report_err(local_err);
                 goto fail;
+            }
         }
         if (strstart(filename, "telnet:", &p))
             qemu_opt_set(opts, "telnet", "on", &error_abort);
@@ -3411,8 +3414,11 @@ QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
     }
     if (strstart(filename, "unix:", &p)) {
         qemu_opt_set(opts, "backend", "socket", &error_abort);
-        if (qemu_opts_do_parse(opts, p, "path") != 0)
+        qemu_opts_do_parse(opts, p, "path", &local_err);
+        if (local_err) {
+            error_report_err(local_err);
             goto fail;
+        }
         return opts;
     }
     if (strstart(filename, "/dev/parport", NULL) ||