qemu-option: restrict qemu_opts_set to merge-lists QemuOpts

qemu_opts_set is used to create default network backends and to
parse sugar options -kernel, -initrd, -append, -bios and -dtb.
These are very different uses:

I would *expect* a function named qemu_opts_set to set an option in a
merge-lists QemuOptsList, such as -kernel, and possibly to set an option
in a non-merge-lists QemuOptsList with non-NULL id, similar to -set.

However, it wouldn't *work* to use qemu_opts_set for the latter
because qemu_opts_set uses fail_if_exists==1. So, for non-merge-lists
QemuOptsList and non-NULL id, the semantics of qemu_opts_set (fail if the
(QemuOptsList, id) pair already exists) are debatable.

On the other hand, I would not expect qemu_opts_set to create a
non-merge-lists QemuOpts with a single option; which it does, though.
For this case of non-merge-lists QemuOptsList and NULL id, qemu_opts_set
hardly adds value over qemu_opts_parse.  It does skip some parsing and
unescaping, but that's not needed when creating default network
backends.

So qemu_opts_set has warty behavior for non-merge-lists QemuOptsList
if id is non-NULL, and it's mostly pointless if id is NULL.  My
solution to keeping the API as simple as possible is to limit
qemu_opts_set to merge-lists QemuOptsList.  For them, it's useful (we
don't want comma-unescaping for -kernel) *and* has sane semantics.
Network backend creation is switched to qemu_opts_parse.

qemu_opts_set is now only used on merge-lists QemuOptsList... except
in the testcase, which is changed to use a merge-list QemuOptsList.

With this change we can also remove the id parameter.  With the
parameter always NULL, we know that qemu_opts_create cannot fail
and can pass &error_abort to it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 12 deletions

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 85b23d5..5571f9f 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -3388,20 +3388,16 @@ void qemu_init(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_kernel:
-                qemu_opts_set(qemu_find_opts("machine"), NULL, "kernel", optarg,
-                              &error_abort);
+                qemu_opts_set(qemu_find_opts("machine"), "kernel", optarg, &error_abort);
                 break;
             case QEMU_OPTION_initrd:
-                qemu_opts_set(qemu_find_opts("machine"), NULL, "initrd", optarg,
-                              &error_abort);
+                qemu_opts_set(qemu_find_opts("machine"), "initrd", optarg, &error_abort);
                 break;
             case QEMU_OPTION_append:
-                qemu_opts_set(qemu_find_opts("machine"), NULL, "append", optarg,
-                              &error_abort);
+                qemu_opts_set(qemu_find_opts("machine"), "append", optarg, &error_abort);
                 break;
             case QEMU_OPTION_dtb:
-                qemu_opts_set(qemu_find_opts("machine"), NULL, "dtb", optarg,
-                              &error_abort);
+                qemu_opts_set(qemu_find_opts("machine"), "dtb", optarg, &error_abort);
                 break;
             case QEMU_OPTION_cdrom:
                 drive_add(IF_DEFAULT, 2, optarg, CDROM_OPTS);
@@ -3511,8 +3507,7 @@ void qemu_init(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_bios:
-                qemu_opts_set(qemu_find_opts("machine"), NULL, "firmware", optarg,
-                              &error_abort);
+                qemu_opts_set(qemu_find_opts("machine"), "firmware", optarg, &error_abort);
                 break;
             case QEMU_OPTION_singlestep:
                 singlestep = 1;
@@ -4395,9 +4390,9 @@ void qemu_init(int argc, char **argv, char **envp)
 
     if (default_net) {
         QemuOptsList *net = qemu_find_opts("net");
-        qemu_opts_set(net, NULL, "type", "nic", &error_abort);
+        qemu_opts_parse(net, "nic", true, &error_abort);
 #ifdef CONFIG_SLIRP
-        qemu_opts_set(net, NULL, "type", "user", &error_abort);
+        qemu_opts_parse(net, "user", true, &error_abort);
 #endif
     }