qemu: command: Refactor floppy controller command formatting

Aggregate the code for the two separate formats used according to the
machine type and add some supporting code so that the function is
actually readable.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_command.c

@@ -2148,55 +2148,53 @@ qemuBuildFloppyCommandLineOptions(virCommandPtr cmd,
 
 {
     virBuffer fdc_opts = VIR_BUFFER_INITIALIZER;
-    char *fdc_opts_str = NULL;
-    char *optstr;
+    char driveLetter;
     char *backendAlias = NULL;
+    char *backendStr = NULL;
+    char *bootindexStr = NULL;
     int ret = -1;
 
+    if (disk->info.addr.drive.unit)
+        driveLetter = 'B';
+    else
+        driveLetter = 'A';
+
     if (!(backendAlias = qemuAliasDiskDriveFromDisk(disk)))
         return -1;
 
-    if (virAsprintf(&optstr, "drive%c=%s",
-                    disk->info.addr.drive.unit ? 'B' : 'A',
-                    backendAlias) < 0)
+    if (virAsprintf(&backendStr, "drive%c=%s", driveLetter, backendAlias) < 0)
         goto cleanup;
 
-    if (!qemuDomainNeedsFDC(def)) {
-        virCommandAddArg(cmd, "-global");
-        virCommandAddArgFormat(cmd, "isa-fdc.%s", optstr);
-    } else {
-        virBufferAsprintf(&fdc_opts, "%s,", optstr);
-    }
-    VIR_FREE(optstr);
-
-    if (bootindex) {
-        if (virAsprintf(&optstr, "bootindex%c=%u",
-                        disk->info.addr.drive.unit
-                        ? 'B' : 'A',
-                        bootindex) < 0)
+    if (bootindex &&
+        virAsprintf(&bootindexStr, "bootindex%c=%u", driveLetter, bootindex) < 0)
         goto cleanup;
 
     if (!qemuDomainNeedsFDC(def)) {
+        if (backendStr) {
             virCommandAddArg(cmd, "-global");
-            virCommandAddArgFormat(cmd, "isa-fdc.%s", optstr);
-        } else {
-            virBufferAsprintf(&fdc_opts, "%s,", optstr);
-        }
-        VIR_FREE(optstr);
+            virCommandAddArgFormat(cmd, "isa-fdc.%s", backendStr);
         }
 
+        if (bootindexStr) {
+            virCommandAddArg(cmd, "-global");
+            virCommandAddArgFormat(cmd, "isa-fdc.%s", bootindexStr);
+        }
+    } else {
         /* Newer Q35 machine types require an explicit FDC controller */
+        virBufferAddLit(&fdc_opts, "isa-fdc,");
+        virBufferStrcat(&fdc_opts, backendStr, ",", NULL);
+        virBufferStrcat(&fdc_opts, bootindexStr, NULL);
         virBufferTrim(&fdc_opts, ",", -1);
-    if ((fdc_opts_str = virBufferContentAndReset(&fdc_opts))) {
         virCommandAddArg(cmd, "-device");
-        virCommandAddArgFormat(cmd, "isa-fdc,%s", fdc_opts_str);
-        VIR_FREE(fdc_opts_str);
+        virCommandAddArgBuffer(cmd, &fdc_opts);
     }
 
     ret = 0;
 
  cleanup:
     VIR_FREE(backendAlias);
+    VIR_FREE(backendStr);
+    VIR_FREE(bootindexStr);
     return ret;
 }