qmp: Clean up design of memchar-read

The data returned has a well-defined size, which makes the size
returned along with it redundant at best.  Drop it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hmp.c

@@ -677,21 +677,18 @@ void hmp_memchar_read(Monitor *mon, const QDict *qdict)
 {
     uint32_t size = qdict_get_int(qdict, "size");
     const char *chardev = qdict_get_str(qdict, "device");
-    MemCharRead *meminfo;
+    char *data;
     Error *errp = NULL;
 
-    meminfo = qmp_memchar_read(chardev, size, false, 0, &errp);
+    data = qmp_memchar_read(chardev, size, false, 0, &errp);
     if (errp) {
         monitor_printf(mon, "%s\n", error_get_pretty(errp));
         error_free(errp);
         return;
     }
 
-    if (meminfo->count > 0) {
-        monitor_printf(mon, "%s\n", meminfo->data);
-    }
-
-    qapi_free_MemCharRead(meminfo);
+    monitor_printf(mon, "%s\n", data);
+    g_free(data);
 }
 
 static void hmp_cont_cb(void *opaque, int err)

qapi-schema.json

@@ -360,20 +360,6 @@
   'data': {'device': 'str', 'data': 'str',
            '*format': 'DataFormat'} }
 
-##
-# @MemCharRead
-#
-# Result of QMP command memchar-read.
-#
-# @data: The data read from memchar as string.
-#
-# @count: The numbers of bytes read from.
-#
-# Since: 1.4
-##
-{ 'type': 'MemCharRead',
-  'data': { 'data': 'str', 'count': 'int' } }
-
 ##
 # @memchar-read:
 #
@@ -387,14 +373,14 @@
 # @format: #optional the format of the data want to read from
 #          memchardev, by default is 'utf8'.
 #
-# Returns: @MemCharRead
+# Returns: data read from the device
 #          If @device is not a valid memchr device, DeviceNotFound
 #
 # Since: 1.4
 ##
 { 'command': 'memchar-read',
   'data': {'device': 'str', 'size': 'int', '*format': 'DataFormat'},
-  'returns': 'MemCharRead' }
+  'returns': 'str' }
 
 ##
 # @CommandInfo:

qemu-char.c

@@ -2788,14 +2788,14 @@ void qmp_memchar_write(const char *device, const char *data,
     }
 }
 
-MemCharRead *qmp_memchar_read(const char *device, int64_t size,
-                              bool has_format, enum DataFormat format,
-                              Error **errp)
+char *qmp_memchar_read(const char *device, int64_t size,
+                       bool has_format, enum DataFormat format,
+                       Error **errp)
 {
     CharDriverState *chr;
     guchar *read_data;
-    MemCharRead *meminfo;
     size_t count;
+    char *data;
 
     chr = qemu_chr_find(device);
     if (!chr) {
@@ -2813,26 +2813,23 @@ MemCharRead *qmp_memchar_read(const char *device, int64_t size,
         return NULL;
     }
 
-    meminfo = g_malloc0(sizeof(MemCharRead));
-
     count = qemu_chr_cirmem_count(chr);
     if (count == 0) {
-        meminfo->data = g_strdup("");
-        return meminfo;
+        return g_strdup("");
     }
 
     size = size > count ? count : size;
     read_data = g_malloc0(size + 1);
 
-    meminfo->count = cirmem_chr_read(chr, read_data, size);
+    cirmem_chr_read(chr, read_data, size);
 
     if (has_format && (format == DATA_FORMAT_BASE64)) {
-        meminfo->data = g_base64_encode(read_data, (size_t)meminfo->count);
+        data = g_base64_encode(read_data, size);
     } else {
-        meminfo->data = (char *)read_data;
+        data = (char *)read_data;
     }
 
-    return meminfo;
+    return data;
 }
 
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)

qmp-commands.hx

@@ -525,7 +525,7 @@ Example:
                 "arguments": { "device": foo,
                                "size": 1000,
                                "format": "utf8" } }
-<- { "return": { "data": "data string...", "count": 1000 } }
+<- {"return": "abcdefgh"}
 
 EQMP