QAPI: Introduce memchar-write QMP command

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

hmp-commands.hx

@@ -837,6 +837,24 @@ STEXI
 @item nmi @var{cpu}
 @findex nmi
 Inject an NMI on the given CPU (x86 only).
+
+ETEXI
+
+    {
+        .name       = "memchar_write",
+        .args_type  = "device:s,data:s",
+        .params     = "device data",
+        .help       = "Provide writing interface for CirMemCharDriver. Write"
+                      "'data' to it.",
+        .mhandler.cmd = hmp_memchar_write,
+    },
+
+STEXI
+@item memchar_write @var{device} @var{data}
+@findex memchar_write
+Provide writing interface for CirMemCharDriver. Write @var{data}
+to char device 'memory'.
+
 ETEXI
 
     {

hmp.c

@@ -662,6 +662,19 @@ void hmp_pmemsave(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, &errp);
 }
 
+void hmp_memchar_write(Monitor *mon, const QDict *qdict)
+{
+    uint32_t size;
+    const char *chardev = qdict_get_str(qdict, "device");
+    const char *data = qdict_get_str(qdict, "data");
+    Error *errp = NULL;
+
+    size = strlen(data);
+    qmp_memchar_write(chardev, size, data, false, 0, &errp);
+
+    hmp_handle_error(mon, &errp);
+}
+
 static void hmp_cont_cb(void *opaque, int err)
 {
     if (!err) {

hmp.h

@@ -43,6 +43,7 @@ void hmp_system_powerdown(Monitor *mon, const QDict *qdict);
 void hmp_cpu(Monitor *mon, const QDict *qdict);
 void hmp_memsave(Monitor *mon, const QDict *qdict);
 void hmp_pmemsave(Monitor *mon, const QDict *qdict);
+void hmp_memchar_write(Monitor *mon, const QDict *qdict);
 void hmp_cont(Monitor *mon, const QDict *qdict);
 void hmp_system_wakeup(Monitor *mon, const QDict *qdict);
 void hmp_inject_nmi(Monitor *mon, const QDict *qdict);

qapi-schema.json

@@ -324,6 +324,44 @@
 ##
 { 'command': 'query-chardev', 'returns': ['ChardevInfo'] }
 
+##
+# @DataFormat:
+#
+# An enumeration of data format.
+#
+# @utf8: The data format is 'utf8'.
+#
+# @base64: The data format is 'base64'.
+#
+# Since: 1.4
+##
+{ 'enum': 'DataFormat'
+  'data': [ 'utf8', 'base64' ] }
+
+##
+# @memchar-write:
+#
+# Provide writing interface for memchardev. Write data to char
+# device 'memory'.
+#
+# @device: the name of the memory char device.
+#
+# @size: the size to write in bytes.
+#
+# @data: the source data write to memchar.
+#
+# @format: #optional the format of the data write to chardev 'memory',
+#          by default is 'utf8'.
+#
+# Returns: Nothing on success
+#          If @device is not a valid char device, DeviceNotFound
+#
+# Since: 1.4
+##
+{ 'command': 'memchar-write',
+  'data': {'device': 'str', 'size': 'int', 'data': 'str',
+           '*format': 'DataFormat'} }
+
 ##
 # @CommandInfo:
 #

qemu-char.c

@@ -2748,6 +2748,48 @@ fail:
     return NULL;
 }
 
+static bool qemu_is_chr(const CharDriverState *chr, const char *filename)
+{
+    return strcmp(chr->filename, filename);
+}
+
+void qmp_memchar_write(const char *device, int64_t size,
+                       const char *data, bool has_format,
+                       enum DataFormat format,
+                       Error **errp)
+{
+    CharDriverState *chr;
+    guchar *write_data;
+    int ret;
+    gsize write_count;
+
+    chr = qemu_chr_find(device);
+    if (!chr) {
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
+    }
+
+    if (qemu_is_chr(chr, "memory")) {
+        error_setg(errp,"%s is not memory char device", device);
+        return;
+    }
+
+    write_count = (gsize)size;
+
+    if (has_format && (format == DATA_FORMAT_BASE64)) {
+        write_data = g_base64_decode(data, &write_count);
+    } else {
+        write_data = (uint8_t *)data;
+    }
+
+    ret = cirmem_chr_write(chr, write_data, write_count);
+
+    if (ret < 0) {
+        error_setg(errp, "Failed to write to device %s", device);
+        return;
+    }
+}
+
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
 {
     char host[65], port[33], width[8], height[8];

qmp-commands.hx

@@ -463,6 +463,39 @@ Example:
 Note: inject-nmi fails when the guest doesn't support injecting.
       Currently, only x86 guests do.
 
+EQMP
+
+    {
+        .name       = "memchar-write",
+        .args_type  = "device:s,size:i,data:s,format:s?",
+        .mhandler.cmd_new = qmp_marshal_input_memchar_write,
+    },
+
+SQMP
+memchar-write
+-------------
+
+Provide writing interface for CirMemCharDriver. Write data to memory
+char device.
+
+Arguments:
+
+- "device": the name of the char device, must be unique (json-string)
+- "size": the memory size, in bytes, should be power of 2 (json-int)
+- "data": the source data write to memory (json-string)
+- "format": the data format write to memory, default is
+            utf8. (json-string, optional)
+          - Possible values: "utf8", "base64"
+
+Example:
+
+-> { "execute": "memchar-write",
+                "arguments": { "device": foo,
+                               "size": 8,
+                               "data": "abcdefgh",
+                               "format": "utf8" } }
+<- { "return": {} }
+
 EQMP
 
     {