qemu-storage-daemon: Add barebone tool

This adds a new binary qemu-storage-daemon that doesn't yet do more than
some typical initialisation for tools and parsing the basic command
options --version, --help and --trace.

Even though this doesn't add any options yet that create things (like
--object or --blockdev), already document that we're planning to process
them in the order they are given on the command line rather than trying
(and failing, like vl.c) to resolve dependencies between options
automatically.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-2-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Makefile

@@ -586,6 +586,7 @@ qemu-img.o: qemu-img-cmds.h
 qemu-img$(EXESUF): qemu-img.o $(authz-obj-y) $(block-obj-y) $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
 qemu-nbd$(EXESUF): qemu-nbd.o $(authz-obj-y) $(block-obj-y) $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
 qemu-io$(EXESUF): qemu-io.o $(authz-obj-y) $(block-obj-y) $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
+qemu-storage-daemon$(EXESUF): qemu-storage-daemon.o $(authz-obj-y) $(block-obj-y) $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
 
 qemu-bridge-helper$(EXESUF): qemu-bridge-helper.o $(COMMON_LDADDS)
 

configure

@@ -6316,7 +6316,7 @@ tools=""
 if test "$want_tools" = "yes" ; then
   tools="qemu-img\$(EXESUF) qemu-io\$(EXESUF) qemu-edid\$(EXESUF) $tools"
   if [ "$linux" = "yes" -o "$bsd" = "yes" -o "$solaris" = "yes" ] ; then
-    tools="qemu-nbd\$(EXESUF) $tools"
+    tools="qemu-nbd\$(EXESUF) qemu-storage-daemon\$(EXESUF) $tools"
   fi
   if [ "$ivshmem" = "yes" ]; then
     tools="ivshmem-client\$(EXESUF) ivshmem-server\$(EXESUF) $tools"

qemu-storage-daemon.c

@@ -0,0 +1,127 @@
+/*
+ * QEMU storage daemon
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2019 Kevin Wolf <kwolf@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+
+#include <getopt.h>
+
+#include "block/block.h"
+#include "crypto/init.h"
+
+#include "qapi/error.h"
+#include "qemu-common.h"
+#include "qemu-version.h"
+#include "qemu/config-file.h"
+#include "qemu/error-report.h"
+#include "qemu/log.h"
+#include "qemu/main-loop.h"
+#include "qemu/module.h"
+
+#include "trace/control.h"
+
+static void help(void)
+{
+    printf(
+"Usage: %s [options]\n"
+"QEMU storage daemon\n"
+"\n"
+"  -h, --help             display this help and exit\n"
+"  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
+"                         specify tracing options\n"
+"  -V, --version          output version information and exit\n"
+"\n"
+QEMU_HELP_BOTTOM "\n",
+    error_get_progname());
+}
+
+static void process_options(int argc, char *argv[])
+{
+    int c;
+
+    static const struct option long_options[] = {
+        {"help", no_argument, NULL, 'h'},
+        {"trace", required_argument, NULL, 'T'},
+        {"version", no_argument, NULL, 'V'},
+        {0, 0, 0, 0}
+    };
+
+    /*
+     * In contrast to the system emulator, options are processed in the order
+     * they are given on the command lines. This means that things must be
+     * defined first before they can be referenced in another option.
+     */
+    while ((c = getopt_long(argc, argv, "hT:V", long_options, NULL)) != -1) {
+        switch (c) {
+        case '?':
+            exit(EXIT_FAILURE);
+        case 'h':
+            help();
+            exit(EXIT_SUCCESS);
+        case 'T':
+            {
+                char *trace_file = trace_opt_parse(optarg);
+                trace_init_file(trace_file);
+                g_free(trace_file);
+                break;
+            }
+        case 'V':
+            printf("qemu-storage-daemon version "
+                   QEMU_FULL_VERSION "\n" QEMU_COPYRIGHT "\n");
+            exit(EXIT_SUCCESS);
+        default:
+            g_assert_not_reached();
+        }
+    }
+    if (optind != argc) {
+        error_report("Unexpected argument: %s", argv[optind]);
+        exit(EXIT_FAILURE);
+    }
+}
+
+int main(int argc, char *argv[])
+{
+#ifdef CONFIG_POSIX
+    signal(SIGPIPE, SIG_IGN);
+#endif
+
+    error_init(argv[0]);
+    qemu_init_exec_dir(argv[0]);
+
+    module_call_init(MODULE_INIT_QOM);
+    module_call_init(MODULE_INIT_TRACE);
+    qemu_add_opts(&qemu_trace_opts);
+    qcrypto_init(&error_fatal);
+    bdrv_init();
+
+    if (!trace_init_backends()) {
+        return EXIT_FAILURE;
+    }
+    qemu_set_log(LOG_TRACE);
+
+    qemu_init_main_loop(&error_fatal);
+    process_options(argc, argv);
+
+    return EXIT_SUCCESS;
+}