qemu-img: move common options parsing before commands processing

This is necessary to enable creation of common qemu-img options which will
be specified before command.

The patch also enables '-V' alias to '--version' (exactly like in other
block utilities) and documents this change.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1466174654-30130-7-git-send-email-den@openvz.org
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

qemu-img.c

@@ -91,9 +91,12 @@ static void QEMU_NORETURN help(void)
 {
     const char *help_msg =
            QEMU_IMG_VERSION
-           "usage: qemu-img command [command options]\n"
+           "usage: qemu-img [standard options] command [command options]\n"
            "QEMU disk image utility\n"
            "\n"
+           "    '-h', '--help'       display this help and exit\n"
+           "    '-V', '--version'    output version information and exit\n"
+           "\n"
            "Command syntax:\n"
 #define DEF(option, callback, arg_string)        \
            "  " arg_string "\n"
@@ -3806,7 +3809,7 @@ int main(int argc, char **argv)
     int c;
     static const struct option long_options[] = {
         {"help", no_argument, 0, 'h'},
-        {"version", no_argument, 0, 'v'},
+        {"version", no_argument, 0, 'V'},
         {0, 0, 0, 0}
     };
 
@@ -3829,28 +3832,38 @@ int main(int argc, char **argv)
     if (argc < 2) {
         error_exit("Not enough arguments");
     }
-    cmdname = argv[1];
 
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_source_opts);
 
+    while ((c = getopt_long(argc, argv, "+hV", long_options, NULL)) != -1) {
+        switch (c) {
+        case 'h':
+            help();
+            return 0;
+        case 'V':
+            printf(QEMU_IMG_VERSION);
+            return 0;
+        }
+    }
+
+    cmdname = argv[optind];
+
+    /* reset getopt_long scanning */
+    argc -= optind;
+    if (argc < 1) {
+        return 0;
+    }
+    argv += optind;
+    optind = 1;
+
     /* find the command */
     for (cmd = img_cmds; cmd->name != NULL; cmd++) {
         if (!strcmp(cmdname, cmd->name)) {
-            return cmd->handler(argc - 1, argv + 1);
+            return cmd->handler(argc, argv);
         }
     }
 
-    c = getopt_long(argc, argv, "h", long_options, NULL);
-
-    if (c == 'h') {
-        help();
-    }
-    if (c == 'v') {
-        printf(QEMU_IMG_VERSION);
-        return 0;
-    }
-
     /* not found */
     error_exit("Command not found: %s", cmdname);
 }

qemu-img.texi

@@ -1,6 +1,6 @@
 @example
 @c man begin SYNOPSIS
-@command{qemu-img} @var{command} [@var{command} @var{options}]
+@command{qemu-img} [@var{standard} @var{options}] @var{command} [@var{command} @var{options}]
 @c man end
 @end example
 
@@ -16,6 +16,14 @@ inconsistent state.
 
 @c man begin OPTIONS
 
+Standard options:
+@table @option
+@item -h, --help
+Display this help and exit
+@item -V, --version
+Display version information and exit
+@end table
+
 The following commands are supported:
 
 @include qemu-img-cmds.texi