block: Add '--version' option to qemu-img

This allows qemu-img to print out version information, without
needing to print the long help wall of text.

While there, perform some minor whitespace cleanup, and remove the
unused option_index variable in the call to getopt_long().

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-img.c

@@ -33,6 +33,9 @@
 #include "block/qapi.h"
 #include <getopt.h>
 
+#define QEMU_IMG_VERSION "qemu-img version " QEMU_VERSION \
+                          ", Copyright (c) 2004-2008 Fabrice Bellard\n"
+
 typedef struct img_cmd_t {
     const char *name;
     int (*handler)(int argc, char **argv);
@@ -75,7 +78,7 @@ static void QEMU_NORETURN GCC_FMT_ATTR(1, 2) error_exit(const char *fmt, ...)
 static void QEMU_NORETURN help(void)
 {
     const char *help_msg =
-           "qemu-img version " QEMU_VERSION ", Copyright (c) 2004-2008 Fabrice Bellard\n"
+           QEMU_IMG_VERSION
            "usage: qemu-img command [command options]\n"
            "QEMU disk image utility\n"
            "\n"
@@ -2790,9 +2793,9 @@ int main(int argc, char **argv)
     const img_cmd_t *cmd;
     const char *cmdname;
     int c;
-    int option_index = 0;
     static const struct option long_options[] = {
         {"help", no_argument, 0, 'h'},
+        {"version", no_argument, 0, 'v'},
         {0, 0, 0, 0}
     };
 
@@ -2811,17 +2814,21 @@ int main(int argc, char **argv)
     cmdname = argv[1];
 
     /* find the command */
-    for(cmd = img_cmds; cmd->name != NULL; cmd++) {
+    for (cmd = img_cmds; cmd->name != NULL; cmd++) {
         if (!strcmp(cmdname, cmd->name)) {
             return cmd->handler(argc - 1, argv + 1);
         }
     }
 
-    c = getopt_long(argc, argv, "h", long_options, &option_index);
+    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);