'qemu-img resize --help' does not work, since it wants more
arguments.  Also -size is only recognized as a very last
argument, but it is common for tools to handle other options
after positional arguments too.

Tell getopt_long() to return non-options together with options,
and process filename and size in the loop, and check if there's
an argument right after filename which looks like -N (number),
and treat it as size (decrement).  This way we can handle --help,
and we can also have options after filename and size, and `--'
will be handled fine too.

The only case which is not handled right is when there's an option
between filename and size, and size is given as decrement, - in
this case -size will be treated as option, not as size.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 qemu-img.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 47dfa137c1..da10fafffc 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4297,7 +4297,7 @@ static int img_resize(const img_cmd_t *ccmd, int argc, char **argv)
 {
     Error *err = NULL;
     int c, ret, relative;
-    const char *filename, *fmt, *size;
+    const char *filename = NULL, *fmt = NULL, *size = NULL;
     int64_t n, total_size, current_size;
     bool quiet = false;
     BlockBackend *blk = NULL;
@@ -4320,17 +4320,7 @@ static int img_resize(const img_cmd_t *ccmd, int argc, char **argv)
     bool image_opts = false;
     bool shrink = false;
 
-    /* Remove size from argv manually so that negative numbers are not treated
-     * as options by getopt. */
-    if (argc < 3) {
-        error_exit(argv[0], "Not enough arguments");
-        return 1;
-    }
-
-    size = argv[--argc];
-
     /* Parse getopt arguments */
-    fmt = NULL;
     for(;;) {
         static const struct option long_options[] = {
             {"help", no_argument, 0, 'h'},
@@ -4340,7 +4330,7 @@ static int img_resize(const img_cmd_t *ccmd, int argc, char **argv)
             {"shrink", no_argument, 0, OPTION_SHRINK},
             {0, 0, 0, 0}
         };
-        c = getopt_long(argc, argv, ":f:hq",
+        c = getopt_long(argc, argv, "-:f:hq",
                         long_options, NULL);
         if (c == -1) {
             break;
@@ -4378,12 +4368,35 @@ static int img_resize(const img_cmd_t *ccmd, int argc, char **argv)
         case OPTION_SHRINK:
             shrink = true;
             break;
+        case 1: /* a non-optional argument */
+            if (!filename) {
+                filename = optarg;
+                /* see if we have -size (number) next to filename */
+                if (optind < argc) {
+                    size = argv[optind];
+                    if (size[0] == '-' && size[1] >= '0' && size[1] <= '9') {
+                        ++optind;
+                    } else {
+                        size = NULL;
+                    }
+                }
+            } else if (!size) {
+                size = optarg;
+            } else {
+                error_exit(argv[0], "Extra argument(s) in command line");
+            }
+            break;
         }
     }
-    if (optind != argc - 1) {
+    if (!filename && optind < argc) {
+        filename = argv[optind++];
+    }
+    if (!size && optind < argc) {
+        size = argv[optind++];
+    }
+    if (!filename || !size || optind < argc) {
         error_exit(argv[0], "Expecting image file name and size");
     }
-    filename = argv[optind++];
 
     /* Choose grow, shrink, or absolute resize mode */
     switch (size[0]) {
-- 
2.39.5