qemu-io: Improve alignment checks

Several copy-and-pasted alignment checks exist in qemu-io, which
could use some minor improvements:

- Manual comparison against 0x1ff is not as clean as using our
alignment macros (QEMU_IS_ALIGNED) from osdep.h.

- The error messages aren't quite grammatically correct.

Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Suggested-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170429191419.30051-2-eblake@redhat.com
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

qemu-io-cmds.c

@@ -740,13 +740,13 @@ static int read_f(BlockBackend *blk, int argc, char **argv)
     }
 
     if (bflag) {
-        if (offset & 0x1ff) {
-            printf("offset %" PRId64 " is not sector aligned\n",
+        if (!QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)) {
+            printf("%" PRId64 " is not a sector-aligned value for 'offset'\n",
                    offset);
             return 0;
         }
-        if (count & 0x1ff) {
-            printf("count %"PRId64" is not sector aligned\n",
+        if (!QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)) {
+            printf("%"PRId64" is not a sector-aligned value for 'count'\n",
                    count);
             return 0;
         }
@@ -1050,14 +1050,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
     }
 
     if (bflag || cflag) {
-        if (offset & 0x1ff) {
-            printf("offset %" PRId64 " is not sector aligned\n",
+        if (!QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)) {
+            printf("%" PRId64 " is not a sector-aligned value for 'offset'\n",
                    offset);
             return 0;
         }
 
-        if (count & 0x1ff) {
-            printf("count %"PRId64" is not sector aligned\n",
+        if (!QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)) {
+            printf("%"PRId64" is not a sector-aligned value for 'count'\n",
                    count);
             return 0;
         }
@@ -1769,8 +1769,8 @@ static int alloc_f(BlockBackend *blk, int argc, char **argv)
     if (offset < 0) {
         print_cvtnum_err(offset, argv[1]);
         return 0;
-    } else if (offset & 0x1ff) {
-        printf("offset %" PRId64 " is not sector aligned\n",
+    } else if (!QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)) {
+        printf("%" PRId64 " is not a sector-aligned value for 'offset'\n",
                offset);
         return 0;
     }