[PULL 4/6] qemu-img: refactor dump_map_entry JSON format output

[Eric Blake <eblake@redhat.com>]

From: Eyal Moscovici <eyal.moscovici@oracle.com>

Previously dump_map_entry identified whether we need to start a new JSON
array based on whether start address == 0. In this refactor we remove
this assumption as in following patches we will allow map to start from
an arbitrary position.

Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Eyal Moscovici <eyal.moscovici@oracle.com>
Message-Id: <20200513133629.18508-4-eyal.moscovici@oracle.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 qemu-img.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index c88f412333ec..4aa9414aba6f 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2902,9 +2902,8 @@ static int dump_map_entry(OutputFormat output_format, MapEntry *e,
         }
         break;
     case OFORMAT_JSON:
-        printf("%s{ \"start\": %"PRId64", \"length\": %"PRId64","
+        printf("{ \"start\": %"PRId64", \"length\": %"PRId64","
                " \"depth\": %"PRId64", \"zero\": %s, \"data\": %s",
-               (e->start == 0 ? "[" : ",\n"),
                e->start, e->length, e->depth,
                e->zero ? "true" : "false",
                e->data ? "true" : "false");
@@ -2913,8 +2912,8 @@ static int dump_map_entry(OutputFormat output_format, MapEntry *e,
         }
         putchar('}');

-        if (!next) {
-            printf("]\n");
+        if (next) {
+            puts(",");
         }
         break;
     }
@@ -3089,6 +3088,8 @@ static int img_map(int argc, char **argv)

     if (output_format == OFORMAT_HUMAN) {
         printf("%-16s%-16s%-16s%s\n", "Offset", "Length", "Mapped to", "File");
+    } else if (output_format == OFORMAT_JSON) {
+        putchar('[');
     }

     length = blk_getlength(blk);
@@ -3125,6 +3126,9 @@ static int img_map(int argc, char **argv)
     }

     ret = dump_map_entry(output_format, &curr, NULL);
+    if (output_format == OFORMAT_JSON) {
+        puts("]");
+    }

 out:
     blk_unref(blk);
-- 
2.26.2