[Qemu-devel] [PATCH V11 13/17] block: dump to buffer for bdrv_snapshot_dump() and bdrv_image_info_dump()

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

  This patch would allow hmp use them just like qemu-img, and avoid
string truncation.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 block/qapi.c         |   65 +++++++++++++++++++++++++++-----------------------
 include/block/qapi.h |    4 +-
 qemu-img.c           |   22 ++++++++++++----
 savevm.c             |   11 ++++++--
 4 files changed, 61 insertions(+), 41 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index df63c97..e27519e 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -327,7 +327,7 @@ BlockInfoList *qmp_query_block(Error **errp)
     return NULL;
 }
 
-char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
+void bdrv_snapshot_dump(GString *buf, QEMUSnapshotInfo *sn)
 {
     char buf1[128], date_buf[128], clock_buf[128];
     struct tm tm;
@@ -335,9 +335,8 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
     int64_t secs;
 
     if (!sn) {
-        snprintf(buf, buf_size,
-                 "%-10s%-20s%7s%20s%15s",
-                 "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
+        g_string_append_printf(buf, "%-10s%-20s%7s%20s%15s",
+                               "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
     } else {
         ti = sn->date_sec;
         localtime_r(&ti, &tm);
@@ -350,17 +349,17 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
                  (int)((secs / 60) % 60),
                  (int)(secs % 60),
                  (int)((sn->vm_clock_nsec / 1000000) % 1000));
-        snprintf(buf, buf_size,
-                 "%-10s%-20s%7s%20s%15s",
-                 sn->id_str, sn->name,
-                 get_human_readable_size(buf1, sizeof(buf1), sn->vm_state_size),
-                 date_buf,
-                 clock_buf);
+        g_string_append_printf(buf,
+                               "%-10s%-20s%7s%20s%15s",
+                               sn->id_str, sn->name,
+                               get_human_readable_size(buf1, sizeof(buf1),
+                                                       sn->vm_state_size),
+                               date_buf,
+                               clock_buf);
     }
-    return buf;
 }
 
-void bdrv_image_info_dump(ImageInfo *info)
+void bdrv_image_info_dump(GString *buf, ImageInfo *info)
 {
     char size_buf[128], dsize_buf[128];
     if (!info->has_actual_size) {
@@ -370,43 +369,48 @@ void bdrv_image_info_dump(ImageInfo *info)
                                 info->actual_size);
     }
     get_human_readable_size(size_buf, sizeof(size_buf), info->virtual_size);
-    printf("image: %s\n"
-           "file format: %s\n"
-           "virtual size: %s (%" PRId64 " bytes)\n"
-           "disk size: %s\n",
-           info->filename, info->format, size_buf,
-           info->virtual_size,
-           dsize_buf);
+    g_string_append_printf(buf,
+                           "image: %s\n"
+                           "file format: %s\n"
+                           "virtual size: %s (%" PRId64 " bytes)\n"
+                           "disk size: %s\n",
+                           info->filename, info->format, size_buf,
+                           info->virtual_size,
+                           dsize_buf);
 
     if (info->has_encrypted && info->encrypted) {
-        printf("encrypted: yes\n");
+        g_string_append_printf(buf, "encrypted: yes\n");
     }
 
     if (info->has_cluster_size) {
-        printf("cluster_size: %" PRId64 "\n", info->cluster_size);
+        g_string_append_printf(buf, "cluster_size: %" PRId64 "\n",
+                               info->cluster_size);
     }
 
     if (info->has_dirty_flag && info->dirty_flag) {
-        printf("cleanly shut down: no\n");
+        g_string_append_printf(buf, "cleanly shut down: no\n");
     }
 
     if (info->has_backing_filename) {
-        printf("backing file: %s", info->backing_filename);
+        g_string_append_printf(buf, "backing file: %s",
+                               info->backing_filename);
         if (info->has_full_backing_filename) {
-            printf(" (actual path: %s)", info->full_backing_filename);
+            g_string_append_printf(buf, " (actual path: %s)",
+                                   info->full_backing_filename);
         }
-        putchar('\n');
+        g_string_append_printf(buf, "\n");
         if (info->has_backing_filename_format) {
-            printf("backing file format: %s\n", info->backing_filename_format);
+            g_string_append_printf(buf, "backing file format: %s\n",
+                                   info->backing_filename_format);
         }
     }
 
     if (info->has_snapshots) {
         SnapshotInfoList *elem;
-        char buf[256];
 
-        printf("Snapshot list:\n");
-        printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
+        g_string_append_printf(buf, "Snapshot list:\n");
+        bdrv_snapshot_dump(buf, NULL);
+        g_string_append_printf(buf, "\n");
 
         /* Ideally bdrv_snapshot_dump() would operate on SnapshotInfoList but
          * we convert to the block layer's native QEMUSnapshotInfo for now.
@@ -422,7 +426,8 @@ void bdrv_image_info_dump(ImageInfo *info)
 
             pstrcpy(sn.id_str, sizeof(sn.id_str), elem->value->id);
             pstrcpy(sn.name, sizeof(sn.name), elem->value->name);
-            printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), &sn));
+            bdrv_snapshot_dump(buf, &sn);
+            g_string_append_printf(buf, "\n");
         }
     }
 }
diff --git a/include/block/qapi.h b/include/block/qapi.h
index 237660f..dc1e090 100644
--- a/include/block/qapi.h
+++ b/include/block/qapi.h
@@ -38,6 +38,6 @@ int bdrv_query_image_info(BlockDriverState *bs,
 void bdrv_query_info(BlockDriverState *bs,
                      BlockInfo **p_info,
                      Error **errp);
-char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn);
-void bdrv_image_info_dump(ImageInfo *info);
+void bdrv_snapshot_dump(GString *buf, QEMUSnapshotInfo *sn);
+void bdrv_image_info_dump(GString *buf, ImageInfo *info);
 #endif
diff --git a/qemu-img.c b/qemu-img.c
index 5b229a9..032f68c 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1558,18 +1558,24 @@ static void dump_snapshots(BlockDriverState *bs)
 {
     QEMUSnapshotInfo *sn_tab, *sn;
     int nb_sns, i;
-    char buf[256];
+    GString *buf = g_string_new(NULL);
 
     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
     if (nb_sns <= 0)
         return;
-    printf("Snapshot list:\n");
-    printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
+    g_string_append_printf(buf, "Snapshot list:\n");
+    bdrv_snapshot_dump(buf, NULL);
+    g_string_append_printf(buf, "\n");
     for(i = 0; i < nb_sns; i++) {
         sn = &sn_tab[i];
-        printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
+        bdrv_snapshot_dump(buf, sn);
+        g_string_append_printf(buf, "\n");
     }
+
+    printf("%s", buf->str);
+    g_string_free(buf, true);
     g_free(sn_tab);
+
 }
 
 static void dump_json_image_info_list(ImageInfoList *list)
@@ -1610,15 +1616,19 @@ static void dump_human_image_info_list(ImageInfoList *list)
 {
     ImageInfoList *elem;
     bool delim = false;
+    GString *buf = g_string_new(NULL);
 
     for (elem = list; elem; elem = elem->next) {
         if (delim) {
-            printf("\n");
+            g_string_append_printf(buf, "\n");
         }
         delim = true;
 
-        bdrv_image_info_dump(elem->value);
+        bdrv_image_info_dump(buf, elem->value);
     }
+
+    printf("%s", buf->str);
+    g_string_free(buf, true);
 }
 
 static gboolean str_equal_func(gconstpointer a, gconstpointer b)
diff --git a/savevm.c b/savevm.c
index e4e0008..ce0bbe1 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2466,7 +2466,7 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
     int nb_sns, i, ret, available;
     int total;
     int *available_snapshots;
-    char buf[256];
+    GString *buf = NULL;
 
     bs = bdrv_snapshots();
     if (!bs) {
@@ -2509,11 +2509,16 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
     }
 
     if (total > 0) {
-        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
+        buf = g_string_new(NULL);
+        bdrv_snapshot_dump(buf, NULL);
+        g_string_append_printf(buf, "\n");
         for (i = 0; i < total; i++) {
             sn = &sn_tab[available_snapshots[i]];
-            monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
+            bdrv_snapshot_dump(buf, sn);
+            g_string_append_printf(buf, "\n");
         }
+        monitor_printf(mon, "%s", buf->str);
+        g_string_free(buf, true);
     } else {
         monitor_printf(mon, "There is no suitable snapshot available\n");
     }
-- 
1.7.1