[Qemu-devel] [PATCH V12 14/18] block: dump to monitor for bdrv_snapshot_dump() and bdrv_image_info_dump()

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

  This patch introduce a new print function, which will output message to
monitor when it present. With it, bdrv_snapshot_dump() need no more buffer
and can avoid string truncation, bdrv_image_info_dump() can also be used by
hmp code later, besides qemu-img code.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 block/qapi.c                |   58 +++++++++++++++++++++---------------------
 include/block/qapi.h        |    2 +-
 include/qemu/error-report.h |    1 +
 qemu-img.c                  |    7 +++--
 savevm.c                    |    7 +++--
 util/qemu-error.c           |   18 +++++++++++++
 6 files changed, 57 insertions(+), 36 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index dc72adc..6e04a7f 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -351,7 +351,7 @@ BlockInfoList *qmp_query_block(Error **errp)
     return NULL;
 }
 
-char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
+void bdrv_snapshot_dump(QEMUSnapshotInfo *sn)
 {
     char buf1[128], date_buf[128], clock_buf[128];
     struct tm tm;
@@ -359,9 +359,8 @@ 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");
+        message_printf("%-10s%-20s%7s%20s%15s",
+                       "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
     } else {
         ti = sn->date_sec;
         localtime_r(&ti, &tm);
@@ -374,14 +373,13 @@ 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);
+        message_printf("%-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)
@@ -394,43 +392,44 @@ 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);
+    message_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);
 
     if (info->has_encrypted && info->encrypted) {
-        printf("encrypted: yes\n");
+        message_printf("encrypted: yes\n");
     }
 
     if (info->has_cluster_size) {
-        printf("cluster_size: %" PRId64 "\n", info->cluster_size);
+        message_printf("cluster_size: %" PRId64 "\n", info->cluster_size);
     }
 
     if (info->has_dirty_flag && info->dirty_flag) {
-        printf("cleanly shut down: no\n");
+        message_printf("cleanly shut down: no\n");
     }
 
     if (info->has_backing_filename) {
-        printf("backing file: %s", info->backing_filename);
+        message_printf("backing file: %s", info->backing_filename);
         if (info->has_full_backing_filename) {
-            printf(" (actual path: %s)", info->full_backing_filename);
+            message_printf(" (actual path: %s)", info->full_backing_filename);
         }
-        putchar('\n');
+        message_printf("\n");
         if (info->has_backing_filename_format) {
-            printf("backing file format: %s\n", info->backing_filename_format);
+            message_printf("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));
+        message_printf("Snapshot list:\n");
+        bdrv_snapshot_dump(NULL);
+        message_printf("\n");
 
         /* Ideally bdrv_snapshot_dump() would operate on SnapshotInfoList but
          * we convert to the block layer's native QEMUSnapshotInfo for now.
@@ -446,7 +445,8 @@ 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(&sn);
+            message_printf("\n");
         }
     }
 }
diff --git a/include/block/qapi.h b/include/block/qapi.h
index 237660f..f7eda89 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_snapshot_dump(QEMUSnapshotInfo *sn);
 void bdrv_image_info_dump(ImageInfo *info);
 #endif
diff --git a/include/qemu/error-report.h b/include/qemu/error-report.h
index c902cc1..90341bd 100644
--- a/include/qemu/error-report.h
+++ b/include/qemu/error-report.h
@@ -40,4 +40,5 @@ void error_set_progname(const char *argv0);
 void error_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 const char *error_get_progname(void);
 
+void message_printf(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 #endif
diff --git a/qemu-img.c b/qemu-img.c
index 5b229a9..8cbcb0b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1558,16 +1558,17 @@ static void dump_snapshots(BlockDriverState *bs)
 {
     QEMUSnapshotInfo *sn_tab, *sn;
     int nb_sns, i;
-    char buf[256];
 
     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));
+    bdrv_snapshot_dump(NULL);
+    printf("\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(sn);
+        printf("\n");
     }
     g_free(sn_tab);
 }
diff --git a/savevm.c b/savevm.c
index 1c8fbee..e125567 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2466,7 +2466,6 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
     int nb_sns, i, ret, available;
     int total;
     int *available_snapshots;
-    char buf[256];
 
     bs = bdrv_snapshots();
     if (!bs) {
@@ -2509,10 +2508,12 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
     }
 
     if (total > 0) {
-        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
+        bdrv_snapshot_dump(NULL);
+        monitor_printf(mon, "\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(sn);
+            monitor_printf(mon, "\n");
         }
     } else {
         monitor_printf(mon, "There is no suitable snapshot available\n");
diff --git a/util/qemu-error.c b/util/qemu-error.c
index 08a36f4..a47bf32 100644
--- a/util/qemu-error.c
+++ b/util/qemu-error.c
@@ -213,3 +213,21 @@ void error_report(const char *fmt, ...)
     va_end(ap);
     error_printf("\n");
 }
+
+/*
+ * Print to current monitor if we have one, else to stdout. It is similar with
+ * error_printf().
+ * TODO just like error_vprintf()
+ */
+void message_printf(const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    if (cur_mon) {
+        monitor_vprintf(cur_mon, fmt, ap);
+    } else {
+        vfprintf(stdout, fmt, ap);
+    }
+    va_end(ap);
+}
-- 
1.7.1