[PATCH hurd v4] libstore: fix warning due to ignoring asprintf result

[dnietoc]

From: Diego Nieto Cid <dnie...@gmail.com>

    ../../libstore/unknown.c: In function 'store_unknown_decode':
    ../../libstore/unknown.c:130:5: warning: ignoring return value of 
'asprintf' declared with attribute 'warn_unused_result' [-Wunused-result]
      130 |     asprintf (&(*store)->name, "notype:%.*s",
          |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      131 |               (int) (us->data_len - us->cur_data), us->data + 
us->cur_data);
          |               
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ../../libstore/unknown.c:133:5: warning: ignoring return value of 
'asprintf' declared with attribute 'warn_unused_result' [-Wunused-result]
      133 |     asprintf (&(*store)->name, "type-%d:%.*s", 
enc->ints[enc->cur_int],
          |     
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      134 |              (int) ( us->data_len - us->cur_data), us->data + 
us->cur_data);
          |              
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

===============================================================================

    ../../libstore/nbd.c: In function 'store_nbd_open':
    ../../libstore/nbd.c:522:13: warning: ignoring return value of 'asprintf' 
declared with attribute 'warn_unused_result' [-Wunused-result]
      522 |             asprintf (&(*store)->name, "%s%s", url_prefix, name);
          |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
---
 libstore/nbd.c     | 6 +++++-
 libstore/unknown.c | 7 +++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/libstore/nbd.c b/libstore/nbd.c
index df949a78..5ddf2dc8 100644
--- a/libstore/nbd.c
+++ b/libstore/nbd.c
@@ -29,6 +29,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/mman.h>
+#include <assert-backtrace.h>
 
 
 // Avoid dragging in the resolver when linking statically.
@@ -519,7 +520,10 @@ store_nbd_open (const char *name, int flags, struct store 
**store)
          if (!strncmp (name, url_prefix, sizeof url_prefix - 1))
            err = store_set_name (*store, name);
          else
-           asprintf (&(*store)->name, "%s%s", url_prefix, name);
+           {
+             int err2 = asprintf (&(*store)->name, "%s%s", url_prefix, name);
+             assert_backtrace (err2 != -1);
+           }
          if (err)
            store_free (*store);
        }
diff --git a/libstore/unknown.c b/libstore/unknown.c
index 8b7f4268..0b06cbf7 100644
--- a/libstore/unknown.c
+++ b/libstore/unknown.c
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
+#include <assert-backtrace.h>
 
 /* You can't do anything with an unknown store but encode it.  */
 
@@ -127,12 +128,14 @@ store_unknown_decode (struct store_enc *enc,
   /* Derive a name for this unknown store from its encoded type field
      (or lack thereof) and the leading string of its encoded data bytes.  */
   if (enc->cur_int == enc->num_ints)
-    asprintf (&(*store)->name, "notype:%.*s",
+    err = asprintf (&(*store)->name, "notype:%.*s",
              (int) (us->data_len - us->cur_data), us->data + us->cur_data);
   else
-    asprintf (&(*store)->name, "type-%d:%.*s", enc->ints[enc->cur_int],
+    err = asprintf (&(*store)->name, "type-%d:%.*s", enc->ints[enc->cur_int],
             (int) ( us->data_len - us->cur_data), us->data + us->cur_data);
 
+  assert_backtrace (err != -1);
+
   return 0;
 }
 
-- 
2.51.0