commit f5e7e95921847bd83186bfe621fc2b48c4de5477
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Oct 30 13:11:47 2018 +0100

    stdlib/test-bz22786: Avoid spurious test failures using alias mappings
    
    On systems without enough random-access memory, stdlib/test-bz22786
    will go deeply into swap and time out, even with a substantial
    TIMEOUTFACTOR.  This commit adds a facility to construct repeating
    strings with alias mappings, so that the requirement for physical
    memory, and uses it in stdlib/test-bz22786.

Adjusted here for the support/ backport in glibc-rh1418978-1.patch.

diff --git a/stdlib/test-bz22786.c b/stdlib/test-bz22786.c
index 777bf9180f4b5022..bb1e04f2debe9042 100644
--- a/stdlib/test-bz22786.c
+++ b/stdlib/test-bz22786.c
@@ -26,6 +26,7 @@
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <support/blob_repeat.h>
 #include <support/check.h>
 #include <support/support.h>
 #include <support/temp_file.h>
@@ -39,17 +40,12 @@ do_test (void)
   const char *lnk = xasprintf ("%s/symlink", dir);
   const size_t path_len = (size_t) INT_MAX + strlen (lnk) + 1;
 
-  DIAG_PUSH_NEEDS_COMMENT;
-#if __GNUC_PREREQ (7, 0)
-  /* GCC 7 warns about too-large allocations; here we need such
-     allocation to succeed for the test to work.  */
-  DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
-#endif
-  char *path = malloc (path_len);
-  DIAG_POP_NEEDS_COMMENT;
+  struct support_blob_repeat repeat
+    = support_blob_repeat_allocate ("a", 1, path_len);
+  char *path = repeat.start;
   if (path == NULL)
     {
-      printf ("malloc (%zu): %m\n", path_len);
+      printf ("Repeated allocation (%zu bytes): %m\n", path_len);
       /* On 31-bit s390 the malloc will always fail as we do not have
 	 so much memory, and we want to mark the test unsupported.
 	 Likewise on systems with little physical memory the test will
@@ -62,7 +58,6 @@ do_test (void)
   /* Construct very long path = "/tmp/bz22786.XXXX/symlink/aaaa....."  */
   char *p = mempcpy (path, lnk, strlen (lnk));
   *(p++) = '/';
-  memset (p, 'a', path_len - (p - path) - 2);
   p[path_len - (p - path) - 1] = '\0';
 
   /* This call crashes before the fix for bz22786 on 32-bit platforms.  */
@@ -76,6 +71,7 @@ do_test (void)
 
   /* Cleanup.  */
   unlink (lnk);
+  support_blob_repeat_free (&repeat);
 
   return 0;
 }