[glibc/fw/glibc-hwcaps] elf: Implement __rtld_malloc_is_full

[glibc/fw/glibc-hwcaps] elf: Implement __rtld_malloc_is_full

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=bd7ec4292a698ad867c64673c2f17049e2fb070b

commit bd7ec4292a698ad867c64673c2f17049e2fb070b
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Jun 18 17:46:57 2020 +0200

    elf: Implement __rtld_malloc_is_full
    
    In some cases, it is difficult to determine the kind of malloc
    based on the execution context, so a function to determine that
    is helpful.

Diff:
---
 elf/dl-minimal.c      | 8 ++++++++
 include/rtld-malloc.h | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/elf/dl-minimal.c b/elf/dl-minimal.c
index 7c64e24c87..dc79f02458 100644
--- a/elf/dl-minimal.c
+++ b/elf/dl-minimal.c
@@ -59,6 +59,14 @@ __rtld_malloc_init_stubs (void)
   __rtld_realloc = &rtld_realloc;
 }
 
+bool
+__rtld_malloc_is_full (void)
+{
+  /* The caller assumes that there is an active malloc.  */
+  assert (__rtld_malloc != NULL);
+  return __rtld_malloc != &rtld_malloc;
+}
+
 /* Lookup NAME at VERSION in the scope of MATCH.  */
 static void *
 lookup_malloc_symbol (struct link_map *main_map, const char *name,
diff --git a/include/rtld-malloc.h b/include/rtld-malloc.h
index b026a3270c..54f53f7888 100644
--- a/include/rtld-malloc.h
+++ b/include/rtld-malloc.h
@@ -66,6 +66,10 @@ realloc (void *ptr, size_t size)
    implementation.  */
 void __rtld_malloc_init_stubs (void) attribute_hidden;
 
+/* Return false if the active malloc is the ld.so minimal malloc, true
+   if it is the full implementation from libc.so.  */
+_Bool __rtld_malloc_is_full (void) attribute_hidden;
+
 /* Called shortly before the final self-relocation (when RELRO
    variables are still writable) to activate the real malloc
    implementation.  MAIN_MAP is the link map of the executable.  */