[RFC PATCH glibc 6/8] support record failure: allow use from constructor

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

Expose support_record_failure_init () so constructors can explicitly
initialize the record failure API.

This is preferred to lazy initialization at first use, because
lazy initialization does not cover use in constructors within
forked children processes (forked from parent constructor).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
CC: Carlos O'Donell <carlos@redhat.com>
CC: Florian Weimer <fweimer@redhat.com>
CC: Joseph Myers <joseph@codesourcery.com>
CC: Szabolcs Nagy <szabolcs.nagy@arm.com>
CC: libc-alpha@sourceware.org
---
 support/check.h                  |  4 ++++
 support/support_record_failure.c | 18 +++++++++++++-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/support/check.h b/support/check.h
index 77d1d1e14d..902cea6878 100644
--- a/support/check.h
+++ b/support/check.h
@@ -88,6 +88,10 @@ void support_test_verify_exit_impl (int status, const char *file, int line,
    does not support reporting failures from a DSO.  */
 void support_record_failure (void);
 
+/* Initialize record failure.  Calling this is only needed when
+   recording failures from constructors.  */
+void support_record_failure_init (void);
+
 /* Static assertion, under a common name for both C++ and C11.  */
 #ifdef __cplusplus
 # define support_static_assert static_assert
diff --git a/support/support_record_failure.c b/support/support_record_failure.c
index f766c06236..957572f487 100644
--- a/support/support_record_failure.c
+++ b/support/support_record_failure.c
@@ -32,8 +32,12 @@
    zero, the failure of a test can be detected.
 
    The init constructor function below puts *state on a shared
-   annonymous mapping, so that failure reports from subprocesses
-   propagate to the parent process.  */
+   anonymous mapping, so that failure reports from subprocesses
+   propagate to the parent process.
+
+   support_record_failure_init is exposed so it can be called explicitly
+   in case this API needs to be used from a constructor.  */
+
 struct test_failures
 {
   unsigned int counter;
@@ -41,10 +45,14 @@ struct test_failures
 };
 static struct test_failures *state;
 
-static __attribute__ ((constructor)) void
-init (void)
+__attribute__ ((constructor)) void
+support_record_failure_init (void)
 {
-  void *ptr = mmap (NULL, sizeof (*state), PROT_READ | PROT_WRITE,
+  void *ptr;
+
+  if (state != NULL)
+    return;
+  ptr = mmap (NULL, sizeof (*state), PROT_READ | PROT_WRITE,
                     MAP_ANONYMOUS | MAP_SHARED, -1, 0);
   if (ptr == MAP_FAILED)
     {
-- 
2.17.1