support: Add <support/next_to_fault.h>

Based on the implementation in resolv/tst-inet_pton.c.

5 files changed, 120 insertions, 56 deletions

diff --git a/ChangeLog b/ChangeLog
index 7482e6d348..ffeb208132 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2017-11-13  Florian Weimer  <fweimer@redhat.com>
+
+	* support/next_to_fault.h, support/next_to_fault.c: New files.
+	* support/Makefile (libsupport-routines): Add next_to_fault.
+	* resolv/tst-inet_pton.c (struct next_to_fault)
+	(next_to_fault_allocate, next_to_fault_free): Remove.
+	(run_one_test): Switch to <support/next_to_fault.h> interfaces.
+
 2017-11-13  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* elf/dl-support.c: Include <dl-procruntime.c>.
diff --git a/resolv/tst-inet_pton.c b/resolv/tst-inet_pton.c
index 4bb9f81193..5a06a802b3 100644
--- a/resolv/tst-inet_pton.c
+++ b/resolv/tst-inet_pton.c
@@ -22,57 +22,10 @@
 #include <stdio.h>
 #include <string.h>
 #include <support/check.h>
+#include <support/next_to_fault.h>
 #include <support/xunistd.h>
-#include <sys/mman.h>
-#include <sys/param.h>
 #include <unistd.h>
 
-/* Memory region created by next_to_fault_allocate.  */
-struct next_to_fault
-{
-  /* The user data.  */
-  char *buffer;
-  size_t length;
-
-  /* The entire allocated region.  */
-  void *region_start;
-  size_t region_size;
-};
-
-/* Allocate a buffer of SIZE bytes just before a page which is mapped
-   with PROT_NONE (so that overrunning the buffer will cause a
-   fault).  */
-static struct next_to_fault
-next_to_fault_allocate (size_t size)
-{
-  long page_size = sysconf (_SC_PAGE_SIZE);
-  TEST_VERIFY_EXIT (page_size > 0);
-  struct next_to_fault result;
-  result.region_size = roundup (size, page_size) + page_size;
-  TEST_VERIFY_EXIT (size + page_size > size);
-  TEST_VERIFY_EXIT (result.region_size > size);
-  result.region_start
-    = xmmap (NULL, result.region_size, PROT_READ | PROT_WRITE,
-             MAP_PRIVATE | MAP_ANONYMOUS, -1);
-  /* Unmap the page after the allocation.  */
-  xmprotect (result.region_start + (result.region_size - page_size),
-             page_size, PROT_NONE);
-  /* Align the allocation within the region so that it ends just
-     before the PROT_NONE page.  */
-  result.buffer = result.region_start + result.region_size - page_size - size;
-  result.length = size;
-  return result;
-}
-
-/* Deallocate the memory region allocated by
-   next_to_fault_allocate.  */
-static void
-next_to_fault_free (struct next_to_fault *ntf)
-{
-  xmunmap (ntf->region_start, ntf->region_size);
-  *ntf = (struct next_to_fault) { NULL, };
-}
-
 struct test_case
 {
   /* The input data.  */
@@ -139,12 +92,13 @@ run_one_test (const struct test_case *t)
 {
   size_t test_len = strlen (t->input);
 
-  struct next_to_fault ntf_out4 = next_to_fault_allocate (4);
-  struct next_to_fault ntf_out6 = next_to_fault_allocate (16);
+  struct support_next_to_fault ntf_out4 = support_next_to_fault_allocate (4);
+  struct support_next_to_fault ntf_out6 = support_next_to_fault_allocate (16);
 
   /* inet_pton requires NUL termination.  */
   {
-    struct next_to_fault ntf_in = next_to_fault_allocate (test_len + 1);
+    struct support_next_to_fault ntf_in
+      = support_next_to_fault_allocate (test_len + 1);
     memcpy (ntf_in.buffer, t->input, test_len + 1);
     memset (ntf_out4.buffer, 0, 4);
     check_result ("inet_pton", t, AF_INET, ntf_out4.buffer,
@@ -152,12 +106,13 @@ run_one_test (const struct test_case *t)
     memset (ntf_out6.buffer, 0, 16);
     check_result ("inet_pton", t, AF_INET6, ntf_out6.buffer,
                   inet_pton (AF_INET6, ntf_in.buffer, ntf_out6.buffer));
-    next_to_fault_free (&ntf_in);
+    support_next_to_fault_free (&ntf_in);
   }
 
   /* __inet_pton_length does not require NUL termination.  */
   {
-    struct next_to_fault ntf_in = next_to_fault_allocate (test_len);
+    struct support_next_to_fault ntf_in
+      = support_next_to_fault_allocate (test_len);
     memcpy (ntf_in.buffer, t->input, test_len);
     memset (ntf_out4.buffer, 0, 4);
     check_result ("__inet_pton_length", t, AF_INET, ntf_out4.buffer,
@@ -167,11 +122,11 @@ run_one_test (const struct test_case *t)
     check_result ("__inet_pton_length", t, AF_INET6, ntf_out6.buffer,
                   __inet_pton_length (AF_INET6, ntf_in.buffer, ntf_in.length,
                                       ntf_out6.buffer));
-    next_to_fault_free (&ntf_in);
+    support_next_to_fault_free (&ntf_in);
   }
 
-  next_to_fault_free (&ntf_out4);
-  next_to_fault_free (&ntf_out6);
+  support_next_to_fault_free (&ntf_out4);
+  support_next_to_fault_free (&ntf_out6);
 }
 
 /* The test cases were manually crafted and the set enhanced with
diff --git a/support/Makefile b/support/Makefile
index dafb1737a4..f7a878b950 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -32,6 +32,7 @@ libsupport-routines = \
   check_netent \
   delayed_exit \
   ignore_stderr \
+  next_to_fault \
   oom_error \
   resolv_test \
   set_fortify_handler \
diff --git a/support/next_to_fault.c b/support/next_to_fault.c
new file mode 100644
index 0000000000..7c6b077898
--- /dev/null
+++ b/support/next_to_fault.c
@@ -0,0 +1,52 @@
+/* Memory allocation next to an unmapped page.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/next_to_fault.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+
+struct support_next_to_fault
+support_next_to_fault_allocate (size_t size)
+{
+  long page_size = sysconf (_SC_PAGE_SIZE);
+  TEST_VERIFY_EXIT (page_size > 0);
+  struct support_next_to_fault result;
+  result.region_size = roundup (size, page_size) + page_size;
+  if (size + page_size <= size || result.region_size <= size)
+    FAIL_EXIT1 ("support_next_to_fault_allocate (%zu): overflow", size);
+  result.region_start
+    = xmmap (NULL, result.region_size, PROT_READ | PROT_WRITE,
+             MAP_PRIVATE | MAP_ANONYMOUS, -1);
+  /* Unmap the page after the allocation.  */
+  xmprotect (result.region_start + (result.region_size - page_size),
+             page_size, PROT_NONE);
+  /* Align the allocation within the region so that it ends just
+     before the PROT_NONE page.  */
+  result.buffer = result.region_start + result.region_size - page_size - size;
+  result.length = size;
+  return result;
+}
+
+void
+support_next_to_fault_free (struct support_next_to_fault *ntf)
+{
+  xmunmap (ntf->region_start, ntf->region_size);
+  *ntf = (struct support_next_to_fault) { NULL, };
+}
diff --git a/support/next_to_fault.h b/support/next_to_fault.h
new file mode 100644
index 0000000000..dd71c28ac0
--- /dev/null
+++ b/support/next_to_fault.h
@@ -0,0 +1,48 @@
+/* Memory allocation next to an unmapped page.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_NEXT_TO_FAULT_H
+#define SUPPORT_NEXT_TO_FAULT_H
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+__BEGIN_DECLS
+
+/* The memory region created by next_to_fault_allocate.  */
+struct support_next_to_fault
+{
+  /* The user data.  */
+  char *buffer;
+  size_t length;
+
+  /* The entire allocated region.  */
+  void *region_start;
+  size_t region_size;
+};
+
+/* Allocate a buffer of SIZE bytes just before a page which is mapped
+   with PROT_NONE (so that overrunning the buffer will cause a
+   fault).  */
+struct support_next_to_fault support_next_to_fault_allocate (size_t size);
+
+/* Deallocate the memory region allocated by
+   next_to_fault_allocate.  */
+void support_next_to_fault_free (struct support_next_to_fault *);
+
+#endif /* SUPPORT_NEXT_TO_FAULT_H */