--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2011-01-26  Bruno Haible  <bruno@clisp.org>
+
+	New module 'get-rusage-data'.
+	* lib/resource-ext.h (get_rusage_data): New declaration.
+	* lib/get-rusage-data.c: New file.
+	* modules/get-rusage-data: New file.
+
 2011-01-25  Bruno Haible  <bruno@clisp.org>
 
 	get-rusage-as: Allow for easier testing.

new file mode 100644
--- /dev/null
+++ b/lib/get-rusage-data.c
@@ -0,0 +1,434 @@
+/* Getter for RLIMIT_DATA.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2011.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "resource-ext.h"
+
+/* The "data segment size" is defined as the virtual memory area of the
+   current process that contains malloc()ed memory.
+
+   There are two ways of retrieving the current data segment size:
+     a) by trying setrlimit with various values and observing whether the
+        kernel allows additional sbrk() calls,
+     b) by using system dependent APIs that allow to iterate over the list
+        of virtual memory areas.
+   We define two functions
+     get_rusage_data_via_setrlimit(),
+     get_rusage_data_via_iterator().
+
+   The variant
+     a') by trying setrlimit with various values and observing whether
+        additional malloc() calls succeed
+   is not as good as a), because a malloc() call can be served by already
+   allocated memory or through mmap(), and because a malloc() of 1 page may
+   require 2 pages.
+
+   Discussion per platform:
+
+   Linux:
+     a) setrlimit with RLIMIT_DATA works.
+     b) The /proc/self/maps file contains a list of the virtual memory areas.
+     get_rusage_data_via_setrlimit() returns the sum of the length of the
+     executable's data segment plus the heap VMA (an anonymous memory area),
+     whereas get_rusage_data_via_iterator() returns only the latter.
+     Note that malloc() falls back on mmap() for large allocations and also
+     for small allocations if there is not enough room in the data segment.
+
+   MacOS X:
+     a) setrlimit with RLIMIT_DATA succeeds but does not really work: The OS
+        ignores RLIMIT_DATA. Therefore get_rusage_data_via_setrlimit() is
+        always 0.
+     b) The Mach based API works.
+     Note that malloc() falls back on mmap() for large allocations.
+
+   FreeBSD:
+     a) setrlimit with RLIMIT_DATA works.
+     b) The /proc/self/maps file contains a list of the virtual memory areas.
+
+   NetBSD:
+     a) setrlimit with RLIMIT_DATA works.
+     b) The /proc/self/maps file contains a list of the virtual memory areas.
+     Both methods agree.
+     Note that malloc() uses mmap() for large allocations.
+
+   OpenBSD:
+     a) setrlimit with RLIMIT_DATA works.
+     b) No VMA iteration API exists.
+     Note that malloc() appears to use mmap() for both large and small
+     allocations.
+
+   AIX:
+     a) setrlimit with RLIMIT_DATA works.
+     b) No VMA iteration API exists.
+
+   HP-UX:
+     a) setrlimit with RLIMIT_DATA works, except on HP-UX 11.00, where it
+        cannot restore the previous limits, and except on HP-UX 11.11, where
+        it sometimes has no effect.
+     b) No VMA iteration API exists.
+
+   IRIX:
+     a) setrlimit with RLIMIT_DATA works.
+     b) The /proc/$pid file supports ioctls PIOCNMAP and PIOCMAP.
+     get_rusage_data_via_setrlimit() works slightly better than
+     get_rusage_data_via_iterator() before the first malloc() call.
+
+   OSF/1:
+     a) setrlimit with RLIMIT_DATA works.
+     b) The /proc/$pid file supports ioctls PIOCNMAP and PIOCMAP.
+     Both methods agree.
+
+   Solaris:
+     a) setrlimit with RLIMIT_DATA works.
+     b) No VMA iteration API exists.
+
+   Cygwin:
+     a) setrlimit with RLIMIT_DATA always fails.
+        get_rusage_data_via_setrlimit() therefore produces a wrong value.
+     b) The /proc/$pid/maps file lists only the memory areas belonging to
+        the executable and shared libraries, not the anonymous memory.
+        But the native Win32 API works.
+     Note that malloc() apparently falls back on mmap() for large allocations.
+
+   mingw:
+     a) There is no setrlimit function.
+     b) There is no sbrk() function.
+     Note that malloc() falls back on VirtualAlloc() for large allocations.
+
+   BeOS, Haiku:
+     a) On BeOS, there is no setrlimit function.
+        On Haiku, setrlimit exists. RLIMIT_DATA is defined but unsupported:
+        getrlimit of RLIMIT_DATA always fails with errno = EINVAL.
+     b) There is a specific BeOS API: get_next_area_info().
+ */
+
+
+#include <errno.h> /* errno */
+#include <stdlib.h> /* size_t, abort, malloc, free, sbrk */
+#include <fcntl.h> /* open, O_RDONLY */
+#include <unistd.h> /* getpagesize, read, close */
+
+
+/* System support for get_rusage_data_via_setrlimit().  */
+
+#if HAVE_SETRLIMIT
+# include <sys/time.h>
+# include <sys/resource.h> /* getrlimit, setrlimit */
+# include <sys/utsname.h>
+# include <string.h> /* strlen, strcmp */
+#endif
+
+
+/* System support for get_rusage_data_via_iterator().  */
+
+#include "vma-iter.h"
+
+
+#if HAVE_SETRLIMIT && defined RLIMIT_DATA
+
+# ifdef _AIX
+#  define errno_expected() (errno == EINVAL || errno == EFAULT)
+# else
+#  define errno_expected() (errno == EINVAL)
+# endif
+
+static inline uintptr_t
+get_rusage_data_via_setrlimit (void)
+{
+  uintptr_t result;
+
+  struct rlimit orig_limit;
+
+# ifdef __hpux
+  /* On HP-UX 11.00, setrlimit() RLIMIT_DATA of does not work: It cannot
+     restore the previous limits.
+     On HP-UX 11.11, setrlimit() RLIMIT_DATA of does not work: It sometimes
+     has no effect on the next sbrk() call.  */
+  {
+    struct utsname buf;
+
+    if (uname (&buf) == 0
+        && strlen (buf.release) >= 5
+        && (strcmp (buf.release + strlen (buf.release) - 5, "11.00") == 0
+            || strcmp (buf.release + strlen (buf.release) - 5, "11.11") == 0))
+      return 0;
+  }
+# endif
+
+  /* Record the original limit.  */
+  if (getrlimit (RLIMIT_DATA, &orig_limit) < 0)
+    return 0;
+
+  if (orig_limit.rlim_max != RLIM_INFINITY
+      && (orig_limit.rlim_cur == RLIM_INFINITY
+          || orig_limit.rlim_cur > orig_limit.rlim_max))
+    /* We may not be able to restore the current rlim_cur value.
+       So bail out.  */
+    return 0;
+
+  {
+    /* The granularity is a single page.  */
+    const intptr_t pagesize = getpagesize ();
+
+    uintptr_t low_bound = 0;
+    uintptr_t high_bound;
+
+    for (;;)
+      {
+        /* Here we know that the data segment size is >= low_bound.  */
+        struct rlimit try_limit;
+        uintptr_t try_next = 2 * low_bound + pagesize;
+
+        if (try_next < low_bound)
+          /* Overflow.  */
+          try_next = ((uintptr_t) (~ 0) / pagesize) * pagesize;
+
+        /* There's no point in trying a value > orig_limit.rlim_max, as
+           setrlimit would fail anyway.  */
+        if (orig_limit.rlim_max != RLIM_INFINITY
+            && orig_limit.rlim_max < try_next)
+          try_next = orig_limit.rlim_max;
+
+        /* Avoid endless loop.  */
+        if (try_next == low_bound)
+          {
+            /* try_next could not be increased.  */
+            result = low_bound;
+            goto done;
+          }
+
+        try_limit.rlim_max = orig_limit.rlim_max;
+        try_limit.rlim_cur = try_next;
+        if (setrlimit (RLIMIT_DATA, &try_limit) == 0)
+          {
+            /* Allocate a page of memory, to compare the current data segment
+               size with try_limit.rlim_cur.  */
+            void *new_page = sbrk (pagesize);
+
+            if (new_page != (void *)(-1))
+              {
+                /* The page could be added successfully.  Free it.  */
+                sbrk (- pagesize);
+                /* We know that the data segment size is
+                   < try_limit.rlim_cur.  */
+                high_bound = try_next;
+                break;
+              }
+            else
+              {
+                /* We know that the data segment size is
+                   >= try_limit.rlim_cur.  */
+                low_bound = try_next;
+              }
+          }
+        else
+          {
+            /* Here we expect only EINVAL or (on AIX) EFAULT, not EPERM.  */
+            if (! errno_expected ())
+              abort ();
+            /* We know that the data segment size is
+               >= try_limit.rlim_cur.  */
+            low_bound = try_next;
+          }
+      }
+
+    /* Here we know that the data segment size is
+       >= low_bound and < high_bound.  */
+    while (high_bound - low_bound > pagesize)
+      {
+        struct rlimit try_limit;
+        uintptr_t try_next =
+          low_bound + (((high_bound - low_bound) / 2) / pagesize) * pagesize;
+
+        /* Here low_bound <= try_next < high_bound.  */
+        try_limit.rlim_max = orig_limit.rlim_max;
+        try_limit.rlim_cur = try_next;
+        if (setrlimit (RLIMIT_DATA, &try_limit) == 0)
+          {
+            /* Allocate a page of memory, to compare the current data segment
+               size with try_limit.rlim_cur.  */
+            void *new_page = sbrk (pagesize);
+
+            if (new_page != (void *)(-1))
+              {
+                /* The page could be added successfully.  Free it.  */
+                sbrk (- pagesize);
+                /* We know that the data segment size is
+                   < try_limit.rlim_cur.  */
+                high_bound = try_next;
+              }
+            else
+              {
+                /* We know that the data segment size is
+                   >= try_limit.rlim_cur.  */
+                low_bound = try_next;
+              }
+          }
+        else
+          {
+            /* Here we expect only EINVAL or (on AIX) EFAULT, not EPERM.  */
+            if (! errno_expected ())
+              abort ();
+            /* We know that the data segment size is
+               >= try_limit.rlim_cur.  */
+            low_bound = try_next;
+          }
+      }
+
+    result = low_bound;
+  }
+
+ done:
+  /* Restore the original rlim_cur value.  */
+  if (setrlimit (RLIMIT_DATA, &orig_limit) < 0)
+    abort ();
+
+  return result;
+}
+
+#else
+
+static inline uintptr_t
+get_rusage_data_via_setrlimit (void)
+{
+  return 0;
+}
+
+#endif
+
+
+#if VMA_ITERATE_SUPPORTED
+
+struct locals
+{
+  uintptr_t brk_value;
+  uintptr_t data_segment_size;
+};
+
+static int
+vma_iterate_callback (void *data, uintptr_t start, uintptr_t end,
+                      unsigned int flags)
+{
+  struct locals *lp = (struct locals *) data;
+
+  if (start <= lp->brk_value && lp->brk_value - 1 <= end - 1)
+    {
+      lp->data_segment_size = end - start;
+      return 1;
+    }
+  return 0;
+}
+
+static inline uintptr_t
+get_rusage_data_via_iterator (void)
+{
+# if ((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__) || defined __BEOS__ || defined __HAIKU__
+  /* On mingw, there is no sbrk() function.
+     On Haiku, sbrk(0) always returns 0.  */
+  static void *brk_value;
+
+  if (brk_value == NULL)
+    {
+      brk_value = malloc (1);
+      if (brk_value == NULL)
+        return 0;
+    }
+# else
+  void *brk_value;
+
+  brk_value = sbrk (0);
+  if (brk_value == (void *)-1)
+    return 0;
+# endif
+
+  {
+    struct locals l;
+
+    l.brk_value = (uintptr_t) brk_value;
+    l.data_segment_size = 0;
+    vma_iterate (vma_iterate_callback, &l);
+
+    return l.data_segment_size;
+  }
+}
+
+#else
+
+static inline uintptr_t
+get_rusage_data_via_iterator (void)
+{
+  return 0;
+}
+
+#endif
+
+
+uintptr_t
+get_rusage_data (void)
+{
+#if (defined __APPLE__ && defined __MACH__) || defined __CYGWIN__ /* MacOS X, Cygwin */
+  /* get_rusage_data_via_setrlimit() does not work.
+     Prefer get_rusage_data_via_iterator().  */
+  return get_rusage_data_via_iterator ();
+#elif HAVE_SETRLIMIT && defined RLIMIT_DATA
+# if defined __linux__ || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ || defined _AIX || defined __sgi || defined __osf__ || defined __sun /* Linux, FreeBSD, NetBSD, OpenBSD, AIX, IRIX, OSF/1, Solaris */
+  /* get_rusage_data_via_setrlimit() works.  */
+  return get_rusage_data_via_setrlimit ();
+# else
+  /* Prefer get_rusage_data_via_setrlimit() if it succeeds,
+     because the caller may want to use the result with setrlimit().  */
+  uintptr_t result;
+
+  result = get_rusage_data_via_setrlimit ();
+  if (result == 0)
+    result = get_rusage_data_via_iterator ();
+  return result;
+# endif
+#else
+  return get_rusage_data_via_iterator ();
+#endif
+}
+
+
+#ifdef TEST
+
+#include <stdio.h>
+
+int
+main ()
+{
+  printf ("Initially:           0x%08lX 0x%08lX 0x%08lX\n",
+          get_rusage_data_via_setrlimit (), get_rusage_data_via_iterator (),
+          get_rusage_data ());
+  malloc (0x88);
+  printf ("After small malloc:  0x%08lX 0x%08lX 0x%08lX\n",
+          get_rusage_data_via_setrlimit (), get_rusage_data_via_iterator (),
+          get_rusage_data ());
+  malloc (0x8812);
+  printf ("After medium malloc: 0x%08lX 0x%08lX 0x%08lX\n",
+          get_rusage_data_via_setrlimit (), get_rusage_data_via_iterator (),
+          get_rusage_data ());
+  malloc (0x281237);
+  printf ("After large malloc:  0x%08lX 0x%08lX 0x%08lX\n",
+          get_rusage_data_via_setrlimit (), get_rusage_data_via_iterator (),
+          get_rusage_data ());
+  return 0;
+}
+
+#endif /* TEST */

--- a/lib/resource-ext.h
+++ b/lib/resource-ext.h
@@ -31,6 +31,14 @@
    Note: This function always returns zero on OpenBSD and AIX.  */
 extern uintptr_t get_rusage_as (void);
 
+/* Returns the size of the data segment, or zero if unknown.
+   This is the quantity which is limited by setrlimit(RLIMIT_DATA,...).
+   Note: This function always returns zero on HP-UX 11.00.
+   Note: The total size of all malloc()ed memory is bounded by the size of
+   the data segment only on the following platforms:
+   FreeBSD, AIX, HP-UX 11.23 and newer, IRIX, OSF/1, Solaris, BeOS, Haiku.  */
+extern uintptr_t get_rusage_data (void);
+
 
 #ifdef __cplusplus
 }

new file mode 100644
--- /dev/null
+++ b/modules/get-rusage-data
@@ -0,0 +1,31 @@
+Description:
+Getter for RLIMIT_DATA: Returns the data segment size.
+
+Files:
+lib/resource-ext.h
+lib/get-rusage-data.c
+m4/mmap-anon.m4
+
+Depends-on:
+stdint
+unistd
+extensions
+getpagesize
+vma-iter
+
+configure.ac:
+AC_REQUIRE([AC_C_INLINE])
+AC_CHECK_FUNCS_ONCE([setrlimit])
+gl_FUNC_MMAP_ANON
+
+Makefile.am:
+lib_SOURCES += get-rusage-data.c
+
+Include:
+"resource-ext.h"
+
+License:
+GPL
+
+Maintainer:
+Bruno Haible