Subject: Re: bug#17622: 24.4.50; bootstrap failure

From: Ken Brown <[email-masked]>
Date: Thu, 29 May 2014 08:38:24 -0400

On 5/29/2014 12:56 AM, Katsumi Yamaoka wrote:
> I verified simply reverting r117168 builds Emacs successfully on
> Cygwin.

The removal of mmap_set_vars is what caused the problem.  The following 
patch fixes restores mmap_set_vars and fixes the problem.  Eli and 
Fabrice, is the w32 build still OK with this patch?

=== modified file 'src/buffer.c'
--- src/buffer.c        2014-05-27 17:31:17 +0000
+++ src/buffer.c        2014-05-29 12:23:53 +0000
@@ -4855,6 +4855,38 @@
  }

+/* Set or reset variables holding references to mapped regions.
+   If not RESTORE_P, set all variables to null.  If RESTORE_P, set all
+   variables to the start of the user-areas of mapped regions.
+
+   This function is called from Fdump_emacs to ensure that the dumped
+   Emacs doesn't contain references to memory that won't be mapped
+   when Emacs starts.  */
+
+void
+mmap_set_vars (bool restore_p)
+{
+  struct mmap_region *r;
+
+  if (restore_p)
+    {
+      mmap_regions = mmap_regions_1;
+      mmap_fd = mmap_fd_1;
+      for (r = mmap_regions; r; r = r->next)
+       *r->var = MMAP_USER_AREA (r);
+    }
+  else
+    {
+      for (r = mmap_regions; r; r = r->next)
+       *r->var = NULL;
+      mmap_regions_1 = mmap_regions;
+      mmap_regions = NULL;
+      mmap_fd_1 = mmap_fd;
+      mmap_fd = -1;
+    }
+}
+
+
  /* Allocate a block of storage large enough to hold NBYTES bytes of
     data.  A pointer to the data is returned in *VAR.  VAR is thus the
     address of some variable which will use the data area.

=== modified file 'src/emacs.c'
--- src/emacs.c 2014-05-27 17:31:17 +0000
+++ src/emacs.c 2014-05-29 12:28:19 +0000
@@ -2155,8 +2155,13 @@
    malloc_state_ptr = malloc_get_state ();
  #endif

+#if defined USE_MMAP_FOR_BUFFERS && !defined WINDOWSNT
+  mmap_set_vars (0);
+#endif
    unexec (SSDATA (filename), !NILP (symfile) ? SSDATA (symfile) : 0);
-
+#if defined USE_MMAP_FOR_BUFFERS && !defined WINDOWSNT
+  mmap_set_vars (1);
+#endif
  #ifdef DOUG_LEA_MALLOC
    free (malloc_state_ptr);
  #endif

Ken