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bug#17622: 24.4.50; bootstrap failure


From: Fabrice Popineau
Subject: bug#17622: 24.4.50; bootstrap failure
Date: Thu, 29 May 2014 15:54:23 +0200

This should fix the problem:

--- ../trunk/src/buffer.c       2014-05-29 15:51:11.632003900 +0200
+++ src/buffer.c        2014-05-29 15:50:54.192190300 +0200
@@ -4703,11 +4703,6 @@

 static int mmap_fd;

-/* Temporary storage for mmap_set_vars, see there.  */
-
-static struct mmap_region *mmap_regions_1;
-static int mmap_fd_1;
-
 /* Page size on this system.  */

 static int mmap_page_size;
@@ -5282,6 +5277,9 @@
   {
     struct buffer *b;

+    mmap_regions = NULL;
+    mmap_fd = -1;
+
     /* We cannot dump buffers with meaningful addresses that can be
        used by the dumped Emacs.  We map new memory for them here.  */
     FOR_EACH_BUFFER (b)

by initializing explicitly variables that need it. We can also remove unsused variables.
Waiting for confirmation (or failure!).

Fabrice


2014-05-29 14:55 GMT+02:00 Fabrice Popineau <address@hidden>:
Probably ok because I ran like this for a while, 
but I wonder if it couldn't be handled at the beginning of bufffer.c:init_buffer() instead.
What I suggest is do what mmap_set_vars(0) does 
inside init_buffer() rather than reinstate mmap_set_vars().
Not a great advantage, except to clarify that these pointers should be initialized
when starting the dumped emacs instead of relying on what is dumped.

Fabrice






2014-05-29 14:38 GMT+02:00 Ken Brown <address@hidden>:

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



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