Fix bug #17622 with crashes in mmap routines.

 src/buffer.c (init_buffer): Accept an argument 'initialized'.
 [USE_MMAP_FOR_BUFFERS]: If 'initialized' is non-zero, reset
 mmap_regions and mmap_fd, to avoid referencing stale data from the
 dump phase.  Add an assertion for buffer text of buffers created
 in temacs before this function is called.
 (mmap_regions_1, mmap_fd_1): Remove unused variables.
 src/lisp.h (init_buffer): Update prototype.
 src/emacs.c (main): Pass 'initialized' as the argument to init_buffer.

4 files changed, 60 insertions, 18 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 7665ccb7083..33b8257cc1c 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2014-05-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * buffer.c (init_buffer): Accept an argument 'initialized'.
+        [USE_MMAP_FOR_BUFFERS]: If 'initialized' is non-zero, reset
+        mmap_regions and mmap_fd, to avoid referencing stale data from the
+        dump phase.  Add an assertion for buffer text of buffers created
+        in temacs before this function is called.  (Bug#17622)
+        (mmap_regions_1, mmap_fd_1): Remove unused variables.
+
+        * lisp.h (init_buffer): Update prototype.
+
+        * emacs.c (main): Pass 'initialized' as the argument to init_buffer.
+
 2014-05-29  Dmitry Antipov  <dmantipov@yandex.ru>
 
         * alloc.c (Fgarbage_collect): Fix compilation with
diff --git a/src/buffer.c b/src/buffer.c
index 3cbb8153bc9..909b3779b06 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4703,11 +4703,6 @@ static struct mmap_region *mmap_regions;
 
 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;
@@ -5272,24 +5267,57 @@ init_buffer_once (void)
 }
 
 void
-init_buffer (void)
+init_buffer (int initialized)
 {
   char *pwd;
   Lisp_Object temp;
   ptrdiff_t len;
 
 #ifdef USE_MMAP_FOR_BUFFERS
-  {
-    struct buffer *b;
+  if (initialized)
+    {
+      struct buffer *b;
 
-    /* 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)
-      {
-        b->text->beg = NULL;
-        enlarge_buffer_text (b, 0);
-      }
-  }
+#ifndef WINDOWSNT
+      /* These must be reset in the dumped Emacs, to avoid stale
+         references to mmap'ed memory from before the dump.
+
+         WINDOWSNT doesn't need this because it doesn't track mmap'ed
+         regions by hand (see w32heap.c, which uses system APIs for
+         that purpose), and thus doesn't use mmap_regions.  */
+      mmap_regions = NULL;
+      mmap_fd = -1;
+#endif
+
+      /* The dumped buffers reference addresses of buffer text
+         recorded by temacs, that cannot be used by the dumped Emacs.
+         We map new memory for their text here.
+
+         Implementation note: the buffers we carry from temacs are:
+         " prin1", "*scratch*", " *Minibuf-0*", "*Messages*", and
+         " *code-conversion-work*".  They are created by
+         init_buffer_once and init_window_once (which are not called
+         in the dumped Emacs), and by the first call to coding.c routines.  */
+      FOR_EACH_BUFFER (b)
+        {
+          b->text->beg = NULL;
+          enlarge_buffer_text (b, 0);
+        }
+    }
+  else
+    {
+      struct buffer *b;
+
+      /* Only buffers with allocated buffer text should be present at
+         this point in temacs.  */
+      FOR_EACH_BUFFER (b)
+        {
+          eassert (b->text->beg != NULL);
+        }
+    }
+#else  /* not USE_MMAP_FOR_BUFFERS */
+  /* Avoid compiler warnings.  */
+  initialized = initialized;
 #endif /* USE_MMAP_FOR_BUFFERS */
 
   Fset_buffer (Fget_buffer_create (build_string ("*scratch*")));
diff --git a/src/emacs.c b/src/emacs.c
index fabea11a3bf..57f713125ee 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1376,7 +1376,8 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
   xputenv ("LANG=C");
 #endif
 
-  init_buffer ();       /* Init default directory of main buffer.  */
+  /* Init buffer storage and default directory of main buffer.  */
+  init_buffer (initialized);
 
   init_callproc_1 ();   /* Must precede init_cmdargs and init_sys_modes.  */
 
diff --git a/src/lisp.h b/src/lisp.h
index 62fca16ec38..bbe2e4e9ce2 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3951,7 +3951,7 @@ extern bool overlay_touches_p (ptrdiff_t);
 extern Lisp_Object other_buffer_safely (Lisp_Object);
 extern Lisp_Object get_truename_buffer (Lisp_Object);
 extern void init_buffer_once (void);
-extern void init_buffer (void);
+extern void init_buffer (int);
 extern void syms_of_buffer (void);
 extern void keys_of_buffer (void);