Subject: Re: 24.1.50; unexec/unexmacosx doesn't grok GCC 4.6+ sections

From: Paul Eggert <[email-masked]>
Date: Wed, 17 Sep 2014 11:39:39 -0700

If I understand that branch correctly, the attached patch should suffice 
to port to GCC 4.6+ on OS X.  It's relative to trunk bzr 117895.  I 
don't have easy access to OS X to try it, though. Peter and/or Samuel, 
does it work for you?

=== modified file 'src/ChangeLog'
--- src/ChangeLog	2014-09-17 18:27:36 +0000
+++ src/ChangeLog	2014-09-17 18:29:28 +0000
@@ -1,3 +1,7 @@
+2014-09-17  Samuel Bronson  <[email-masked]>
+
+	* unexmacosx.c (copy_data_segment): Port to GCC 4.6+ (Bug#9927).
+
 2014-09-17  Paul Eggert  <[email-masked]>
 
 	Fix minor problems found by static checking.

=== modified file 'src/unexmacosx.c'
--- src/unexmacosx.c	2014-09-01 02:37:22 +0000
+++ src/unexmacosx.c	2014-09-17 18:28:19 +0000
@@ -879,6 +879,27 @@
 	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
 	    unexec_error ("cannot write section %.16s's header", sectp->sectname);
 	}
+      else if (strncmp (sectp->sectname, "__bss", 5) == 0
+	       || strncmp (sectp->sectname, "__pu_bss", 8) == 0)
+	{
+	  sectp->flags = S_REGULAR;
+
+	  /* These sections are produced by GCC 4.6+.
+
+	     FIXME: We possibly ought to clear uninitialized local
+	     variables in statically linked libraries like for
+	     SECT_BSS (__bss) above, but setting up the markers we
+	     need in lastfile.c would be rather messy. See
+	     darwin_output_aligned_bss () in gcc/config/darwin.c for
+	     the root of the problem, keeping in mind that the
+	     sections are numbered by their alignment in GCC 4.6, but
+	     by log2(alignment) in GCC 4.7. */
+
+	  if (!unexec_write (sectp->offset, (void *) sectp->addr, sectp->size))
+	    unexec_error ("cannot copy section %.16s", sectp->sectname);
+	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
+	    unexec_error ("cannot write section %.16s's header", sectp->sectname);
+	}
       else if (strncmp (sectp->sectname, "__la_symbol_ptr", 16) == 0
 	       || strncmp (sectp->sectname, "__nl_symbol_ptr", 16) == 0
 	       || strncmp (sectp->sectname, "__got", 16) == 0
@@ -890,6 +911,7 @@
 	       || strncmp (sectp->sectname, "__program_vars", 16) == 0
 	       || strncmp (sectp->sectname, "__mod_init_func", 16) == 0
 	       || strncmp (sectp->sectname, "__mod_term_func", 16) == 0
+	       || strncmp (sectp->sectname, "__static_data", 16) == 0
 	       || strncmp (sectp->sectname, "__objc_", 7) == 0)
 	{
 	  if (!unexec_copy (sectp->offset, old_file_offset, sectp->size))