[Patch mach-o] correct vmsize calculation for zerofill cases.

[Iain Sandoe <developer at sandoe-acoustics dot co dot uk>]

We have to place zerofill sections at the end of segments (in vm terms).
However, they appear in MH_OBJECTS in source-specification order.

When one counts the vmsize (during building the segment command) with  
the zerofills in the file position, it is possible to end up with a  
difference of a few bytes owing to alignment rounding.  This shows up  
pretty rarely, but Darwin 10's ld barfs on it.

So, unfortunately, we need to compute the segment vmsize in three  
loops (two for zerofill sections and zerofill GB sections). ... if  
only the MH_OBJECT specified actually placing the sections at the  
end ...

OK?

Iain

bfd:

	* mach-o.c (bfd_mach_o_build_seg_command): Count zerofill section
	vma additions in their logical, rather than physical order.

Index: bfd/mach-o.c
===================================================================
RCS file: /cvs/src/src/bfd/mach-o.c,v
retrieving revision 1.99
diff -u -p -r1.99 mach-o.c
--- bfd/mach-o.c	2 Feb 2012 11:55:42 -0000	1.99
+++ bfd/mach-o.c	9 Feb 2012 14:54:16 -0000
@@ -2026,7 +2026,12 @@ bfd_mach_o_build_seg_command (const char
   seg->sect_head = NULL;
   seg->sect_tail = NULL;

-  /*  Append sections to the segment.  */
+  /*  Append sections to the segment.
+
+      This is a little tedious, we have to honor the need to account  
zerofill
+      sections after all the rest.  This forces us to do the  
calculation of
+      total vmsize in three passes so that any alignment increments are
+      properly accounted.  */

   for (i = 0; i < mdata->nsects; ++i)
     {
@@ -2039,14 +2044,10 @@ bfd_mach_o_build_seg_command (const char
 	  && strncmp (segment, s->segname, BFD_MACH_O_SEGNAME_SIZE) != 0)
 	continue;

+      /* Although we account for zerofill section sizes in vm order,  
they are
+	 placed in the file in source sequence.  */
       bfd_mach_o_append_section_to_segment (seg, sec);
-
       s->offset = 0;
-      if (s->size > 0)
-       {
-          seg->vmsize = FILE_ALIGN (seg->vmsize, s->align);
-	  seg->vmsize += s->size;
-        }

       /* Zerofill sections have zero file size & offset,
 	 and are not written.  */
@@ -2057,19 +2058,59 @@ bfd_mach_o_build_seg_command (const char

       if (s->size > 0)
        {
+	  seg->vmsize = FILE_ALIGN (seg->vmsize, s->align);
+	  seg->vmsize += s->size;
+
+	  seg->filesize = FILE_ALIGN (seg->filesize, s->align);
+	  seg->filesize += s->size;
+
           mdata->filelen = FILE_ALIGN (mdata->filelen, s->align);
           s->offset = mdata->filelen;
         }

       sec->filepos = s->offset;
-
       mdata->filelen += s->size;
     }

-  seg->filesize = mdata->filelen - seg->fileoff;
-  seg->filesize = FILE_ALIGN(seg->filesize, 2);
+  /* Now pass through again, for zerofill, only now we just update  
the vmsize.  */
+  for (i = 0; i < mdata->nsects; ++i)
+    {
+      bfd_mach_o_section *s = mdata->sections[i];
+
+      if (! is_mho
+	  && strncmp (segment, s->segname, BFD_MACH_O_SEGNAME_SIZE) != 0)
+	continue;
+
+      if ((s->flags & BFD_MACH_O_SECTION_TYPE_MASK) !=  
BFD_MACH_O_S_ZEROFILL)
+        continue;
+
+      if (s->size > 0)
+	{
+	  seg->vmsize = FILE_ALIGN (seg->vmsize, s->align);
+	  seg->vmsize += s->size;
+	}
+    }
+
+  /* Now pass through again, for zerofill_GB.  */
+  for (i = 0; i < mdata->nsects; ++i)
+    {
+      bfd_mach_o_section *s = mdata->sections[i];
+
+      if (! is_mho
+	  && strncmp (segment, s->segname, BFD_MACH_O_SEGNAME_SIZE) != 0)
+	continue;
+
+      if ((s->flags & BFD_MACH_O_SECTION_TYPE_MASK) !=  
BFD_MACH_O_S_GB_ZEROFILL)
+        continue;
+
+      if (s->size > 0)
+	{
+	  seg->vmsize = FILE_ALIGN (seg->vmsize, s->align);
+	  seg->vmsize += s->size;
+	}
+    }

-  /* Allocate relocation room.  */
+  /* Allocate space for the relocations.  */
   mdata->filelen = FILE_ALIGN(mdata->filelen, 2);

   for (i = 0; i < mdata->nsects; ++i)