bfd/mmo.c: handle "objcopy --extract-symbols" generating and reading back.

bfd:
	* mmo.c (struct mmo_data_struct): New members
	symbol_consistency_override_calculated and ignore_symbol_consistency.
	(mmo_section_has_contents, mmo_ignore_symbol_consistency): New
	functions.
	(mmo_create_symbol): Check with mmo_ignore_symbol_consistency if to
	report an error for unexpected value of Main.
	(mmo_write_symbols_and_terminator): Similar.

2 files changed, 51 insertions, 3 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 961a3857f6c..e647a2b8ccd 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,13 @@
+2015-10-22  Hans-Peter Nilsson  <hp@bitrange.com>
+
+	* mmo.c (struct mmo_data_struct): New members
+	symbol_consistency_override_calculated and ignore_symbol_consistency.
+	(mmo_section_has_contents, mmo_ignore_symbol_consistency): New
+	functions.
+	(mmo_create_symbol): Check with mmo_ignore_symbol_consistency if to
+	report an error for unexpected value of Main.
+	(mmo_write_symbols_and_terminator): Similar.
+
 2015-10-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* elf32-i386.c (elf_i386_convert_load): Use call_nop_byte and
diff --git a/bfd/mmo.c b/bfd/mmo.c
index 484a370fd9f..316afe89918 100644
--- a/bfd/mmo.c
+++ b/bfd/mmo.c
@@ -330,6 +330,14 @@ struct mmo_data_struct
 
     /* We also need a buffer to hold the bytes we count reading or writing.  */
     bfd_byte buf[4];
+
+    /* Whether we've calculated symbol consistency requirement yet.  We do this
+       when-needed, which must be at some time after all section
+       contents is known.  */
+    bfd_boolean symbol_consistency_override_calculated;
+
+    /* Whether to consistency-check symbol values, in particular "Main".  */
+    bfd_boolean ignore_symbol_consistency;
   };
 
 typedef struct mmo_data_struct tdata_type;
@@ -586,6 +594,34 @@ mmo_mkobject (bfd *abfd)
 }
 
 static bfd_boolean
+mmo_section_has_contents (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, void *p ATTRIBUTE_UNUSED)
+{
+  /* The point is to match what --extract-symbols does (well, negated).  */
+  return bfd_get_section_size (sec) != 0;
+}
+
+/* Find out whether we should omit symbol consistency checks for this
+   bfd and cache the value.
+
+   This function must only be called when all section contents is
+   known.  However, calculating symbol consistency at the time the
+   private BFD data is initialized is too late for some uses.  */
+
+static bfd_boolean
+mmo_ignore_symbol_consistency (bfd *abfd)
+{
+  if (!abfd->tdata.mmo_data->symbol_consistency_override_calculated)
+    {
+      abfd->tdata.mmo_data->ignore_symbol_consistency =
+	bfd_sections_find_if (abfd, mmo_section_has_contents, NULL) == NULL;
+
+      abfd->tdata.mmo_data->symbol_consistency_override_calculated = TRUE;
+    }
+
+  return abfd->tdata.mmo_data->ignore_symbol_consistency;
+}
+
+static bfd_boolean
 mmo_bfd_copy_private_bfd_data (bfd *ibfd, bfd *obfd)
 {
   if (bfd_get_flavour (ibfd) != bfd_target_mmo_flavour
@@ -1208,7 +1244,8 @@ mmo_create_symbol (bfd *abfd, const char *symname, bfd_vma addr, enum
      object.  For written objects, we do it while setting the symbol
      table.  */
   if (strcmp (symname, MMIX_START_SYMBOL_NAME) == 0
-      && bfd_get_start_address (abfd) != addr)
+      && bfd_get_start_address (abfd) != addr
+      && !mmo_ignore_symbol_consistency (abfd))
     {
       (*_bfd_error_handler)
 	(_("%s: invalid mmo file: initialization value for $255 is not `Main'\n"),
@@ -2900,13 +2937,14 @@ mmo_write_symbols_and_terminator (bfd *abfd)
 	  = (mainsym->value
 	     + mainsym->section->output_section->vma
 	     + mainsym->section->output_offset);
-	  memcpy (table + 1, orig_table, i * sizeof (asymbol *));
+	memcpy (table + 1, orig_table, i * sizeof (asymbol *));
 	table[0] = mainsym;
 
 	/* Check that the value assigned to :Main is the same as the entry
 	   address.  The default linker script asserts this.  This is as
 	   good a place as any to check this consistency. */
-	if (mainvalue != bfd_get_start_address (abfd))
+	if (mainvalue != bfd_get_start_address (abfd)
+	    && !mmo_ignore_symbol_consistency (abfd))
 	  {
 	    /* Arbitrary buffer to hold the printable representation of a
 	       vma.  */