[PATCH] Do not allow .global on section symbols

[Nick Clifton <nickc at cambridge dot redhat dot com>]

Hi Guys,

  A customer recently discovered that GAS did not stop you using
  .globl on a section symbol.  Unfortunately it did corrupt the symbol
  table that was produced (moving sections symbols into the local
  symbol area), which then resulted in seg faults inside the linker.
  To see this, assemble and link the following x86 test program:

          .section ddd,"a"
          .align 1
          .global  ddd 
      
      ddd_data:
          .space              0x0064
      
          .section ccc, "ax"
          .align 2
      
      ccc_code:
           mov %eax,ddd_data

  The patch below fixes this by preventing .globl from changing a
  section symbol's status and instead making it issue a warning
  message.

  I was not sure however, how to add this code as a test case.  I did
  not want to add it to the assembler's testsuite, since it needs the
  linker in order to demonstrate the fault, and I did not want to add
  it to the linker's testsuite since it contains ELF and x86 specific
  code.  Any suggestions for how to incorporate it as a test as most
  welcome.

Cheers
        Nick

2001-06-05  Nick Clifton  <nickc@cambridge.redhat.com>

	* symbols.c (S_SET_EXTERNAL): Do not override a section symbol's
	status.

Index: gas/symbols.c
===================================================================
RCS file: /cvs/src/src/gas/symbols.c,v
retrieving revision 1.24
diff -p -r1.24 symbols.c
*** symbols.c	2001/05/25 10:07:43	1.24
--- symbols.c	2001/06/05 08:22:06
*************** S_SET_EXTERNAL (s)
*** 1824,1829 ****
--- 1824,1840 ----
        /* Let .weak override .global.  */
        return;
      }
+   if (s->bsym->flags & BSF_SECTION_SYM)
+     {
+       char * file;
+       unsigned int line;
+       
+       /* Do not reassign section symbols.  */
+       as_where (& file, & line);
+       as_warn_where (file, line,
+ 		     _("Section symbols are already global"));
+       return;
+     }
    s->bsym->flags |= BSF_GLOBAL;
    s->bsym->flags &= ~(BSF_LOCAL | BSF_WEAK);
  }