PATCH: objcopy.c: redefine-sym-specific for archive files

PATCH: objcopy.c: redefine-sym-specific for archive files

[Daniel Marques]

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If an archive file (e.g. libc.a) consists of more than one object file 
(e.g, a.o & b.o) each containing a definition for a symbol named 'foo', 
objcopy --redefine-sym foo=bar libc.a will redefine both symbols.

Example 1:

	[marques@c3linux objectdumps]$ nm libc.a

	a.o:
	00000000 b foo

	b.o:
	00000000 b foo

	[marques@c3linux objectdumps]$ objcopy --redefine-sym foo=bar libc.a

	[marques@c3linux objectdumps]$ nm libc.a

	a.o:
	00000000 b bar

	b.o:
	00000000 b bar


This might not always be the desired behavior.  The attached patch adds 
the --redefine-sym-specific option to object copy.  Its usage is

--redefine-sym-specific <objectfile>:<old>=<new>
               Redefine symbol name <old> to <new>, only for
                 specific <objectfile> component of input archive file


This flag allows the user to specify that the redefinition should only 
affect the symbol in the specified 'component' (object file) of the archive.



Example 2:

	[marques@c3linux objectdumps]$ nm libc.a

	a.o:
	00000000 b foo

	b.o:
	00000000 b foo

	[marques@c3linux objectdumps]$ objcopy --redefine-sym-specific 
a.o:foo=bar libc.a

	[marques@c3linux objectdumps]$ nm libc.a
	
	a.o:
	00000000 b bar

	b.o:
	00000000 b foo


Notice that a specify redefine will always override a general override 
for the same symbol name


Example 3:

	[marques@c3linux objectdumps]$ nm libc.a

	a.o:
	00000000 b foo

	b.o:
	00000000 b foo

	[marques@c3linux objectdumps]$ objcopy --redefine-sym foo=gnu 
--redefine-sym-specific a.o:foo=bar libc.a

	[marques@c3linux objectdumps]$ nm libc.a

	a.o:
	00000000 b bar

	b.o:
	00000000 b gnu


I did not include a version for reading these from a file, as that would 
require either 'generalizing' add_redefine_syms_file() or 'cloning' that 
function, and I though such a decision should be left to the maintainers.


Thanks.

Dan

P.S. Please cc me on reply, as I am not a subscriber to this list.


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Index: objcopy.c
===================================================================
RCS file: /cvs/src/src/binutils/objcopy.c,v
retrieving revision 1.81
diff -u -r1.81 objcopy.c
--- objcopy.c	25 Apr 2005 14:27:00 -0000	1.81
+++ objcopy.c	25 Apr 2005 23:27:41 -0000
@@ -50,6 +50,16 @@
   struct redefine_node *next;
 };
 
+/* A list to support specific_redefine_sym */
+struct specific_redefine_node
+{
+  char *source;
+  char *target;
+  char *ofilename;
+  struct specific_redefine_node *next;
+};
+
+
 typedef struct section_rename
 {
   const char *            old_name;
@@ -199,6 +209,11 @@
 static struct symlist *keepglobal_specific_list = NULL;
 static struct symlist *weaken_specific_list = NULL;
 static struct redefine_node *redefine_sym_list = NULL;
+static struct specific_redefine_node *specific_redefine_sym_list = NULL;
+
+
+
+
 
 /* If this is TRUE, we weaken global symbols (set BSF_WEAK).  */
 static bfd_boolean weaken = FALSE;
@@ -229,6 +244,7 @@
     OPTION_STRIP_UNNEEDED,
     OPTION_WEAKEN,
     OPTION_REDEFINE_SYM,
+    OPTION_REDEFINE_SYM_SPECIFIC,
     OPTION_REDEFINE_SYMS,
     OPTION_SREC_LEN,
     OPTION_SREC_FORCES3,
@@ -337,6 +353,7 @@
   {"pure", no_argument, 0, OPTION_PURE},
   {"readonly-text", no_argument, 0, OPTION_READONLY_TEXT},
   {"redefine-sym", required_argument, 0, OPTION_REDEFINE_SYM},
+  {"redefine-sym-specific", required_argument, 0, OPTION_REDEFINE_SYM_SPECIFIC},
   {"redefine-syms", required_argument, 0, OPTION_REDEFINE_SYMS},
   {"remove-leading-char", no_argument, 0, OPTION_REMOVE_LEADING_CHAR},
   {"remove-section", required_argument, 0, 'R'},
@@ -394,6 +411,8 @@
 static void mark_symbols_used_in_relocations (bfd *, asection *, void *);
 static bfd_boolean write_debugging_info (bfd *, void *, long *, asymbol ***);
 static const char *lookup_sym_redefinition (const char *);
+static const char *lookup_specific_sym_redefinition (const char *, const char *);
+
 \f
 static void
 copy_usage (FILE *stream, int exit_status)
@@ -454,6 +473,9 @@
      --redefine-sym <old>=<new>    Redefine symbol name <old> to <new>\n\
      --redefine-syms <file>        --redefine-sym for all symbol pairs \n\
                                      listed in <file>\n\
+     --redefine-sym-specific <objectfile>:<old>=<new> \n\
+                                   Redefine symbol name <old> to <new>, only for \n\
+                                     specific <objectfile> component of input archive file\n\
      --srec-len <number>           Restrict the length of generated Srecords\n\
      --srec-forceS3                Restrict the type of generated Srecords to S3\n\
      --strip-symbols <file>        -N for all symbols listed in <file>\n\
@@ -824,12 +846,26 @@
 
       undefined = bfd_is_und_section (bfd_get_section (sym));
 
-      if (redefine_sym_list)
+      if ( redefine_sym_list || specific_redefine_sym_list )
 	{
-	  char *old_name, *new_name;
+	  char *old_name, *new_name, *specific_new_name;
 
 	  old_name = (char *) bfd_asymbol_name (sym);
 	  new_name = (char *) lookup_sym_redefinition (old_name);
+
+	  if(specific_redefine_sym_list)
+	    {
+	      specific_new_name = (char *) lookup_specific_sym_redefinition 
+		(old_name, bfd_get_filename(abfd));
+
+	      if (strcmp(specific_new_name, old_name) != 0)
+		{
+		  /* If there was a specific redefine for this .o file, */
+		  /* it will override the more general one.             */
+		  new_name = specific_new_name;
+		}
+	    }
+
 	  bfd_asymbol_name (sym) = new_name;
 	  name = new_name;
 	}
@@ -1009,6 +1045,62 @@
   *p = new_node;
 }
 
+
+
+/* For specific redefinitions, find the redefined name of symbol SOURCE  */
+/* for the specified ofile.                                             */
+
+static const char *
+lookup_specific_sym_redefinition (const char *source, const char *ofilename)
+{
+  struct specific_redefine_node *list;
+
+  for (list = specific_redefine_sym_list; list != NULL; list = list->next)
+    if (strcmp (source, list->source) == 0)
+      if (strcmp (ofilename, list->ofilename) == 0)
+	return list->target;
+
+  return source;
+}
+
+
+
+
+
+/* Add a node to a symbol specific redefine list.  */
+
+static void
+specific_redefine_list_append (const char *cause, const char *source, const char *target, const char *ofilename)
+{
+  struct specific_redefine_node **p;
+  struct specific_redefine_node *list;
+  struct specific_redefine_node *new_node;
+
+
+  for (p = &specific_redefine_sym_list; (list = *p) != NULL; p = &list->next)
+    {
+      if (strcmp (source, list->source) == 0)
+	if (strcmp (ofilename, list->ofilename) == 0)
+	  fatal (_("%s: Multiple redefinition of symbol \"%s\" for component \"%s\""),
+		 cause, source, ofilename);
+
+      if (strcmp (target, list->target) == 0)
+	if (strcmp (ofilename, list->ofilename) == 0)
+	  fatal (_("%s: Symbol \"%s\" is target of more than one redefinition for component \"%s\""),
+		 cause, source, ofilename);
+    }
+
+  new_node = xmalloc (sizeof (struct specific_redefine_node));
+
+  new_node->source = strdup (source);
+  new_node->target = strdup (target);
+  new_node->ofilename = strdup (ofilename);
+  new_node->next = NULL;
+
+  *p = new_node;
+}
+
+
 /* Handle the --redefine-syms option.  Read lines containing "old new"
    from the file, and add them to the symbol redefine list.  */
 
@@ -1418,6 +1510,7 @@
       || change_leading_char
       || remove_leading_char
       || redefine_sym_list
+      || specific_redefine_sym_list
       || weaken)
     {
       /* Mark symbols used in output relocations so that they
@@ -1734,6 +1827,12 @@
       bfd_boolean delete;
     do_copy:
 
+      if(specific_redefine_sym_list)
+	{
+	  non_fatal(_("warning: --redefine-sym-specific used but input file '%s' is not an archive"), 
+		    input_filename);
+	}
+
       /* bfd_get_target does not return the correct value until
          bfd_check_format succeeds.  */
       if (output_target == NULL)
@@ -2820,6 +2919,53 @@
 	  add_redefine_syms_file (optarg);
 	  break;
 
+
+	case OPTION_REDEFINE_SYM_SPECIFIC:
+	  {
+	    /* Push this redefinition onto specific_redefine_symbol_list.  */
+
+	    int len;
+	    const char *s;
+	    const char *pair;
+	    const char *nextarg;
+	    char *source, *target;
+	    char *ofilename;
+
+
+	    pair = strchr(optarg, ':');
+	    if (pair == NULL)
+	      fatal (_("bad format for %s"), "--redefine-sym-specific");
+
+	    s = strchr (optarg, '=');
+	    if (s == NULL)
+	      fatal (_("bad format for %s"), "--redefine-sym-specific");
+
+	    
+	    len = pair - optarg;
+	    ofilename = xmalloc (len + 1);
+	    strncpy (ofilename, optarg, len);
+	    ofilename[len] = '\0';
+
+	    len = s - pair - 1;
+	    source = xmalloc (len + 1);
+	    strncpy (source, pair + 1, len);
+	    source[len] = '\0';
+
+	    nextarg = s + 1;
+	    len = strlen (nextarg);
+	    target = xmalloc (len + 1);
+	    strcpy (target, nextarg);
+
+
+	    specific_redefine_list_append ("--redefine-sym-specific", 
+					   source, target, ofilename);
+
+	    free (source);
+	    free (target);
+	    free (ofilename);
+	  }
+	  break;
+
 	case OPTION_SET_SECTION_FLAGS:
 	  {
 	    const char *s;

Re: PATCH: objcopy.c: redefine-sym-specific for archive files

[Nick Clifton]

Hi Daniel,

> If an archive file (e.g. libc.a) consists of more than one object file 
> (e.g, a.o & b.o) each containing a definition for a symbol named 'foo', 
> objcopy --redefine-sym foo=bar libc.a will redefine both symbols.

> This might not always be the desired behavior.  The attached patch adds 
> the --redefine-sym-specific option to object copy.  Its usage is

Why add a new switch ?  Why not simply extend the syntax accepted by the 
--redefine-sym switch so that if a colon is present it behaves as per 
your new switch ?

> --redefine-sym-specific <objectfile>:<old>=<new>

Also - with a patch like this that adds a new feature, we really need an 
FSF copyright assignment in place before we can accept the patch.  Would 
you be interested in completing such an assignment ?

> I did not include a version for reading these from a file, as that 
 > would require either 'generalizing' add_redefine_syms_file() or
> 'cloning' that function, and I though such a decision should be left 
> to the maintainers.

Actually I would definitely encourage breaking out the code from 
add_redefine_syms_file, generalizing it and making it available to other 
  switches which might benefit.

Cheers
   Nick

Re: PATCH: objcopy.c: redefine-sym-specific for archive files

[Daniel Marques]

> 
> 
> Why add a new switch ?  Why not simply extend the syntax accepted by the 
> --redefine-sym switch so that if a colon is present it behaves as per 
> your new switch ?
> 

I wasn't sure if the colon could be a valid character in a symbol 
somewhere, if it isn't then it probably makes more sense to do like you 
said and just have one flag.


> 
> Also - with a patch like this that adds a new feature, we really need an 
> FSF copyright assignment in place before we can accept the patch.  Would 
> you be interested in completing such an assignment ?
> 

Sure.  Send me the details.



> 
> Actually I would definitely encourage breaking out the code from 
> add_redefine_syms_file, generalizing it and making it available to other 
>  switches which might benefit.
> 

I'll take a look.  If we reuse the old switch, then we might not need to 
do any changes here.


Thanks.

Dan

Re: PATCH: objcopy.c: redefine-sym-specific for archive files

[Nick Clifton]

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Hi Daniel,

>> Why add a new switch ?  Why not simply extend the syntax accepted by 
>> the --redefine-sym switch so that if a colon is present it behaves as 
>> per your new switch ?

> I wasn't sure if the colon could be a valid character in a symbol 
> somewhere, if it isn't then it probably makes more sense to do like you 
> said and just have one flag.

I wondered that as well.  I think that in the interested of simplicity 
though it would be better to reuse an existing switch if possible.  You 
could make the code quite intelligent - if multiple colons are detected 
in the switch's argument then it could all possible permutations of 
colon-as-file-name-separator and colon-as-symbol-character and only 
report an error if there is more than one valid solution.

Of course colons can be valid parts of file names as well.  For example 
how should the code cope with this:

    --redefine-sym-specific c:\program files\a.o:foo=bar


>> Also - with a patch like this that adds a new feature, we really need 
>> an FSF copyright assignment in place before we can accept the patch.  
>> Would you be interested in completing such an assignment ?

> Sure.  Send me the details.

I have attached a form.  Please fill it in and email it off to the FSF 
at the address given.

Cheers
   Nick



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Re: PATCH: objcopy.c: redefine-sym-specific for archive files

[Nick Clifton]

Hi Daniel,

 > Nick Clifton wrote:

> I wondered that as well.  I think that in the interested of simplicity 
> though it would be better to reuse an existing switch if possible.  You 
> could make the code quite intelligent - if multiple colons are detected 
> in the switch's argument then it could all possible permutations of 
> colon-as-file-name-separator and colon-as-symbol-character and only 
> report an error if there is more than one valid solution.

   Let's try rewriting that paragraph with a few grammatical fixes:

"I wondered that as well.  I think that in the interests of simplicity 
though it would be better to reuse an existing switch if possible.  You 
could make the code quite intelligent - if multiple colons are detected
in the switch's argument then it could try all possible permutations of
colon-as-file-name-separator and colon-as-symbol-character and only 
report an error if there is more than one valid solution."

   There - that's better.

Cheers
   Nick