RFA: Simpler get_relocated_section_contents interface

[Daniel Jacobowitz <drow at mvista dot com>]

This patch adds a new file, `simple.c', which is aimed at providing
lightweight interfaces.  This is designed for clients instead of linkers.
It serves as a combination interface and programming example.  These are
things which it would probably be wiser to do with something like libelf;
but I figure there's very little point in requiring _both_ libelf and BFD,
when BFD should be entirely capable of these relatively simple jobs.

The only method in it right now is bfd_simple_get_relocated_section_contents.
Right now it supports only cases where all referenced symbols appear in the
same BFD; it's very quiet about errors.  This is targeted at relocating
DWARF-2 information in readelf and GDB.

It's not efficient.  It adds the BFD's symbols to the hash table every time
you relocate a session.  I chose this added cost - relatively small number
of debugging sections will be going through this mechanism - over the
complexity of having begin and end routines.  When something wants to use
this interface for more than a handful of sections per BFD, then I'll
generalize it; for now I don't think the cost is worthwhile.  Simplicity was
my king here.  It's enough to meet GDB's needs, and I'll make readelf use it
also.

Does this look OK?  Any prefered interface changes?  Any other mechanisms
that it would be nice to expose this way?

[Oh, and I added linker.c's annotations to bfd-in2.h; it was missing from
the list.]

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

2002-09-27  Daniel Jacobowitz  <drow@mvista.com>

	* Makefile.am: Run dep-am.
	(BFD32_LIBS): Add simple.lo.
	(BFD32_LIBS_CFILES): Add simple.c.
	* Makefile.in: Regenerated.
	* bfd-in2.h: Regenerated.
	* simple.c: New file.

2002-09-27  Daniel Jacobowitz  <drow@mvista.com>

	* Makefile.am (BFD_H_DEP): Add simple.c and linker.c.
	* Makefile.in: Regenerated.

Index: bfd/Makefile.am
===================================================================
RCS file: /cvs/src/src/bfd/Makefile.am,v
retrieving revision 1.102
diff -u -p -r1.102 Makefile.am
--- bfd/Makefile.am	21 Sep 2002 09:59:19 -0000	1.102
+++ bfd/Makefile.am	27 Sep 2002 19:56:26 -0000
@@ -32,7 +32,7 @@ BFD32_LIBS = \
 	format.lo init.lo libbfd.lo opncls.lo reloc.lo \
 	section.lo syms.lo targets.lo hash.lo linker.lo \
 	srec.lo binary.lo tekhex.lo ihex.lo stabs.lo stab-syms.lo \
-	merge.lo dwarf2.lo
+	merge.lo dwarf2.lo simple.lo
 
 BFD64_LIBS = archive64.lo
 
@@ -41,7 +41,7 @@ BFD32_LIBS_CFILES = \
 	format.c init.c libbfd.c opncls.c reloc.c \
 	section.c syms.c targets.c hash.c linker.c \
 	srec.c binary.c tekhex.c ihex.c stabs.c stab-syms.c \
-	merge.c dwarf2.c
+	merge.c dwarf2.c simple.c
 
 BFD64_LIBS_CFILES = archive64.c
 
@@ -900,6 +900,7 @@ merge.lo: merge.c $(INCDIR)/filenames.h 
 dwarf2.lo: dwarf2.c $(INCDIR)/filenames.h $(INCDIR)/libiberty.h \
   elf-bfd.h $(INCDIR)/elf/common.h $(INCDIR)/elf/internal.h \
   $(INCDIR)/elf/external.h $(INCDIR)/bfdlink.h $(INCDIR)/elf/dwarf2.h
+simple.lo: simple.c $(INCDIR)/filenames.h
 archive64.lo: archive64.c $(INCDIR)/filenames.h $(INCDIR)/aout/ar.h
 cpu-a29k.lo: cpu-a29k.c $(INCDIR)/filenames.h
 cpu-alpha.lo: cpu-alpha.c $(INCDIR)/filenames.h
Index: bfd/Makefile.in
===================================================================
RCS file: /cvs/src/src/bfd/Makefile.in,v
retrieving revision 1.111
diff -u -p -r1.111 Makefile.in
--- bfd/Makefile.in	21 Sep 2002 09:59:19 -0000	1.111
+++ bfd/Makefile.in	27 Sep 2002 19:56:27 -0000
@@ -1,6 +1,6 @@
-# Makefile.in generated automatically by automake 1.4-p5 from Makefile.am
+# Makefile.in generated automatically by automake 1.4 from Makefile.am
 
-# Copyright (C) 1994, 1995-8, 1999, 2001 Free Software Foundation, Inc.
+# Copyright (C) 1994, 1995-8, 1999 Free Software Foundation, Inc.
 # This Makefile.in is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -156,7 +156,7 @@ BFD32_LIBS = \
 	format.lo init.lo libbfd.lo opncls.lo reloc.lo \
 	section.lo syms.lo targets.lo hash.lo linker.lo \
 	srec.lo binary.lo tekhex.lo ihex.lo stabs.lo stab-syms.lo \
-	merge.lo dwarf2.lo
+	merge.lo dwarf2.lo simple.lo
 
 
 BFD64_LIBS = archive64.lo
@@ -166,7 +166,7 @@ BFD32_LIBS_CFILES = \
 	format.c init.c libbfd.c opncls.c reloc.c \
 	section.c syms.c targets.c hash.c linker.c \
 	srec.c binary.c tekhex.c ihex.c stabs.c stab-syms.c \
-	merge.c dwarf2.c
+	merge.c dwarf2.c simple.c
 
 
 BFD64_LIBS_CFILES = archive64.c
@@ -785,7 +785,7 @@ LTLIBRARIES =  $(bfdlib_LTLIBRARIES)
 libbfd_la_OBJECTS =  archive.lo archures.lo bfd.lo cache.lo coffgen.lo \
 corefile.lo format.lo init.lo libbfd.lo opncls.lo reloc.lo section.lo \
 syms.lo targets.lo hash.lo linker.lo srec.lo binary.lo tekhex.lo \
-ihex.lo stabs.lo stab-syms.lo merge.lo dwarf2.lo archive64.lo
+ihex.lo stabs.lo stab-syms.lo merge.lo dwarf2.lo simple.lo archive64.lo
 CFLAGS = @CFLAGS@
 COMPILE = $(CC) $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
 LTCOMPILE = $(LIBTOOL) --mode=compile $(CC) $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
@@ -949,7 +949,7 @@ maintainer-clean-recursive:
 	dot_seen=no; \
 	rev=''; list='$(SUBDIRS)'; for subdir in $$list; do \
 	  rev="$$subdir $$rev"; \
-	  test "$$subdir" != "." || dot_seen=yes; \
+	  test "$$subdir" = "." && dot_seen=yes; \
 	done; \
 	test "$$dot_seen" = "no" && rev=". $$rev"; \
 	target=`echo $@ | sed s/-recursive//`; \
@@ -1430,6 +1430,7 @@ merge.lo: merge.c $(INCDIR)/filenames.h 
 dwarf2.lo: dwarf2.c $(INCDIR)/filenames.h $(INCDIR)/libiberty.h \
   elf-bfd.h $(INCDIR)/elf/common.h $(INCDIR)/elf/internal.h \
   $(INCDIR)/elf/external.h $(INCDIR)/bfdlink.h $(INCDIR)/elf/dwarf2.h
+simple.lo: simple.c $(INCDIR)/filenames.h
 archive64.lo: archive64.c $(INCDIR)/filenames.h $(INCDIR)/aout/ar.h
 cpu-a29k.lo: cpu-a29k.c $(INCDIR)/filenames.h
 cpu-alpha.lo: cpu-alpha.c $(INCDIR)/filenames.h
Index: bfd/bfd-in2.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in2.h,v
retrieving revision 1.171
diff -u -p -r1.171 bfd-in2.h
--- bfd/bfd-in2.h	19 Sep 2002 19:01:11 -0000	1.171
+++ bfd/bfd-in2.h	27 Sep 2002 19:56:28 -0000
@@ -1,7 +1,7 @@
 /* DO NOT EDIT!  -*- buffer-read-only: t -*-  This file is automatically 
    generated from "bfd-in.h", "init.c", "opncls.c", "libbfd.c", 
    "section.c", "archures.c", "reloc.c", "syms.c", "bfd.c", "archive.c", 
-   "corefile.c", "targets.c" and "format.c".
+   "corefile.c", "targets.c", "format.c", "linker.c" and "simple.c".
    Run "make headers" in your build bfd/ to regenerate.  */
 
 /* Main header file for the bfd library -- portable access to object files.
@@ -4109,6 +4109,17 @@ bfd_set_format PARAMS ((bfd *abfd, bfd_f
 
 const char *
 bfd_format_string PARAMS ((bfd_format format));
+
+/* Extracted from linker.c.  */
+boolean
+bfd_link_split_section PARAMS ((bfd *abfd, asection *sec));
+
+#define bfd_link_split_section(abfd, sec) \
+       BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))
+
+/* Extracted from simple.c.  */
+bfd_byte *
+bfd_simple_get_relocated_section_contents PARAMS ((bfd *abfd, asection *sec, bfd_byte *outbuf));
 
 #ifdef __cplusplus
 }
Index: bfd/simple.c
===================================================================
RCS file: bfd/simple.c
diff -N bfd/simple.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ bfd/simple.c	27 Sep 2002 19:56:28 -0000
@@ -0,0 +1,166 @@
+/* simple.c -- BFD simple client routines
+   Copyright 2002
+   Free Software Foundation, Inc.
+   Contributed by MontaVista Software, Inc.
+
+   This file is part of BFD, the Binary File Descriptor library.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#include "bfd.h"
+#include "sysdep.h"
+#include "libbfd.h"
+#include "bfdlink.h"
+
+static boolean
+simple_dummy_warning (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
+		      const char *warning ATTRIBUTE_UNUSED,
+		      const char *symbol ATTRIBUTE_UNUSED,
+		      bfd *abfd ATTRIBUTE_UNUSED,
+		      asection *section ATTRIBUTE_UNUSED,
+		      bfd_vma address ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
+static boolean
+simple_dummy_undefined_symbol (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
+			       const char *name ATTRIBUTE_UNUSED,
+			       bfd *abfd ATTRIBUTE_UNUSED,
+			       asection *section ATTRIBUTE_UNUSED,
+			       bfd_vma address ATTRIBUTE_UNUSED,
+			       boolean fatal ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
+static boolean
+simple_dummy_reloc_overflow (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
+			     const char *name ATTRIBUTE_UNUSED,
+			     const char *reloc_name ATTRIBUTE_UNUSED,
+			     bfd_vma addend ATTRIBUTE_UNUSED,
+			     bfd *abfd ATTRIBUTE_UNUSED,
+			     asection *section ATTRIBUTE_UNUSED,
+			     bfd_vma address ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
+static boolean
+simple_dummy_reloc_dangerous (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
+			      const char *message ATTRIBUTE_UNUSED,
+			      bfd *abfd ATTRIBUTE_UNUSED,
+			      asection *section ATTRIBUTE_UNUSED,
+			      bfd_vma address ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
+static boolean
+simple_dummy_unattached_reloc (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
+			       const char *name ATTRIBUTE_UNUSED,
+			       bfd *abfd ATTRIBUTE_UNUSED,
+			       asection *section ATTRIBUTE_UNUSED,
+			       bfd_vma address ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
+/*
+FUNCTION
+	bfd_simple_relocate_secton
+
+SYNOPSIS
+	bfd_byte *bfd_simple_get_relocated_section_contents (bfd *abfd, asection *sec, bfd_byte *outbuf);
+
+DESCRIPTION
+	Returns the relocated contents of section @var{sec}.  Only symbols
+	from @var{abfd} and the output offsets assigned to sections in
+	@var{abfd} are used.  The result will be stored at @var{outbuf}
+	or allocated with @code{bfd_malloc} if @var{outbuf} is @code{NULL}.
+
+	Generally all sections in @var{abfd} should have their
+	@code{output_section} pointing back to the original section.
+
+	Returns @code{NULL} on a fatal error; ignores errors applying
+	particular relocations.
+*/
+
+bfd_byte *
+bfd_simple_get_relocated_section_contents (bfd *abfd, asection *sec,
+					   bfd_byte *outbuf)
+{
+  struct bfd_link_info link_info;
+  struct bfd_link_order link_order;
+  struct bfd_link_callbacks callbacks;
+  bfd_byte *contents, *data;
+  int storage_needed, number_of_symbols;
+  asymbol **symbol_table;
+
+  /* In order to use bfd_get_relocated_section_contents, we need
+     to forge some data structures that it expects.  */
+
+  /* Fill in the bare minimum number of fields for our purposes.  */
+  memset (&link_info, 0, sizeof (link_info));
+  link_info.input_bfds = abfd;
+
+  link_info.hash = bfd_link_hash_table_create (abfd);
+  link_info.callbacks = &callbacks;
+  callbacks.warning = simple_dummy_warning;
+  callbacks.undefined_symbol = simple_dummy_undefined_symbol;
+  callbacks.reloc_overflow = simple_dummy_reloc_overflow;
+  callbacks.reloc_dangerous = simple_dummy_reloc_dangerous;
+  callbacks.unattached_reloc = simple_dummy_unattached_reloc;
+
+  memset (&link_order, 0, sizeof (link_order));
+  link_order.next = NULL;
+  link_order.type = bfd_indirect_link_order;
+  link_order.offset = 0;
+  link_order.size = bfd_section_size (abfd, sec);
+  link_order.u.indirect.section = sec;
+
+  data = NULL;
+  if (outbuf == NULL)
+    {
+      data = bfd_malloc (bfd_section_size (abfd, sec));
+      outbuf = data;
+    }
+  bfd_link_add_symbols (abfd, &link_info);
+
+  storage_needed = bfd_get_symtab_upper_bound (abfd);
+  symbol_table = (asymbol **) bfd_malloc (storage_needed);
+  number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+
+  contents = bfd_get_relocated_section_contents (abfd,
+						 &link_info,
+						 &link_order,
+						 outbuf,
+						 0,
+						 symbol_table);
+  if (contents == NULL && data != NULL)
+    free (data);
+
+  /* Foul hack to prevent bfd_section_size aborts.  This flag only controls
+     that macro (and the related size macros), selecting between _raw_size
+     and _cooked_size.  Debug sections won't change size while we're only
+     relocating.  There may be trouble here someday if it tries to run
+     relaxation unexpectedly, so make sure.  */
+  BFD_ASSERT (sec->_raw_size == sec->_cooked_size);
+  sec->reloc_done = 0;
+
+  bfd_link_hash_table_free (abfd, link_info.hash);
+
+  return contents;
+}
Index: bfd/doc/Makefile.am
===================================================================
RCS file: /cvs/src/src/bfd/doc/Makefile.am,v
retrieving revision 1.8
diff -u -p -r1.8 Makefile.am
--- bfd/doc/Makefile.am	8 Jun 2002 08:50:44 -0000	1.8
+++ bfd/doc/Makefile.am	27 Sep 2002 19:56:28 -0000
@@ -248,6 +248,8 @@ BFD_H_DEP = \
 	$(srcdir)/../corefile.c		\
 	$(srcdir)/../targets.c		\
 	$(srcdir)/../format.c		\
+	$(srcdir)/../linker.c		\
+	$(srcdir)/../simple.c		\
 	$(srcdir)/header.sed		\
 	$(srcdir)/proto.str		\
 	$(srcdir)/../version.h		\
Index: bfd/doc/Makefile.in
===================================================================
RCS file: /cvs/src/src/bfd/doc/Makefile.in,v
retrieving revision 1.39
diff -u -p -r1.39 Makefile.in
--- bfd/doc/Makefile.in	9 Aug 2002 15:38:23 -0000	1.39
+++ bfd/doc/Makefile.in	27 Sep 2002 19:56:28 -0000
@@ -1,6 +1,6 @@
-# Makefile.in generated automatically by automake 1.4-p5 from Makefile.am
+# Makefile.in generated automatically by automake 1.4 from Makefile.am
 
-# Copyright (C) 1994, 1995-8, 1999, 2001 Free Software Foundation, Inc.
+# Copyright (C) 1994, 1995-8, 1999 Free Software Foundation, Inc.
 # This Makefile.in is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -216,6 +216,8 @@ BFD_H_DEP = \
 	$(srcdir)/../corefile.c		\
 	$(srcdir)/../targets.c		\
 	$(srcdir)/../format.c		\
+	$(srcdir)/../linker.c		\
+	$(srcdir)/../simple.c		\
 	$(srcdir)/header.sed		\
 	$(srcdir)/proto.str		\
 	$(srcdir)/../version.h		\
@@ -244,7 +246,7 @@ DIST_COMMON =  ChangeLog Makefile.am Mak
 
 DISTFILES = $(DIST_COMMON) $(SOURCES) $(HEADERS) $(TEXINFOS) $(EXTRA_DIST)
 
-TAR = gtar
+TAR = tar
 GZIP_ENV = --best
 all: all-redirect
 .SUFFIXES:
@@ -330,7 +332,7 @@ uninstall-info:
 	else ii=; fi; \
 	list='$(INFO_DEPS)'; \
 	for file in $$list; do \
-	  test -z "$$ii" \
+	  test -z "$ii" \
 	    || install-info --info-dir=$(DESTDIR)$(infodir) --remove $$file; \
 	done
 	@$(NORMAL_UNINSTALL)