Re: [patch/rfc] New (!) BFD target

[Andrew Cagney <cagney at gnu dot org>]

> Hello,
>
> The attached adds a really simple BFD "target" and is used:
>
>     bfd = bfd_open.. (...);
>     targ = target_bfd_reopen (bfd)
>     ... operation involving targ ...
>     target_close (targ, 0);
>
> Looking at solib-svr4, this object makes it possible to change this:
>
>   load_addr = read_pc () - tmp_bfd->start_address;
>
> into this:
>
>   load_addr = (read_pc ()
>                - gdbarch_convert_from_func_ptr_addr (current_gdbarch,
> bfd_get_start_address (tmp_bfd),                  tmp_bfd_target));
>
> i.e., pointer conversion is performed using the original executable and not the running program.  Something needed to fix PPC64 needs.

I've attached the updated patch which I've just committed.

Andrew

> 2003-10-22  Andrew Cagney  <cagney@redhat.com>
>
> 	* target.h (struct target_ops): Add "to_data";
> 	* bfd-target.h, bfd-target.c: New files.
> 	* Makefile.in (SFILES): Add "bfd-target.c".
> 	(COMMON_OBS): Add "bfd-target.o".
> 	(bfd-target.o): Specify dependencies.
> 	(bfd_target_h): Define.
> 	* defs.h (XZALLOC): Define.

2003-10-31  Andrew Cagney  <cagney@redhat.com>
 
	* defs.h (XZALLOC): Define.
	* target.h (struct target_ops): Add "to_data";
	* bfd-target.h, bfd-target.c: New files.
	* Makefile.in (SFILES): Add "bfd-target.c".
	(COMMON_OBS): Add "bfd-target.o".
	(bfd-target.o): Specify dependencies.
	(bfd_target_h): Define.
	* defs.h (XZALLOC): Define.

Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.464
diff -u -r1.464 Makefile.in
--- Makefile.in	31 Oct 2003 16:37:03 -0000	1.464
+++ Makefile.in	31 Oct 2003 19:17:12 -0000
@@ -511,7 +511,9 @@
 
 SFILES = ada-exp.y ada-lang.c ada-typeprint.c ada-valprint.c ada-tasks.c \
 	ax-general.c ax-gdb.c \
-	bcache.c block.c blockframe.c breakpoint.c buildsym.c \
+	bcache.c \
+	bfd-target.c \
+	block.c blockframe.c breakpoint.c buildsym.c \
 	c-exp.y c-lang.c c-typeprint.c c-valprint.c \
 	charset.c cli-out.c coffread.c coff-pe-read.c \
 	complaints.c completer.c corefile.c \
@@ -634,6 +636,7 @@
 ax_gdb_h = ax-gdb.h
 ax_h = ax.h $(doublest_h)
 bcache_h = bcache.h
+bfd_target_h = bfd-target.h
 block_h = block.h
 breakpoint_h = breakpoint.h $(frame_h) $(value_h) $(gdb_events_h)
 buildsym_h = buildsym.h
@@ -867,7 +870,9 @@
 	$(SUBDIR_CLI_SRCS)
 TAGFILES_WITH_SRCDIR = $(HFILES_WITH_SRCDIR)
 
-COMMON_OBS = version.o blockframe.o breakpoint.o findvar.o regcache.o \
+COMMON_OBS = version.o \
+	bfd-target.o \
+	blockframe.o breakpoint.o findvar.o regcache.o \
 	charset.o disasm.o dummy-frame.o \
 	source.o values.o eval.o valops.o valarith.o valprint.o printcmd.o \
 	block.o symtab.o symfile.o symmisc.o linespec.o dictionary.o \
@@ -1600,6 +1605,8 @@
 	$(regcache_h)
 ax-general.o: ax-general.c $(defs_h) $(ax_h) $(value_h) $(gdb_string_h)
 bcache.o: bcache.c $(defs_h) $(gdb_obstack_h) $(bcache_h) $(gdb_string_h)
+bfd-target.o: bfd-target.c $(defs_h) $(target_h) $(bfd_target_h) \
+	$(gdb_assert_h) $(gdb_string_h)
 block.o: block.c $(defs_h) $(block_h) $(symtab_h) $(symfile_h) \
 	$(gdb_obstack_h) $(cp_support_h)
 blockframe.o: blockframe.c $(defs_h) $(symtab_h) $(bfd_h) $(symfile_h) \
Index: bfd-target.c
===================================================================
RCS file: bfd-target.c
diff -N bfd-target.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ bfd-target.c	31 Oct 2003 19:17:12 -0000
@@ -0,0 +1,131 @@
+/* Very simple "bfd" target, for GDB, the GNU debugger.
+
+   Copyright 2003 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 "defs.h"
+#include "target.h"
+#include "bfd-target.h"
+#include "gdb_assert.h"
+#include "gdb_string.h"
+
+/* Locate all mappable sections of a BFD file, filling in a target
+   section for each.  */
+
+struct section_closure
+{
+  struct section_table *end;
+};
+
+static void
+add_to_section_table (struct bfd *abfd, struct bfd_section *asect,
+		      void *closure)
+{
+  struct section_closure *pp = closure;
+  flagword aflag;
+
+  /* NOTE: cagney/2003-10-22: Is this pruning useful?  */
+  aflag = bfd_get_section_flags (abfd, asect);
+  if (!(aflag & SEC_ALLOC))
+    return;
+  if (bfd_section_size (abfd, asect) == 0)
+    return;
+  pp->end->bfd = abfd;
+  pp->end->the_bfd_section = asect;
+  pp->end->addr = bfd_section_vma (abfd, asect);
+  pp->end->endaddr = pp->end->addr + bfd_section_size (abfd, asect);
+  pp->end++;
+}
+
+void
+build_target_sections_from_bfd (struct target_ops *targ, struct bfd *abfd)
+{
+  unsigned count;
+  struct section_table *start;
+  struct section_closure cl;
+
+  count = bfd_count_sections (abfd);
+  target_resize_to_sections (targ, count);
+  start = targ->to_sections;
+  cl.end = targ->to_sections;
+  bfd_map_over_sections (abfd, add_to_section_table, &cl);
+  gdb_assert (cl.end - start <= count);
+}
+
+LONGEST
+target_bfd_xfer_partial (struct target_ops *ops,
+			 enum target_object object,
+			 const char *annex, const void *writebuf, 
+			 void *readbuf, ULONGEST offset, LONGEST len)
+{
+  switch (object)
+    {
+    case TARGET_OBJECT_MEMORY:
+      {
+	struct section_table *s = target_section_by_addr (ops, offset);
+	if (s == NULL)
+	  return -1;
+	/* If the length extends beyond the section, truncate it.  Be
+           careful to not suffer from overflow (wish S contained a
+           length).  */
+	if ((offset - s->addr + len) > (s->endaddr - s->addr))
+	  len = (s->endaddr - s->addr) - (offset - s->addr);
+	if (readbuf != NULL
+	    && !bfd_get_section_contents (s->bfd, s->the_bfd_section,
+					  readbuf, offset - s->addr, len))
+	  return -1;
+#if 1
+	if (writebuf != NULL)
+	  return -1;
+#else
+	/* FIXME: cagney/2003-10-31: The BFD interface doesn't yet
+           take a const buffer.  */
+	if (writebuf != NULL
+	    && !bfd_set_section_contents (s->bfd, s->the_bfd_section,
+					  writebuf, offset - s->addr, len))
+	  return -1;
+#endif
+	return len;
+      }
+    default:
+      return -1;
+    }
+}
+
+void
+target_bfd_xclose (struct target_ops *t, int quitting)
+{
+  bfd_close (t->to_data);
+  xfree (t->to_sections);
+  xfree (t);
+}
+
+struct target_ops *
+target_bfd_reopen (struct bfd *bfd)
+{
+  struct target_ops *t = XZALLOC (struct target_ops);
+  t->to_shortname = "bfd";
+  t->to_longname = "BFD backed target";
+  t->to_doc = "You should never see this";
+  t->to_xfer_partial = target_bfd_xfer_partial;
+  t->to_xclose = target_bfd_xclose;
+  t->to_data = bfd;
+  build_target_sections_from_bfd (t, bfd);
+  return t;
+}
Index: bfd-target.h
===================================================================
RCS file: bfd-target.h
diff -N bfd-target.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ bfd-target.h	31 Oct 2003 19:17:12 -0000
@@ -0,0 +1,39 @@
+/* Very simple "bfd" target, for GDB, the GNU debugger.
+
+   Copyright 2003 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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.  */
+
+#ifndef BFD_TARGET_H
+#define BFD_TARGET_H
+
+struct bfd;
+struct target_ops;
+
+/* Given an existing BFD, re-open it as a "struct target_ops".  On
+   close, it will also close the corresponding BFD (which is like
+   freopen and fdopen).  */
+struct target_ops *target_bfd_reopen (struct bfd *bfd);
+
+/* Map over ABFD's sections, creating corresponding entries in the
+   target's section table.  */
+
+void build_target_sections_from_bfd (struct target_ops *targ,
+				     struct bfd *abfd);
+
+#endif
Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.132
diff -u -r1.132 defs.h
--- defs.h	20 Oct 2003 15:37:58 -0000	1.132
+++ defs.h	31 Oct 2003 19:17:13 -0000
@@ -868,9 +868,10 @@
    "libiberty.h". */
 extern void xfree (void *);
 
-/* Utility macros to allocate typed memory.  Avoids errors like
-   ``struct foo *foo = xmalloc (sizeof bar)'' and ``struct foo *foo =
-   (struct foo *) xmalloc (sizeof bar)''.  */
+/* Utility macros to allocate typed memory.  Avoids errors like:
+   struct foo *foo = xmalloc (sizeof struct bar); and memset (foo,
+   sizeof (struct foo), 0).  */
+#define XZALLOC(TYPE) ((TYPE*) memset (xmalloc (sizeof (TYPE)), 0, sizeof (TYPE)))
 #define XMALLOC(TYPE) ((TYPE*) xmalloc (sizeof (TYPE)))
 #define XCALLOC(NMEMB, TYPE) ((TYPE*) xcalloc ((NMEMB), sizeof (TYPE)))
 
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/target.h,v
retrieving revision 1.50
diff -u -r1.50 target.h
--- target.h	31 Oct 2003 15:25:34 -0000	1.50
+++ target.h	31 Oct 2003 19:17:13 -0000
@@ -280,6 +280,8 @@
     char *to_doc;		/* Documentation.  Does not include trailing
 				   newline, and starts with a one-line descrip-
 				   tion (probably similar to to_longname).  */
+    /* Per-target scratch pad.  */
+    void *to_data;
     /* The open routine takes the rest of the parameters from the
        command, and (if successful) pushes a new target onto the
        stack.  Targets should supply this routine, if only to provide