[RFA] Add cmd "set bfd" to make gdb handle bfd_error_file_ambiguously_recognized better

[Hui Zhu <teawater@gmail.com>]

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Hello guys,

As I said in http://sourceware.org/ml/gdb/2010-01/msg00122.html

I make patches for them.
setbfd.txt is for gdb, it add a new cmd "set bfd".  It can set the
default executable format when more than one executable format support
for the object file.
And when user load file get bfd_error_file_ambiguously_recognized, gdb
will output:
"/ls":Matching formats: elf32-nbigmips elf32-ntradbigmips
Use command "set bfd" handle it.

And I to let gdb set bfd_associated_vector, I make a patch bfd.txt.

Please help me review it.

Thanks,
Hui

2010-01-13  Hui Zhu  <teawater@gmail.com>
	* arch-utils.c (libbfd.h): New include.
	(bfds): New variable.
	(set_bfd_string): New variable.
	(show_bfd): New function.
	(set_bfd): New function.
	(_initialize_gdbarch_utils): Add new command "set bfd".
	* exec.c (exec_file_attach): Output special works when
	bfd_get_error is bfd_error_file_ambiguously_recognized.

2010-01-13  Hui Zhu  <teawater@gmail.com>
	* libbfd-in.h (bfd_associated_vector): Remove second const.
	* libbfd.h (bfd_associated_vector): Ditto.
	* targets.c (bfd_associated_vector): Ditto.
	(_bfd_associated_vector): Add DEFAULT_VECTOR.

[-- Attachment #2: bfd.txt --]
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---
 libbfd-in.h |    2 +-
 libbfd.h    |    2 +-
 targets.c   |    7 +++++--
 3 files changed, 7 insertions(+), 4 deletions(-)

--- a/libbfd-in.h
+++ b/libbfd-in.h
@@ -686,7 +686,7 @@ extern const bfd_target * const *bfd_tar
 extern const bfd_target *bfd_default_vector[];
 
 /* List of associated target vectors.  */
-extern const bfd_target * const *bfd_associated_vector;
+extern const bfd_target **bfd_associated_vector;
 
 /* Functions shared by the ECOFF and MIPS ELF backends, which have no
    other common header files.  */
--- a/libbfd.h
+++ b/libbfd.h
@@ -691,7 +691,7 @@ extern const bfd_target * const *bfd_tar
 extern const bfd_target *bfd_default_vector[];
 
 /* List of associated target vectors.  */
-extern const bfd_target * const *bfd_associated_vector;
+extern const bfd_target **bfd_associated_vector;
 
 /* Functions shared by the ECOFF and MIPS ELF backends, which have no
    other common header files.  */
--- a/targets.c
+++ b/targets.c
@@ -1287,13 +1287,16 @@ const bfd_target *bfd_default_vector[] =
 /* bfd_associated_vector[] contains the associated target vectors used
    to reduce the ambiguity in bfd_check_format_matches.  */
 
-static const bfd_target *_bfd_associated_vector[] = {
+static bfd_target const *_bfd_associated_vector[] = {
+#ifdef DEFAULT_VECTOR
+	&DEFAULT_VECTOR,
+#endif
 #ifdef ASSOCIATED_VECS
 	ASSOCIATED_VECS,
 #endif
 	NULL
 };
-const bfd_target * const *bfd_associated_vector = _bfd_associated_vector;
+const bfd_target **bfd_associated_vector = _bfd_associated_vector;
 
 /* When there is an ambiguous match, bfd_check_format_matches puts the
    names of the matching targets in an array.  This variable is the maximum

[-- Attachment #3: setbfd.txt --]
[-- Type: text/plain, Size: 3711 bytes --]

---
 arch-utils.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 exec.c       |   21 ++++++++++++++++++---
 2 files changed, 74 insertions(+), 3 deletions(-)

--- a/arch-utils.c
+++ b/arch-utils.c
@@ -32,6 +32,7 @@
 #include "osabi.h"
 #include "target-descriptions.h"
 #include "objfiles.h"
+#include "libbfd.h"
 
 #include "version.h"
 
@@ -776,6 +777,36 @@ default_fast_tracepoint_valid_at (struct
   return 1;
 }
 
+/* For cmd "set bfd".  */
+
+static const char **bfds;
+
+static const char *set_bfd_string;
+
+static void
+show_bfd (struct ui_file *file, int from_tty,
+          struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("\
+The default executable format is %s\n"), set_bfd_string);
+}
+
+static void
+set_bfd (char *ignore_args, int from_tty, struct cmd_list_element *c)
+{
+  int nr;
+
+  for (nr = 0; bfd_target_vector[nr]; nr++)
+    {
+      if (bfd_target_vector[nr]->name == set_bfd_string)
+        {
+          bfd_associated_vector[0] = bfd_target_vector[nr];
+          show_bfd (gdb_stdout, from_tty, NULL, NULL);
+          return;
+        }
+    }
+}
+
 /* */
 
 extern initialize_file_ftype _initialize_gdbarch_utils; /* -Wmissing-prototypes */
@@ -790,4 +821,29 @@ Set endianness of target."), _("\
 Show endianness of target."), NULL,
 			set_endian, show_endian,
 			&setlist, &showlist);
+
+  /* Add cmd "set bfd".  */
+  if (bfd_associated_vector[0])
+    {
+      int nr;
+
+      /* Initialize bfds.  */
+      for (nr = 0; bfd_target_vector[nr]; nr++);
+      bfds = xcalloc (sizeof (char *), nr + 1);
+      for (nr = 0; bfd_target_vector[nr]; nr++)
+        bfds[nr] = bfd_target_vector[nr]->name;
+      bfds[nr + 1] = NULL;
+
+      /* Initialize set_bfd_string. */
+      set_bfd_string = bfd_associated_vector[0]->name;
+
+      add_setshow_enum_cmd ("bfd", class_support,
+                            bfds, &set_bfd_string, _("\
+Set the default executable format when more than \n\
+one executable format support for the object file."), _("\
+Show the default executable format when more than \n\
+one executable format support for the object file."), NULL,
+                            set_bfd, show_bfd,
+                            &setlist, &showlist);
+    }
 }
--- a/exec.c
+++ b/exec.c
@@ -207,6 +207,8 @@ exec_file_clear (int from_tty)
 void
 exec_file_attach (char *filename, int from_tty)
 {
+  char **matching;
+
   /* Remove any previous exec file.  */
   exec_close ();
 
@@ -259,13 +261,26 @@ exec_file_attach (char *filename, int fr
       scratch_pathname = xstrdup (scratch_pathname);
       cleanups = make_cleanup (xfree, scratch_pathname);
 
-      if (!bfd_check_format (exec_bfd, bfd_object))
+      if (!bfd_check_format_matches (exec_bfd, bfd_object, &matching))
 	{
 	  /* Make sure to close exec_bfd, or else "run" might try to use
 	     it.  */
 	  exec_close ();
-	  error (_("\"%s\": not in executable format: %s"),
-		 scratch_pathname, bfd_errmsg (bfd_get_error ()));
+
+          if (bfd_get_error () == bfd_error_file_ambiguously_recognized)
+            {
+              char **p = matching;
+              fprintf_filtered (gdb_stderr, _("\"%s\":Matching formats:"),
+                                scratch_pathname);
+              while (*p)
+                fprintf_filtered (gdb_stderr, " %s", *p++);
+              fprintf_filtered (gdb_stderr, "\n");
+              free (matching);
+              error (_("Use command \"set bfd\" handle it."));
+            }
+          else
+	    error (_("\"%s\": not in executable format: %s"),
+		   scratch_pathname, bfd_errmsg (bfd_get_error ()));
 	}
 
       /* FIXME - This should only be run for RS6000, but the ifdef is a poor