[RFC-v2] Allow explicit 16 or 32 char in 'x /s'

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Tom Tromey
> Envoyé : Tuesday, March 30, 2010 10:33 PM
> À : Pierre Muller
> Cc : 'Eli Zaretskii'; gdb-patches@sourceware.org
> Objet : Re: [RFC] Allow explicit 16 or 32 char in 'x /s'
> 
> >>>>> "Pierre" == Pierre Muller <pierre.muller@ics-cnrs.unistra.fr>
> writes:
> 
> Pierre>   But I don't know exactly for other languages and I would like
> Pierre> to be sure about what you want me to add to the docs...
> 
> I think no other language has been updated to deal with wide
> characters.

  At least pascal language was able to display
"simple" wide characters correctly (i.e. 16-bit strings with numeric values
in the 32-127 range)
before the patch that explicitly discarded the size modifier for /s.
 
> Pierre>   Furthermore if you look into charset_for_string_type
> Pierre> function in c-lang.c source, you will see that there are two
> FIXME
> Pierre> just right at the position of these charset name settings.
> 
> Yeah ... those are actually pedantic FIXMEs, in that (IIRC) nothing
> guarantees that char16_t==UTF-16, even though that is the common
> meaning.
> 
> Pierre>   To answer Tom's concern about the change in classify_type
> function,
> Pierre> I modified my patch to change the elttype in do_examine to
> match exactly
> Pierre> what is expected by charset_for_string_type function.
> Pierre> Thus this new version has no modification in c-lang.c file.
> 
> Suppose the inferior does not define char16_t.  Won't this new code
> allocate a new type each time the user uses x/hs?  That seems bad.
 
  Well, I supposed (wrongly) that the arch_type call would
make that newly defined type accessible to the next call to lookup_typename
but, after verification, it appears that you are right
and that the newly type is lost...
  I don't know how we should handle this case, but I don't think that it is 
the first time we use arch_type function inside GDB.
  Should I add two new fields to builtin_type struct?
  That is what I tried below.
 
> What about passing the desired encoding to LA_PRINT_STRING, via a new
> argument to val_print_string?  That makes the patch a lot bigger,
> though
> it is mostly mechanical.
> 
> Pierre>   I also added a very basic check for string display using 'x
> Pierre> /hs' and 'x /ws'.
> 
> Thanks.
> 
> Pierre> +      case 's':
> Pierre> +	/* Display strings with byte size chars unless explicitly
> specified.
> Pierre> */
> Pierre> +	val.size = 'b';
> Pierre> +	break;
> 
> I think x/hs followed by x should probably print another wide string.
> I couldn't tell offhand if it does this or not.

  This is what I wrote in the documentation part of the patch,
the idea was to limit the behavior change as compared to previous versions
of GDB: 
  only 'x /hs' or 'x /ws' would display 16 or 32 bit strings,
any use without the explicit size specifier would fall back to implicit 'x
/bs'
this of course also would happen if you use 'x ' command without any
specifier
at all. It seems nevertheless that the patch I sent out finally 
failed to do this properly. This new version seems to be closer to the
documentation I gave.

  Here is a new version of the patch
using builtin_char16 and builtin_char32.

Pierre


2010-03-31  Pierre Muller  <muller@ics.u-strasbg.fr>

	* gdbtypes.h (builtin_type): Add BUILTIN_CHAR16 and BUILTIN_CHAR32
	fields.
	* gdbtypes.c (gdbtypes_post_init): Set BUILTIN_CHAR16 and 
	BUILTIN_CHAR32 fields.
	* printcmd.c (decode_format): Set char size to '\0'
	for strings unless explicit size is given.
	(print_formatted): Correct calculation of NEXT_ADDRESS
	for 16 or 32 bit strings.
	(do_examine): Do not force byte size for strings.
	Use builtin_char16 and builtin_char32 types to display
	16 or 32 bit-wide strings. 
	(x_command): Set LAST_SIZE to 'b' for string type.


2010-03-31  Pierre Muller  <muller@ics.u-strasbg.fr>

      * gdb.texinfo (Examining memory): Update for
	change in string display with explicit size.

2010-03-31  Pierre Muller  <muller@ics.u-strasbg.fr>

	* gdb.base/charset.c (Strin16, String32): New variables.
	* gdb.base/charset.exp (gdb_test): Test correct display
	of 16 or 32 bit strings.
	
Index: src/gdb/gdbtypes.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbtypes.h,v
retrieving revision 1.125
diff -u -p -r1.125 gdbtypes.h
--- src/gdb/gdbtypes.h	15 Mar 2010 02:42:54 -0000	1.125
+++ src/gdb/gdbtypes.h	31 Mar 2010 12:57:26 -0000
@@ -1099,6 +1099,9 @@ struct builtin_type
   struct type *builtin_int128;
   struct type *builtin_uint128;
 
+  /* Multi-byte character types.  */
+  struct type *builtin_char16;
+  struct type *builtin_char32;
 
   /* Pointer types.  */
 
Index: src/gdb/gdbtypes.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbtypes.c,v
retrieving revision 1.188
diff -u -p -r1.188 gdbtypes.c
--- src/gdb/gdbtypes.c	1 Mar 2010 17:19:22 -0000	1.188
+++ src/gdb/gdbtypes.c	31 Mar 2010 12:57:25 -0000
@@ -3474,6 +3474,13 @@ gdbtypes_post_init (struct gdbarch *gdba
   TYPE_NOTTEXT (builtin_type->builtin_int8) = 1;
   TYPE_NOTTEXT (builtin_type->builtin_uint8) = 1;
 
+  /* Multi-byte character types.  */
+  builtin_type->builtin_char16
+    = arch_integer_type (gdbarch, 16, 0, "char16_t");
+  builtin_type->builtin_char32
+    = arch_integer_type (gdbarch, 32, 0, "char32_t");
+	
+
   /* Default data/code pointer types.  */
   builtin_type->builtin_data_ptr
     = lookup_pointer_type (builtin_type->builtin_void);
Index: src/gdb/printcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/printcmd.c,v
retrieving revision 1.173
diff -u -p -r1.173 printcmd.c
--- src/gdb/printcmd.c	5 Mar 2010 20:18:14 -0000	1.173
+++ src/gdb/printcmd.c	31 Mar 2010 15:20:22 -0000
@@ -260,6 +260,11 @@ decode_format (char **string_ptr, int of
 	/* Characters default to one byte.  */
 	val.size = osize ? 'b' : osize;
 	break;
+      case 's':
+	/* Display strings with byte size chars unless explicitly specified.
*/
+	val.size = '\0';
+	break;
+
       default:
 	/* The default is the size most recently specified.  */
 	val.size = osize;
@@ -295,7 +300,7 @@ print_formatted (struct value *val, int 
 	    next_address = (value_address (val)
 			    + val_print_string (elttype,
 						value_address (val), -1,
-						stream, options));
+						stream, options) * len);
 	  }
 	  return;
 
@@ -802,9 +807,11 @@ do_examine (struct format_data fmt, stru
   next_gdbarch = gdbarch;
   next_address = addr;
 
-  /* String or instruction format implies fetch single bytes
-     regardless of the specified size.  */
-  if (format == 's' || format == 'i')
+  /* Instruction format implies fetch single bytes
+     regardless of the specified size.
+     The case of strings is handled n decode_format, only explicit
+     size operator are not changed to 'b'.  */
+  if (format == 'i')
     size = 'b';
 
   if (size == 'a')
@@ -831,6 +838,27 @@ do_examine (struct format_data fmt, stru
   else if (size == 'g')
     val_type = builtin_type (next_gdbarch)->builtin_int64;
 
+  if (format == 's')
+    {
+      struct type *char_type = NULL;
+      /* Search for "char16_t"  or "char32_t" types or fall back to 8-bit
char
+	 if type is not found.  */
+      if (size == 'h')
+	char_type = builtin_type (next_gdbarch)->builtin_char16;
+      else if (size == 'w')
+	char_type = builtin_type (next_gdbarch)->builtin_char32;
+      if (char_type)
+        val_type = char_type;
+      else
+        {
+	  if (size != '\0' && size != 'b')
+	    warning (_("Unable to display strings with size '%c', using 'b'
\
+instead."), size);
+	  size = 'b';
+	  val_type = builtin_type (next_gdbarch)->builtin_int8;
+        }
+    }
+
   maxelts = 8;
   if (size == 'w')
     maxelts = 4;
@@ -1412,8 +1440,11 @@ x_command (char *exp, int from_tty)
   do_examine (fmt, next_gdbarch, next_address);
 
   /* If the examine succeeds, we remember its size and format for next
-     time.  */
-  last_size = fmt.size;
+     time.  Set last_size to 'b' for strings.  */
+  if (fmt.format == 's')
+    last_size = 'b'
+  else
+    last_size = fmt.size;
   last_format = fmt.format;
 
   /* Set a couple of internal variables if appropriate. */
Index: src/gdb/doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.680
diff -u -p -r1.680 gdb.texinfo
--- src/gdb/doc/gdb.texinfo     12 Mar 2010 19:15:52 -0000      1.680
+++ src/gdb/doc/gdb.texinfo     18 Mar 2010 20:43:12 -0000
@@ -7236,8 +7236,11 @@ Giant words (eight bytes).
 @end table

 Each time you specify a unit size with @code{x}, that size becomes the
-default unit the next time you use @code{x}.  (For the @samp{s} and
-@samp{i} formats, the unit size is ignored and is normally not written.)
+default unit the next time you use @code{x}.  For the @samp{i} format,
+the unit size is ignored and is normally not written.  For the @samp{s}
format,
+the unit size defaults to @samp{b}, unless it is explicitly given.
+Use @kbd{x /hs} to display 16-bit char strings and @kbd{x /ws} to display
+32-bit strings.  The next use of @kbd{x /s} will again display 8-bit
strings.

 @item @var{addr}, starting display address
 @var{addr} is the address where you want @value{GDBN} to begin displaying
Index: src/gdb/testsuite/gdb.base/charset.c
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/charset.c,v
retrieving revision 1.12
diff -u -p -r1.12 charset.c
--- src/gdb/testsuite/gdb.base/charset.c	1 Jan 2010 07:32:00 -0000
1.12
+++ src/gdb/testsuite/gdb.base/charset.c	22 Mar 2010 22:25:34 -0000
@@ -65,6 +65,9 @@ typedef unsigned int char32_t;
 char16_t uvar;
 char32_t Uvar;
 
+char16_t *String16;
+char32_t *String32;
+
 /* A typedef to a typedef should also work.  */
 typedef wchar_t my_wchar_t;
 my_wchar_t myvar;
Index: src/gdb/testsuite/gdb.base/charset.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/charset.exp,v
retrieving revision 1.21
diff -u -p -r1.21 charset.exp
--- src/gdb/testsuite/gdb.base/charset.exp	17 Feb 2010 22:05:58 -0000
1.21
+++ src/gdb/testsuite/gdb.base/charset.exp	22 Mar 2010 22:25:35 -0000
@@ -616,4 +616,21 @@ gdb_test "print 'a' == 'a' || 'b' == 'b'
   ".* = 1" \
   "EVAL_SKIP cleanup handling regression test"
 
+
+proc string_display { var_name set_prefix x_size x_type} {
+  gdb_test "set ${var_name} = ${set_prefix}\"Test String\\0with zeroes\""
"" "Assign ${var_name} with prefix ${set_prefix}"
+  gdb_test "x /2${x_size}s ${var_name}" ".* ${x_type}\"Test
String\"\[\r\n\]+.* ${x_type}\"with zeroes\"" "Display String ${var_name}
with x/${x_size}s"
+}
+
+string_display String16 u h u
+if {$wchar_size == 2} {
+  string_display String16 L h u
+}
+ 
+string_display String32 U w U
+if {$wchar_size == 4} {
+  string_display String32 L w U
+}
+
+
 gdb_exit