* [PATCH] gdb: add support for %V to printf command
@ 2023-03-30 12:22 Andrew Burgess
2023-03-30 14:20 ` Eli Zaretskii
2023-04-17 15:47 ` Tom Tromey
0 siblings, 2 replies; 10+ messages in thread
From: Andrew Burgess @ 2023-03-30 12:22 UTC (permalink / raw)
To: gdb-patches; +Cc: Andrew Burgess
This commit adds a new format for the printf and dprintf commands:
'%V'. This new format takes any GDB expression and formats it as a
string, just as GDB would for a 'print' command, e.g.:
(gdb) print a1
$a = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb) printf "%V\n", a1
{2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb)
It is also possible to pass the same options to %V as you might pass
to the print command, e.g.:
(gdb) print -elements 3 -- a1
$4 = {2, 4, 6...}
(gdb) printf "%V[-elements 3]\n", a1
{2, 4, 6...}
(gdb)
This new feature would effectively replace an existing feature of GDB,
the $_as_string builtin convenience function. However, the
$_as_string function has a few problems which this new feature solves:
1. $_as_string doesn't currently work when the inferior is not
running, e.g:
(gdb) printf "%s", $_as_string(a1)
You can't do that without a process to debug.
(gdb)
The reason for this is that $_as_string returns a value object with
string type. When we try to print this we call value_as_address,
which ends up trying to push the string into the inferior's address
space.
Clearly we could solve this problem, the string data exists in GDB, so
there's no reason why we have to push it into the inferior, but this
is an existing problem that would need solving.
2. $_as_string suffers from the fact that C degrades arrays to
pointers, e.g.:
(gdb) printf "%s\n", $_as_string(a1)
0x404260 <a1>
(gdb)
The implementation of $_as_string is passed a gdb.Value object that is
a pointer, it doesn't understand that it's actually an array. Solving
this would be harder than issue #1 I think. The whole array to
pointer transformation is part of our expression evaluation. And in
most cases this is exactly what we want. It's not clear to me how
we'd (easily) tell GDB that we didn't want this reduction in _some_
cases. But I'm sure this is solvable if we really wanted to.
3. $_as_string is a gdb.Function sub-class, and as such is passed
gdb.Value objects. There's no super convenient way to pass formatting
options to $_as_string. By this I mean that the new %V feature
supports print formatting options. Ideally, we might want to add this
feature to $_as_string, we might imagine it working something like:
(gdb) printf "%s\n", $_as_string(a1,
elements = 3,
array_indexes = True)
where the first item is the value to print, while the remaining
options are the print formatting options. However, this relies on
Python calling syntax, which isn't something that convenience
functions handle. We could possibly rely on strictly positional
arguments, like:
(gdb) printf "%s\n", $_as_string(a1, 3, 1)
But that's clearly terrible as there's far more print formatting
options, and if you needed to set the 9th option you'd need to fill in
all the previous options.
And right now, the only way to pass these options to a gdb.Function is
to have GDB first convert them all into gdb.Value objects, which is
really overkill for what we want.
The new %V format solves all these problems: the string is computed
and printed entirely on the GDB side, we are able to print arrays as
actual arrays rather than pointers, and we can pass named format
arguments.
Finally, the $_as_string is sold in the manual as allowing users to
print the string representation of flag enums, so given:
enum flags
{
FLAG_A = (1 << 0),
FLAG_B = (1 << 1),
FLAG_C = (1 << 1)
};
enum flags ff = FLAG_B;
We can:
(gdb) printf "%s\n", $_as_string(ff)
FLAG_B
This works just fine with %V too:
(gdb) printf "%V\n", ff
FLAG_B
So all functionality of $_as_string is replaced by %V. I'm not
proposing to remove $_as_string, there might be users currently
depending on it, but I am proposing that we don't push $_as_string in
the documentation.
---
gdb/NEWS | 9 ++++++++
gdb/doc/gdb.texinfo | 34 ++++++++++++++++++++++++++++
gdb/printcmd.c | 32 +++++++++++++++++++++++++-
gdb/testsuite/gdb.base/printcmds.c | 13 +++++++++++
gdb/testsuite/gdb.base/printcmds.exp | 28 ++++++++++++++++++++++-
gdbsupport/format.cc | 26 +++++++++++++++++++--
gdbsupport/format.h | 6 +++--
7 files changed, 142 insertions(+), 6 deletions(-)
diff --git a/gdb/NEWS b/gdb/NEWS
index ba5ae520112..bde8116cf4a 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -63,6 +63,15 @@
break foo thread 1 task 1
watch var thread 2 task 3
+* The printf command now accepts a '%V' output format which will
+ format an expression just as the 'print' command would. Print
+ options can be placed withing '[...]' after the '%V' to modify how
+ the value is printed. E.g:
+ printf "%V", some_array
+ printf "%V[-array-indexes on]", some_array
+ Will print the array without, or with array indexes included, just
+ as the array would be printed by the 'print' command.
+
* New commands
maintenance print record-instruction [ N ]
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 92d99349dbf..54412177290 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -13131,6 +13131,10 @@
@findex $_as_string@r{, convenience function}
@item $_as_string(@var{value})
+This convenience function is considered deprecated, and could be
+removed from future versions of @value{GDBN}. Use the @kbd{%V} format
+specifier instead (@pxref{%V Format Specifier}).
+
Return the string representation of @var{value}.
This function is useful to obtain the textual label (enumerator) of an
@@ -29025,6 +29029,36 @@
printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
@end smallexample
+@anchor{%V Format Specifier}
+Additionally, @code{printf} supports a special @kbd{%V} output format.
+This format prints the string representation of an expression just as
+@value{GDBN} would produce with the standard @kbd{print} command
+(@pxref{Data, ,Examining Data}):
+
+@smallexample
+(@value{GDBP}) print array
+$1 = @{0, 1, 2, 3, 4, 5@}
+(@value{GDBP}) printf "Array is: %V\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}
+@end smallexample
+
+Additionally, it is possible to include print options with the
+@kbd{%V} format by placing them in @kbd{[...]} immediately after the
+@kbd{%V}, like this:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[-array-indexes on]\n", array
+Array is: @{[0] = 0, [1] = 1, [2] = 2, [3] = 3, [4] = 4, [5] = 5@}
+@end smallexample
+
+If you need to print a literal @kbd{[} directly after a @kbd{%V} then
+just include an empty print options list:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[][Hello]\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}[Hello]
+@end smallexample
+
@anchor{eval}
@kindex eval
@item eval @var{template}, @var{expressions}@dots{}
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index dd92e31d31b..7783606fd9a 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2733,7 +2733,7 @@ ui_printf (const char *arg, struct ui_file *stream)
if (*s++ != '"')
error (_("Bad format string, missing '\"'."));
- format_pieces fpieces (&s);
+ format_pieces fpieces (&s, false, true);
if (*s++ != '"')
error (_("Bad format string, non-terminated '\"'."));
@@ -2875,6 +2875,36 @@ ui_printf (const char *arg, struct ui_file *stream)
case ptr_arg:
printf_pointer (stream, current_substring, val_args[i]);
break;
+ case value_arg:
+ {
+ value_print_options print_opts;
+ get_user_print_options (&print_opts);
+
+ if (current_substring[2] == '[')
+ {
+ std::string args (¤t_substring[3],
+ strlen (¤t_substring[3]) - 1);
+
+ const char *args_ptr = args.c_str ();
+
+ /* Override global settings with explicit options, if
+ any. */
+ auto group
+ = make_value_print_options_def_group (&print_opts);
+ gdb::option::process_options
+ (&args_ptr, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR,
+ group);
+
+ if (*args_ptr != '\0')
+ error (_("unexpected content in print options: %s"),
+ args_ptr);
+ }
+
+ string_file buffer;
+ print_formatted (val_args[i], 0, &print_opts, &buffer);
+ gdb_puts (buffer.string ().c_str ());
+ }
+ break;
case literal_piece:
/* Print a portion of the format string that has no
directives. Note that this will not include any
diff --git a/gdb/testsuite/gdb.base/printcmds.c b/gdb/testsuite/gdb.base/printcmds.c
index 78291a2803c..fa3a62d6cdd 100644
--- a/gdb/testsuite/gdb.base/printcmds.c
+++ b/gdb/testsuite/gdb.base/printcmds.c
@@ -108,6 +108,7 @@ enum flag_enum
FE_TWO_LEGACY = 0x02,
};
+enum flag_enum one = FE_ONE;
enum flag_enum three = (enum flag_enum) (FE_ONE | FE_TWO);
/* Another enum considered as a "flag enum", but with no enumerator with value
@@ -152,6 +153,18 @@ struct some_struct
}
};
+/* This is used in the printf test. */
+struct small_struct
+{
+ int a;
+ int b;
+ int c;
+} a_small_struct = {
+ 1,
+ 2,
+ 3
+};
+
/* The following variables are used for testing byte repeat sequences.
The variable names are encoded: invalid_XYZ where:
X = start
diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index 21a2cad458c..10275720e8f 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -957,6 +957,32 @@ proc test_printf_with_dfp {} {
gdb_test "printf \"%Hf %Hf\\n\",1.2df,1.3df" "1.2 1.3"
}
+# Test the printf '%V' format.
+proc test_printf_V_format {} {
+ # Enums.
+ gdb_test {printf "%V\n", one} "FE_ONE"
+ gdb_test {printf "%V\n", three} "\\(FE_ONE \\| FE_TWO\\)"
+ gdb_test {printf "%V\n", flag_enum_without_zero} "0"
+ gdb_test {printf "%V\n", three_not_flag} "3"
+
+ # Arrays.
+ gdb_test {printf "%V\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[]\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[][]\n", a1} \
+ "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3]\n", a1} "\\{2, 4, 6\\.\\.\\.\\}"
+ gdb_test {printf "%V[-elements 3][]\n", a1} \
+ "\\{2, 4, 6\\.\\.\\.\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3 -array-indexes on]\n", a1} \
+ "\\{\\\[0\\\] = 2, \\\[1\\\] = 4, \\\[2\\\] = 6\\.\\.\\.\\}"
+
+ # Structures.
+ gdb_test {printf "%V\n", a_small_struct} \
+ "\\{a = 1, b = 2, c = 3\\}"
+ gdb_test {printf "%V[-pretty on]\n", a_small_struct} \
+ "\\{\r\n a = 1,\r\n b = 2,\r\n c = 3\r\n\\}"
+}
+
proc test_print_symbol {} {
gdb_test_no_output "set print symbol on"
@@ -1086,7 +1112,6 @@ proc test_printf_convenience_var {prefix} {
}
}
-
clean_restart
gdb_test "print \$pc" "No registers\\."
@@ -1171,6 +1196,7 @@ test_print_array_constants
test_print_enums
test_printf
test_printf_with_dfp
+test_printf_V_format
test_print_symbol
test_repeat_bytes
test_radices
diff --git a/gdbsupport/format.cc b/gdbsupport/format.cc
index 19f37ec8e0c..2edeb5033be 100644
--- a/gdbsupport/format.cc
+++ b/gdbsupport/format.cc
@@ -20,7 +20,8 @@
#include "common-defs.h"
#include "format.h"
-format_pieces::format_pieces (const char **arg, bool gdb_extensions)
+format_pieces::format_pieces (const char **arg, bool gdb_extensions,
+ bool value_extension)
{
const char *s;
const char *string;
@@ -44,7 +45,7 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
char *f = (char *) alloca (strlen (s) + 1);
string = f;
- while ((gdb_extensions || *s != '"') && *s != '\0')
+ while (*s != '"' && *s != '\0')
{
int c = *s++;
switch (c)
@@ -340,6 +341,27 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
bad = 1;
break;
+ case 'V':
+ if (!value_extension)
+ error (_("Unrecognized format specifier '%c' in printf"), *f);
+
+ if (lcount > 1 || seen_h || seen_big_h || seen_big_h
+ || seen_big_d || seen_double_big_d || seen_size_t
+ || seen_prec || seen_zero || seen_space || seen_plus)
+ bad = 1;
+
+ this_argclass = value_arg;
+
+ if (f[1] == '[')
+ {
+ const char *tmp;
+ for (tmp = f; *tmp != ']' && *tmp != '\0'; ++tmp)
+ ;
+ if (*tmp == ']')
+ f = tmp;
+ }
+ break;
+
case '*':
error (_("`*' not supported for precision or width in printf"));
diff --git a/gdbsupport/format.h b/gdbsupport/format.h
index 342b473c3ed..2af34ab9450 100644
--- a/gdbsupport/format.h
+++ b/gdbsupport/format.h
@@ -41,7 +41,8 @@ enum argclass
int_arg, long_arg, long_long_arg, size_t_arg, ptr_arg,
string_arg, wide_string_arg, wide_char_arg,
double_arg, long_double_arg,
- dec32float_arg, dec64float_arg, dec128float_arg
+ dec32float_arg, dec64float_arg, dec128float_arg,
+ value_arg
};
/* A format piece is a section of the format string that may include a
@@ -75,7 +76,8 @@ class format_pieces
{
public:
- format_pieces (const char **arg, bool gdb_extensions = false);
+ format_pieces (const char **arg, bool gdb_extensions = false,
+ bool value_extension = false);
~format_pieces () = default;
DISABLE_COPY_AND_ASSIGN (format_pieces);
base-commit: 3712e78cab09017bf59105d44e2f745c5e608c5a
--
2.25.4
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] gdb: add support for %V to printf command
2023-03-30 12:22 [PATCH] gdb: add support for %V to printf command Andrew Burgess
@ 2023-03-30 14:20 ` Eli Zaretskii
2023-04-11 12:34 ` Andrew Burgess
2023-04-17 15:47 ` Tom Tromey
1 sibling, 1 reply; 10+ messages in thread
From: Eli Zaretskii @ 2023-03-30 14:20 UTC (permalink / raw)
To: Andrew Burgess; +Cc: gdb-patches
> Cc: Andrew Burgess <aburgess@redhat.com>
> Date: Thu, 30 Mar 2023 13:22:10 +0100
> From: Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org>
>
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -63,6 +63,15 @@
> break foo thread 1 task 1
> watch var thread 2 task 3
>
> +* The printf command now accepts a '%V' output format which will
> + format an expression just as the 'print' command would. Print
> + options can be placed withing '[...]' after the '%V' to modify how
> + the value is printed. E.g:
> + printf "%V", some_array
> + printf "%V[-array-indexes on]", some_array
> + Will print the array without, or with array indexes included, just
^^^^
That "Will" should not be capitalized.
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -13131,6 +13131,10 @@
>
> @findex $_as_string@r{, convenience function}
> @item $_as_string(@var{value})
> +This convenience function is considered deprecated, and could be
> +removed from future versions of @value{GDBN}. Use the @kbd{%V} format
> +specifier instead (@pxref{%V Format Specifier}). ^^^^^^^^
Please use @samp, not @kbd there, as we are not describing commands
typed by the user.
> +@anchor{%V Format Specifier}
> +Additionally, @code{printf} supports a special @kbd{%V} output format.
^^^^^^^^
Likewise.
> +Additionally, it is possible to include print options with the
> +@kbd{%V} format by placing them in @kbd{[...]} immediately after the
> +@kbd{%V}, like this: ^^^^^^^^^^^
^^^^^^^^
@samp again there.
Thanks.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] gdb: add support for %V to printf command
2023-03-30 14:20 ` Eli Zaretskii
@ 2023-04-11 12:34 ` Andrew Burgess
0 siblings, 0 replies; 10+ messages in thread
From: Andrew Burgess @ 2023-04-11 12:34 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: gdb-patches
Eli Zaretskii <eliz@gnu.org> writes:
>> Cc: Andrew Burgess <aburgess@redhat.com>
>> Date: Thu, 30 Mar 2023 13:22:10 +0100
>> From: Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org>
>>
>> --- a/gdb/NEWS
>> +++ b/gdb/NEWS
>> @@ -63,6 +63,15 @@
>> break foo thread 1 task 1
>> watch var thread 2 task 3
>>
>> +* The printf command now accepts a '%V' output format which will
>> + format an expression just as the 'print' command would. Print
>> + options can be placed withing '[...]' after the '%V' to modify how
>> + the value is printed. E.g:
>> + printf "%V", some_array
>> + printf "%V[-array-indexes on]", some_array
>> + Will print the array without, or with array indexes included, just
> ^^^^
> That "Will" should not be capitalized.
>
>> --- a/gdb/doc/gdb.texinfo
>> +++ b/gdb/doc/gdb.texinfo
>> @@ -13131,6 +13131,10 @@
>>
>> @findex $_as_string@r{, convenience function}
>> @item $_as_string(@var{value})
>> +This convenience function is considered deprecated, and could be
>> +removed from future versions of @value{GDBN}. Use the @kbd{%V} format
>> +specifier instead (@pxref{%V Format Specifier}). ^^^^^^^^
>
> Please use @samp, not @kbd there, as we are not describing commands
> typed by the user.
>
>> +@anchor{%V Format Specifier}
>> +Additionally, @code{printf} supports a special @kbd{%V} output format.
> ^^^^^^^^
> Likewise.
>
>> +Additionally, it is possible to include print options with the
>> +@kbd{%V} format by placing them in @kbd{[...]} immediately after the
>> +@kbd{%V}, like this: ^^^^^^^^^^^
> ^^^^^^^^
> @samp again there.
>
> Thanks.
>
> Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Thanks for the feedback. I fixed all the issues you pointed out.
The updated patch is below, but there's no need to reread it unless you
want to. The fixes all seemed pretty straight forward.
Thanks,
Andrew
---
commit 58458800a40bd066a9621b4a19b63630bc087c1f
Author: Andrew Burgess <aburgess@redhat.com>
Date: Thu Mar 23 12:12:38 2023 +0000
gdb: add support for %V to printf command
This commit adds a new format for the printf and dprintf commands:
'%V'. This new format takes any GDB expression and formats it as a
string, just as GDB would for a 'print' command, e.g.:
(gdb) print a1
$a = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb) printf "%V\n", a1
{2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb)
It is also possible to pass the same options to %V as you might pass
to the print command, e.g.:
(gdb) print -elements 3 -- a1
$4 = {2, 4, 6...}
(gdb) printf "%V[-elements 3]\n", a1
{2, 4, 6...}
(gdb)
This new feature would effectively replace an existing feature of GDB,
the $_as_string builtin convenience function. However, the
$_as_string function has a few problems which this new feature solves:
1. $_as_string doesn't currently work when the inferior is not
running, e.g:
(gdb) printf "%s", $_as_string(a1)
You can't do that without a process to debug.
(gdb)
The reason for this is that $_as_string returns a value object with
string type. When we try to print this we call value_as_address,
which ends up trying to push the string into the inferior's address
space.
Clearly we could solve this problem, the string data exists in GDB, so
there's no reason why we have to push it into the inferior, but this
is an existing problem that would need solving.
2. $_as_string suffers from the fact that C degrades arrays to
pointers, e.g.:
(gdb) printf "%s\n", $_as_string(a1)
0x404260 <a1>
(gdb)
The implementation of $_as_string is passed a gdb.Value object that is
a pointer, it doesn't understand that it's actually an array. Solving
this would be harder than issue #1 I think. The whole array to
pointer transformation is part of our expression evaluation. And in
most cases this is exactly what we want. It's not clear to me how
we'd (easily) tell GDB that we didn't want this reduction in _some_
cases. But I'm sure this is solvable if we really wanted to.
3. $_as_string is a gdb.Function sub-class, and as such is passed
gdb.Value objects. There's no super convenient way to pass formatting
options to $_as_string. By this I mean that the new %V feature
supports print formatting options. Ideally, we might want to add this
feature to $_as_string, we might imagine it working something like:
(gdb) printf "%s\n", $_as_string(a1,
elements = 3,
array_indexes = True)
where the first item is the value to print, while the remaining
options are the print formatting options. However, this relies on
Python calling syntax, which isn't something that convenience
functions handle. We could possibly rely on strictly positional
arguments, like:
(gdb) printf "%s\n", $_as_string(a1, 3, 1)
But that's clearly terrible as there's far more print formatting
options, and if you needed to set the 9th option you'd need to fill in
all the previous options.
And right now, the only way to pass these options to a gdb.Function is
to have GDB first convert them all into gdb.Value objects, which is
really overkill for what we want.
The new %V format solves all these problems: the string is computed
and printed entirely on the GDB side, we are able to print arrays as
actual arrays rather than pointers, and we can pass named format
arguments.
Finally, the $_as_string is sold in the manual as allowing users to
print the string representation of flag enums, so given:
enum flags
{
FLAG_A = (1 << 0),
FLAG_B = (1 << 1),
FLAG_C = (1 << 1)
};
enum flags ff = FLAG_B;
We can:
(gdb) printf "%s\n", $_as_string(ff)
FLAG_B
This works just fine with %V too:
(gdb) printf "%V\n", ff
FLAG_B
So all functionality of $_as_string is replaced by %V. I'm not
proposing to remove $_as_string, there might be users currently
depending on it, but I am proposing that we don't push $_as_string in
the documentation.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
diff --git a/gdb/NEWS b/gdb/NEWS
index 10a1a70fa52..d84f04b9a88 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -63,6 +63,15 @@
break foo thread 1 task 1
watch var thread 2 task 3
+* The printf command now accepts a '%V' output format which will
+ format an expression just as the 'print' command would. Print
+ options can be placed withing '[...]' after the '%V' to modify how
+ the value is printed. E.g:
+ printf "%V", some_array
+ printf "%V[-array-indexes on]", some_array
+ will print the array without, or with array indexes included, just
+ as the array would be printed by the 'print' command.
+
* New commands
maintenance print record-instruction [ N ]
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 2d5358a792b..b0621b297f1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -13131,6 +13131,10 @@
@findex $_as_string@r{, convenience function}
@item $_as_string(@var{value})
+This convenience function is considered deprecated, and could be
+removed from future versions of @value{GDBN}. Use the @samp{%V} format
+specifier instead (@pxref{%V Format Specifier}).
+
Return the string representation of @var{value}.
This function is useful to obtain the textual label (enumerator) of an
@@ -29031,6 +29035,36 @@
printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
@end smallexample
+@anchor{%V Format Specifier}
+Additionally, @code{printf} supports a special @samp{%V} output format.
+This format prints the string representation of an expression just as
+@value{GDBN} would produce with the standard @kbd{print} command
+(@pxref{Data, ,Examining Data}):
+
+@smallexample
+(@value{GDBP}) print array
+$1 = @{0, 1, 2, 3, 4, 5@}
+(@value{GDBP}) printf "Array is: %V\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}
+@end smallexample
+
+Additionally, it is possible to include print options with the
+@samp{%V} format by placing them in @samp{[...]} immediately after the
+@samp{%V}, like this:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[-array-indexes on]\n", array
+Array is: @{[0] = 0, [1] = 1, [2] = 2, [3] = 3, [4] = 4, [5] = 5@}
+@end smallexample
+
+If you need to print a literal @samp{[} directly after a @samp{%V} then
+just include an empty print options list:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[][Hello]\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}[Hello]
+@end smallexample
+
@anchor{eval}
@kindex eval
@item eval @var{template}, @var{expressions}@dots{}
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index dd92e31d31b..7783606fd9a 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2733,7 +2733,7 @@ ui_printf (const char *arg, struct ui_file *stream)
if (*s++ != '"')
error (_("Bad format string, missing '\"'."));
- format_pieces fpieces (&s);
+ format_pieces fpieces (&s, false, true);
if (*s++ != '"')
error (_("Bad format string, non-terminated '\"'."));
@@ -2875,6 +2875,36 @@ ui_printf (const char *arg, struct ui_file *stream)
case ptr_arg:
printf_pointer (stream, current_substring, val_args[i]);
break;
+ case value_arg:
+ {
+ value_print_options print_opts;
+ get_user_print_options (&print_opts);
+
+ if (current_substring[2] == '[')
+ {
+ std::string args (¤t_substring[3],
+ strlen (¤t_substring[3]) - 1);
+
+ const char *args_ptr = args.c_str ();
+
+ /* Override global settings with explicit options, if
+ any. */
+ auto group
+ = make_value_print_options_def_group (&print_opts);
+ gdb::option::process_options
+ (&args_ptr, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR,
+ group);
+
+ if (*args_ptr != '\0')
+ error (_("unexpected content in print options: %s"),
+ args_ptr);
+ }
+
+ string_file buffer;
+ print_formatted (val_args[i], 0, &print_opts, &buffer);
+ gdb_puts (buffer.string ().c_str ());
+ }
+ break;
case literal_piece:
/* Print a portion of the format string that has no
directives. Note that this will not include any
diff --git a/gdb/testsuite/gdb.base/printcmds.c b/gdb/testsuite/gdb.base/printcmds.c
index 78291a2803c..fa3a62d6cdd 100644
--- a/gdb/testsuite/gdb.base/printcmds.c
+++ b/gdb/testsuite/gdb.base/printcmds.c
@@ -108,6 +108,7 @@ enum flag_enum
FE_TWO_LEGACY = 0x02,
};
+enum flag_enum one = FE_ONE;
enum flag_enum three = (enum flag_enum) (FE_ONE | FE_TWO);
/* Another enum considered as a "flag enum", but with no enumerator with value
@@ -152,6 +153,18 @@ struct some_struct
}
};
+/* This is used in the printf test. */
+struct small_struct
+{
+ int a;
+ int b;
+ int c;
+} a_small_struct = {
+ 1,
+ 2,
+ 3
+};
+
/* The following variables are used for testing byte repeat sequences.
The variable names are encoded: invalid_XYZ where:
X = start
diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index 21a2cad458c..10275720e8f 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -957,6 +957,32 @@ proc test_printf_with_dfp {} {
gdb_test "printf \"%Hf %Hf\\n\",1.2df,1.3df" "1.2 1.3"
}
+# Test the printf '%V' format.
+proc test_printf_V_format {} {
+ # Enums.
+ gdb_test {printf "%V\n", one} "FE_ONE"
+ gdb_test {printf "%V\n", three} "\\(FE_ONE \\| FE_TWO\\)"
+ gdb_test {printf "%V\n", flag_enum_without_zero} "0"
+ gdb_test {printf "%V\n", three_not_flag} "3"
+
+ # Arrays.
+ gdb_test {printf "%V\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[]\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[][]\n", a1} \
+ "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3]\n", a1} "\\{2, 4, 6\\.\\.\\.\\}"
+ gdb_test {printf "%V[-elements 3][]\n", a1} \
+ "\\{2, 4, 6\\.\\.\\.\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3 -array-indexes on]\n", a1} \
+ "\\{\\\[0\\\] = 2, \\\[1\\\] = 4, \\\[2\\\] = 6\\.\\.\\.\\}"
+
+ # Structures.
+ gdb_test {printf "%V\n", a_small_struct} \
+ "\\{a = 1, b = 2, c = 3\\}"
+ gdb_test {printf "%V[-pretty on]\n", a_small_struct} \
+ "\\{\r\n a = 1,\r\n b = 2,\r\n c = 3\r\n\\}"
+}
+
proc test_print_symbol {} {
gdb_test_no_output "set print symbol on"
@@ -1086,7 +1112,6 @@ proc test_printf_convenience_var {prefix} {
}
}
-
clean_restart
gdb_test "print \$pc" "No registers\\."
@@ -1171,6 +1196,7 @@ test_print_array_constants
test_print_enums
test_printf
test_printf_with_dfp
+test_printf_V_format
test_print_symbol
test_repeat_bytes
test_radices
diff --git a/gdbsupport/format.cc b/gdbsupport/format.cc
index 19f37ec8e0c..2edeb5033be 100644
--- a/gdbsupport/format.cc
+++ b/gdbsupport/format.cc
@@ -20,7 +20,8 @@
#include "common-defs.h"
#include "format.h"
-format_pieces::format_pieces (const char **arg, bool gdb_extensions)
+format_pieces::format_pieces (const char **arg, bool gdb_extensions,
+ bool value_extension)
{
const char *s;
const char *string;
@@ -44,7 +45,7 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
char *f = (char *) alloca (strlen (s) + 1);
string = f;
- while ((gdb_extensions || *s != '"') && *s != '\0')
+ while (*s != '"' && *s != '\0')
{
int c = *s++;
switch (c)
@@ -340,6 +341,27 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
bad = 1;
break;
+ case 'V':
+ if (!value_extension)
+ error (_("Unrecognized format specifier '%c' in printf"), *f);
+
+ if (lcount > 1 || seen_h || seen_big_h || seen_big_h
+ || seen_big_d || seen_double_big_d || seen_size_t
+ || seen_prec || seen_zero || seen_space || seen_plus)
+ bad = 1;
+
+ this_argclass = value_arg;
+
+ if (f[1] == '[')
+ {
+ const char *tmp;
+ for (tmp = f; *tmp != ']' && *tmp != '\0'; ++tmp)
+ ;
+ if (*tmp == ']')
+ f = tmp;
+ }
+ break;
+
case '*':
error (_("`*' not supported for precision or width in printf"));
diff --git a/gdbsupport/format.h b/gdbsupport/format.h
index 342b473c3ed..2af34ab9450 100644
--- a/gdbsupport/format.h
+++ b/gdbsupport/format.h
@@ -41,7 +41,8 @@ enum argclass
int_arg, long_arg, long_long_arg, size_t_arg, ptr_arg,
string_arg, wide_string_arg, wide_char_arg,
double_arg, long_double_arg,
- dec32float_arg, dec64float_arg, dec128float_arg
+ dec32float_arg, dec64float_arg, dec128float_arg,
+ value_arg
};
/* A format piece is a section of the format string that may include a
@@ -75,7 +76,8 @@ class format_pieces
{
public:
- format_pieces (const char **arg, bool gdb_extensions = false);
+ format_pieces (const char **arg, bool gdb_extensions = false,
+ bool value_extension = false);
~format_pieces () = default;
DISABLE_COPY_AND_ASSIGN (format_pieces);
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] gdb: add support for %V to printf command
2023-03-30 12:22 [PATCH] gdb: add support for %V to printf command Andrew Burgess
2023-03-30 14:20 ` Eli Zaretskii
@ 2023-04-17 15:47 ` Tom Tromey
2023-04-28 13:14 ` [PATCHv2] " Andrew Burgess
1 sibling, 1 reply; 10+ messages in thread
From: Tom Tromey @ 2023-04-17 15:47 UTC (permalink / raw)
To: Andrew Burgess via Gdb-patches; +Cc: Andrew Burgess
>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
Andrew> This commit adds a new format for the printf and dprintf commands:
Andrew> '%V'. This new format takes any GDB expression and formats it as a
Andrew> string, just as GDB would for a 'print' command, e.g.:
Thank you for doing this. I'm definitely a fan of the idea.
Andrew> --- a/gdb/printcmd.c
Andrew> +++ b/gdb/printcmd.c
Andrew> @@ -2733,7 +2733,7 @@ ui_printf (const char *arg, struct ui_file *stream)
Andrew> if (*s++ != '"')
Andrew> error (_("Bad format string, missing '\"'."));
Andrew> - format_pieces fpieces (&s);
Andrew> + format_pieces fpieces (&s, false, true);
I was going to ask if there is a spot that sets gdb_extensions=false and
the new flag=true. This setting seems odd to me, but I didn't dig
through to find out why it's needed.
Andrew> + string_file buffer;
Andrew> + print_formatted (val_args[i], 0, &print_opts, &buffer);
Andrew> + gdb_puts (buffer.string ().c_str ());
Why is a second stream needed here? Like, couldn't print_formatted be
called with 'stream'? Wouldn't that preserve any styling done by
print_formatted? Or is the intention to strip styling?
Andrew> + if (f[1] == '[')
Andrew> + {
Andrew> + const char *tmp;
Andrew> + for (tmp = f; *tmp != ']' && *tmp != '\0'; ++tmp)
Andrew> + ;
Andrew> + if (*tmp == ']')
Andrew> + f = tmp;
strchr if it simplifies things.
I didn't dig into this either, but I don't think %V could work in
dprintf's call or agent modes. So, maybe gdb should reject this
somewhere. Or maybe this is already done by the default setting in the
constructor?
Tom
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCHv2] gdb: add support for %V to printf command
2023-04-17 15:47 ` Tom Tromey
@ 2023-04-28 13:14 ` Andrew Burgess
2023-04-28 15:34 ` Eli Zaretskii
2023-05-12 13:01 ` [PATCHv3] " Andrew Burgess
0 siblings, 2 replies; 10+ messages in thread
From: Andrew Burgess @ 2023-04-28 13:14 UTC (permalink / raw)
To: Tom Tromey, Andrew Burgess via Gdb-patches, Eli Zaretskii
Tom Tromey <tom@tromey.com> writes:
>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>
> Andrew> This commit adds a new format for the printf and dprintf commands:
> Andrew> '%V'. This new format takes any GDB expression and formats it as a
> Andrew> string, just as GDB would for a 'print' command, e.g.:
>
> Thank you for doing this. I'm definitely a fan of the idea.
>
> Andrew> --- a/gdb/printcmd.c
> Andrew> +++ b/gdb/printcmd.c
> Andrew> @@ -2733,7 +2733,7 @@ ui_printf (const char *arg, struct ui_file *stream)
> Andrew> if (*s++ != '"')
> Andrew> error (_("Bad format string, missing '\"'."));
>
> Andrew> - format_pieces fpieces (&s);
> Andrew> + format_pieces fpieces (&s, false, true);
>
> I was going to ask if there is a spot that sets gdb_extensions=false and
> the new flag=true. This setting seems odd to me, but I didn't dig
> through to find out why it's needed.
I'm not 100% sure what you're asking here, so apologies if I just go
broad with my reply hoping I address your question.
The gdb_extensions flag turns on/off features are format_pieces that are
used internal by GDB, e.g. field width support and styling support. We
don't want to allow these within printf/dprintf hence the first flag
being false in the above.
The new flag (value_extension) is separate, this is something (I
propose) we offer in printf/dprintf, but isn't something that I think we
should offer to GDB's internal print routines -- though that is
potentially an interesting idea? But is more than I wanted to take on
in a first cut of this work.
Hopefully that explains why we have two separate flags, and why we see
the false/true combo above -- this is the printf code, so we don't want
the GDB internal printf features, but we do want the %V value extension.
>
> Andrew> + string_file buffer;
> Andrew> + print_formatted (val_args[i], 0, &print_opts, &buffer);
> Andrew> + gdb_puts (buffer.string ().c_str ());
>
> Why is a second stream needed here? Like, couldn't print_formatted be
> called with 'stream'? Wouldn't that preserve any styling done by
> print_formatted? Or is the intention to strip styling?
The intention was to remove any styling. But thinking about it a little
more, I don't think we actually style any value text right now. So
given the extra overhead, it's probably best to just go directly to
stream.
... but I'm glad you said something, notice the gdb_puts call doesn't
actually write to stream, but instead always writes to gdb_stdout --
that's a bug :/
Anyway, simplified to write directly to stream now.
>
> Andrew> + if (f[1] == '[')
> Andrew> + {
> Andrew> + const char *tmp;
> Andrew> + for (tmp = f; *tmp != ']' && *tmp != '\0'; ++tmp)
> Andrew> + ;
> Andrew> + if (*tmp == ']')
> Andrew> + f = tmp;
>
> strchr if it simplifies things.
It does. Done.
>
> I didn't dig into this either, but I don't think %V could work in
> dprintf's call or agent modes. So, maybe gdb should reject this
> somewhere. Or maybe this is already done by the default setting in the
> constructor?
You're right that %V isn't going to work with 'agent' mode. For 'call'
mode, I think my answer is, well... maybe...
In call mode I don't think we should validate the format string at
all -- we certainly don't right now. The user might be calling a
function that already supports custom format specifiers, maybe even
including '%V', and that's fine, I don't see any problem with that. In
'call' mode we just forward the format string and arguments as the user
wrote them. What I have done is extend the documentation to make it
clear in this case that support for '%V' (or any format specifier)
depends on the output function being used.
In agent mode the user will get an error just as they would with any
other unknown format specifier. Currently the only place we accept '%V'
is when handling a 'printf' -- the 'agent-printf' code (which is used
when in 'agent' style) doesn't check for '%V' and so will error if one
is seen. I've extended the documentation to make this clear.
So I think this last concern is addressed by extending the
documentation.
The updated patch is below. Let me know what you think.
Thanks,
Andrew
---
Changes since V1:
- Documentation extensions to explain support for %V in different
dprintf styles,
- Write value directly to stream in ui_printf (printcmd.c),
- Use of strchr to simplify code in format_pieces::format_pieces
(format.cc).
---
commit df87c78703e6b5585bb6a63fc2799fd0348e36c5
Author: Andrew Burgess <aburgess@redhat.com>
Date: Thu Mar 23 12:12:38 2023 +0000
gdb: add support for %V to printf command
This commit adds a new format for the printf and dprintf commands:
'%V'. This new format takes any GDB expression and formats it as a
string, just as GDB would for a 'print' command, e.g.:
(gdb) print a1
$a = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb) printf "%V\n", a1
{2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb)
It is also possible to pass the same options to %V as you might pass
to the print command, e.g.:
(gdb) print -elements 3 -- a1
$4 = {2, 4, 6...}
(gdb) printf "%V[-elements 3]\n", a1
{2, 4, 6...}
(gdb)
This new feature would effectively replace an existing feature of GDB,
the $_as_string builtin convenience function. However, the
$_as_string function has a few problems which this new feature solves:
1. $_as_string doesn't currently work when the inferior is not
running, e.g:
(gdb) printf "%s", $_as_string(a1)
You can't do that without a process to debug.
(gdb)
The reason for this is that $_as_string returns a value object with
string type. When we try to print this we call value_as_address,
which ends up trying to push the string into the inferior's address
space.
Clearly we could solve this problem, the string data exists in GDB, so
there's no reason why we have to push it into the inferior, but this
is an existing problem that would need solving.
2. $_as_string suffers from the fact that C degrades arrays to
pointers, e.g.:
(gdb) printf "%s\n", $_as_string(a1)
0x404260 <a1>
(gdb)
The implementation of $_as_string is passed a gdb.Value object that is
a pointer, it doesn't understand that it's actually an array. Solving
this would be harder than issue #1 I think. The whole array to
pointer transformation is part of our expression evaluation. And in
most cases this is exactly what we want. It's not clear to me how
we'd (easily) tell GDB that we didn't want this reduction in _some_
cases. But I'm sure this is solvable if we really wanted to.
3. $_as_string is a gdb.Function sub-class, and as such is passed
gdb.Value objects. There's no super convenient way to pass formatting
options to $_as_string. By this I mean that the new %V feature
supports print formatting options. Ideally, we might want to add this
feature to $_as_string, we might imagine it working something like:
(gdb) printf "%s\n", $_as_string(a1,
elements = 3,
array_indexes = True)
where the first item is the value to print, while the remaining
options are the print formatting options. However, this relies on
Python calling syntax, which isn't something that convenience
functions handle. We could possibly rely on strictly positional
arguments, like:
(gdb) printf "%s\n", $_as_string(a1, 3, 1)
But that's clearly terrible as there's far more print formatting
options, and if you needed to set the 9th option you'd need to fill in
all the previous options.
And right now, the only way to pass these options to a gdb.Function is
to have GDB first convert them all into gdb.Value objects, which is
really overkill for what we want.
The new %V format solves all these problems: the string is computed
and printed entirely on the GDB side, we are able to print arrays as
actual arrays rather than pointers, and we can pass named format
arguments.
Finally, the $_as_string is sold in the manual as allowing users to
print the string representation of flag enums, so given:
enum flags
{
FLAG_A = (1 << 0),
FLAG_B = (1 << 1),
FLAG_C = (1 << 1)
};
enum flags ff = FLAG_B;
We can:
(gdb) printf "%s\n", $_as_string(ff)
FLAG_B
This works just fine with %V too:
(gdb) printf "%V\n", ff
FLAG_B
So all functionality of $_as_string is replaced by %V. I'm not
proposing to remove $_as_string, there might be users currently
depending on it, but I am proposing that we don't push $_as_string in
the documentation.
As %V is a feature of printf, GDB's dprintf breakpoints naturally gain
access to this feature too. dprintf breakpoints can be operated in
three different styles 'gdb' (use GDB's printf), 'call' (call a
function in the inferior), or 'agent' (perform the dprintf on the
remote).
The use of '%V' will work just fine when dprintf-style is 'gdb'.
When dprintf-style is 'call' the format string and arguments are
passed to an inferior function (printf by default). In this case GDB
doesn't prevent use of '%V', but the documentation makes it clear that
support for '%V' will depend on the inferior function being called.
I chose this approach because the current implementation doesn't place
any restrictions on the format string when operating in 'call' style.
That is, the user might already be calling a function that supports
custom print format specifiers (maybe including '%V') so, I claim, it
would be wrong to block use of '%V' in this case. The documentation
does make it clear that users shouldn't expect this to "just work"
though.
When dprintf-style is 'agent' then GDB does no support the use of
'%V' (right now). This is handled at the point when GDB tries to
process the format string and send the dprintf command to the remote,
here's an example:
Reading symbols from /tmp/hello.x...
(gdb) dprintf call_me, "%V", a1
Dprintf 1 at 0x401152: file /tmp/hello.c, line 8.
(gdb) set sysroot /
(gdb) target remote | gdbserver --once - /tmp/hello.x
Remote debugging using | gdbserver --once - /tmp/hello.x
stdin/stdout redirected
Process /tmp/hello.x created; pid = 3088822
Remote debugging using stdio
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007ffff7fd3110 in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) set dprintf-style agent
(gdb) c
Continuing.
Unrecognized format specifier 'V' in printf
Command aborted.
(gdb)
This is exactly how GDB would handle any other invalid format
specifier, for example:
Reading symbols from /tmp/hello.x...
(gdb) dprintf call_me, "%Q", a1
Dprintf 1 at 0x401152: file /tmp/hello.c, line 8.
(gdb) set sysroot /
(gdb) target remote | gdbserver --once - /tmp/hello.x
Remote debugging using | gdbserver --once - /tmp/hello.x
stdin/stdout redirected
Process /tmp/hello.x created; pid = 3089193
Remote debugging using stdio
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007ffff7fd3110 in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) set dprintf-style agent
(gdb) c
Continuing.
Unrecognized format specifier 'Q' in printf
Command aborted.
(gdb)
The error message isn't the greatest, but improving that can be put
off for another day I hope.
diff --git a/gdb/NEWS b/gdb/NEWS
index 54b5da21245..c85d071e390 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -67,6 +67,15 @@
break foo thread 1 task 1
watch var thread 2 task 3
+* The printf command now accepts a '%V' output format which will
+ format an expression just as the 'print' command would. Print
+ options can be placed withing '[...]' after the '%V' to modify how
+ the value is printed. E.g:
+ printf "%V", some_array
+ printf "%V[-array-indexes on]", some_array
+ will print the array without, or with array indexes included, just
+ as the array would be printed by the 'print' command.
+
* New commands
maintenance print record-instruction [ N ]
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 263326d54e7..f37e238ea41 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -5961,18 +5961,29 @@
@table @code
@item gdb
@kindex dprintf-style gdb
-Handle the output using the @value{GDBN} @code{printf} command.
+Handle the output using the @value{GDBN} @code{printf} command. When
+using this style it is possible to use the @samp{%V} format specifier
+(@pxref{%V Format Specifier}).
@item call
@kindex dprintf-style call
Handle the output by calling a function in your program (normally
-@code{printf}).
+@code{printf}). When using this style the supported format specifiers
+depend entirely on the function being called.
+
+Most of @value{GDB}'s format specifiers align with those supported by
+the @code{printf} function, however, @value{GDB}'s @samp{%V} format
+specifier extension is not supported by @code{printf}. When using
+@samp{call} style dprintf care should be taken to ensure that only
+format specifiers supported by the output function are used otherwise
+the results will be undefined.
@item agent
@kindex dprintf-style agent
-Have the remote debugging agent (such as @code{gdbserver}) handle
-the output itself. This style is only available for agents that
-support running commands on the target.
+Have the remote debugging agent (such as @code{gdbserver}) handle the
+output itself. This style is only available for agents that support
+running commands on the target. This style does not support the
+@samp{%V} format specifier.
@end table
@item set dprintf-function @var{function}
@@ -13139,6 +13150,10 @@
@findex $_as_string@r{, convenience function}
@item $_as_string(@var{value})
+This convenience function is considered deprecated, and could be
+removed from future versions of @value{GDBN}. Use the @samp{%V} format
+specifier instead (@pxref{%V Format Specifier}).
+
Return the string representation of @var{value}.
This function is useful to obtain the textual label (enumerator) of an
@@ -29047,6 +29062,36 @@
printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
@end smallexample
+@anchor{%V Format Specifier}
+Additionally, @code{printf} supports a special @samp{%V} output format.
+This format prints the string representation of an expression just as
+@value{GDBN} would produce with the standard @kbd{print} command
+(@pxref{Data, ,Examining Data}):
+
+@smallexample
+(@value{GDBP}) print array
+$1 = @{0, 1, 2, 3, 4, 5@}
+(@value{GDBP}) printf "Array is: %V\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}
+@end smallexample
+
+Additionally, it is possible to include print options with the
+@samp{%V} format by placing them in @samp{[...]} immediately after the
+@samp{%V}, like this:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[-array-indexes on]\n", array
+Array is: @{[0] = 0, [1] = 1, [2] = 2, [3] = 3, [4] = 4, [5] = 5@}
+@end smallexample
+
+If you need to print a literal @samp{[} directly after a @samp{%V} then
+just include an empty print options list:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[][Hello]\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}[Hello]
+@end smallexample
+
@anchor{eval}
@kindex eval
@item eval @var{template}, @var{expressions}@dots{}
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index dd92e31d31b..d7126cc5d15 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2733,7 +2733,7 @@ ui_printf (const char *arg, struct ui_file *stream)
if (*s++ != '"')
error (_("Bad format string, missing '\"'."));
- format_pieces fpieces (&s);
+ format_pieces fpieces (&s, false, true);
if (*s++ != '"')
error (_("Bad format string, non-terminated '\"'."));
@@ -2875,6 +2875,34 @@ ui_printf (const char *arg, struct ui_file *stream)
case ptr_arg:
printf_pointer (stream, current_substring, val_args[i]);
break;
+ case value_arg:
+ {
+ value_print_options print_opts;
+ get_user_print_options (&print_opts);
+
+ if (current_substring[2] == '[')
+ {
+ std::string args (¤t_substring[3],
+ strlen (¤t_substring[3]) - 1);
+
+ const char *args_ptr = args.c_str ();
+
+ /* Override global settings with explicit options, if
+ any. */
+ auto group
+ = make_value_print_options_def_group (&print_opts);
+ gdb::option::process_options
+ (&args_ptr, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR,
+ group);
+
+ if (*args_ptr != '\0')
+ error (_("unexpected content in print options: %s"),
+ args_ptr);
+ }
+
+ print_formatted (val_args[i], 0, &print_opts, stream);
+ }
+ break;
case literal_piece:
/* Print a portion of the format string that has no
directives. Note that this will not include any
diff --git a/gdb/testsuite/gdb.base/printcmds.c b/gdb/testsuite/gdb.base/printcmds.c
index 78291a2803c..fa3a62d6cdd 100644
--- a/gdb/testsuite/gdb.base/printcmds.c
+++ b/gdb/testsuite/gdb.base/printcmds.c
@@ -108,6 +108,7 @@ enum flag_enum
FE_TWO_LEGACY = 0x02,
};
+enum flag_enum one = FE_ONE;
enum flag_enum three = (enum flag_enum) (FE_ONE | FE_TWO);
/* Another enum considered as a "flag enum", but with no enumerator with value
@@ -152,6 +153,18 @@ struct some_struct
}
};
+/* This is used in the printf test. */
+struct small_struct
+{
+ int a;
+ int b;
+ int c;
+} a_small_struct = {
+ 1,
+ 2,
+ 3
+};
+
/* The following variables are used for testing byte repeat sequences.
The variable names are encoded: invalid_XYZ where:
X = start
diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index 21a2cad458c..10275720e8f 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -957,6 +957,32 @@ proc test_printf_with_dfp {} {
gdb_test "printf \"%Hf %Hf\\n\",1.2df,1.3df" "1.2 1.3"
}
+# Test the printf '%V' format.
+proc test_printf_V_format {} {
+ # Enums.
+ gdb_test {printf "%V\n", one} "FE_ONE"
+ gdb_test {printf "%V\n", three} "\\(FE_ONE \\| FE_TWO\\)"
+ gdb_test {printf "%V\n", flag_enum_without_zero} "0"
+ gdb_test {printf "%V\n", three_not_flag} "3"
+
+ # Arrays.
+ gdb_test {printf "%V\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[]\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[][]\n", a1} \
+ "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3]\n", a1} "\\{2, 4, 6\\.\\.\\.\\}"
+ gdb_test {printf "%V[-elements 3][]\n", a1} \
+ "\\{2, 4, 6\\.\\.\\.\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3 -array-indexes on]\n", a1} \
+ "\\{\\\[0\\\] = 2, \\\[1\\\] = 4, \\\[2\\\] = 6\\.\\.\\.\\}"
+
+ # Structures.
+ gdb_test {printf "%V\n", a_small_struct} \
+ "\\{a = 1, b = 2, c = 3\\}"
+ gdb_test {printf "%V[-pretty on]\n", a_small_struct} \
+ "\\{\r\n a = 1,\r\n b = 2,\r\n c = 3\r\n\\}"
+}
+
proc test_print_symbol {} {
gdb_test_no_output "set print symbol on"
@@ -1086,7 +1112,6 @@ proc test_printf_convenience_var {prefix} {
}
}
-
clean_restart
gdb_test "print \$pc" "No registers\\."
@@ -1171,6 +1196,7 @@ test_print_array_constants
test_print_enums
test_printf
test_printf_with_dfp
+test_printf_V_format
test_print_symbol
test_repeat_bytes
test_radices
diff --git a/gdbsupport/format.cc b/gdbsupport/format.cc
index 19f37ec8e0c..6e5a3cb6603 100644
--- a/gdbsupport/format.cc
+++ b/gdbsupport/format.cc
@@ -20,7 +20,8 @@
#include "common-defs.h"
#include "format.h"
-format_pieces::format_pieces (const char **arg, bool gdb_extensions)
+format_pieces::format_pieces (const char **arg, bool gdb_extensions,
+ bool value_extension)
{
const char *s;
const char *string;
@@ -44,7 +45,7 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
char *f = (char *) alloca (strlen (s) + 1);
string = f;
- while ((gdb_extensions || *s != '"') && *s != '\0')
+ while (*s != '"' && *s != '\0')
{
int c = *s++;
switch (c)
@@ -340,6 +341,27 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
bad = 1;
break;
+ case 'V':
+ if (!value_extension)
+ error (_("Unrecognized format specifier '%c' in printf"), *f);
+
+ if (lcount > 1 || seen_h || seen_big_h || seen_big_h
+ || seen_big_d || seen_double_big_d || seen_size_t
+ || seen_prec || seen_zero || seen_space || seen_plus)
+ bad = 1;
+
+ this_argclass = value_arg;
+
+ if (f[1] == '[')
+ {
+ /* Move F forward to the next ']' character if such a
+ character exists, otherwise leave F unchanged. */
+ const char *tmp = strchr (f, ']');
+ if (tmp != nullptr)
+ f = tmp;
+ }
+ break;
+
case '*':
error (_("`*' not supported for precision or width in printf"));
diff --git a/gdbsupport/format.h b/gdbsupport/format.h
index 342b473c3ed..2af34ab9450 100644
--- a/gdbsupport/format.h
+++ b/gdbsupport/format.h
@@ -41,7 +41,8 @@ enum argclass
int_arg, long_arg, long_long_arg, size_t_arg, ptr_arg,
string_arg, wide_string_arg, wide_char_arg,
double_arg, long_double_arg,
- dec32float_arg, dec64float_arg, dec128float_arg
+ dec32float_arg, dec64float_arg, dec128float_arg,
+ value_arg
};
/* A format piece is a section of the format string that may include a
@@ -75,7 +76,8 @@ class format_pieces
{
public:
- format_pieces (const char **arg, bool gdb_extensions = false);
+ format_pieces (const char **arg, bool gdb_extensions = false,
+ bool value_extension = false);
~format_pieces () = default;
DISABLE_COPY_AND_ASSIGN (format_pieces);
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv2] gdb: add support for %V to printf command
2023-04-28 13:14 ` [PATCHv2] " Andrew Burgess
@ 2023-04-28 15:34 ` Eli Zaretskii
2023-05-12 13:01 ` [PATCHv3] " Andrew Burgess
1 sibling, 0 replies; 10+ messages in thread
From: Eli Zaretskii @ 2023-04-28 15:34 UTC (permalink / raw)
To: Andrew Burgess; +Cc: tom, gdb-patches
> From: Andrew Burgess <aburgess@redhat.com>
> Date: Fri, 28 Apr 2023 14:14:18 +0100
>
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -67,6 +67,15 @@
> break foo thread 1 task 1
> watch var thread 2 task 3
>
> +* The printf command now accepts a '%V' output format which will
> + format an expression just as the 'print' command would. Print
> + options can be placed withing '[...]' after the '%V' to modify how
> + the value is printed. E.g:
> + printf "%V", some_array
> + printf "%V[-array-indexes on]", some_array
> + will print the array without, or with array indexes included, just
> + as the array would be printed by the 'print' command.
Should this mention the effect on dprintf?
> @kindex dprintf-style gdb
> -Handle the output using the @value{GDBN} @code{printf} command.
> +Handle the output using the @value{GDBN} @code{printf} command. When
> +using this style it is possible to use the @samp{%V} format specifier
^
A comma missing there.
> +Most of @value{GDB}'s format specifiers align with those supported by
> +the @code{printf} function, however, @value{GDB}'s @samp{%V} format
> +specifier extension is not supported by @code{printf}. When using
> +@samp{call} style dprintf care should be taken to ensure that only
^
Comma missing.
> +format specifiers supported by the output function are used otherwise
^
And another one.
> +@anchor{%V Format Specifier}
> +Additionally, @code{printf} supports a special @samp{%V} output format.
> +This format prints the string representation of an expression just as
> +@value{GDBN} would produce with the standard @kbd{print} command
> +(@pxref{Data, ,Examining Data}):
> +
> +@smallexample
> +(@value{GDBP}) print array
> +$1 = @{0, 1, 2, 3, 4, 5@}
> +(@value{GDBP}) printf "Array is: %V\n", array
> +Array is: @{0, 1, 2, 3, 4, 5@}
> +@end smallexample
> +
> +Additionally, it is possible to include print options with the
> +@samp{%V} format by placing them in @samp{[...]} immediately after the
> +@samp{%V}, like this:
There are two "additionally" here, and I wonder whether replacing one
of tyhem with "also" would read better.
> +If you need to print a literal @samp{[} directly after a @samp{%V} then
^
Comma missing.
Thanks.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCHv3] gdb: add support for %V to printf command
2023-04-28 13:14 ` [PATCHv2] " Andrew Burgess
2023-04-28 15:34 ` Eli Zaretskii
@ 2023-05-12 13:01 ` Andrew Burgess
2023-05-12 13:47 ` Simon Marchi
2023-05-26 20:44 ` Tom Tromey
1 sibling, 2 replies; 10+ messages in thread
From: Andrew Burgess @ 2023-05-12 13:01 UTC (permalink / raw)
To: gdb-patches; +Cc: Tom Tromey, Andrew Burgess, Eli Zaretskii
In v3:
- Addressed all Eli's doc feedback. It was pretty minor, so I don't
think another doc review is required,
- Rebased, and fixed a minor merge conflict in the testsuite,
- No other code changes since v2,
- Still need to check that Tom's query is satisfied (see V2 email):
https://sourceware.org/pipermail/gdb-patches/2023-April/199178.html
---
This commit adds a new format for the printf and dprintf commands:
'%V'. This new format takes any GDB expression and formats it as a
string, just as GDB would for a 'print' command, e.g.:
(gdb) print a1
$a = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb) printf "%V\n", a1
{2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
(gdb)
It is also possible to pass the same options to %V as you might pass
to the print command, e.g.:
(gdb) print -elements 3 -- a1
$4 = {2, 4, 6...}
(gdb) printf "%V[-elements 3]\n", a1
{2, 4, 6...}
(gdb)
This new feature would effectively replace an existing feature of GDB,
the $_as_string builtin convenience function. However, the
$_as_string function has a few problems which this new feature solves:
1. $_as_string doesn't currently work when the inferior is not
running, e.g:
(gdb) printf "%s", $_as_string(a1)
You can't do that without a process to debug.
(gdb)
The reason for this is that $_as_string returns a value object with
string type. When we try to print this we call value_as_address,
which ends up trying to push the string into the inferior's address
space.
Clearly we could solve this problem, the string data exists in GDB, so
there's no reason why we have to push it into the inferior, but this
is an existing problem that would need solving.
2. $_as_string suffers from the fact that C degrades arrays to
pointers, e.g.:
(gdb) printf "%s\n", $_as_string(a1)
0x404260 <a1>
(gdb)
The implementation of $_as_string is passed a gdb.Value object that is
a pointer, it doesn't understand that it's actually an array. Solving
this would be harder than issue #1 I think. The whole array to
pointer transformation is part of our expression evaluation. And in
most cases this is exactly what we want. It's not clear to me how
we'd (easily) tell GDB that we didn't want this reduction in _some_
cases. But I'm sure this is solvable if we really wanted to.
3. $_as_string is a gdb.Function sub-class, and as such is passed
gdb.Value objects. There's no super convenient way to pass formatting
options to $_as_string. By this I mean that the new %V feature
supports print formatting options. Ideally, we might want to add this
feature to $_as_string, we might imagine it working something like:
(gdb) printf "%s\n", $_as_string(a1,
elements = 3,
array_indexes = True)
where the first item is the value to print, while the remaining
options are the print formatting options. However, this relies on
Python calling syntax, which isn't something that convenience
functions handle. We could possibly rely on strictly positional
arguments, like:
(gdb) printf "%s\n", $_as_string(a1, 3, 1)
But that's clearly terrible as there's far more print formatting
options, and if you needed to set the 9th option you'd need to fill in
all the previous options.
And right now, the only way to pass these options to a gdb.Function is
to have GDB first convert them all into gdb.Value objects, which is
really overkill for what we want.
The new %V format solves all these problems: the string is computed
and printed entirely on the GDB side, we are able to print arrays as
actual arrays rather than pointers, and we can pass named format
arguments.
Finally, the $_as_string is sold in the manual as allowing users to
print the string representation of flag enums, so given:
enum flags
{
FLAG_A = (1 << 0),
FLAG_B = (1 << 1),
FLAG_C = (1 << 1)
};
enum flags ff = FLAG_B;
We can:
(gdb) printf "%s\n", $_as_string(ff)
FLAG_B
This works just fine with %V too:
(gdb) printf "%V\n", ff
FLAG_B
So all functionality of $_as_string is replaced by %V. I'm not
proposing to remove $_as_string, there might be users currently
depending on it, but I am proposing that we don't push $_as_string in
the documentation.
As %V is a feature of printf, GDB's dprintf breakpoints naturally gain
access to this feature too. dprintf breakpoints can be operated in
three different styles 'gdb' (use GDB's printf), 'call' (call a
function in the inferior), or 'agent' (perform the dprintf on the
remote).
The use of '%V' will work just fine when dprintf-style is 'gdb'.
When dprintf-style is 'call' the format string and arguments are
passed to an inferior function (printf by default). In this case GDB
doesn't prevent use of '%V', but the documentation makes it clear that
support for '%V' will depend on the inferior function being called.
I chose this approach because the current implementation doesn't place
any restrictions on the format string when operating in 'call' style.
That is, the user might already be calling a function that supports
custom print format specifiers (maybe including '%V') so, I claim, it
would be wrong to block use of '%V' in this case. The documentation
does make it clear that users shouldn't expect this to "just work"
though.
When dprintf-style is 'agent' then GDB does no support the use of
'%V' (right now). This is handled at the point when GDB tries to
process the format string and send the dprintf command to the remote,
here's an example:
Reading symbols from /tmp/hello.x...
(gdb) dprintf call_me, "%V", a1
Dprintf 1 at 0x401152: file /tmp/hello.c, line 8.
(gdb) set sysroot /
(gdb) target remote | gdbserver --once - /tmp/hello.x
Remote debugging using | gdbserver --once - /tmp/hello.x
stdin/stdout redirected
Process /tmp/hello.x created; pid = 3088822
Remote debugging using stdio
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007ffff7fd3110 in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) set dprintf-style agent
(gdb) c
Continuing.
Unrecognized format specifier 'V' in printf
Command aborted.
(gdb)
This is exactly how GDB would handle any other invalid format
specifier, for example:
Reading symbols from /tmp/hello.x...
(gdb) dprintf call_me, "%Q", a1
Dprintf 1 at 0x401152: file /tmp/hello.c, line 8.
(gdb) set sysroot /
(gdb) target remote | gdbserver --once - /tmp/hello.x
Remote debugging using | gdbserver --once - /tmp/hello.x
stdin/stdout redirected
Process /tmp/hello.x created; pid = 3089193
Remote debugging using stdio
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007ffff7fd3110 in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) set dprintf-style agent
(gdb) c
Continuing.
Unrecognized format specifier 'Q' in printf
Command aborted.
(gdb)
The error message isn't the greatest, but improving that can be put
off for another day I hope.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
---
gdb/NEWS | 11 ++++++
gdb/doc/gdb.texinfo | 55 +++++++++++++++++++++++++---
gdb/printcmd.c | 30 ++++++++++++++-
gdb/testsuite/gdb.base/printcmds.c | 13 +++++++
gdb/testsuite/gdb.base/printcmds.exp | 28 +++++++++++++-
gdbsupport/format.cc | 26 ++++++++++++-
gdbsupport/format.h | 6 ++-
7 files changed, 158 insertions(+), 11 deletions(-)
diff --git a/gdb/NEWS b/gdb/NEWS
index 6aa0d5171f2..d60a1a3fc01 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -67,6 +67,17 @@
break foo thread 1 task 1
watch var thread 2 task 3
+* The printf command now accepts a '%V' output format which will
+ format an expression just as the 'print' command would. Print
+ options can be placed withing '[...]' after the '%V' to modify how
+ the value is printed. E.g:
+ printf "%V", some_array
+ printf "%V[-array-indexes on]", some_array
+ will print the array without, or with array indexes included, just
+ as the array would be printed by the 'print' command. This
+ functionality is also available for dprintf when dprintf-style is
+ 'gdb'.
+
* New commands
maintenance print record-instruction [ N ]
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 531147f6e6b..e2a33d9acd7 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -5962,18 +5962,29 @@
@table @code
@item gdb
@kindex dprintf-style gdb
-Handle the output using the @value{GDBN} @code{printf} command.
+Handle the output using the @value{GDBN} @code{printf} command. When
+using this style, it is possible to use the @samp{%V} format specifier
+(@pxref{%V Format Specifier}).
@item call
@kindex dprintf-style call
Handle the output by calling a function in your program (normally
-@code{printf}).
+@code{printf}). When using this style the supported format specifiers
+depend entirely on the function being called.
+
+Most of @value{GDB}'s format specifiers align with those supported by
+the @code{printf} function, however, @value{GDB}'s @samp{%V} format
+specifier extension is not supported by @code{printf}. When using
+@samp{call} style dprintf, care should be taken to ensure that only
+format specifiers supported by the output function are used, otherwise
+the results will be undefined.
@item agent
@kindex dprintf-style agent
-Have the remote debugging agent (such as @code{gdbserver}) handle
-the output itself. This style is only available for agents that
-support running commands on the target.
+Have the remote debugging agent (such as @code{gdbserver}) handle the
+output itself. This style is only available for agents that support
+running commands on the target. This style does not support the
+@samp{%V} format specifier.
@end table
@item set dprintf-function @var{function}
@@ -13141,6 +13152,10 @@
@findex $_as_string@r{, convenience function}
@item $_as_string(@var{value})
+This convenience function is considered deprecated, and could be
+removed from future versions of @value{GDBN}. Use the @samp{%V} format
+specifier instead (@pxref{%V Format Specifier}).
+
Return the string representation of @var{value}.
This function is useful to obtain the textual label (enumerator) of an
@@ -29049,6 +29064,36 @@
printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
@end smallexample
+@anchor{%V Format Specifier}
+Additionally, @code{printf} supports a special @samp{%V} output format.
+This format prints the string representation of an expression just as
+@value{GDBN} would produce with the standard @kbd{print} command
+(@pxref{Data, ,Examining Data}):
+
+@smallexample
+(@value{GDBP}) print array
+$1 = @{0, 1, 2, 3, 4, 5@}
+(@value{GDBP}) printf "Array is: %V\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}
+@end smallexample
+
+It is possible to include print options with the @samp{%V} format by
+placing them in @samp{[...]} immediately after the @samp{%V}, like
+this:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[-array-indexes on]\n", array
+Array is: @{[0] = 0, [1] = 1, [2] = 2, [3] = 3, [4] = 4, [5] = 5@}
+@end smallexample
+
+If you need to print a literal @samp{[} directly after a @samp{%V}, then
+just include an empty print options list:
+
+@smallexample
+(@value{GDBP}) printf "Array is: %V[][Hello]\n", array
+Array is: @{0, 1, 2, 3, 4, 5@}[Hello]
+@end smallexample
+
@anchor{eval}
@kindex eval
@item eval @var{template}, @var{expressions}@dots{}
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 679a24e665a..68c561019de 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2732,7 +2732,7 @@ ui_printf (const char *arg, struct ui_file *stream)
if (*s++ != '"')
error (_("Bad format string, missing '\"'."));
- format_pieces fpieces (&s);
+ format_pieces fpieces (&s, false, true);
if (*s++ != '"')
error (_("Bad format string, non-terminated '\"'."));
@@ -2874,6 +2874,34 @@ ui_printf (const char *arg, struct ui_file *stream)
case ptr_arg:
printf_pointer (stream, current_substring, val_args[i]);
break;
+ case value_arg:
+ {
+ value_print_options print_opts;
+ get_user_print_options (&print_opts);
+
+ if (current_substring[2] == '[')
+ {
+ std::string args (¤t_substring[3],
+ strlen (¤t_substring[3]) - 1);
+
+ const char *args_ptr = args.c_str ();
+
+ /* Override global settings with explicit options, if
+ any. */
+ auto group
+ = make_value_print_options_def_group (&print_opts);
+ gdb::option::process_options
+ (&args_ptr, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR,
+ group);
+
+ if (*args_ptr != '\0')
+ error (_("unexpected content in print options: %s"),
+ args_ptr);
+ }
+
+ print_formatted (val_args[i], 0, &print_opts, stream);
+ }
+ break;
case literal_piece:
/* Print a portion of the format string that has no
directives. Note that this will not include any
diff --git a/gdb/testsuite/gdb.base/printcmds.c b/gdb/testsuite/gdb.base/printcmds.c
index 78291a2803c..fa3a62d6cdd 100644
--- a/gdb/testsuite/gdb.base/printcmds.c
+++ b/gdb/testsuite/gdb.base/printcmds.c
@@ -108,6 +108,7 @@ enum flag_enum
FE_TWO_LEGACY = 0x02,
};
+enum flag_enum one = FE_ONE;
enum flag_enum three = (enum flag_enum) (FE_ONE | FE_TWO);
/* Another enum considered as a "flag enum", but with no enumerator with value
@@ -152,6 +153,18 @@ struct some_struct
}
};
+/* This is used in the printf test. */
+struct small_struct
+{
+ int a;
+ int b;
+ int c;
+} a_small_struct = {
+ 1,
+ 2,
+ 3
+};
+
/* The following variables are used for testing byte repeat sequences.
The variable names are encoded: invalid_XYZ where:
X = start
diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index db57769c303..dcc6a3f85d2 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -981,6 +981,32 @@ proc test_printf_with_strings {} {
}
}
+# Test the printf '%V' format.
+proc test_printf_V_format {} {
+ # Enums.
+ gdb_test {printf "%V\n", one} "FE_ONE"
+ gdb_test {printf "%V\n", three} "\\(FE_ONE \\| FE_TWO\\)"
+ gdb_test {printf "%V\n", flag_enum_without_zero} "0"
+ gdb_test {printf "%V\n", three_not_flag} "3"
+
+ # Arrays.
+ gdb_test {printf "%V\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[]\n", a1} "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}"
+ gdb_test {printf "%V[][]\n", a1} \
+ "\\{2, 4, 6, 8, 10, 12, 14, 16, 18, 20\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3]\n", a1} "\\{2, 4, 6\\.\\.\\.\\}"
+ gdb_test {printf "%V[-elements 3][]\n", a1} \
+ "\\{2, 4, 6\\.\\.\\.\\}\\\[\\\]"
+ gdb_test {printf "%V[-elements 3 -array-indexes on]\n", a1} \
+ "\\{\\\[0\\\] = 2, \\\[1\\\] = 4, \\\[2\\\] = 6\\.\\.\\.\\}"
+
+ # Structures.
+ gdb_test {printf "%V\n", a_small_struct} \
+ "\\{a = 1, b = 2, c = 3\\}"
+ gdb_test {printf "%V[-pretty on]\n", a_small_struct} \
+ "\\{\r\n a = 1,\r\n b = 2,\r\n c = 3\r\n\\}"
+}
+
proc test_print_symbol {} {
gdb_test_no_output "set print symbol on"
@@ -1110,7 +1136,6 @@ proc test_printf_convenience_var {prefix} {
}
}
-
clean_restart
gdb_test "print \$pc" "No registers\\."
@@ -1196,6 +1221,7 @@ test_print_enums
test_printf
test_printf_with_dfp
test_printf_with_strings
+test_printf_V_format
test_print_symbol
test_repeat_bytes
test_radices
diff --git a/gdbsupport/format.cc b/gdbsupport/format.cc
index 19f37ec8e0c..6e5a3cb6603 100644
--- a/gdbsupport/format.cc
+++ b/gdbsupport/format.cc
@@ -20,7 +20,8 @@
#include "common-defs.h"
#include "format.h"
-format_pieces::format_pieces (const char **arg, bool gdb_extensions)
+format_pieces::format_pieces (const char **arg, bool gdb_extensions,
+ bool value_extension)
{
const char *s;
const char *string;
@@ -44,7 +45,7 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
char *f = (char *) alloca (strlen (s) + 1);
string = f;
- while ((gdb_extensions || *s != '"') && *s != '\0')
+ while (*s != '"' && *s != '\0')
{
int c = *s++;
switch (c)
@@ -340,6 +341,27 @@ format_pieces::format_pieces (const char **arg, bool gdb_extensions)
bad = 1;
break;
+ case 'V':
+ if (!value_extension)
+ error (_("Unrecognized format specifier '%c' in printf"), *f);
+
+ if (lcount > 1 || seen_h || seen_big_h || seen_big_h
+ || seen_big_d || seen_double_big_d || seen_size_t
+ || seen_prec || seen_zero || seen_space || seen_plus)
+ bad = 1;
+
+ this_argclass = value_arg;
+
+ if (f[1] == '[')
+ {
+ /* Move F forward to the next ']' character if such a
+ character exists, otherwise leave F unchanged. */
+ const char *tmp = strchr (f, ']');
+ if (tmp != nullptr)
+ f = tmp;
+ }
+ break;
+
case '*':
error (_("`*' not supported for precision or width in printf"));
diff --git a/gdbsupport/format.h b/gdbsupport/format.h
index 342b473c3ed..2af34ab9450 100644
--- a/gdbsupport/format.h
+++ b/gdbsupport/format.h
@@ -41,7 +41,8 @@ enum argclass
int_arg, long_arg, long_long_arg, size_t_arg, ptr_arg,
string_arg, wide_string_arg, wide_char_arg,
double_arg, long_double_arg,
- dec32float_arg, dec64float_arg, dec128float_arg
+ dec32float_arg, dec64float_arg, dec128float_arg,
+ value_arg
};
/* A format piece is a section of the format string that may include a
@@ -75,7 +76,8 @@ class format_pieces
{
public:
- format_pieces (const char **arg, bool gdb_extensions = false);
+ format_pieces (const char **arg, bool gdb_extensions = false,
+ bool value_extension = false);
~format_pieces () = default;
DISABLE_COPY_AND_ASSIGN (format_pieces);
base-commit: a02fcd08ddc5080696248ed7fb4bf50a24763431
--
2.25.4
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3] gdb: add support for %V to printf command
2023-05-12 13:01 ` [PATCHv3] " Andrew Burgess
@ 2023-05-12 13:47 ` Simon Marchi
2023-05-26 20:44 ` Tom Tromey
1 sibling, 0 replies; 10+ messages in thread
From: Simon Marchi @ 2023-05-12 13:47 UTC (permalink / raw)
To: Andrew Burgess, gdb-patches; +Cc: Tom Tromey, Eli Zaretskii
On 5/12/23 09:01, Andrew Burgess via Gdb-patches wrote:
> In v3:
>
> - Addressed all Eli's doc feedback. It was pretty minor, so I don't
> think another doc review is required,
>
> - Rebased, and fixed a minor merge conflict in the testsuite,
>
> - No other code changes since v2,
>
> - Still need to check that Tom's query is satisfied (see V2 email):
> https://sourceware.org/pipermail/gdb-patches/2023-April/199178.html
I've skimmed the patch, the idea looks fine to me. Not sure if we typically
use Acked-By, but I think it's pretty standard:
Acked-By: Simon Marchi <simon.marchi@efficios.com>
Simon
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3] gdb: add support for %V to printf command
2023-05-12 13:01 ` [PATCHv3] " Andrew Burgess
2023-05-12 13:47 ` Simon Marchi
@ 2023-05-26 20:44 ` Tom Tromey
2023-05-30 20:56 ` Andrew Burgess
1 sibling, 1 reply; 10+ messages in thread
From: Tom Tromey @ 2023-05-26 20:44 UTC (permalink / raw)
To: Andrew Burgess via Gdb-patches; +Cc: Andrew Burgess, Tom Tromey, Eli Zaretskii
>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
Andrew> - Still need to check that Tom's query is satisfied (see V2 email):
Andrew> https://sourceware.org/pipermail/gdb-patches/2023-April/199178.html
It is. Thank you for doing this.
Also, it turns out this will be handy for DAP, to implement the
logMessage support.
Tom
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3] gdb: add support for %V to printf command
2023-05-26 20:44 ` Tom Tromey
@ 2023-05-30 20:56 ` Andrew Burgess
0 siblings, 0 replies; 10+ messages in thread
From: Andrew Burgess @ 2023-05-30 20:56 UTC (permalink / raw)
To: gdb-patches; +Cc: Tom Tromey
Tom Tromey <tom@tromey.com> writes:
>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>
> Andrew> - Still need to check that Tom's query is satisfied (see V2 email):
> Andrew> https://sourceware.org/pipermail/gdb-patches/2023-April/199178.html
>
> It is. Thank you for doing this.
Excellent. I went ahead and pushed this.
>
> Also, it turns out this will be handy for DAP, to implement the
> logMessage support.
Glad this helps!
Thanks,
Andrew
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2023-05-30 20:56 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-30 12:22 [PATCH] gdb: add support for %V to printf command Andrew Burgess
2023-03-30 14:20 ` Eli Zaretskii
2023-04-11 12:34 ` Andrew Burgess
2023-04-17 15:47 ` Tom Tromey
2023-04-28 13:14 ` [PATCHv2] " Andrew Burgess
2023-04-28 15:34 ` Eli Zaretskii
2023-05-12 13:01 ` [PATCHv3] " Andrew Burgess
2023-05-12 13:47 ` Simon Marchi
2023-05-26 20:44 ` Tom Tromey
2023-05-30 20:56 ` Andrew Burgess
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