2012-07-02 23:29:39 +08:00
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/* Parse a printf-style format string.
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2024-01-12 23:30:44 +08:00
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Copyright (C) 1986-2024 Free Software Foundation, Inc.
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2012-07-02 23:29:39 +08:00
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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2017-11-23 00:37:05 +08:00
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#ifndef COMMON_FORMAT_H
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#define COMMON_FORMAT_H
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2023-10-13 18:17:02 +08:00
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#include <string_view>
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2018-05-18 01:05:59 +08:00
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2012-07-02 23:29:39 +08:00
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#if defined(__MINGW32__) && !defined(PRINTF_HAS_LONG_LONG)
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# define USE_PRINTF_I64 1
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# define PRINTF_HAS_LONG_LONG
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#else
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# define USE_PRINTF_I64 0
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#endif
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/* The argclass represents the general type of data that goes with a
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format directive; int_arg for %d, long_arg for %l, and so forth.
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Note that these primarily distinguish types by size and need for
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special handling, so for instance %u and %x are (at present) also
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classed as int_arg. */
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enum argclass
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{
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literal_piece,
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gdb: Support printf 'z' size modifier
The gdb format mechanism doesn't currently support the 'z' size
modifier, there are a few places in GDB where this is used. Instead
of removing these uses lets just add support to GDB for using 'z'.
I found this issue when trying to use some of the debug output.
Before this commit:
(gdb) set debug dwarf-line 9
(gdb) file test
Reading symbols from test...
Unrecognized format specifier 'z' in printf
(No debugging symbols found in test)
(gdb)
After this commit:
(gdb) set debug dwarf-line 9
(gdb) file test
Reading symbols from test...
Adding dir 1: /usr/include
Adding file 1: test.c
Adding file 2: stdc-predef.h
Processing actual line 3: file 1, address 0x4004a0, is_stmt 1, discrim 0
Processing actual line 4: file 1, address 0x4004a0, is_stmt 1, discrim 0
.... lots of debug output ...
Processing actual line 10: file 1, address 0x4003b7, is_stmt 0, discrim 0
(gdb)
I've added a self test to cover the integer format size modifiers,
including the 'z' modifier.
gdb/ChangeLog:
* gdbsupport/format.c (format_pieces::format_pieces): Support
printf 'z' size modifier.
* gdbsupport/format.h (enum argclass): Add size_t_arg.
* printcmd.c (ui_printf): Handle size_t_arg.
* ui-out.c (ui_out::vmessage): Likewise.
* unittests/format_pieces-selftests.c (test_format_int_sizes): New
function.
(run_tests): Call test_format_int_sizes.
gdb/gdbserver/ChangeLog:
* ax.c (ax_printf): Handle size_t_arg.
Change-Id: Ib6c44d88aa5bce265d757e4c0698881803dd186f
2019-11-05 22:24:17 +08:00
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int_arg, long_arg, long_long_arg, size_t_arg, ptr_arg,
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2012-07-02 23:29:39 +08:00
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string_arg, wide_string_arg, wide_char_arg,
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Target FP printing: Simplify and fix ui_printf
This patch adds support for handling format strings to both
floatformat_to_string and decimal_to_string, and then uses
those routines to implement ui_printf formatted printing.
There is already a subroutine printf_decfloat that ui_printf uses to
handle decimal FP. This is renamed to printf_floating and updated
to handle both binary and decimal FP. This includes the following
set of changes:
- printf_decfloat currently parses the format string again to determine
the intended target format. This seems superfluous since the common
parsing code in parse_format_string already did this, but then did
not pass the result on to its users. Fixed by splitting the decfloat_arg
argument class into three distinct classes, and passing them through.
- Now we can rename printf_decfloat to printf_floating and also call it
for the argument classes representing binary FP types.
- The code will now use the argclass to detect the type the value should
be printed at, and converts the input value to this type if necessary.
To remain compatible with current behavior, for binary FP the code
instead tries to re-interpret the input value as a FP type of the
same size if that exists. (Maybe this behavior is more confusing
than useful -- but this can be changed later if we want to ...)
- Finally, we can use floatformat_to_string / decimal_to_string passing
the format string to perform the formatted output using the desired
target FP type.
Note that we no longer generate different code depending on whether or not
the host supports "long double" -- this check is obsolete anyway since C++11
mandates "long double", and in any case a %lg format string is intended to
refer to the *target* long double type, not the host version.
Note also that formatted printing of DFP numbers may not work correctly,
since it attempts to use the host printf to do so (and makes unwarranted
assumptions about the host ABI while doing so!). This is no change to
the current behavior -- I simply moved the code from printf_decfloat to
the decimal_to_string routine in dfp.c. If we want to fix it in the
future, that is a more appropriate place anyway.
ChangeLog:
2017-10-24 Ulrich Weigand <uweigand@de.ibm.com>
* common/format.h (enum argclass): Replace decfloat_arg by
dec32float_arg, dec64float_arg, and dec128float_arg.
* common/format.c (parse_format_string): Update to return
new decimal float argument classes.
* printcmd.c (printf_decfloat): Rename to ...
(printf_floating): ... this. Add argclass argument, and use it
instead of parsing the format string again. Add support for
binary floating-point values, using floatformat_to_string.
Convert value to the target format if it doesn't already match.
(ui_printf): Call printf_floating instead of printf_decfloat,
also for double_arg / long_double_arg. Pass argclass.
* dfp.c (decimal_to_string): Add format string argument.
* dfp.h (decimal_to_string): Likewise.
* doublest.c (floatformat_to_string): Add format string argument.
* doublest.h (floatformat_to_string): Likewise.
2017-10-25 00:00:50 +08:00
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double_arg, long_double_arg,
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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.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Acked-By: Simon Marchi <simon.marchi@efficios.com>
2023-03-23 20:12:38 +08:00
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dec32float_arg, dec64float_arg, dec128float_arg,
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value_arg
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2012-07-02 23:29:39 +08:00
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};
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/* A format piece is a section of the format string that may include a
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single print directive somewhere in it, and the associated class
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for the argument. */
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struct format_piece
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{
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Introduce gdb-specific %p format suffixes
This introduces a few gdb-specific %p format suffixes. This is useful
for emitting gdb-specific output in an ergonomic way. It also yields
code that is more i18n-friendly.
The comment before ui_out::message explains the details.
Note that the tests had to change a little. When using one of the gdb
printf functions with styling, there can be spurious style changes
emitted to the output. This did not seem worthwhile to fix, as the
low-level output functions are rather spaghetti-ish already, and I
didn't want to make them even worse.
This change also necessitated adding support for "*" as precision and
width in format_pieces. These are used in various spots in gdb, and
it seemed better to me to implement them than to remove the uses.
gdb/ChangeLog
2019-10-01 Pedro Alves <palves@redhat.com>
Tom Tromey <tom@tromey.com>
* unittests/format_pieces-selftests.c: Add gdb_format parameter.
(test_gdb_formats): New function.
(run_tests): Call it.
(test_format_specifier): Update.
* utils.h (fputs_filtered): Update comment.
(vfprintf_styled, vfprintf_styled_no_gdbfmt)
(fputs_styled_unfiltered): Declare.
* utils.c (fputs_styled_unfiltered): New function.
(vfprintf_maybe_filtered): Add gdbfmt parameter.
(vfprintf_filtered): Update.
(vfprintf_unfiltered, vprintf_filtered): Update.
(vfprintf_styled, vfprintf_styled_no_gdbfmt): New functions.
* ui-out.h (enum ui_out_flag) <unfiltered_output,
disallow_ui_out_field>: New constants.
(enum class field_kind): New.
(struct base_field_s, struct signed_field_s): New.
(signed_field): New function.
(struct string_field_s): New.
(string_field): New function.
(struct styled_string_s): New.
(styled_string): New function.
(class ui_out) <message>: Add comment.
<vmessage, call_do_message>: New methods.
<do_message>: Add style parameter.
* ui-out.c (ui_out::call_do_message, ui_out::vmessage): New
methods.
(ui_out::message): Rewrite.
* mi/mi-out.h (class mi_ui_out) <do_message>: Add style
parameter.
* mi/mi-out.c (mi_ui_out::do_message): Add style parameter.
* gdbsupport/format.h (class format_pieces) <format_pieces>: Add
gdb_extensions parameter.
(class format_piece): Add parameter to constructor.
(n_int_args): New field.
* gdbsupport/format.c (format_pieces::format_pieces): Add
gdb_extensions parameter. Handle '*'.
* cli-out.h (class cli_ui_out) <do_message>: Add style parameter.
* cli-out.c (cli_ui_out::do_message): Add style parameter. Call
vfprintf_styled_no_gdbfmt.
(cli_ui_out::do_field_string, cli_ui_out::do_spaces)
(cli_ui_out::do_text, cli_ui_out::field_separator): Allow
unfiltered output.
* ui-style.h (struct ui_file_style) <ptr>: New method.
gdb/testsuite/ChangeLog
2019-10-01 Tom Tromey <tom@tromey.com>
* gdb.base/style.exp: Update tests.
2019-06-05 16:17:16 +08:00
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format_piece (const char *str, enum argclass argc, int n)
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2017-11-23 11:17:28 +08:00
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: string (str),
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Introduce gdb-specific %p format suffixes
This introduces a few gdb-specific %p format suffixes. This is useful
for emitting gdb-specific output in an ergonomic way. It also yields
code that is more i18n-friendly.
The comment before ui_out::message explains the details.
Note that the tests had to change a little. When using one of the gdb
printf functions with styling, there can be spurious style changes
emitted to the output. This did not seem worthwhile to fix, as the
low-level output functions are rather spaghetti-ish already, and I
didn't want to make them even worse.
This change also necessitated adding support for "*" as precision and
width in format_pieces. These are used in various spots in gdb, and
it seemed better to me to implement them than to remove the uses.
gdb/ChangeLog
2019-10-01 Pedro Alves <palves@redhat.com>
Tom Tromey <tom@tromey.com>
* unittests/format_pieces-selftests.c: Add gdb_format parameter.
(test_gdb_formats): New function.
(run_tests): Call it.
(test_format_specifier): Update.
* utils.h (fputs_filtered): Update comment.
(vfprintf_styled, vfprintf_styled_no_gdbfmt)
(fputs_styled_unfiltered): Declare.
* utils.c (fputs_styled_unfiltered): New function.
(vfprintf_maybe_filtered): Add gdbfmt parameter.
(vfprintf_filtered): Update.
(vfprintf_unfiltered, vprintf_filtered): Update.
(vfprintf_styled, vfprintf_styled_no_gdbfmt): New functions.
* ui-out.h (enum ui_out_flag) <unfiltered_output,
disallow_ui_out_field>: New constants.
(enum class field_kind): New.
(struct base_field_s, struct signed_field_s): New.
(signed_field): New function.
(struct string_field_s): New.
(string_field): New function.
(struct styled_string_s): New.
(styled_string): New function.
(class ui_out) <message>: Add comment.
<vmessage, call_do_message>: New methods.
<do_message>: Add style parameter.
* ui-out.c (ui_out::call_do_message, ui_out::vmessage): New
methods.
(ui_out::message): Rewrite.
* mi/mi-out.h (class mi_ui_out) <do_message>: Add style
parameter.
* mi/mi-out.c (mi_ui_out::do_message): Add style parameter.
* gdbsupport/format.h (class format_pieces) <format_pieces>: Add
gdb_extensions parameter.
(class format_piece): Add parameter to constructor.
(n_int_args): New field.
* gdbsupport/format.c (format_pieces::format_pieces): Add
gdb_extensions parameter. Handle '*'.
* cli-out.h (class cli_ui_out) <do_message>: Add style parameter.
* cli-out.c (cli_ui_out::do_message): Add style parameter. Call
vfprintf_styled_no_gdbfmt.
(cli_ui_out::do_field_string, cli_ui_out::do_spaces)
(cli_ui_out::do_text, cli_ui_out::field_separator): Allow
unfiltered output.
* ui-style.h (struct ui_file_style) <ptr>: New method.
gdb/testsuite/ChangeLog
2019-10-01 Tom Tromey <tom@tromey.com>
* gdb.base/style.exp: Update tests.
2019-06-05 16:17:16 +08:00
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argclass (argc),
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n_int_args (n)
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2017-11-23 11:17:28 +08:00
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{
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2023-10-13 18:17:02 +08:00
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gdb_assert (str != nullptr);
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2017-11-23 11:17:28 +08:00
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}
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2018-05-18 01:05:59 +08:00
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bool operator== (const format_piece &other) const
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{
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return (this->argclass == other.argclass
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2023-10-13 18:17:02 +08:00
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&& std::string_view (this->string) == other.string);
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2018-05-18 01:05:59 +08:00
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}
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2017-11-23 11:17:28 +08:00
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const char *string;
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2012-07-02 23:29:39 +08:00
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enum argclass argclass;
|
Introduce gdb-specific %p format suffixes
This introduces a few gdb-specific %p format suffixes. This is useful
for emitting gdb-specific output in an ergonomic way. It also yields
code that is more i18n-friendly.
The comment before ui_out::message explains the details.
Note that the tests had to change a little. When using one of the gdb
printf functions with styling, there can be spurious style changes
emitted to the output. This did not seem worthwhile to fix, as the
low-level output functions are rather spaghetti-ish already, and I
didn't want to make them even worse.
This change also necessitated adding support for "*" as precision and
width in format_pieces. These are used in various spots in gdb, and
it seemed better to me to implement them than to remove the uses.
gdb/ChangeLog
2019-10-01 Pedro Alves <palves@redhat.com>
Tom Tromey <tom@tromey.com>
* unittests/format_pieces-selftests.c: Add gdb_format parameter.
(test_gdb_formats): New function.
(run_tests): Call it.
(test_format_specifier): Update.
* utils.h (fputs_filtered): Update comment.
(vfprintf_styled, vfprintf_styled_no_gdbfmt)
(fputs_styled_unfiltered): Declare.
* utils.c (fputs_styled_unfiltered): New function.
(vfprintf_maybe_filtered): Add gdbfmt parameter.
(vfprintf_filtered): Update.
(vfprintf_unfiltered, vprintf_filtered): Update.
(vfprintf_styled, vfprintf_styled_no_gdbfmt): New functions.
* ui-out.h (enum ui_out_flag) <unfiltered_output,
disallow_ui_out_field>: New constants.
(enum class field_kind): New.
(struct base_field_s, struct signed_field_s): New.
(signed_field): New function.
(struct string_field_s): New.
(string_field): New function.
(struct styled_string_s): New.
(styled_string): New function.
(class ui_out) <message>: Add comment.
<vmessage, call_do_message>: New methods.
<do_message>: Add style parameter.
* ui-out.c (ui_out::call_do_message, ui_out::vmessage): New
methods.
(ui_out::message): Rewrite.
* mi/mi-out.h (class mi_ui_out) <do_message>: Add style
parameter.
* mi/mi-out.c (mi_ui_out::do_message): Add style parameter.
* gdbsupport/format.h (class format_pieces) <format_pieces>: Add
gdb_extensions parameter.
(class format_piece): Add parameter to constructor.
(n_int_args): New field.
* gdbsupport/format.c (format_pieces::format_pieces): Add
gdb_extensions parameter. Handle '*'.
* cli-out.h (class cli_ui_out) <do_message>: Add style parameter.
* cli-out.c (cli_ui_out::do_message): Add style parameter. Call
vfprintf_styled_no_gdbfmt.
(cli_ui_out::do_field_string, cli_ui_out::do_spaces)
(cli_ui_out::do_text, cli_ui_out::field_separator): Allow
unfiltered output.
* ui-style.h (struct ui_file_style) <ptr>: New method.
gdb/testsuite/ChangeLog
2019-10-01 Tom Tromey <tom@tromey.com>
* gdb.base/style.exp: Update tests.
2019-06-05 16:17:16 +08:00
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/* Count the number of preceding 'int' arguments that must be passed
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along. This is used for a width or precision of '*'. Note that
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this feature is only available in "gdb_extensions" mode. */
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int n_int_args;
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2012-07-02 23:29:39 +08:00
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};
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2017-11-23 11:17:28 +08:00
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class format_pieces
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{
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public:
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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.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Acked-By: Simon Marchi <simon.marchi@efficios.com>
2023-03-23 20:12:38 +08:00
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format_pieces (const char **arg, bool gdb_extensions = false,
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bool value_extension = false);
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2017-11-23 11:17:28 +08:00
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~format_pieces () = default;
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DISABLE_COPY_AND_ASSIGN (format_pieces);
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2012-07-02 23:29:39 +08:00
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2017-11-23 11:17:28 +08:00
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typedef std::vector<format_piece>::iterator iterator;
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2012-07-02 23:29:39 +08:00
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2017-11-23 11:17:28 +08:00
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iterator begin ()
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{
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return m_pieces.begin ();
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}
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2012-07-02 23:29:39 +08:00
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2017-11-23 11:17:28 +08:00
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iterator end ()
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{
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return m_pieces.end ();
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}
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2012-07-02 23:29:39 +08:00
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2017-11-23 11:17:28 +08:00
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private:
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std::vector<format_piece> m_pieces;
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gdb::unique_xmalloc_ptr<char> m_storage;
|
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};
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2017-11-23 00:37:05 +08:00
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#endif /* COMMON_FORMAT_H */
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