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gdb: Buffer output streams during events that might download debuginfo

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Introduce new ui_file buffering_file to temporarily collect output
written to gdb_std* output streams during print_thread, print_frame_info
and print_stop_event.

This ensures that output during these functions is not interrupted
by debuginfod progress messages.

With the addition of deferred debuginfo downloading it is possible
for download progress messages to print during these events.
Without any intervention we can end up with poorly formatted output:

    (gdb) backtrace
    [...]
    #8  0x00007fbe8af7d7cf in pygi_invoke_c_callable (Downloading separate debug info for /lib64/libpython3.11.so.1.0
    function_cache=0x561221b224d0, state=<optimized out>...

To fix this we buffer writes to gdb_std* output streams while allowing
debuginfod progress messages to skip the buffers and print to the
underlying output streams immediately.  Buffered output is then written
to the output streams.  This ensures that progress messages print first,
followed by uninterrupted frame/thread/stop info:

    (gdb) backtrace
    [...]
    Downloading separate debug info for /lib64/libpython3.11.so.1.0
    #8  0x00007fbe8af7d7cf in pygi_invoke_c_callable (function_cache=0x561221b224d0, state=<optimized out>...

Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
This commit is contained in:
Aaron Merey 2024-01-12 14:38:45 -05:00
parent 64db3e4d88
commit 519d634396
10 changed files with 492 additions and 98 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
gdb/cli-out.c
View File

@ -299,7 +299,7 @@ cli_ui_out::do_progress_notify (const std::string &msg,
double howmuch, double total)
{
int chars_per_line = get_chars_per_line ();
struct ui_file *stream = m_streams.back ();
struct ui_file *stream = get_unbuffered (m_streams.back ());
cli_progress_info &info (m_progress_info.back ());
if (chars_per_line > MAX_CHARS_PER_LINE)
@ -384,7 +384,7 @@ cli_ui_out::do_progress_notify (const std::string &msg,
void
cli_ui_out::clear_progress_notify ()
{
struct ui_file *stream = m_streams.back ();
struct ui_file *stream = get_unbuffered (m_streams.back ());
int chars_per_line = get_chars_per_line ();
scoped_restore save_pagination
@ -413,10 +413,12 @@ void
cli_ui_out::do_progress_end ()
{
struct ui_file *stream = m_streams.back ();
m_progress_info.pop_back ();
cli_progress_info &info (m_progress_info.back ());
if (stream->isatty ())
if (stream->isatty () && info.state != progress_update::START)
clear_progress_notify ();
m_progress_info.pop_back ();
}
/* local functions */

3
gdb/cli-out.h
View File

@ -35,6 +35,9 @@ public:
bool can_emit_style_escape () const override;
ui_file *current_stream () const override
{ return m_streams.back (); }
protected:
virtual void do_table_begin (int nbrofcols, int nr_rows,

15
gdb/debuginfod-support.c
View File

@ -155,7 +155,8 @@ progressfn (debuginfod_client *c, long cur, long total)
if (check_quit_flag ())
{
gdb_printf ("Cancelling download of %s %s...\n",
ui_file *outstream = get_unbuffered (gdb_stdout);
gdb_printf (outstream, _("Cancelling download of %s %s...\n"),
data->desc, styled_fname.c_str ());
return 1;
}
@ -295,10 +296,14 @@ static void
print_outcome (int fd, const char *desc, const char *fname)
{
if (fd < 0 && fd != -ENOENT)
gdb_printf (_("Download failed: %s. Continuing without %s %ps.\n"),
safe_strerror (-fd),
desc,
styled_string (file_name_style.style (), fname));
{
ui_file *outstream = get_unbuffered (gdb_stdout);
gdb_printf (outstream,
_("Download failed: %s. Continuing without %s %ps.\n"),
safe_strerror (-fd),
desc,
styled_string (file_name_style.style (), fname));
}
}
/* See debuginfod-support.h */

16
gdb/infrun.c
View File

@ -9277,10 +9277,10 @@ print_stop_location (const target_waitstatus &ws)
print_stack_frame (get_selected_frame (nullptr), 0, source_flag, 1);
}
/* See infrun.h. */
/* See `print_stop_event` in infrun.h. */
void
print_stop_event (struct ui_out *uiout, bool displays)
static void
do_print_stop_event (struct ui_out *uiout, bool displays)
{
struct target_waitstatus last;
struct thread_info *tp;
@ -9309,6 +9309,16 @@ print_stop_event (struct ui_out *uiout, bool displays)
}
}
/* See infrun.h. This function itself sets up buffered output for the
duration of do_print_stop_event, which performs the actual event
printing. */
void
print_stop_event (struct ui_out *uiout, bool displays)
{
do_with_buffered_output (do_print_stop_event, uiout, displays);
}
/* See infrun.h. */
void

3
gdb/mi/mi-out.h
View File

@ -45,6 +45,9 @@ public:
return false;
}
ui_file *current_stream () const override
{ return m_streams.back (); }
protected:
virtual void do_table_begin (int nbrofcols, int nr_rows, const char *tblid)

3
gdb/python/py-uiout.h
View File

@ -56,6 +56,9 @@ public:
return std::move (current ().obj);
}
ui_file *current_stream () const override
{ return nullptr; }
protected:
void do_progress_end () override { }

35
gdb/stack.c
View File

@ -220,7 +220,8 @@ static void print_frame_local_vars (frame_info_ptr frame,
const char *regexp, const char *t_regexp,
int num_tabs, struct ui_file *stream);
static void print_frame (const frame_print_options &opts,
static void print_frame (struct ui_out *uiout,
const frame_print_options &opts,
frame_info_ptr frame, int print_level,
enum print_what print_what, int print_args,
struct symtab_and_line sal);
@ -1020,16 +1021,15 @@ get_user_print_what_frame_info (std::optional<enum print_what> *what)
Used in "where" output, and to emit breakpoint or step
messages. */
void
print_frame_info (const frame_print_options &fp_opts,
frame_info_ptr frame, int print_level,
enum print_what print_what, int print_args,
int set_current_sal)
static void
do_print_frame_info (struct ui_out *uiout, const frame_print_options &fp_opts,
frame_info_ptr frame, int print_level,
enum print_what print_what, int print_args,
int set_current_sal)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
int source_print;
int location_print;
struct ui_out *uiout = current_uiout;
if (!current_uiout->is_mi_like_p ()
&& fp_opts.print_frame_info != print_frame_info_auto)
@ -1105,7 +1105,8 @@ print_frame_info (const frame_print_options &fp_opts,
|| print_what == LOC_AND_ADDRESS
|| print_what == SHORT_LOCATION);
if (location_print || !sal.symtab)
print_frame (fp_opts, frame, print_level, print_what, print_args, sal);
print_frame (uiout, fp_opts, frame, print_level,
print_what, print_args, sal);
source_print = (print_what == SRC_LINE || print_what == SRC_AND_LOC);
@ -1185,6 +1186,20 @@ print_frame_info (const frame_print_options &fp_opts,
gdb_flush (gdb_stdout);
}
/* Redirect output to a temporary buffer for the duration
of do_print_frame_info. */
void
print_frame_info (const frame_print_options &fp_opts,
frame_info_ptr frame, int print_level,
enum print_what print_what, int print_args,
int set_current_sal)
{
do_with_buffered_output (do_print_frame_info, current_uiout,
fp_opts, frame, print_level, print_what,
print_args, set_current_sal);
}
/* See stack.h. */
void
@ -1309,13 +1324,13 @@ find_frame_funname (frame_info_ptr frame, enum language *funlang,
}
static void
print_frame (const frame_print_options &fp_opts,
print_frame (struct ui_out *uiout,
const frame_print_options &fp_opts,
frame_info_ptr frame, int print_level,
enum print_what print_what, int print_args,
struct symtab_and_line sal)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
struct ui_out *uiout = current_uiout;
enum language funlang = language_unknown;
struct value_print_options opts;
struct symbol *func;

180
gdb/thread.c
View File

@ -1089,6 +1089,107 @@ thread_target_id_str (thread_info *tp)
return target_id;
}
/* Print thread TP. GLOBAL_IDS indicates whether REQUESTED_THREADS
is a list of global or per-inferior thread ids. */
static void
do_print_thread (ui_out *uiout, const char *requested_threads,
int global_ids, int pid, int show_global_ids,
int default_inf_num, thread_info *tp,
thread_info *current_thread)
{
int core;
/* In case REQUESTED_THREADS contains $_thread. */
if (current_thread != nullptr)
switch_to_thread (current_thread);
if (!should_print_thread (requested_threads, default_inf_num,
global_ids, pid, tp))
return;
ui_out_emit_tuple tuple_emitter (uiout, NULL);
if (!uiout->is_mi_like_p ())
{
if (tp == current_thread)
uiout->field_string ("current", "*");
else
uiout->field_skip ("current");
uiout->field_string ("id-in-tg", print_thread_id (tp));
}
if (show_global_ids || uiout->is_mi_like_p ())
uiout->field_signed ("id", tp->global_num);
/* Switch to the thread (and inferior / target). */
switch_to_thread (tp);
/* For the CLI, we stuff everything into the target-id field.
This is a gross hack to make the output come out looking
correct. The underlying problem here is that ui-out has no
way to specify that a field's space allocation should be
shared by several fields. For MI, we do the right thing
instead. */
if (uiout->is_mi_like_p ())
{
uiout->field_string ("target-id", target_pid_to_str (tp->ptid));
const char *extra_info = target_extra_thread_info (tp);
if (extra_info != nullptr)
uiout->field_string ("details", extra_info);
const char *name = thread_name (tp);
if (name != NULL)
uiout->field_string ("name", name);
}
else
{
uiout->field_string ("target-id", thread_target_id_str (tp));
}
if (tp->state == THREAD_RUNNING)
uiout->text ("(running)\n");
else
{
/* The switch above put us at the top of the stack (leaf
frame). */
print_stack_frame (get_selected_frame (NULL),
/* For MI output, print frame level. */
uiout->is_mi_like_p (),
LOCATION, 0);
}
if (uiout->is_mi_like_p ())
{
const char *state = "stopped";
if (tp->state == THREAD_RUNNING)
state = "running";
uiout->field_string ("state", state);
}
core = target_core_of_thread (tp->ptid);
if (uiout->is_mi_like_p () && core != -1)
uiout->field_signed ("core", core);
}
/* Redirect output to a temporary buffer for the duration
of do_print_thread. */
static void
print_thread (ui_out *uiout, const char *requested_threads,
int global_ids, int pid, int show_global_ids,
int default_inf_num, thread_info *tp, thread_info *current_thread)
{
do_with_buffered_output (do_print_thread, uiout, requested_threads,
global_ids, pid, show_global_ids,
default_inf_num, tp, current_thread);
}
/* Like print_thread_info, but in addition, GLOBAL_IDS indicates
whether REQUESTED_THREADS is a list of global or per-inferior
thread ids. */
@ -1176,86 +1277,13 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
for (inferior *inf : all_inferiors ())
for (thread_info *tp : inf->threads ())
{
int core;
any_thread = true;
if (tp == current_thread && tp->state == THREAD_EXITED)
current_exited = true;
/* In case REQUESTED_THREADS contains $_thread. */
if (current_thread != nullptr)
switch_to_thread (current_thread);
if (!should_print_thread (requested_threads, default_inf_num,
global_ids, pid, tp))
continue;
ui_out_emit_tuple tuple_emitter (uiout, NULL);
if (!uiout->is_mi_like_p ())
{
if (tp == current_thread)
uiout->field_string ("current", "*");
else
uiout->field_skip ("current");
uiout->field_string ("id-in-tg", print_thread_id (tp));
}
if (show_global_ids || uiout->is_mi_like_p ())
uiout->field_signed ("id", tp->global_num);
/* Switch to the thread (and inferior / target). */
switch_to_thread (tp);
/* For the CLI, we stuff everything into the target-id field.
This is a gross hack to make the output come out looking
correct. The underlying problem here is that ui-out has no
way to specify that a field's space allocation should be
shared by several fields. For MI, we do the right thing
instead. */
if (uiout->is_mi_like_p ())
{
uiout->field_string ("target-id", target_pid_to_str (tp->ptid));
const char *extra_info = target_extra_thread_info (tp);
if (extra_info != nullptr)
uiout->field_string ("details", extra_info);
const char *name = thread_name (tp);
if (name != NULL)
uiout->field_string ("name", name);
}
else
{
uiout->field_string ("target-id", thread_target_id_str (tp));
}
if (tp->state == THREAD_RUNNING)
uiout->text ("(running)\n");
else
{
/* The switch above put us at the top of the stack (leaf
frame). */
print_stack_frame (get_selected_frame (NULL),
/* For MI output, print frame level. */
uiout->is_mi_like_p (),
LOCATION, 0);
}
if (uiout->is_mi_like_p ())
{
const char *state = "stopped";
if (tp->state == THREAD_RUNNING)
state = "running";
uiout->field_string ("state", state);
}
core = target_core_of_thread (tp->ptid);
if (uiout->is_mi_like_p () && core != -1)
uiout->field_signed ("core", core);
print_thread (uiout, requested_threads, global_ids, pid,
show_global_ids, default_inf_num, tp, current_thread);
}
/* This end scope restores the current thread and the frame

141
gdb/ui-out.c
View File

@ -871,3 +871,144 @@ ui_out::ui_out (ui_out_flags flags)
ui_out::~ui_out ()
{
}
/* See ui-out.h. */
void
buffer_group::output_unit::flush () const
{
if (!m_msg.empty ())
m_stream->puts (m_msg.c_str ());
if (m_wrap_hint >= 0)
m_stream->wrap_here (m_wrap_hint);
if (m_flush)
m_stream->flush ();
}
/* See ui-out.h. */
void
buffer_group::write (const char *buf, long length_buf, ui_file *stream)
{
/* Record each line separately. */
for (size_t prev = 0, cur = 0; cur < length_buf; ++cur)
if (buf[cur] == '\n' || cur == length_buf - 1)
{
std::string msg (buf + prev, cur - prev + 1);
if (m_buffered_output.size () > 0
&& m_buffered_output.back ().m_wrap_hint == -1
&& m_buffered_output.back ().m_stream == stream
&& m_buffered_output.back ().m_msg.size () > 0
&& m_buffered_output.back ().m_msg.back () != '\n')
m_buffered_output.back ().m_msg.append (msg);
else
{
m_buffered_output.emplace_back (msg);
m_buffered_output.back ().m_stream = stream;
}
prev = cur + 1;
}
}
/* See ui-out.h. */
void
buffer_group::wrap_here (int indent, ui_file *stream)
{
m_buffered_output.emplace_back ("", indent);
m_buffered_output.back ().m_stream = stream;
}
/* See ui-out.h. */
void
buffer_group::flush_here (ui_file *stream)
{
m_buffered_output.emplace_back ("", -1, true);
m_buffered_output.back ().m_stream = stream;
}
/* See ui-out.h. */
ui_file *
get_unbuffered (ui_file *stream)
{
buffering_file *buf = dynamic_cast<buffering_file *> (stream);
if (buf == nullptr)
return stream;
return get_unbuffered (buf->stream ());
}
buffered_streams::buffered_streams (buffer_group *group, ui_out *uiout)
: m_buffered_stdout (group, gdb_stdout),
m_buffered_stderr (group, gdb_stderr),
m_buffered_stdlog (group, gdb_stdlog),
m_buffered_stdtarg (group, gdb_stdtarg),
m_buffered_stdtargerr (group, gdb_stdtargerr),
m_uiout (uiout)
{
gdb_stdout = &m_buffered_stdout;
gdb_stderr = &m_buffered_stderr;
gdb_stdlog = &m_buffered_stdlog;
gdb_stdtarg = &m_buffered_stdtarg;
gdb_stdtargerr = &m_buffered_stdtargerr;
ui_file *stream = current_uiout->current_stream ();
if (stream != nullptr)
{
m_buffered_current_uiout.emplace (group, stream);
current_uiout->redirect (&(*m_buffered_current_uiout));
}
stream = m_uiout->current_stream ();
if (stream != nullptr && current_uiout != m_uiout)
{
m_buffered_uiout.emplace (group, stream);
m_uiout->redirect (&(*m_buffered_uiout));
}
m_buffers_in_place = true;
}
/* See ui-out.h. */
void
buffered_streams::remove_buffers ()
{
if (!m_buffers_in_place)
return;
m_buffers_in_place = false;
gdb_stdout = m_buffered_stdout.stream ();
gdb_stderr = m_buffered_stderr.stream ();
gdb_stdlog = m_buffered_stdlog.stream ();
gdb_stdtarg = m_buffered_stdtarg.stream ();
gdb_stdtargerr = m_buffered_stdtargerr.stream ();
if (m_buffered_current_uiout.has_value ())
current_uiout->redirect (nullptr);
if (m_buffered_uiout.has_value ())
m_uiout->redirect (nullptr);
}
buffer_group::buffer_group (ui_out *uiout)
: m_buffered_streams (new buffered_streams (this, uiout))
{ /* Nothing. */ }
/* See ui-out.h. */
void
buffer_group::flush () const
{
m_buffered_streams->remove_buffers ();
for (const output_unit &ou : m_buffered_output)
ou.flush ();
}

184
gdb/ui-out.h
View File

@ -278,6 +278,9 @@ class ui_out
escapes. */
virtual bool can_emit_style_escape () const = 0;
/* Return the ui_file currently used for output. */
virtual ui_file *current_stream () const = 0;
/* An object that starts and finishes displaying progress updates. */
class progress_update
{
@ -470,4 +473,185 @@ private:
struct ui_out *m_uiout;
};
struct buffered_streams;
/* Organizes writes to a collection of buffered output streams
so that when flushed, output is written to all streams in
chronological order. */
struct buffer_group
{
buffer_group (ui_out *uiout);
/* Flush all buffered writes to the underlying output streams. */
void flush () const;
/* Record contents of BUF and associate it with STREAM. */
void write (const char *buf, long length_buf, ui_file *stream);
/* Record a wrap_here and associate it with STREAM. */
void wrap_here (int indent, ui_file *stream);
/* Record a call to flush and associate it with STREAM. */
void flush_here (ui_file *stream);
private:
struct output_unit
{
output_unit (std::string msg, int wrap_hint = -1, bool flush = false)
: m_msg (msg), m_wrap_hint (wrap_hint), m_flush (flush)
{}
/* Write contents of this output_unit to the underlying stream. */
void flush () const;
/* Underlying stream for which this output unit will be written to. */
ui_file *m_stream;
/* String to be written to underlying buffer. */
std::string m_msg;
/* Argument to wrap_here. -1 indicates no wrap. Used to call wrap_here
during buffer flush. */
int m_wrap_hint;
/* Indicate that the underlying output stream's flush should be called. */
bool m_flush;
};
/* Output_units to be written to buffered output streams. */
std::vector<output_unit> m_buffered_output;
/* Buffered output streams. */
std::unique_ptr<buffered_streams> m_buffered_streams;
};
/* If FILE is a buffering_file, return it's underlying stream. */
extern ui_file *get_unbuffered (ui_file *file);
/* Buffer output to gdb_stdout and gdb_stderr for the duration of FUNC. */
template<typename F, typename... Arg>
void
do_with_buffered_output (F func, ui_out *uiout, Arg... args)
{
buffer_group g (uiout);
try
{
func (uiout, std::forward<Arg> (args)...);
}
catch (const gdb_exception &ex)
{
/* Ideally flush would be called in the destructor of buffer_group,
however flushing might cause an exception to be thrown. Catch it
and ensure the first exception propagates. */
try
{
g.flush ();
}
catch (const gdb_exception &)
{
}
throw (std::move (ex));
}
/* Try was successful. Let any further exceptions propagate. */
g.flush ();
}
/* Accumulate writes to an underlying ui_file. Output to the
underlying file is deferred until required. */
struct buffering_file : public ui_file
{
buffering_file (buffer_group *group, ui_file *stream)
: m_group (group),
m_stream (stream)
{ /* Nothing. */ }
/* Return the underlying output stream. */
ui_file *stream () const
{
return m_stream;
}
/* Record the contents of BUF. */
void write (const char *buf, long length_buf) override
{
m_group->write (buf, length_buf, m_stream);
}
/* Record a wrap_here call with argument INDENT. */
void wrap_here (int indent) override
{
m_group->wrap_here (indent, m_stream);
}
/* Return true if the underlying stream is a tty. */
bool isatty () override
{
return m_stream->isatty ();
}
/* Return true if ANSI escapes can be used on the underlying stream. */
bool can_emit_style_escape () override
{
return m_stream->can_emit_style_escape ();
}
/* Flush the underlying output stream. */
void flush () override
{
return m_group->flush_here (m_stream);
}
private:
/* Coordinates buffering across multiple buffering_files. */
buffer_group *m_group;
/* The underlying output stream. */
ui_file *m_stream;
};
/* Attaches and detaches buffers for each of the gdb_std* streams. */
struct buffered_streams
{
buffered_streams (buffer_group *group, ui_out *uiout);
~buffered_streams ()
{
this->remove_buffers ();
}
/* Remove buffering_files from all underlying streams. */
void remove_buffers ();
private:
/* True if buffers are still attached to each underlying output stream. */
bool m_buffers_in_place;
/* Buffers for each gdb_std* output stream. */
buffering_file m_buffered_stdout;
buffering_file m_buffered_stderr;
buffering_file m_buffered_stdlog;
buffering_file m_buffered_stdtarg;
buffering_file m_buffered_stdtargerr;
/* Buffer for current_uiout's output stream. */
std::optional<buffering_file> m_buffered_current_uiout;
/* Additional ui_out being buffered. */
ui_out *m_uiout;
/* Buffer for m_uiout's output stream. */
std::optional<buffering_file> m_buffered_uiout;
};
#endif /* UI_OUT_H */