3b431a3c90
PR 30219 shows an internal error due to a "Bad switch" in
print_exception() in gdb/exceptions.c. The switch in question
contains cases for RETURN_QUIT and RETURN_ERROR, but is missing a case
for the recently added RETURN_FORCED_QUIT. This commit adds that case.
Making the above change allows the errant test case to pass, but does
not fix the underlying problem, which I'll describe shortly. Even
though the addition of a case for RETURN_FORCED_QUIT isn't the actual
fix, I still think it's important to add this case so that other
situations which lead to print_exeption() being called won't generate
that "Bad switch" internal error.
In order to understand the underlying problem, please examine
this portion of the backtrace from the bug report:
0x5576e4ff5780 print_exception
/home/smarchi/src/binutils-gdb/gdb/exceptions.c:100
0x5576e4ff5930 exception_print(ui_file*, gdb_exception const&)
/home/smarchi/src/binutils-gdb/gdb/exceptions.c:110
0x5576e6a896dd quit_force(int*, int)
/home/smarchi/src/binutils-gdb/gdb/top.c:1849
The real problem is in quit_force; here's the try/catch which
eventually leads to the internal error:
/* Get out of tfind mode, and kill or detach all inferiors. */
try
{
disconnect_tracing ();
for (inferior *inf : all_inferiors ())
kill_or_detach (inf, from_tty);
}
catch (const gdb_exception &ex)
{
exception_print (gdb_stderr, ex);
}
While running the calls in the try-block, a QUIT check is being
performed. This check finds that sync_quit_force_run is (still) set,
causing a gdb_exception_forced_quit to be thrown. The exception
gdb_exception_forced_quit is derived from gdb_exception, causing
exception_print to be called. As shown by the backtrace,
print_exception is then called, leading to the internal error.
The actual fix, also implemented by this commit, is to clear
sync_quit_force_run along with the quit flag. This will allow the
various cleanup code, called by quit_force, to run without triggering
a gdb_exception_forced_quit. (Though, if another SIGTERM is sent to
the gdb process, these flags will be set again and a QUIT check in the
cleanup code will detect it and throw the exception.)
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30219
Approved-By: Simon Marchi <simon.marchi@efficios.com>
132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
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Copyright (C) 1986-2023 Free Software Foundation, Inc.
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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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#include "defs.h"
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#include "exceptions.h"
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#include "breakpoint.h"
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#include "target.h"
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#include "inferior.h"
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#include "annotate.h"
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#include "ui-out.h"
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#include "serial.h"
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#include "gdbthread.h"
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#include "top.h"
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#include "gdbsupport/gdb_optional.h"
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static void
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print_flush (void)
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{
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struct ui *ui = current_ui;
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struct serial *gdb_stdout_serial;
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if (deprecated_error_begin_hook)
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deprecated_error_begin_hook ();
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gdb::optional<target_terminal::scoped_restore_terminal_state> term_state;
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if (target_supports_terminal_ours ())
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{
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term_state.emplace ();
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target_terminal::ours_for_output ();
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}
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/* We want all output to appear now, before we print the error. We
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have 2 levels of buffering we have to flush (it's possible that
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some of these should be changed to flush the lower-level ones
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too): */
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/* 1. The stdio buffer. */
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gdb_flush (gdb_stdout);
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gdb_flush (gdb_stderr);
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/* 2. The system-level buffer. */
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gdb_stdout_serial = serial_fdopen (fileno (ui->outstream));
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if (gdb_stdout_serial)
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{
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serial_drain_output (gdb_stdout_serial);
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serial_un_fdopen (gdb_stdout_serial);
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}
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annotate_error_begin ();
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}
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static void
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print_exception (struct ui_file *file, const struct gdb_exception &e)
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{
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/* KLUDGE: cagney/2005-01-13: Write the string out one line at a time
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as that way the MI's behavior is preserved. */
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const char *start;
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const char *end;
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for (start = e.what (); start != NULL; start = end)
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{
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end = strchr (start, '\n');
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if (end == NULL)
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gdb_puts (start, file);
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else
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{
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end++;
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file->write (start, end - start);
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}
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}
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gdb_printf (file, "\n");
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/* Now append the annotation. */
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switch (e.reason)
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{
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case RETURN_QUIT:
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case RETURN_FORCED_QUIT:
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annotate_quit ();
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break;
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case RETURN_ERROR:
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/* Assume that these are all errors. */
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annotate_error ();
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break;
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default:
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internal_error (_("Bad switch."));
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}
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}
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void
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exception_print (struct ui_file *file, const struct gdb_exception &e)
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{
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if (e.reason < 0 && e.message != NULL)
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{
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print_flush ();
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print_exception (file, e);
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}
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}
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void
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exception_fprintf (struct ui_file *file, const struct gdb_exception &e,
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const char *prefix, ...)
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{
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if (e.reason < 0 && e.message != NULL)
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{
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va_list args;
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print_flush ();
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/* Print the prefix. */
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va_start (args, prefix);
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gdb_vprintf (file, prefix, args);
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va_end (args);
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print_exception (file, e);
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}
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}
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