gdb-readline-6.0-signal.patch

   1 http://sourceware.org/ml/gdb-patches/2009-11/msg00596.html
   2 Subject: [gdb FYI-patch] callback-mode readline-6.0 regression
   3
   4 Hi Chet,
   5
   6 FSF GDB currently ships bundled with readline-5.2 which works fine.
   7 But using --with-system-readline and readline-6.0-patchlevel4 has
   8 a regression:
   9
  10 readline-5.2: Run `gdb -nx -q' and type CTRL-C:
  11 (gdb) Quit
  12 (gdb) _
  13
  14 readline-6.0: Run `gdb -nx -q' and type CTRL-C:
  15 (gdb) _
  16  = nothing happens (it gets buffered and executed later)
  17         (It does also FAIL on gdb.gdb/selftest.exp.)
  18
  19 It is because GDB waits in its own poll() mainloop and readline uses via
  20 rl_callback_handler_install and rl_callback_handler_remove.  This way the
  21 readline internal variable _rl_interrupt_immediately remains 0 and CTRL-C gets
  22 only stored to _rl_caught_signal but not executed.
  23
  24 Seen in rl_signal_handler even if _rl_interrupt_immediately is set and
  25 _rl_handle_signal is called then the signal is still stored to
  26 _rl_caught_signal.  In the _rl_interrupt_immediately case it should not be
  27 stored when it was already processed.
  28
  29 rl_signal_handler does `_rl_interrupt_immediately = 0;' - while I am not aware
  30 of its meaning it breaks the nest-counting of other routines which do
  31 `_rl_interrupt_immediately++;' and `_rl_interrupt_immediately--;' possibly
  32 creating problematic `_rl_interrupt_immediately == -1'.
  33
  34 `_rl_interrupt_immediately' is an internal variable, how it could be accessed
  35 by a readline application? (OK, maybe it should not be used.)
  36
  37 Attaching a current GDB-side patch but it must access readline internal
  38 variable _rl_caught_signal and it is generally just a workaround.  Could you
  39 please include support for signals in this asynchronous mode in readline-6.1?
  40 I find it would be enough to make RL_CHECK_SIGNALS public?
  41
  42
  43 GDB: No regressions on {x86_64,x86_64-m32,i686}-fedora12-linux-gnu.
  44 But this is not a patch intended to be accepted.
  45
  46
  47 Thanks,
  48 Jan
  49
  50
  51 gdb/
  52 2009-11-29  Jan Kratochvil  <jan.kratochvil@redhat.com>
  53
  54         * config.in, configure: Regenerate.
  55         * configure.ac (for readline_echoing_p): Move inside $LIBS change.
  56         (for _rl_caught_signal): New.
  57         * event-loop.c: Include readline/readline.h.
  58         (gdb_do_one_event) [HAVE_READLINE_CAUGHT_SIGNAL]: New.
  59
  60 gdb/testsuite/
  61 2009-11-29  Jan Kratochvil  <jan.kratochvil@redhat.com>
  62
  63         * gdb.gdb/selftest.exp (backtrace through signal handler): Move before
  64         SIGINT pass, drop the timeout case.
  65         (send SIGINT signal to child process): Use gdb_test.
  66         (backtrace through readline handler): New.
  67
  68 --- a/gdb/config.in
  69 +++ b/gdb/config.in
  70 @@ -351,6 +351,9 @@
  71  /* Define if Python interpreter is being linked in. */
  72  #undef HAVE_PYTHON
  73
  74 +/* readline-6.0 workaround of blocked signals. */
  75 +#undef HAVE_READLINE_CAUGHT_SIGNAL
  76 +
  77  /* Define to 1 if you have the `realpath' function. */
  78  #undef HAVE_REALPATH
  79
  80 --- a/gdb/configure.ac
  81 +++ b/gdb/configure.ac
  82 @@ -539,17 +539,25 @@ if test "$with_system_readline" = yes; then
  83    # readline-6.0 started to use the name `_rl_echoing_p'.
  84    # `$(READLINE_DIR)/' of bundled readline would not resolve in configure.
  85
  86 -  AC_MSG_CHECKING([for readline_echoing_p])
  87    save_LIBS=$LIBS
  88    LIBS="$LIBS $READLINE"
  89 +  AC_MSG_CHECKING([for readline_echoing_p])
  90    AC_LINK_IFELSE(AC_LANG_PROGRAM(,[[extern int readline_echoing_p;
  91                                     return readline_echoing_p;]]),
  92                  [READLINE_ECHOING_P=yes],
  93                  [READLINE_ECHOING_P=no
  94                   AC_DEFINE([readline_echoing_p], [_rl_echoing_p],
  95                             [readline-6.0 started to use different name.])])
  96 -  LIBS="$save_LIBS"
  97    AC_MSG_RESULT([$READLINE_ECHOING_P])
  98 +  AC_MSG_CHECKING([for _rl_caught_signal])
  99 +  AC_LINK_IFELSE(AC_LANG_PROGRAM(,[[extern int volatile _rl_caught_signal;
 100 +                                   return _rl_caught_signal;]]),
 101 +                [READLINE_CAUGHT_SIGNAL=yes
 102 +                 AC_DEFINE([HAVE_READLINE_CAUGHT_SIGNAL],,
 103 +                           [readline-6.0 workaround of blocked signals.])],
 104 +                [READLINE_CAUGHT_SIGNAL=no])
 105 +  AC_MSG_RESULT([$READLINE_CAUGHT_SIGNAL])
 106 +  LIBS="$save_LIBS"
 107  else
 108    READLINE='$(READLINE_DIR)/libreadline.a'
 109    READLINE_DEPS='$(READLINE)'
 110 --- a/gdb/event-loop.c
 111 +++ b/gdb/event-loop.c
 112 @@ -37,6 +37,7 @@
 113  #include "exceptions.h"
 114  #include "gdb_assert.h"
 115  #include "gdb_select.h"
 116 +#include "readline/readline.h"
 117
 118  /* Data point to pass to the event handler.  */
 119  typedef union event_data
 120 @@ -411,6 +412,9 @@ gdb_do_one_event (void *data)
 121    static int event_source_head = 0;
 122    const int number_of_sources = 3;
 123    int current = 0;
 124 +#ifdef HAVE_READLINE_CAUGHT_SIGNAL
 125 +  extern int volatile _rl_caught_signal;
 126 +#endif
 127
 128    /* Any events already waiting in the queue?  */
 129    if (process_event ())
 130 @@ -455,6 +459,16 @@ gdb_do_one_event (void *data)
 131    if (gdb_wait_for_event (1) < 0)
 132      return -1;
 133
 134 +#ifdef HAVE_READLINE_CAUGHT_SIGNAL
 135 +  if (async_command_editing_p && RL_ISSTATE (RL_STATE_CALLBACK)
 136 +      && _rl_caught_signal)
 137 +    {
 138 +      /* Call RL_CHECK_SIGNALS this way.  */
 139 +      rl_callback_handler_remove ();
 140 +      rl_callback_handler_install (NULL, input_handler);
 141 +    }
 142 +#endif
 143 +
 144    /* Handle any new events occurred while waiting.  */
 145    if (process_event ())
 146      return 1;
 147 --- a/gdb/testsuite/gdb.gdb/selftest.exp
 148 +++ b/gdb/testsuite/gdb.gdb/selftest.exp
 149 @@ -464,31 +464,42 @@ GDB.*Copyright \[0-9\]+ Free Software Foundation, Inc..*$gdb_prompt $"\
 150             fail "$description (timeout)"
 151         }
 152      }
 153 -
 154 -    set description "send SIGINT signal to child process"
 155 -    send_gdb "signal SIGINT\n"
 156 -    gdb_expect {
 157 -       -re "Continuing with signal SIGINT.*$gdb_prompt $" {
 158 +
 159 +    # get a stack trace with the poll function
 160 +    #
 161 +    # This fails on some linux systems for unknown reasons.  On the
 162 +    # systems where it fails, sometimes it works fine when run manually.
 163 +    # The testsuite failures may not be limited to just aout systems.
 164 +    setup_xfail "i*86-pc-linuxaout-gnu"
 165 +    set description "backtrace through signal handler"
 166 +    gdb_test_multiple "backtrace" $description {
 167 +       -re "#0.*(read|poll).*in main \\(.*\\) at .*gdb\\.c.*$gdb_prompt $" {
 168             pass "$description"
 169         }
 170         -re ".*$gdb_prompt $" {
 171 +           # On the alpha, we hit the infamous problem about gdb
 172 +           # being unable to get the frame pointer (mentioned in
 173 +           # gdb/README).  As it is intermittent, there is no way to
 174 +           # XFAIL it which will give us an XPASS if the problem goes
 175 +           # away.
 176 +           setup_xfail "alpha*-*-osf*"
 177             fail "$description"
 178         }
 179 -       timeout {
 180 -           fail "$description (timeout)"
 181 -       }
 182      }
 183
 184 -    # get a stack trace
 185 +    gdb_test "signal SIGINT" "Continuing with signal SIGINT.*" \
 186 +            "send SIGINT signal to child process"
 187 +
 188 +    # get a stack trace being redelivered by readline
 189      #
 190      # This fails on some linux systems for unknown reasons.  On the
 191      # systems where it fails, sometimes it works fine when run manually.
 192      # The testsuite failures may not be limited to just aout systems.
 193 +    # Optional system readline may not have symbols to be shown.
 194      setup_xfail "i*86-pc-linuxaout-gnu"
 195 -    set description "backtrace through signal handler"
 196 -    send_gdb "backtrace\n"
 197 -    gdb_expect {
 198 -       -re "#0.*(read|poll).*in main \\(.*\\) at .*gdb\\.c.*$gdb_prompt $" {
 199 +    set description "backtrace through readline handler"
 200 +    gdb_test_multiple "backtrace" $description {
 201 +       -re "#0.*gdb_do_one_event.*in main \\(.*\\) at .*gdb\\.c.*$gdb_prompt $" {
 202             pass "$description"
 203         }
 204         -re ".*$gdb_prompt $" {
 205 @@ -500,9 +510,6 @@ GDB.*Copyright \[0-9\]+ Free Software Foundation, Inc..*$gdb_prompt $"\
 206             setup_xfail "alpha*-*-osf*"
 207             fail "$description"
 208         }
 209 -       timeout {
 210 -           fail "$description (timeout)"
 211 -       }
 212      }
 213
 214
 215 --- gdb-7.0/gdb/configure       2009-12-07 18:53:30.000000000 +0100
 216 +++ gdb-7.0-x/gdb/configure     2009-12-07 18:53:14.000000000 +0100
 217 @@ -9201,15 +9201,11 @@ if test "$with_system_readline" = yes; t
 218    # readline-6.0 started to use the name `_rl_echoing_p'.
 219    # `$(READLINE_DIR)/' of bundled readline would not resolve in configure.
 220
 221 -  echo "$as_me:$LINENO: checking for readline_echoing_p" >&5
 222 -echo $ECHO_N "checking for readline_echoing_p... $ECHO_C" >&6
 223    save_LIBS=$LIBS
 224    LIBS="$LIBS $READLINE"
 225 -  cat >conftest.$ac_ext <<_ACEOF
 226 -/* confdefs.h.  */
 227 -_ACEOF
 228 -cat confdefs.h >>conftest.$ac_ext
 229 -cat >>conftest.$ac_ext <<_ACEOF
 230 +  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for readline_echoing_p" >&5
 231 +$as_echo_n "checking for readline_echoing_p... " >&6; }
 232 +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 233  /* end confdefs.h.  */
 234
 235  int
 236 @@ -9221,45 +9217,45 @@ extern int readline_echoing_p;
 237    return 0;
 238  }
 239  _ACEOF
 240 -rm -f conftest.$ac_objext conftest$ac_exeext
 241 -if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
 242 -  (eval $ac_link) 2>conftest.er1
 243 -  ac_status=$?
 244 -  grep -v '^ *+' conftest.er1 >conftest.err
 245 -  rm -f conftest.er1
 246 -  cat conftest.err >&5
 247 -  echo "$as_me:$LINENO: \$? = $ac_status" >&5
 248 -  (exit $ac_status); } &&
 249 -        { ac_try='test -z "$ac_c_werror_flag"
 250 -                        || test ! -s conftest.err'
 251 -  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
 252 -  (eval $ac_try) 2>&5
 253 -  ac_status=$?
 254 -  echo "$as_me:$LINENO: \$? = $ac_status" >&5
 255 -  (exit $ac_status); }; } &&
 256 -        { ac_try='test -s conftest$ac_exeext'
 257 -  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
 258 -  (eval $ac_try) 2>&5
 259 -  ac_status=$?
 260 -  echo "$as_me:$LINENO: \$? = $ac_status" >&5
 261 -  (exit $ac_status); }; }; then
 262 +if ac_fn_c_try_link "$LINENO"; then :
 263    READLINE_ECHOING_P=yes
 264  else
 265 -  echo "$as_me: failed program was:" >&5
 266 -sed 's/^/| /' conftest.$ac_ext >&5
 267 +  READLINE_ECHOING_P=no
 268
 269 -READLINE_ECHOING_P=no
 270 +$as_echo "#define readline_echoing_p _rl_echoing_p" >>confdefs.h
 271 +
 272 +fi
 273 +rm -f core conftest.err conftest.$ac_objext \
 274 +    conftest$ac_exeext conftest.$ac_ext
 275 +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READLINE_ECHOING_P" >&5
 276 +$as_echo "$READLINE_ECHOING_P" >&6; }
 277 +  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for _rl_caught_signal" >&5
 278 +$as_echo_n "checking for _rl_caught_signal... " >&6; }
 279 +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 280 +/* end confdefs.h.  */
 281
 282 -cat >>confdefs.h <<\_ACEOF
 283 -#define readline_echoing_p _rl_echoing_p
 284 +int
 285 +main ()
 286 +{
 287 +extern int volatile _rl_caught_signal;
 288 +                                   return _rl_caught_signal;
 289 +  ;
 290 +  return 0;
 291 +}
 292  _ACEOF
 293 +if ac_fn_c_try_link "$LINENO"; then :
 294 +  READLINE_CAUGHT_SIGNAL=yes
 295 +
 296 +$as_echo "#define HAVE_READLINE_CAUGHT_SIGNAL /**/" >>confdefs.h
 297
 298 +else
 299 +  READLINE_CAUGHT_SIGNAL=no
 300  fi
 301 -rm -f conftest.err conftest.$ac_objext \
 302 -      conftest$ac_exeext conftest.$ac_ext
 303 +rm -f core conftest.err conftest.$ac_objext \
 304 +    conftest$ac_exeext conftest.$ac_ext
 305 +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READLINE_CAUGHT_SIGNAL" >&5
 306 +$as_echo "$READLINE_CAUGHT_SIGNAL" >&6; }
 307    LIBS="$save_LIBS"
 308 -  echo "$as_me:$LINENO: result: $READLINE_ECHOING_P" >&5
 309 -echo "${ECHO_T}$READLINE_ECHOING_P" >&6
 310  else
 311    READLINE='$(READLINE_DIR)/libreadline.a'
 312    READLINE_DEPS='$(READLINE)'