gdb/exceptions.c

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2017 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "exceptions.h"
  22 #include "breakpoint.h"
  23 #include "target.h"
  24 #include "inferior.h"
  25 #include "annotate.h"
  26 #include "ui-out.h"
  27 #include "serial.h"
  28 #include "gdbthread.h"
  29 #include "top.h"
  30
  31 static void
  32 print_flush (void)
  33 {
  34   struct ui *ui = current_ui;
  35   struct serial *gdb_stdout_serial;
  36   struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
  37
  38   if (deprecated_error_begin_hook)
  39     deprecated_error_begin_hook ();
  40
  41   if (target_supports_terminal_ours ())
  42     {
  43       make_cleanup_restore_target_terminal ();
  44       target_terminal_ours_for_output ();
  45     }
  46
  47   /* We want all output to appear now, before we print the error.  We
  48      have 3 levels of buffering we have to flush (it's possible that
  49      some of these should be changed to flush the lower-level ones
  50      too):  */
  51
  52   /* 1.  The _filtered buffer.  */
  53   if (filtered_printing_initialized ())
  54     wrap_here ("");
  55
  56   /* 2.  The stdio buffer.  */
  57   gdb_flush (gdb_stdout);
  58   gdb_flush (gdb_stderr);
  59
  60   /* 3.  The system-level buffer.  */
  61   gdb_stdout_serial = serial_fdopen (fileno (ui->outstream));
  62   if (gdb_stdout_serial)
  63     {
  64       serial_drain_output (gdb_stdout_serial);
  65       serial_un_fdopen (gdb_stdout_serial);
  66     }
  67
  68   annotate_error_begin ();
  69
  70   do_cleanups (old_chain);
  71 }
  72
  73 static void
  74 print_exception (struct ui_file *file, struct gdb_exception e)
  75 {
  76   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
  77      as that way the MI's behavior is preserved.  */
  78   const char *start;
  79   const char *end;
  80
  81   for (start = e.message; start != NULL; start = end)
  82     {
  83       end = strchr (start, '\n');
  84       if (end == NULL)
  85         fputs_filtered (start, file);
  86       else
  87         {
  88           end++;
  89           ui_file_write (file, start, end - start);
  90         }
  91     }
  92   fprintf_filtered (file, "\n");
  93
  94   /* Now append the annotation.  */
  95   switch (e.reason)
  96     {
  97     case RETURN_QUIT:
  98       annotate_quit ();
  99       break;
 100     case RETURN_ERROR:
 101       /* Assume that these are all errors.  */
 102       annotate_error ();
 103       break;
 104     default:
 105       internal_error (__FILE__, __LINE__, _("Bad switch."));
 106     }
 107 }
 108
 109 void
 110 exception_print (struct ui_file *file, struct gdb_exception e)
 111 {
 112   if (e.reason < 0 && e.message != NULL)
 113     {
 114       print_flush ();
 115       print_exception (file, e);
 116     }
 117 }
 118
 119 void
 120 exception_fprintf (struct ui_file *file, struct gdb_exception e,
 121                    const char *prefix, ...)
 122 {
 123   if (e.reason < 0 && e.message != NULL)
 124     {
 125       va_list args;
 126
 127       print_flush ();
 128
 129       /* Print the prefix.  */
 130       va_start (args, prefix);
 131       vfprintf_filtered (file, prefix, args);
 132       va_end (args);
 133
 134       print_exception (file, e);
 135     }
 136 }
 137
 138 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 139    handler.  If an exception (enum return_reason) is thrown using
 140    throw_exception() than all cleanups installed since
 141    catch_exceptions() was entered are invoked, the (-ve) exception
 142    value is then returned by catch_exceptions.  If FUNC() returns
 143    normally (with a positive or zero return value) then that value is
 144    returned by catch_exceptions().  It is an internal_error() for
 145    FUNC() to return a negative value.
 146
 147    See exceptions.h for further usage details.  */
 148
 149 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
 150    error() et al. could maintain a set of flags that indicate the
 151    current state of each of the longjmp buffers.  This would give the
 152    longjmp code the chance to detect a longjmp botch (before it gets
 153    to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
 154    code also randomly used a SET_TOP_LEVEL macro that directly
 155    initialized the longjmp buffers.  */
 156
 157 int
 158 catch_exceptions (struct ui_out *uiout,
 159                   catch_exceptions_ftype *func,
 160                   void *func_args,
 161                   return_mask mask)
 162 {
 163   return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
 164 }
 165
 166 int
 167 catch_exceptions_with_msg (struct ui_out *func_uiout,
 168                            catch_exceptions_ftype *func,
 169                            void *func_args,
 170                            char **gdberrmsg,
 171                            return_mask mask)
 172 {
 173   struct gdb_exception exception = exception_none;
 174   volatile int val = 0;
 175   struct ui_out *saved_uiout;
 176
 177   /* Save and override the global ``struct ui_out'' builder.  */
 178   saved_uiout = current_uiout;
 179   current_uiout = func_uiout;
 180
 181   TRY
 182     {
 183       val = (*func) (current_uiout, func_args);
 184     }
 185   CATCH (ex, RETURN_MASK_ALL)
 186     {
 187       exception = ex;
 188     }
 189   END_CATCH
 190
 191   /* Restore the global builder.  */
 192   current_uiout = saved_uiout;
 193
 194   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 195     {
 196       /* The caller didn't request that the event be caught.
 197          Rethrow.  */
 198       throw_exception (exception);
 199     }
 200
 201   exception_print (gdb_stderr, exception);
 202   gdb_assert (val >= 0);
 203   gdb_assert (exception.reason <= 0);
 204   if (exception.reason < 0)
 205     {
 206       /* If caller wants a copy of the low-level error message, make
 207          one.  This is used in the case of a silent error whereby the
 208          caller may optionally want to issue the message.  */
 209       if (gdberrmsg != NULL)
 210         {
 211           if (exception.message != NULL)
 212             *gdberrmsg = xstrdup (exception.message);
 213           else
 214             *gdberrmsg = NULL;
 215         }
 216       return exception.reason;
 217     }
 218   return val;
 219 }
 220
 221 /* This function is superseded by catch_exceptions().  */
 222
 223 int
 224 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
 225               return_mask mask)
 226 {
 227   struct gdb_exception exception = exception_none;
 228   volatile int val = 0;
 229   struct ui_out *saved_uiout;
 230
 231   /* Save the global ``struct ui_out'' builder.  */
 232   saved_uiout = current_uiout;
 233
 234   TRY
 235     {
 236       val = func (func_args);
 237     }
 238   CATCH (ex, RETURN_MASK_ALL)
 239     {
 240       exception = ex;
 241     }
 242   END_CATCH
 243
 244   /* Restore the global builder.  */
 245   current_uiout = saved_uiout;
 246
 247   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 248     {
 249       /* The caller didn't request that the event be caught.
 250          Rethrow.  */
 251       throw_exception (exception);
 252     }
 253
 254   exception_fprintf (gdb_stderr, exception, "%s", errstring);
 255   if (exception.reason != 0)
 256     return 0;
 257   return val;
 258 }
 259
 260 /* See exceptions.h.  */
 261
 262 int
 263 exception_print_same (struct gdb_exception e1, struct gdb_exception e2)
 264 {
 265   const char *msg1 = e1.message;
 266   const char *msg2 = e2.message;
 267
 268   if (msg1 == NULL)
 269     msg1 = "";
 270   if (msg2 == NULL)
 271     msg2 = "";
 272
 273   return (e1.reason == e2.reason
 274           && e1.error == e2.error
 275           && strcmp (msg1, msg2) == 0);
 276 }