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 #include "common/gdb_optional.h"
  31
  32 static void
  33 print_flush (void)
  34 {
  35   struct ui *ui = current_ui;
  36   struct serial *gdb_stdout_serial;
  37
  38   if (deprecated_error_begin_hook)
  39     deprecated_error_begin_hook ();
  40
  41   gdb::optional<target_terminal::scoped_restore_terminal_state> term_state;
  42   if (target_supports_terminal_ours ())
  43     {
  44       term_state.emplace ();
  45       target_terminal::ours_for_output ();
  46     }
  47
  48   /* We want all output to appear now, before we print the error.  We
  49      have 3 levels of buffering we have to flush (it's possible that
  50      some of these should be changed to flush the lower-level ones
  51      too):  */
  52
  53   /* 1.  The _filtered buffer.  */
  54   if (filtered_printing_initialized ())
  55     wrap_here ("");
  56
  57   /* 2.  The stdio buffer.  */
  58   gdb_flush (gdb_stdout);
  59   gdb_flush (gdb_stderr);
  60
  61   /* 3.  The system-level buffer.  */
  62   gdb_stdout_serial = serial_fdopen (fileno (ui->outstream));
  63   if (gdb_stdout_serial)
  64     {
  65       serial_drain_output (gdb_stdout_serial);
  66       serial_un_fdopen (gdb_stdout_serial);
  67     }
  68
  69   annotate_error_begin ();
  70 }
  71
  72 static void
  73 print_exception (struct ui_file *file, struct gdb_exception e)
  74 {
  75   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
  76      as that way the MI's behavior is preserved.  */
  77   const char *start;
  78   const char *end;
  79
  80   for (start = e.message; start != NULL; start = end)
  81     {
  82       end = strchr (start, '\n');
  83       if (end == NULL)
  84         fputs_filtered (start, file);
  85       else
  86         {
  87           end++;
  88           ui_file_write (file, start, end - start);
  89         }
  90     }
  91   fprintf_filtered (file, "\n");
  92
  93   /* Now append the annotation.  */
  94   switch (e.reason)
  95     {
  96     case RETURN_QUIT:
  97       annotate_quit ();
  98       break;
  99     case RETURN_ERROR:
 100       /* Assume that these are all errors.  */
 101       annotate_error ();
 102       break;
 103     default:
 104       internal_error (__FILE__, __LINE__, _("Bad switch."));
 105     }
 106 }
 107
 108 void
 109 exception_print (struct ui_file *file, struct gdb_exception e)
 110 {
 111   if (e.reason < 0 && e.message != NULL)
 112     {
 113       print_flush ();
 114       print_exception (file, e);
 115     }
 116 }
 117
 118 void
 119 exception_fprintf (struct ui_file *file, struct gdb_exception e,
 120                    const char *prefix, ...)
 121 {
 122   if (e.reason < 0 && e.message != NULL)
 123     {
 124       va_list args;
 125
 126       print_flush ();
 127
 128       /* Print the prefix.  */
 129       va_start (args, prefix);
 130       vfprintf_filtered (file, prefix, args);
 131       va_end (args);
 132
 133       print_exception (file, e);
 134     }
 135 }
 136
 137 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 138    handler.  If an exception (enum return_reason) is thrown using
 139    throw_exception() than all cleanups installed since
 140    catch_exceptions() was entered are invoked, the (-ve) exception
 141    value is then returned by catch_exceptions.  If FUNC() returns
 142    normally (with a positive or zero return value) then that value is
 143    returned by catch_exceptions().  It is an internal_error() for
 144    FUNC() to return a negative value.
 145
 146    See exceptions.h for further usage details.  */
 147
 148 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
 149    error() et al. could maintain a set of flags that indicate the
 150    current state of each of the longjmp buffers.  This would give the
 151    longjmp code the chance to detect a longjmp botch (before it gets
 152    to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
 153    code also randomly used a SET_TOP_LEVEL macro that directly
 154    initialized the longjmp buffers.  */
 155
 156 int
 157 catch_exceptions (struct ui_out *uiout,
 158                   catch_exceptions_ftype *func,
 159                   void *func_args,
 160                   return_mask mask)
 161 {
 162   return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
 163 }
 164
 165 int
 166 catch_exceptions_with_msg (struct ui_out *func_uiout,
 167                            catch_exceptions_ftype *func,
 168                            void *func_args,
 169                            char **gdberrmsg,
 170                            return_mask mask)
 171 {
 172   struct gdb_exception exception = exception_none;
 173   volatile int val = 0;
 174   struct ui_out *saved_uiout;
 175
 176   /* Save and override the global ``struct ui_out'' builder.  */
 177   saved_uiout = current_uiout;
 178   current_uiout = func_uiout;
 179
 180   TRY
 181     {
 182       val = (*func) (current_uiout, func_args);
 183     }
 184   CATCH (ex, RETURN_MASK_ALL)
 185     {
 186       exception = ex;
 187     }
 188   END_CATCH
 189
 190   /* Restore the global builder.  */
 191   current_uiout = saved_uiout;
 192
 193   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 194     {
 195       /* The caller didn't request that the event be caught.
 196          Rethrow.  */
 197       throw_exception (exception);
 198     }
 199
 200   exception_print (gdb_stderr, exception);
 201   gdb_assert (val >= 0);
 202   gdb_assert (exception.reason <= 0);
 203   if (exception.reason < 0)
 204     {
 205       /* If caller wants a copy of the low-level error message, make
 206          one.  This is used in the case of a silent error whereby the
 207          caller may optionally want to issue the message.  */
 208       if (gdberrmsg != NULL)
 209         {
 210           if (exception.message != NULL)
 211             *gdberrmsg = xstrdup (exception.message);
 212           else
 213             *gdberrmsg = NULL;
 214         }
 215       return exception.reason;
 216     }
 217   return val;
 218 }
 219
 220 /* This function is superseded by catch_exceptions().  */
 221
 222 int
 223 catch_errors (catch_errors_ftype *func, void *func_args,
 224               const char *errstring, return_mask mask)
 225 {
 226   struct gdb_exception exception = exception_none;
 227   volatile int val = 0;
 228   struct ui_out *saved_uiout;
 229
 230   /* Save the global ``struct ui_out'' builder.  */
 231   saved_uiout = current_uiout;
 232
 233   TRY
 234     {
 235       val = func (func_args);
 236     }
 237   CATCH (ex, RETURN_MASK_ALL)
 238     {
 239       exception = ex;
 240     }
 241   END_CATCH
 242
 243   /* Restore the global builder.  */
 244   current_uiout = saved_uiout;
 245
 246   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 247     {
 248       /* The caller didn't request that the event be caught.
 249          Rethrow.  */
 250       throw_exception (exception);
 251     }
 252
 253   exception_fprintf (gdb_stderr, exception, "%s", errstring);
 254   if (exception.reason != 0)
 255     return 0;
 256   return val;
 257 }
 258
 259 /* See exceptions.h.  */
 260
 261 int
 262 exception_print_same (struct gdb_exception e1, struct gdb_exception e2)
 263 {
 264   const char *msg1 = e1.message;
 265   const char *msg2 = e2.message;
 266
 267   if (msg1 == NULL)
 268     msg1 = "";
 269   if (msg2 == NULL)
 270     msg2 = "";
 271
 272   return (e1.reason == e2.reason
 273           && e1.error == e2.error
 274           && strcmp (msg1, msg2) == 0);
 275 }