gdb/exceptions.c

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2016 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
  30 static void
  31 print_flush (void)
  32 {
  33   struct serial *gdb_stdout_serial;
  34   struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
  35
  36   if (deprecated_error_begin_hook)
  37     deprecated_error_begin_hook ();
  38
  39   if (target_supports_terminal_ours ())
  40     {
  41       make_cleanup_restore_target_terminal ();
  42       target_terminal_ours_for_output ();
  43     }
  44
  45   /* We want all output to appear now, before we print the error.  We
  46      have 3 levels of buffering we have to flush (it's possible that
  47      some of these should be changed to flush the lower-level ones
  48      too):  */
  49
  50   /* 1.  The _filtered buffer.  */
  51   if (filtered_printing_initialized ())
  52     wrap_here ("");
  53
  54   /* 2.  The stdio buffer.  */
  55   gdb_flush (gdb_stdout);
  56   gdb_flush (gdb_stderr);
  57
  58   /* 3.  The system-level buffer.  */
  59   gdb_stdout_serial = serial_fdopen (1);
  60   if (gdb_stdout_serial)
  61     {
  62       serial_drain_output (gdb_stdout_serial);
  63       serial_un_fdopen (gdb_stdout_serial);
  64     }
  65
  66   annotate_error_begin ();
  67
  68   do_cleanups (old_chain);
  69 }
  70
  71 static void
  72 print_exception (struct ui_file *file, struct gdb_exception e)
  73 {
  74   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
  75      as that way the MI's behavior is preserved.  */
  76   const char *start;
  77   const char *end;
  78
  79   for (start = e.message; start != NULL; start = end)
  80     {
  81       end = strchr (start, '\n');
  82       if (end == NULL)
  83         fputs_filtered (start, file);
  84       else
  85         {
  86           end++;
  87           ui_file_write (file, start, end - start);
  88         }
  89     }
  90   fprintf_filtered (file, "\n");
  91
  92   /* Now append the annotation.  */
  93   switch (e.reason)
  94     {
  95     case RETURN_QUIT:
  96       annotate_quit ();
  97       break;
  98     case RETURN_ERROR:
  99       /* Assume that these are all errors.  */
 100       annotate_error ();
 101       break;
 102     default:
 103       internal_error (__FILE__, __LINE__, _("Bad switch."));
 104     }
 105 }
 106
 107 void
 108 exception_print (struct ui_file *file, struct gdb_exception e)
 109 {
 110   if (e.reason < 0 && e.message != NULL)
 111     {
 112       print_flush ();
 113       print_exception (file, e);
 114     }
 115 }
 116
 117 void
 118 exception_fprintf (struct ui_file *file, struct gdb_exception e,
 119                    const char *prefix, ...)
 120 {
 121   if (e.reason < 0 && e.message != NULL)
 122     {
 123       va_list args;
 124
 125       print_flush ();
 126
 127       /* Print the prefix.  */
 128       va_start (args, prefix);
 129       vfprintf_filtered (file, prefix, args);
 130       va_end (args);
 131
 132       print_exception (file, e);
 133     }
 134 }
 135
 136 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 137    handler.  If an exception (enum return_reason) is thrown using
 138    throw_exception() than all cleanups installed since
 139    catch_exceptions() was entered are invoked, the (-ve) exception
 140    value is then returned by catch_exceptions.  If FUNC() returns
 141    normally (with a positive or zero return value) then that value is
 142    returned by catch_exceptions().  It is an internal_error() for
 143    FUNC() to return a negative value.
 144
 145    See exceptions.h for further usage details.  */
 146
 147 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
 148    error() et al. could maintain a set of flags that indicate the
 149    current state of each of the longjmp buffers.  This would give the
 150    longjmp code the chance to detect a longjmp botch (before it gets
 151    to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
 152    code also randomly used a SET_TOP_LEVEL macro that directly
 153    initialized the longjmp buffers.  */
 154
 155 int
 156 catch_exceptions (struct ui_out *uiout,
 157                   catch_exceptions_ftype *func,
 158                   void *func_args,
 159                   return_mask mask)
 160 {
 161   return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
 162 }
 163
 164 int
 165 catch_exceptions_with_msg (struct ui_out *func_uiout,
 166                            catch_exceptions_ftype *func,
 167                            void *func_args,
 168                            char **gdberrmsg,
 169                            return_mask mask)
 170 {
 171   struct gdb_exception exception = exception_none;
 172   volatile int val = 0;
 173   struct ui_out *saved_uiout;
 174
 175   /* Save and override the global ``struct ui_out'' builder.  */
 176   saved_uiout = current_uiout;
 177   current_uiout = func_uiout;
 178
 179   TRY
 180     {
 181       val = (*func) (current_uiout, func_args);
 182     }
 183   CATCH (ex, RETURN_MASK_ALL)
 184     {
 185       exception = ex;
 186     }
 187   END_CATCH
 188
 189   /* Restore the global builder.  */
 190   current_uiout = saved_uiout;
 191
 192   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 193     {
 194       /* The caller didn't request that the event be caught.
 195          Rethrow.  */
 196       throw_exception (exception);
 197     }
 198
 199   exception_print (gdb_stderr, exception);
 200   gdb_assert (val >= 0);
 201   gdb_assert (exception.reason <= 0);
 202   if (exception.reason < 0)
 203     {
 204       /* If caller wants a copy of the low-level error message, make
 205          one.  This is used in the case of a silent error whereby the
 206          caller may optionally want to issue the message.  */
 207       if (gdberrmsg != NULL)
 208         {
 209           if (exception.message != NULL)
 210             *gdberrmsg = xstrdup (exception.message);
 211           else
 212             *gdberrmsg = NULL;
 213         }
 214       return exception.reason;
 215     }
 216   return val;
 217 }
 218
 219 /* This function is superseded by catch_exceptions().  */
 220
 221 int
 222 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
 223               return_mask mask)
 224 {
 225   struct gdb_exception exception = exception_none;
 226   volatile int val = 0;
 227   struct ui_out *saved_uiout;
 228
 229   /* Save the global ``struct ui_out'' builder.  */
 230   saved_uiout = current_uiout;
 231
 232   TRY
 233     {
 234       val = func (func_args);
 235     }
 236   CATCH (ex, RETURN_MASK_ALL)
 237     {
 238       exception = ex;
 239     }
 240   END_CATCH
 241
 242   /* Restore the global builder.  */
 243   current_uiout = saved_uiout;
 244
 245   if (exception.reason < 0 && (mask & RETURN_MASK (exception.reason)) == 0)
 246     {
 247       /* The caller didn't request that the event be caught.
 248          Rethrow.  */
 249       throw_exception (exception);
 250     }
 251
 252   exception_fprintf (gdb_stderr, exception, "%s", errstring);
 253   if (exception.reason != 0)
 254     return 0;
 255   return val;
 256 }