gdb/mingw-hdep.c

   1 /* Host support routines for MinGW, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2006-2018 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 "main.h"
  22 #include "serial.h"
  23 #include "event-loop.h"
  24
  25 #include "gdb_select.h"
  26 #include "readline/readline.h"
  27
  28 #include <windows.h>
  29
  30 /* Return an absolute file name of the running GDB, if possible, or
  31    ARGV0 if not.  The return value is in malloc'ed storage.  */
  32
  33 char *
  34 windows_get_absolute_argv0 (const char *argv0)
  35 {
  36   char full_name[PATH_MAX];
  37
  38   if (GetModuleFileName (NULL, full_name, PATH_MAX))
  39     return xstrdup (full_name);
  40   return xstrdup (argv0);
  41 }
  42
  43 /* Wrapper for select.  On Windows systems, where the select interface
  44    only works for sockets, this uses the GDB serial abstraction to
  45    handle sockets, consoles, pipes, and serial ports.
  46
  47    The arguments to this function are the same as the traditional
  48    arguments to select on POSIX platforms.  */
  49
  50 int
  51 gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
  52             struct timeval *timeout)
  53 {
  54   static HANDLE never_handle;
  55   HANDLE handles[MAXIMUM_WAIT_OBJECTS];
  56   HANDLE h;
  57   DWORD event;
  58   DWORD num_handles;
  59   /* SCBS contains serial control objects corresponding to file
  60      descriptors in READFDS and WRITEFDS.  */
  61   struct serial *scbs[MAXIMUM_WAIT_OBJECTS];
  62   /* The number of valid entries in SCBS.  */
  63   size_t num_scbs;
  64   int fd;
  65   int num_ready;
  66   size_t indx;
  67
  68   num_ready = 0;
  69   num_handles = 0;
  70   num_scbs = 0;
  71   for (fd = 0; fd < n; ++fd)
  72     {
  73       HANDLE read = NULL, except = NULL;
  74       struct serial *scb;
  75
  76       /* There is no support yet for WRITEFDS.  At present, this isn't
  77          used by GDB -- but we do not want to silently ignore WRITEFDS
  78          if something starts using it.  */
  79       gdb_assert (!writefds || !FD_ISSET (fd, writefds));
  80
  81       if ((!readfds || !FD_ISSET (fd, readfds))
  82           && (!exceptfds || !FD_ISSET (fd, exceptfds)))
  83         continue;
  84
  85       scb = serial_for_fd (fd);
  86       if (scb)
  87         {
  88           serial_wait_handle (scb, &read, &except);
  89           scbs[num_scbs++] = scb;
  90         }
  91
  92       if (read == NULL)
  93         read = (HANDLE) _get_osfhandle (fd);
  94       if (except == NULL)
  95         {
  96           if (!never_handle)
  97             never_handle = CreateEvent (0, FALSE, FALSE, 0);
  98
  99           except = never_handle;
 100         }
 101
 102       if (readfds && FD_ISSET (fd, readfds))
 103         {
 104           gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
 105           handles[num_handles++] = read;
 106         }
 107
 108       if (exceptfds && FD_ISSET (fd, exceptfds))
 109         {
 110           gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
 111           handles[num_handles++] = except;
 112         }
 113     }
 114
 115   gdb_assert (num_handles <= MAXIMUM_WAIT_OBJECTS);
 116
 117   event = WaitForMultipleObjects (num_handles,
 118                                   handles,
 119                                   FALSE,
 120                                   timeout
 121                                   ? (timeout->tv_sec * 1000
 122                                      + timeout->tv_usec / 1000)
 123                                   : INFINITE);
 124   /* EVENT can only be a value in the WAIT_ABANDONED_0 range if the
 125      HANDLES included an abandoned mutex.  Since GDB doesn't use
 126      mutexes, that should never occur.  */
 127   gdb_assert (!(WAIT_ABANDONED_0 <= event
 128                 && event < WAIT_ABANDONED_0 + num_handles));
 129   /* We no longer need the helper threads to check for activity.  */
 130   for (indx = 0; indx < num_scbs; ++indx)
 131     serial_done_wait_handle (scbs[indx]);
 132   if (event == WAIT_FAILED)
 133     return -1;
 134   if (event == WAIT_TIMEOUT)
 135     return 0;
 136   /* Run through the READFDS, clearing bits corresponding to descriptors
 137      for which input is unavailable.  */
 138   h = handles[event - WAIT_OBJECT_0];
 139   for (fd = 0, indx = 0; fd < n; ++fd)
 140     {
 141       HANDLE fd_h;
 142
 143       if ((!readfds || !FD_ISSET (fd, readfds))
 144           && (!exceptfds || !FD_ISSET (fd, exceptfds)))
 145         continue;
 146
 147       if (readfds && FD_ISSET (fd, readfds))
 148         {
 149           fd_h = handles[indx++];
 150           /* This handle might be ready, even though it wasn't the handle
 151              returned by WaitForMultipleObjects.  */
 152           if (fd_h != h && WaitForSingleObject (fd_h, 0) != WAIT_OBJECT_0)
 153             FD_CLR (fd, readfds);
 154           else
 155             num_ready++;
 156         }
 157
 158       if (exceptfds && FD_ISSET (fd, exceptfds))
 159         {
 160           fd_h = handles[indx++];
 161           /* This handle might be ready, even though it wasn't the handle
 162              returned by WaitForMultipleObjects.  */
 163           if (fd_h != h && WaitForSingleObject (fd_h, 0) != WAIT_OBJECT_0)
 164             FD_CLR (fd, exceptfds);
 165           else
 166             num_ready++;
 167         }
 168     }
 169
 170   /* With multi-threaded SIGINT handling, there is a race between the
 171      readline signal handler and GDB.  It may still be in
 172      rl_prep_terminal in another thread.  Do not return until it is
 173      done; we can check the state here because we never longjmp from
 174      signal handlers on Windows.  */
 175   while (RL_ISSTATE (RL_STATE_SIGHANDLER))
 176     Sleep (1);
 177
 178   return num_ready;
 179 }