gdb/mingw-hdep.c

   1 /* Host support routines for MinGW, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2006-2013 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_assert.h"
  26 #include "gdb_select.h"
  27 #include "gdb_string.h"
  28 #include "readline/readline.h"
  29
  30 #include <windows.h>
  31
  32 /* This event is signalled whenever an asynchronous SIGINT handler
  33    needs to perform an action in the main thread.  */
  34 static HANDLE sigint_event;
  35
  36 /* When SIGINT_EVENT is signalled, gdb_select will call this
  37    function.  */
  38 struct async_signal_handler *sigint_handler;
  39
  40 /* The strerror() function can return NULL for errno values that are
  41    out of range.  Provide a "safe" version that always returns a
  42    printable string.
  43
  44    The Windows runtime implementation of strerror never returns NULL,
  45    but does return a useless string for anything above sys_nerr;
  46    unfortunately this includes all socket-related error codes.
  47    This replacement tries to find a system-provided error message.  */
  48
  49 char *
  50 safe_strerror (int errnum)
  51 {
  52   static char *buffer;
  53   int len;
  54
  55   if (errnum >= 0 && errnum < sys_nerr)
  56     return strerror (errnum);
  57
  58   if (buffer)
  59     {
  60       LocalFree (buffer);
  61       buffer = NULL;
  62     }
  63
  64   if (FormatMessage (FORMAT_MESSAGE_ALLOCATE_BUFFER
  65                      | FORMAT_MESSAGE_FROM_SYSTEM,
  66                      NULL, errnum,
  67                      MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
  68                      (LPTSTR) &buffer, 0, NULL) == 0)
  69     {
  70       static char buf[32];
  71       xsnprintf (buf, sizeof buf, "(undocumented errno %d)", errnum);
  72       return buf;
  73     }
  74
  75   /* Windows error messages end with a period and a CR-LF; strip that
  76      out.  */
  77   len = strlen (buffer);
  78   if (len > 3 && strcmp (buffer + len - 3, ".\r\n") == 0)
  79     buffer[len - 3] = '\0';
  80
  81   return buffer;
  82 }
  83
  84 /* Return an absolute file name of the running GDB, if possible, or
  85    ARGV0 if not.  The return value is in malloc'ed storage.  */
  86
  87 char *
  88 windows_get_absolute_argv0 (const char *argv0)
  89 {
  90   char full_name[PATH_MAX];
  91
  92   if (GetModuleFileName (NULL, full_name, PATH_MAX))
  93     return xstrdup (full_name);
  94   return xstrdup (argv0);
  95 }
  96
  97 /* Wrapper for select.  On Windows systems, where the select interface
  98    only works for sockets, this uses the GDB serial abstraction to
  99    handle sockets, consoles, pipes, and serial ports.
 100
 101    The arguments to this function are the same as the traditional
 102    arguments to select on POSIX platforms.  */
 103
 104 int
 105 gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 106             struct timeval *timeout)
 107 {
 108   static HANDLE never_handle;
 109   HANDLE handles[MAXIMUM_WAIT_OBJECTS];
 110   HANDLE h;
 111   DWORD event;
 112   DWORD num_handles;
 113   /* SCBS contains serial control objects corresponding to file
 114      descriptors in READFDS and WRITEFDS.  */
 115   struct serial *scbs[MAXIMUM_WAIT_OBJECTS];
 116   /* The number of valid entries in SCBS.  */
 117   size_t num_scbs;
 118   int fd;
 119   int num_ready;
 120   size_t indx;
 121
 122   num_ready = 0;
 123   num_handles = 0;
 124   num_scbs = 0;
 125   for (fd = 0; fd < n; ++fd)
 126     {
 127       HANDLE read = NULL, except = NULL;
 128       struct serial *scb;
 129
 130       /* There is no support yet for WRITEFDS.  At present, this isn't
 131          used by GDB -- but we do not want to silently ignore WRITEFDS
 132          if something starts using it.  */
 133       gdb_assert (!writefds || !FD_ISSET (fd, writefds));
 134
 135       if ((!readfds || !FD_ISSET (fd, readfds))
 136           && (!exceptfds || !FD_ISSET (fd, exceptfds)))
 137         continue;
 138
 139       scb = serial_for_fd (fd);
 140       if (scb)
 141         {
 142           serial_wait_handle (scb, &read, &except);
 143           scbs[num_scbs++] = scb;
 144         }
 145
 146       if (read == NULL)
 147         read = (HANDLE) _get_osfhandle (fd);
 148       if (except == NULL)
 149         {
 150           if (!never_handle)
 151             never_handle = CreateEvent (0, FALSE, FALSE, 0);
 152
 153           except = never_handle;
 154         }
 155
 156       if (readfds && FD_ISSET (fd, readfds))
 157         {
 158           gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
 159           handles[num_handles++] = read;
 160         }
 161
 162       if (exceptfds && FD_ISSET (fd, exceptfds))
 163         {
 164           gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
 165           handles[num_handles++] = except;
 166         }
 167     }
 168
 169   gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
 170   handles[num_handles++] = sigint_event;
 171
 172   event = WaitForMultipleObjects (num_handles,
 173                                   handles,
 174                                   FALSE,
 175                                   timeout
 176                                   ? (timeout->tv_sec * 1000
 177                                      + timeout->tv_usec / 1000)
 178                                   : INFINITE);
 179   /* EVENT can only be a value in the WAIT_ABANDONED_0 range if the
 180      HANDLES included an abandoned mutex.  Since GDB doesn't use
 181      mutexes, that should never occur.  */
 182   gdb_assert (!(WAIT_ABANDONED_0 <= event
 183                 && event < WAIT_ABANDONED_0 + num_handles));
 184   /* We no longer need the helper threads to check for activity.  */
 185   for (indx = 0; indx < num_scbs; ++indx)
 186     serial_done_wait_handle (scbs[indx]);
 187   if (event == WAIT_FAILED)
 188     return -1;
 189   if (event == WAIT_TIMEOUT)
 190     return 0;
 191   /* Run through the READFDS, clearing bits corresponding to descriptors
 192      for which input is unavailable.  */
 193   h = handles[event - WAIT_OBJECT_0];
 194   for (fd = 0, indx = 0; fd < n; ++fd)
 195     {
 196       HANDLE fd_h;
 197
 198       if ((!readfds || !FD_ISSET (fd, readfds))
 199           && (!exceptfds || !FD_ISSET (fd, exceptfds)))
 200         continue;
 201
 202       if (readfds && FD_ISSET (fd, readfds))
 203         {
 204           fd_h = handles[indx++];
 205           /* This handle might be ready, even though it wasn't the handle
 206              returned by WaitForMultipleObjects.  */
 207           if (fd_h != h && WaitForSingleObject (fd_h, 0) != WAIT_OBJECT_0)
 208             FD_CLR (fd, readfds);
 209           else
 210             num_ready++;
 211         }
 212
 213       if (exceptfds && FD_ISSET (fd, exceptfds))
 214         {
 215           fd_h = handles[indx++];
 216           /* This handle might be ready, even though it wasn't the handle
 217              returned by WaitForMultipleObjects.  */
 218           if (fd_h != h && WaitForSingleObject (fd_h, 0) != WAIT_OBJECT_0)
 219             FD_CLR (fd, exceptfds);
 220           else
 221             num_ready++;
 222         }
 223     }
 224
 225   /* With multi-threaded SIGINT handling, there is a race between the
 226      readline signal handler and GDB.  It may still be in
 227      rl_prep_terminal in another thread.  Do not return until it is
 228      done; we can check the state here because we never longjmp from
 229      signal handlers on Windows.  */
 230   while (RL_ISSTATE (RL_STATE_SIGHANDLER))
 231     Sleep (1);
 232
 233   if (h == sigint_event
 234       || WaitForSingleObject (sigint_event, 0) == WAIT_OBJECT_0)
 235     {
 236       if (sigint_handler != NULL)
 237         call_async_signal_handler (sigint_handler);
 238
 239       if (num_ready == 0)
 240         {
 241           errno = EINTR;
 242           return -1;
 243         }
 244     }
 245
 246   return num_ready;
 247 }
 248
 249 /* Wrapper for the body of signal handlers.  On Windows systems, a
 250    SIGINT handler runs in its own thread.  We can't longjmp from
 251    there, and we shouldn't even prompt the user.  Delay HANDLER
 252    until the main thread is next in gdb_select.  */
 253
 254 void
 255 gdb_call_async_signal_handler (struct async_signal_handler *handler,
 256                                int immediate_p)
 257 {
 258   if (immediate_p)
 259     sigint_handler = handler;
 260   else
 261     {
 262       mark_async_signal_handler (handler);
 263       sigint_handler = NULL;
 264     }
 265   SetEvent (sigint_event);
 266 }
 267
 268 /* -Wmissing-prototypes */
 269 extern initialize_file_ftype _initialize_mingw_hdep;
 270
 271 void
 272 _initialize_mingw_hdep (void)
 273 {
 274   sigint_event = CreateEvent (0, FALSE, FALSE, 0);
 275 }