Improve process exit status macros on MinGW

When a Windows program is terminated by a fatal exception, its exit
code is the value of that exception, as defined by the various
EXCEPTION_* symbols in the Windows API headers.  This commit emulates
WTERMSIG etc. by translating the fatal exception codes to more-or-less
equivalent Posix signals.

gdb/ChangeLog:
2020-01-06  Eli Zaretskii  <eliz@gnu.org>
	    Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMMON_SFILES): Add gdbsupport/gdb_wait.c.
	* windows-tdep.c: New enumeration of WINDOWS_SIG* signals.
	(windows_gdb_signal_to_target): New function, uses the above
	enumeration to convert GDB internal signal codes to equivalent
	Windows codes.
	(windows_init_abi): Call set_gdbarch_gdb_signal_to_target.
	* windows-nat.c: Include "gdb_wait.h".
	(get_windows_debug_event): Extract the fatal exception from the
	exit status and convert to the equivalent Posix signal number.
	* cli/cli-cmds.c (exit_status_set_internal_vars): Account for the
	possibility that WTERMSIG returns GDB_SIGNAL_UNKNOWN.
	* gdbsupport/gdb_wait.c: New file, implements
	windows_status_to_termsig.
	* gdbsupport/gdb_wait.h (WIFEXITED, WIFSIGNALED, WEXITSTATUS)
	(WTERMSIG) [__MINGW32__]: Separate definitions for MinGW.

gdb/gdbserver/ChangeLog:
2020-01-06  Eli Zaretskii  <eliz@gnu.org>
	    Pedro Alves  <palves@redhat.com>

	* win32-low.c (get_child_debug_event): Extract the fatal exception
	from the exit status and convert to the equivalent Posix signal
	number.
	(win32_wait): Allow TARGET_WAITKIND_SIGNALLED status as well.
	* Makefile.in (OBS, SFILES): Add gdb_wait.[co].

1 files changed, 130 insertions, 0 deletions

diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index ca9b81d..58f8838 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -35,6 +35,57 @@
 #include "solib-target.h"
 #include "gdbcore.h"
 
+/* Windows signal numbers differ between MinGW flavors and between
+   those and Cygwin.  The below enumeration was gleaned from the
+   respective headers; the ones marked with MinGW64/Cygwin are defined
+   only by MinGW64 and Cygwin, not by mingw.org's MinGW.  FIXME: We
+   should really have distinct MinGW vs Cygwin OSABIs, and two
+   separate enums, selected at runtime.  */
+
+enum
+  {
+   WINDOWS_SIGHUP = 1,	/* MinGW64/Cygwin */
+   WINDOWS_SIGINT = 2,
+   WINDOWS_SIGQUIT = 3,	/* MinGW64/Cygwin */
+   WINDOWS_SIGILL = 4,
+   WINDOWS_SIGTRAP = 5,	/* MinGW64/Cygwin */
+#ifdef __CYGWIN__
+   WINDOWS_SGABRT = 6,
+#else
+   WINDOWS_SIGIOT = 6,	/* MinGW64 */
+#endif
+   WINDOWS_SIGEMT = 7,	/* MinGW64/Cygwin */
+   WINDOWS_SIGFPE = 8,
+   WINDOWS_SIGKILL = 9,	/* MinGW64/Cygwin */
+   WINDOWS_SIGBUS = 10,	/* MinGW64/Cygwin */
+   WINDOWS_SIGSEGV = 11,
+   WINDOWS_SIGSYS = 12,	/* MinGW64/Cygwin */
+   WINDOWS_SIGPIPE = 13,/* MinGW64/Cygwin */
+   WINDOWS_SIGALRM = 14,/* MinGW64/Cygwin */
+   WINDOWS_SIGTERM = 15,
+#ifdef __CYGWIN__
+   WINDOWS_SIGURG = 16,
+   WINDOWS_SIGSTOP = 17,
+   WINDOWS_SIGTSTP = 18,
+   WINDOWS_SIGCONT = 19,
+   WINDOWS_SIGCHLD = 20,
+   WINDOWS_SIGTTIN = 21,
+   WINDOWS_SIGTTOU = 22,
+   WINDOWS_SIGIO = 23,
+   WINDOWS_SIGXCPU = 24,
+   WINDOWS_SIGXFSZ = 25,
+   WINDOWS_SIGVTALRM = 26,
+   WINDOWS_SIGPROF = 27,
+   WINDOWS_SIGWINCH = 28,
+   WINDOWS_SIGLOST = 29,
+   WINDOWS_SIGUSR1 = 30,
+   WINDOWS_SIGUSR2 = 31
+#else
+   WINDOWS_SIGBREAK = 21,
+   WINDOWS_SIGABRT = 22
+#endif
+  };
+
 struct cmd_list_element *info_w32_cmdlist;
 
 typedef struct thread_information_block_32
@@ -461,6 +512,83 @@ init_w32_command_list (void)
     }
 }
 
+/* Implementation of `gdbarch_gdb_signal_to_target'.  */
+
+static int
+windows_gdb_signal_to_target (struct gdbarch *gdbarch, enum gdb_signal signal)
+{
+  switch (signal)
+    {
+    case GDB_SIGNAL_0:
+      return 0;
+    case GDB_SIGNAL_HUP:
+      return WINDOWS_SIGHUP;
+    case GDB_SIGNAL_INT:
+      return WINDOWS_SIGINT;
+    case GDB_SIGNAL_QUIT:
+      return WINDOWS_SIGQUIT;
+    case GDB_SIGNAL_ILL:
+      return WINDOWS_SIGILL;
+    case GDB_SIGNAL_TRAP:
+      return WINDOWS_SIGTRAP;
+    case GDB_SIGNAL_ABRT:
+      return WINDOWS_SIGABRT;
+    case GDB_SIGNAL_EMT:
+      return WINDOWS_SIGEMT;
+    case GDB_SIGNAL_FPE:
+      return WINDOWS_SIGFPE;
+    case GDB_SIGNAL_KILL:
+      return WINDOWS_SIGKILL;
+    case GDB_SIGNAL_BUS:
+      return WINDOWS_SIGBUS;
+    case GDB_SIGNAL_SEGV:
+      return WINDOWS_SIGSEGV;
+    case GDB_SIGNAL_SYS:
+      return WINDOWS_SIGSYS;
+    case GDB_SIGNAL_PIPE:
+      return WINDOWS_SIGPIPE;
+    case GDB_SIGNAL_ALRM:
+      return WINDOWS_SIGALRM;
+    case GDB_SIGNAL_TERM:
+      return WINDOWS_SIGTERM;
+#ifdef __CYGWIN__
+    case GDB_SIGNAL_URG:
+      return WINDOWS_SIGURG;
+    case GDB_SIGNAL_STOP:
+      return WINDOWS_SIGSTOP;
+    case GDB_SIGNAL_TSTP:
+      return WINDOWS_SIGTSTP;
+    case GDB_SIGNAL_CONT:
+      return WINDOWS_SIGCONT;
+    case GDB_SIGNAL_CHLD:
+      return WINDOWS_SIGCHLD;
+    case GDB_SIGNAL_TTIN:
+      return WINDOWS_SIGTTIN;
+    case GDB_SIGNAL_TTOU:
+      return WINDOWS_SIGTTOU;
+    case GDB_SIGNAL_IO:
+      return WINDOWS_SIGIO;
+    case GDB_SIGNAL_XCPU:
+      return WINDOWS_SIGXCPU;
+    case GDB_SIGNAL_XFSZ:
+      return WINDOWS_SIGXFSZ;
+    case GDB_SIGNAL_VTALRM:
+      return WINDOWS_SIGVTALRM;
+    case GDB_SIGNAL_PROF:
+      return WINDOWS_SIGPROF;
+    case GDB_SIGNAL_WINCH:
+      return WINDOWS_SIGWINCH;
+    case GDB_SIGNAL_PWR:
+      return WINDOWS_SIGLOST;
+    case GDB_SIGNAL_USR1:
+      return WINDOWS_SIGUSR1;
+    case GDB_SIGNAL_USR2:
+      return WINDOWS_SIGUSR2;
+#endif	/* __CYGWIN__ */
+    }
+  return -1;
+}
+
 /* To be called from the various GDB_OSABI_CYGWIN handlers for the
    various Windows architectures and machine types.  */
 
@@ -477,6 +605,8 @@ windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_iterate_over_objfiles_in_search_order
     (gdbarch, windows_iterate_over_objfiles_in_search_order);
 
+  set_gdbarch_gdb_signal_to_target (gdbarch, windows_gdb_signal_to_target);
+
   set_solib_ops (gdbarch, &solib_target_so_ops);
 }