Reduce stack pressure throughout Cygwin

* dcrt0.cc (initial_env): Reduce size of local path buffers to
        PATH_MAX.  Allocate debugger_command from process heap.
        (init_windows_system_directory): Very early initialize new global
        variable global_progname.
        * dll_init.cc (dll_list::alloc): Make path buffer static.  Explain why.
        (dll_list::populate_deps): Use tmp_pathbuf for local path buffer.
        * exceptions.cc (debugger_command): Convert to PWCHAR.
        (error_start_init): Allocate debugger_command and fill with wide char
        strings.  Only allocate if NULL.
        (try_to_debug): Just check if debugger_command is a NULL pointer to
        return.  Drop conversion from char to WCHAR and drop local variable
        dbg_cmd.
        * globals.cc (global_progname): New global variable to store Windows
        application path.
        * pinfo.cc (pinfo_basic::pinfo_basic): Just copy progname over from
        global_progname.
        (pinfo::status_exit): Let path_conv create the POSIX path to
        avoid local buffer.
        * pseudo_reloc.cc (__report_error): Utilize global_progname, drop local
        buffer.
        * smallprint.cc (__small_vsprintf): Just utilize global_progname for
        %P format specifier.
        (__small_vswprintf): Ditto.
        * strace.cc (PROTECT): Change to reflect x being a pointer.  Reformat.
        (CHECK): Ditto.  Reformat.
        (strace::activate): Utilize global_progname, drop local buffer.
        Fix formatting.
        (strace::vsprntf): Reduce size of local progname buffer to NAME_MAX.
        Copy and, if necessary, convert only the last path component to
        progname.
        (strace_buf_guard): New muto.
        (buf): New static pointer.
        (strace::vprntf): Use buf under strace_buf_guard lock only.  Allocate
        buffer space for buf on Windows heap.
        * wow64.cc (wow64_respawn_process): Utilize global_progname, drop
        local path buffer.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/exceptions.cc

@@ -46,7 +46,7 @@ details. */
 #define CALL_HANDLER_RETRY_OUTER 10
 #define CALL_HANDLER_RETRY_INNER 10
 
-char debugger_command[2 * NT_MAX_PATH + 20];
+PWCHAR debugger_command;
 extern u_char _sigbe;
 extern u_char _sigdelayed_end;
 
@@ -112,18 +112,19 @@ extern "C" void
 error_start_init (const char *buf)
 {
   if (!buf || !*buf)
-    {
-      debugger_command[0] = '\0';
-      return;
-    }
+    return;
+  if (!debugger_command &&
+      !(debugger_command = (PWCHAR) malloc ((2 * NT_MAX_PATH + 20)
+					    * sizeof (WCHAR))))
+    return;
 
-  char pgm[NT_MAX_PATH];
-  if (!GetModuleFileName (NULL, pgm, NT_MAX_PATH))
-    strcpy (pgm, "cygwin1.dll");
-  for (char *p = strchr (pgm, '\\'); p; p = strchr (p, '\\'))
-    *p = '/';
-
-  __small_sprintf (debugger_command, "%s \"%s\"", buf, pgm);
+  PWCHAR cp = debugger_command
+	      + sys_mbstowcs (debugger_command, NT_MAX_PATH, buf) - 1;
+  cp = wcpcpy (cp, L" \"");
+  wcpcpy (cp, global_progname);
+  for (PWCHAR p = wcschr (cp, L'\\'); p; p = wcschr (p, L'\\'))
+    *p = L'/';
+  wcscat (cp, L"\"");
 }
 
 void
@@ -474,9 +475,9 @@ cygwin_stackdump ()
 extern "C" int
 try_to_debug (bool waitloop)
 {
-  debug_printf ("debugger_command '%s'", debugger_command);
-  if (*debugger_command == '\0')
+  if (!debugger_command)
     return 0;
+  debug_printf ("debugger_command '%W'", debugger_command);
   if (being_debugged ())
     {
       extern void break_here ();
@@ -484,8 +485,8 @@ try_to_debug (bool waitloop)
       return 0;
     }
 
-  __small_sprintf (strchr (debugger_command, '\0'), " %u",
-		   GetCurrentProcessId ());
+  PWCHAR dbg_end = wcschr (debugger_command, L'\0');
+  __small_swprintf (dbg_end, L" %u", GetCurrentProcessId ());
 
   LONG prio = GetThreadPriority (GetCurrentThread ());
   SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_HIGHEST);
@@ -529,10 +530,8 @@ try_to_debug (bool waitloop)
   console_printf ("*** starting debugger for pid %u, tid %u\n",
 		  cygwin_pid (GetCurrentProcessId ()), GetCurrentThreadId ());
   BOOL dbg;
-  WCHAR dbg_cmd[strlen(debugger_command) + 1];
-  sys_mbstowcs (dbg_cmd, strlen(debugger_command) + 1, debugger_command);
   dbg = CreateProcessW (NULL,
-			dbg_cmd,
+			debugger_command,
 			NULL,
 			NULL,
 			FALSE,
@@ -542,6 +541,7 @@ try_to_debug (bool waitloop)
 			&si,
 			&pi);
 
+  *dbg_end = L'\0';
   if (!dbg)
     system_printf ("Failed to start debugger, %E");
   else