Re: [Bug-XBoard] Infinite recursion

[Byrial Jensen]

Den 12-04-2012 16:19, Byrial Jensen skrev:
> Den 12-04-2012 11:54, h.g. muller skrev:
> > > If Xboard is dependent on untranslated error messages from libc, it 
> > > should run the engines in the C locale. It can be done by calling 
> > > putenv("LANGUAGE=C") in the child proces before the exec() call.
> >
> > It is not that simple. One would want the engines to run in the same 
> > locale as XBoard, in order to get translation of the engine-defined 
> > options in the Engine Settings dialogs. The libc messages that are 
> > recognized by XBoard are supposed to come from intermediaries like 
> > ssh, which you typically use when you run the engines on a remote 
> > machine (using -firstHost, -secondHost). This is needed because such 
> > interediaries might not exit when they fail to execute the engine 
> > binary. The engine itself, when run locally, can inform XBoard of its 
> > failure to start by simply quitting. Failure to exectute the engine 
> > is announced by XBoard to itself (i.e. from the child process to the 
> > main process through the pipe) using perror(), which presumably would 
> > use the current locale. So perhaps we should make the child switch to 
> > the C locale after exec failure, before using perror(). Is that 
> > possible?
>
> Yes it is possible to change locale at any time. In order to force 
> gettext to notice the change, you can use the this code according to 
> the gettext manual:
>
>               extern int  _nl_msg_cat_cntr;
>               ++_nl_msg_cat_cntr;
>
> However if exec fails, or if the child cannot change to the engine 
> directory, it could just send some recognizable code which an engine 
> never would use, followed by the localized perror() message.

How about this patch or something similar to make a better detection of 
engine startup error?

diff --git a/backend.c b/backend.c
index a2ff648..a80bf38 100644
--- a/backend.c
+++ b/backend.c
@@ -8536,16 +8536,10 @@ if(appData.debugMode) fprintf(debugFP, "nodes = 
%d, %lld\n", (int) programStats.
      * If chess program startup fails, exit with an error message.
      * Attempts to recover here are futile. [HGM] Well, we try anyway
      */
-    if ((StrStr(message, "unknown host") != NULL)
-    || (StrStr(message, "No remote directory") != NULL)
-    || (StrStr(message, "not found") != NULL)
-    || (StrStr(message, "No such file") != NULL)
-    || (StrStr(message, "can't alloc") != NULL)
-    || (StrStr(message, "Permission denied") != NULL)) {
-
+    if (strncmp(message, "XBoard StartChildProcess error:", 
strlen("XBoard StartChildProcess error:")) == 0) {
     cps->maybeThinking = FALSE;
     snprintf(buf1, sizeof(buf1), _("Failed to start %s chess program 
%s on %s: %s\n"),
-        _(cps->which), cps->program, cps->host, message);
+        _(cps->which), cps->program, cps->host, message + 
strlen("XBoard StartChildProcess error:"));
     RemoveInputSource(cps->isr);
     if(appData.icsActive) DisplayFatalError(buf1, 0, 1); else {
         if(LoadError(oldError ? NULL : buf1, cps)) return; // error 
has then been handled by LoadError
diff --git a/usystem.c b/usystem.c
index a24d04f..fb35ad2 100644
--- a/usystem.c
+++ b/usystem.c
@@ -465,6 +465,7 @@ StartChildProcess (char *cmdLine, char *dir, ProcRef 
*pr)
         dup2(1, fileno(stderr)); /* force stderr to the pipe */

     if (dir[0] != NULLCHAR && chdir(dir) != 0) {
+        fputs("XBoard StartChildProcess error:", stdout);
         perror(dir);
         exit(1);
     }
@@ -474,6 +475,7 @@ StartChildProcess (char *cmdLine, char *dir, ProcRef 
*pr)
         execvp(argv[0], argv);

     /* If we get here, exec failed */
+    fputs("XBoard StartChildProcess error:", stdout);
     perror(argv[0]);
     exit(1);
     }