ICU: fix the use of locales for collators

If the locale is bad the ICU default locale is used in the collator. But if the
ICU default locale is not specified by the uloc_setDefault function, its value
depends on the environment variables for the locales.

Author: Marina Polyakova

src/port/chklocale.c

@@ -40,6 +40,9 @@
 #define FREE(s) free(s)
 #endif
 
+#ifdef USE_ICU
+#define ICU_ROOT_LOCALE "root"
+#endif
 
 /*
  * This table needs to recognize all the CODESET spellings for supported
@@ -712,8 +715,45 @@ UCollator *
 open_collator(const char *collate)
 {
 	UCollator  *collator;
-	UErrorCode	status = U_ZERO_ERROR;
+	UErrorCode	status;
+	const char *save = uloc_getDefault();
+	char	   *save_dup;
+
+	if (!save)
+	{
+#ifdef FRONTEND
+		fprintf(stderr, _("ICU error: uloc_getDefault() failed"));
+		/* keep newline separate so there's only one translatable string */
+		fputc('\n', stderr);
+#else
+		ereport(ERROR, (errmsg("ICU error: uloc_getDefault() failed")));
+#endif
+		return NULL;
+	}
 
+	/* save may be pointing at a modifiable scratch variable, so copy it. */
+	save_dup = STRDUP(save);
+
+	/* set the default locale to root */
+	status = U_ZERO_ERROR;
+	uloc_setDefault(ICU_ROOT_LOCALE, &status);
+	if (U_FAILURE(status))
+	{
+#ifdef FRONTEND
+		fprintf(stderr, _("ICU error: failed to set the default locale to \"%s\": %s"),
+				ICU_ROOT_LOCALE, u_errorName(status));
+		/* keep newline separate so there's only one translatable string */
+		fputc('\n', stderr);
+#else
+		ereport(ERROR,
+				(errmsg("ICU error: failed to set the default locale to \"%s\": %s",
+						ICU_ROOT_LOCALE, u_errorName(status))));
+#endif
+		return NULL;
+	}
+
+	/* get a collator for this collate */
+	status = U_ZERO_ERROR;
 	collator = ucol_open(collate, &status);
 	if (U_FAILURE(status))
 	{
@@ -730,6 +770,25 @@ open_collator(const char *collate)
 		collator = NULL;
 	}
 
+	/* restore old value of the default locale. */
+	status = U_ZERO_ERROR;
+	uloc_setDefault(save_dup, &status);
+	if (U_FAILURE(status))
+	{
+#ifdef FRONTEND
+		fprintf(stderr, _("ICU error: failed to restore old locale \"%s\": %s"),
+				save_dup, u_errorName(status));
+		/* keep newline separate so there's only one translatable string */
+		fputc('\n', stderr);
+#else
+		ereport(ERROR,
+				(errmsg("ICU error: failed to restore old locale \"%s\": %s",
+						save_dup, u_errorName(status))));
+#endif
+		return NULL;
+	}
+	FREE(save_dup);
+
 	return collator;
 }