libposix: allow custom translations of exit status

sys/include/posix.h

@@ -3,16 +3,16 @@
  *
  * Copyright (C) 2017 Giacomo Tesio <giacomo@tesio.it>
  *
- * Jehanne is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3 of the License.
+ * This is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
  *
  * Jehanne is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
- * You should have received a copy of the GNU General Public License
+ * You should have received a copy of the GNU Affero General Public License
  * along with Jehanne.  If not, see <http://www.gnu.org/licenses/>.
  */
 
@@ -68,6 +68,7 @@ extern void POSIX_free(void *ptr);
  *
  *	libposix_define_errno to set the value of each PosixError
  *	libposix_translate_error to translate error strings to PosixError
+ * 	libposix_set_signal_trampoline to dispatch signal received as notes
  *	libposix_set_stat_reader
  *	libposix_set_tms_reader
  *	libposix_set_timeval_reader
@@ -147,6 +148,18 @@ extern int libposix_translate_open(PosixOpenTranslator translation);
 
 extern int libposix_translate_seek_whence(int seek_set, int seek_cur, int seek_end);
 
+/* Map the main exit status received by POSIX_exit to the exit status
+ * string for Jehanne.
+ *
+ * Must return nil if unable to translate the status, so that the
+ * default translation strategy will be adopted.
+ */
+typedef char* (*PosixExitStatusTranslator)(int status);
+
+extern int libposix_translate_exit_status(PosixExitStatusTranslator translator);
+
+/* Dispatch the signal to the registered handlers.
+ */
 typedef int (*PosixSignalTrampoline)(int signal);
 
 extern int libposix_set_signal_trampoline(PosixSignalTrampoline trampoline);

sys/src/lib/posix/processes.c

@@ -23,17 +23,23 @@
 extern char **environ;
 
 static PosixSignalTrampoline __libposix_signal_trampoline;
+static PosixExitStatusTranslator __libposix_exit_status_translator;
 
 #define __POSIX_SIGNAL_PREFIX_LEN (sizeof(__POSIX_SIGNAL_PREFIX)-1)
 
 void
 POSIX_exit(int code)
 {
-	char buf[64];
+	char buf[64], *s;
 
-	if(code == 0)
-		exits(nil);
-	snprint(buf, sizeof(buf), __POSIX_EXIT_PREFIX "%d", code);
+	if(__libposix_exit_status_translator != nil
+	&&(s = __libposix_exit_status_translator(code)) != nil){
+		snprint(buf, sizeof(buf), "%s", s);
+	} else {
+		if(code == 0)
+			exits(nil);
+		snprint(buf, sizeof(buf), __POSIX_EXIT_PREFIX "%d", code);
+	}
 	exits(buf);
 }
 
@@ -175,6 +181,17 @@ __libposix_note_handler(void *ureg, char *note)
 	return __libposix_signal_trampoline(sig);
 }
 
+int
+libposix_translate_exit_status(PosixExitStatusTranslator translator)
+{
+	if(__libposix_initialized())
+		return 0;
+	if(translator == nil)
+		return 0;
+	__libposix_exit_status_translator = translator;
+	return 1;
+}
+
 int
 libposix_set_signal_trampoline(PosixSignalTrampoline trampoline)
 {
@@ -191,4 +208,5 @@ __libposix_processes_check_conf(void)
 {
 	if(__libposix_signal_trampoline == nil)
 		sysfatal("libposix: no signal trampoline");
+	/* __libposix_exit_status_translator is optional */
 }