log: better bug avoidance for libraries incorrectly handling fd=0

src/log.c

@@ -39,13 +39,27 @@ static int err_fd = -1;
 static const char *out_filename;
 static const char *err_filename;
 
-/* redirect stdin to /dev/null to work around a libao bug */
+/*
+ * redirect stdin to /dev/null to work around a libao bug
+ * there are likely other bugs in other libraries (and even our code!)
+ * that check for fd > 0, so it's easiest to just keep
+ * fd = 0 == /dev/null for now...
+ */
 static void redirect_stdin(void)
 {
 	int fd, st;
 	struct stat ss;
 
-	if ((st = fstat(STDIN_FILENO, &ss)) < 0 || ! isatty(STDIN_FILENO))
+	if ((st = fstat(STDIN_FILENO, &ss)) < 0) {
+		if ((fd = open("/dev/null", O_RDONLY) > 0))
+			DEBUG("stdin closed, and could not open /dev/null "
+			      "as fd=0, some external library bugs "
+			      "may be exposed...\n");
+			close(fd);
+		}
+		return;
+	}
+	if (!isatty(STDIN_FILENO))
 		return;
 	if ((fd = open("/dev/null", O_RDONLY)) < 0)
 		FATAL("failed to open /dev/null %s\n", strerror(errno));