scanner: use batch mode; nuke isatty calls.

The flex-generated scanner wastefully calls isatty(0) whenever
it is initialized, even though we don't read from a stdio
stream. Even (read "abc") will call isatty(0), which is
unacceptable.

Moreover, this happens even if Flex is told to operate in
batch mode rather than interactive.

With the following change, the isatty calls are gone.
Let's switch Flex to batch mode, too.

* parser.l: Remove <unistd.h> inclusion. Define isatty as a
macro that returns zero. Add the batch option to the scanner.

1 files changed, 5 insertions, 4 deletions

diff --git a/parser.l b/parser.l
index 9d2ecd4f..8bcb53ba 100644
--- a/parser.l
+++ b/parser.l
@@ -35,9 +35,6 @@
 #include <wchar.h>
 #include <signal.h>
 #include "config.h"
-#if HAVE_UNISTD_H
-#include <unistd.h>
-#endif
 #include "lib.h"
 #include "gc.h"
 #include "stream.h"
@@ -51,6 +48,10 @@
 
 #define YY_NO_UNISTD_H
 
+/* Defeat flex's calls to isatty, which happene even in batch mode */
+#undef isatty
+#define isatty(x) 0
+
 #define YY_INPUT(buf, result, max_size)                                 \
   do {                                                                  \
     val self = lit("parser");                                           \
@@ -233,7 +234,7 @@ static wchar_t *unicode_ident(scanner_t *scn, const char *lex)
 
 %}
 
-%option stack noinput reentrant bison-bridge extra-type="parser_t *"
+%option stack noinput reentrant bison-bridge extra-type="parser_t *" batch
 
 TOK     [a-zA-Z0-9_]+
 SGN     [+\-]