Use -1 rather than 0 as the SCAN_FAILED return value from the lexical

analyzer on errors, and check for SCAN_FAILED from the lexical analyzer
and abort the parse if we see it; 0 means "end of input", and we want to
distinguish errors from end-of-input, so that we can report errors as
such.

If we see end-of-input while parsing a double-quoted string, report the
error (missing closing quote).

Fix the URL for the "Start conditions" section of the Flex manual.

svn path=/trunk/; revision=10044

3 files changed, 31 insertions, 9 deletions

diff --git a/epan/dfilter/dfilter-int.h b/epan/dfilter/dfilter-int.h
index faf4e7cc90..ee2345ceb0 100644
--- a/epan/dfilter/dfilter-int.h
+++ b/epan/dfilter/dfilter-int.h
@@ -1,5 +1,5 @@
 /*
- * $Id: dfilter-int.h,v 1.7 2002/08/28 20:40:55 jmayer Exp $
+ * $Id: dfilter-int.h,v 1.8 2004/02/11 22:52:54 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -34,8 +34,8 @@ struct _dfilter_t {
 	int		num_registers;
 	GList		**registers;
 	gboolean	*attempted_load;
-    int         *interesting_fields;
-    int         num_interesting_fields;
+	int		*interesting_fields;
+	int		num_interesting_fields;
 };
 
 typedef struct {
@@ -57,9 +57,11 @@ void Dfilter(void*, int, stnode_t*, dfwork_t*);
 /* Scanner's lval */
 extern stnode_t *df_lval;
 
+/* Return value for error in scanner. */
+#define SCAN_FAILED	-1	/* not 0, as that means end-of-input */
+
 /* Set dfilter_error_msg_buf and dfilter_error_msg */
 void
 dfilter_fail(char *format, ...);
 
-
 #endif
diff --git a/epan/dfilter/dfilter.c b/epan/dfilter/dfilter.c
index 77333226cd..16f6ae9329 100644
--- a/epan/dfilter/dfilter.c
+++ b/epan/dfilter/dfilter.c
@@ -1,5 +1,5 @@
 /*
- * $Id: dfilter.c,v 1.14 2002/12/02 23:28:16 guy Exp $
+ * $Id: dfilter.c,v 1.15 2004/02/11 22:52:54 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -204,6 +204,17 @@ dfilter_compile(const gchar *text, dfilter_t **dfp)
 		df_lval = stnode_new(STTYPE_UNINITIALIZED, NULL);
 		token = df_lex();
 
+		/* Check for scanner failure */
+		if (token == SCAN_FAILED) {
+			/* Free the stnode_t that we just generated, since
+			 * we're going to give up on parsing. */
+			stnode_free(df_lval);
+			df_lval = NULL;
+
+			/* Give up. */
+			goto FAILURE;
+		}
+
 		/* Check for end-of-input */
 		if (token == 0) {
 			/* Tell the parser that we have reached the end of input */
diff --git a/epan/dfilter/scanner.l b/epan/dfilter/scanner.l
index 78f0f86f40..874a6bca85 100644
--- a/epan/dfilter/scanner.l
+++ b/epan/dfilter/scanner.l
@@ -1,6 +1,6 @@
 %{
 /*
- * $Id: scanner.l,v 1.14 2004/01/07 05:24:04 gram Exp $
+ * $Id: scanner.l,v 1.15 2004/02/11 22:52:54 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -48,8 +48,6 @@ static int simple(int token);
 static gboolean str_to_guint32(char *s, guint32* pint);
 GString* quoted_string = NULL;
 
-#define SCAN_FAILED	0
-
 %}
 
 %x RANGE_INT
@@ -128,7 +126,7 @@ GString* quoted_string = NULL;
 	/* The example of how to scan for strings was taken from
 	the flex 2.5.4 manual, from the section "Start Conditions".
 	See:
-	http://www.gnu.org/manual/flex-2.5.4/html_node/flex_11.html */
+	http://www.gnu.org/software/flex/manual/html_node/flex_11.html */
 
 	BEGIN(DQUOTE);
 	/* A previous filter that failed to compile due to
@@ -144,6 +142,17 @@ GString* quoted_string = NULL;
 	quoted_string = g_string_new("");
 }
 
+<DQUOTE><<EOF>>				{
+	/* unterminated string */
+	/* The example of how to handle unclosed strings was taken from
+	the flex 2.5.4 manual, from the section "End-of-file rules".
+	See:
+	http://www.gnu.org/software/flex/manual/html_node/flex_13.html */
+
+	dfilter_fail("The final quote was missing from a quoted string.");
+	return SCAN_FAILED;
+}
+
 <DQUOTE>\"				{
 	/* end quote */
 	char *my_string = g_strdup(quoted_string->str);