From 45a8861b1ed6d394de786e276db8998ea0ea0efc Mon Sep 17 00:00:00 2001
From: Guy Harris <guy@alum.mit.edu>
Date: Wed, 17 Aug 2016 19:03:11 -0700
Subject: [PATCH] Don't distinguish between PARSED_NONRECORD and PARSE_FAILED.

If we got no bytes of data from a putative packet, the file isn't a
valid Ascend file, regardless of whether the parser failed or not.  Just
have parse_ascend() return a Boolean, TRUE if we got a packet and FALSE
if not, and, in the case where we got no data but the parser didn't
fail, provide "no data returned by parse" as the error string.

(We weren't actually distinguishing between them when we called
parse_ascend() - we were treating all non-PARSED_RECORD returns as an
error.)

Change-Id: I85a3e318015258f6a62c8d23ac2f906e28789982
Reviewed-on: https://code.wireshark.org/review/17130
Reviewed-by: Guy Harris <guy@alum.mit.edu>
---
 wiretap/ascendtext.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/wiretap/ascendtext.c b/wiretap/ascendtext.c
index a220c020ee..bcb0267b4a 100644
--- a/wiretap/ascendtext.c
+++ b/wiretap/ascendtext.c
@@ -301,18 +301,9 @@ wtap_open_return_val ascend_open(wtap *wth, int *err, gchar **err_info)
   return WTAP_OPEN_MINE;
 }
 
-typedef enum {
-    PARSED_RECORD,
-    PARSED_NONRECORD,
-    PARSE_FAILED
-} parse_t;
-
 /* Parse the capture file.
-   Returns:
-     PARSED_RECORD if we got a packet
-     PARSED_NONRECORD if the parser succeeded but didn't see a packet
-     PARSE_FAILED if the parser failed. */
-static parse_t
+   Returns TRUE if we got a packet, FALSE otherwise. */
+static gboolean
 parse_ascend(ascend_t *ascend, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
              guint length, int *err, gchar **err_info)
 {
@@ -389,20 +380,26 @@ parse_ascend(ascend_t *ascend, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
         phdr->pseudo_header.eth.fcs_len = 0;
         break;
     }
-    return PARSED_RECORD;
+    return TRUE;
   }
 
   /* Didn't see any data. Still, perhaps the parser was happy.  */
   if (retval) {
     if (*err == 0) {
-      /* Not a bad record, so a parse error.  Return WTAP_ERR_BAD_FILE,
-         with the parse error as the error string. */
+      /* Parser failed, but didn't report an I/O error, so a parse error.
+         Return WTAP_ERR_BAD_FILE, with the parse error as the error string. */
       *err = WTAP_ERR_BAD_FILE;
       *err_info = g_strdup((parser_state.ascend_parse_error != NULL) ? parser_state.ascend_parse_error : "parse error");
     }
-    return PARSE_FAILED;
-  } else
-    return PARSED_NONRECORD;
+  } else {
+    if (*err == 0) {
+      /* Parser succeeded, but got no data, and didn't report an I/O error.
+         Return WTAP_ERR_BAD_FILE, with a "got no data" error string. */
+      *err = WTAP_ERR_BAD_FILE;
+      *err_info = g_strdup("no data returned by parse");
+    }
+  }
+  return FALSE;
 }
 
 /* Read the next packet; called from wtap_read(). */
@@ -423,8 +420,8 @@ static gboolean ascend_read(wtap *wth, int *err, gchar **err_info,
   offset = ascend_seek(wth, err, err_info);
   if (offset == -1)
     return FALSE;
-  if (parse_ascend(ascend, wth->fh, &wth->phdr, wth->frame_buffer,
-                   wth->snapshot_length, err, err_info) != PARSED_RECORD)
+  if (!parse_ascend(ascend, wth->fh, &wth->phdr, wth->frame_buffer,
+                   wth->snapshot_length, err, err_info))
     return FALSE;
 
   *data_offset = offset;
@@ -439,8 +436,8 @@ static gboolean ascend_seek_read(wtap *wth, gint64 seek_off,
 
   if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
     return FALSE;
-  if (parse_ascend(ascend, wth->random_fh, phdr, buf,
-                   wth->snapshot_length, err, err_info) != PARSED_RECORD)
+  if (!parse_ascend(ascend, wth->random_fh, phdr, buf,
+                   wth->snapshot_length, err, err_info))
     return FALSE;
 
   return TRUE;