Change wtap_read() API so that the data offset is set via a pointer, and

a "keep reading" boolean value is returned from the function.
This avoids having to hack around the fact that some file formats truly
do have records that start at offset 0. (i4btrace and csids have no
file header. Neither does the pppdump-style file that I'm looking at right now).

svn path=/trunk/; revision=2392

16 files changed, 186 insertions, 214 deletions

diff --git a/wiretap/ascend.c b/wiretap/ascend.c
index ae66b75f6b..6d31919d9e 100644
--- a/wiretap/ascend.c
+++ b/wiretap/ascend.c
@@ -1,6 +1,6 @@
 /* ascend.c
  *
- * $Id: ascend.c,v 1.17 2000/08/11 13:32:37 deniel Exp $
+ * $Id: ascend.c,v 1.18 2000/09/07 05:34:07 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -99,7 +99,7 @@ static const char ascend_w2magic[] = { 'W', 'D', '_', 'D', 'I', 'A', 'L', 'O', '
 #define ASCEND_W1_SIZE (sizeof ascend_w1magic / sizeof ascend_w1magic[0])
 #define ASCEND_W2_SIZE (sizeof ascend_w2magic / sizeof ascend_w2magic[0])
 
-static int ascend_read(wtap *wth, int *err);
+static gboolean ascend_read(wtap *wth, int *err, int *data_offset);
 static int ascend_seek_read (wtap *wth, int seek_off,
 	union wtap_pseudo_header *pseudo_header, guint8 *pd, int len);
 static void ascend_close(wtap *wth);
@@ -192,7 +192,7 @@ int ascend_open(wtap *wth, int *err)
 }
 
 /* Read the next packet; called from wtap_loop(). */
-static int ascend_read(wtap *wth, int *err)
+static gboolean ascend_read(wtap *wth, int *err, int *data_offset)
 {
   int offset;
   guint8 *buf = buffer_start_ptr(wth->frame_buffer);
@@ -207,11 +207,11 @@ static int ascend_read(wtap *wth, int *err)
   wth->capture.ascend->seek_add = 0;
   offset = ascend_seek(wth, ASCEND_MAX_SEEK);
   if (offset < 1) {
-    return 0;
+    return FALSE;
   }
   if (! parse_ascend(wth->fh, buf, &wth->pseudo_header.ascend, &header, 0)) {
     *err = WTAP_ERR_BAD_RECORD;
-    return -1;
+    return FALSE;
   }
 
   buffer_assure_space(wth->frame_buffer, wth->snapshot_length);
@@ -227,7 +227,8 @@ static int ascend_read(wtap *wth, int *err)
   wth->phdr.pkt_encap = wth->file_encap;
   wth->data_offset = offset;
 
-  return offset;
+  *data_offset = offset;
+  return TRUE;
 }
 
 static int ascend_seek_read (wtap *wth, int seek_off,
diff --git a/wiretap/csids.c b/wiretap/csids.c
index 419db2af02..fbe2d946bd 100644
--- a/wiretap/csids.c
+++ b/wiretap/csids.c
@@ -1,6 +1,6 @@
 /* csids.c
  *
- * $Id: csids.c,v 1.3 2000/08/31 16:44:47 gram Exp $
+ * $Id: csids.c,v 1.4 2000/09/07 05:34:07 gram Exp $
  *
  * Copyright (c) 2000 by Mike Hall <mlh@io.com>
  * Copyright (c) 2000 by Cisco Systems
@@ -44,7 +44,7 @@
  *
  */
 
-static int csids_read(wtap *wth, int *err);
+static gboolean csids_read(wtap *wth, int *err, int *data_offset);
 static int csids_seek_read(wtap *wth, int seek_off,
 	union wtap_pseudo_header *pseudo_header, guint8 *pd, int len);
 
@@ -140,21 +140,18 @@ int csids_open(wtap *wth, int *err)
 }
 
 /* Find the next packet and parse it; called from wtap_loop(). */
-static int csids_read(wtap *wth, int *err)
+static gboolean csids_read(wtap *wth, int *err, int *data_offset)
 {
   guint8 *buf;
   int bytesRead = 0;
   struct csids_header hdr;
-  int packet_offset = wth->data_offset;
+
+  *data_offset = wth->data_offset;
 
   bytesRead = file_read( &hdr, 1, sizeof( struct csids_header) , wth->fh );
   if( bytesRead != sizeof( struct csids_header) ) {
     *err = file_error( wth->fh );
-    if( *err != 0 ) {
-      return -1;
-    } else {
-      return 0;
-    }
+    return FALSE;
   }
   hdr.seconds = pntohl(&hdr.seconds);
   hdr.caplen = pntohs(&hdr.caplen);
@@ -168,9 +165,7 @@ static int csids_read(wtap *wth, int *err)
   bytesRead = file_read( buf, 1, hdr.caplen, wth->fh );
   if( bytesRead != hdr.caplen ) {
     *err = file_error( wth->fh );
-    if( *err != 0 ) {
-      return -1;
-    }       
+    return FALSE;
   }
   
   wth->data_offset += hdr.caplen;
@@ -188,12 +183,7 @@ static int csids_read(wtap *wth, int *err)
     *(++swap) = BSWAP16(*swap); /* ip flags and fragoff */
   }
 
-  /* This is a hack to fix the fact that have to atleast return 1 
-   * or we stop processing. csids has no file header. We recover from 
-   * this hack in csids_seek_read by checking the seek_off == 1 and 
-   * setting it back to 0.
-   */
-  return packet_offset ? packet_offset : 1;
+  return TRUE;
 }
 
 /* Used to read packets in random-access fashion */
@@ -208,18 +198,7 @@ csids_seek_read (wtap *wth,
   int bytesRead = 0;
   struct csids_header hdr;
 
-  /* hack to fix a problem with the way error checking is done. If the 
-   * the return value from csids_read is 0 for the first packet, then
-   * we stop there. So I return 1. But that messes up the offset for 
-   * the seek_off on this call. So if seek_off is 1 then make it 0 and 
-   * if it is not 1 leave it alone. --mlh 
-   */
-  int real_seek_off = seek_off;
-  if( real_seek_off == 1 ) {
-    real_seek_off = 0;
-  }
-
-  file_seek(wth->random_fh, real_seek_off , SEEK_SET);
+  file_seek(wth->random_fh, seek_off , SEEK_SET);
 
   bytesRead = file_read( &hdr, 1, sizeof( struct csids_header) , wth->random_fh );
   if( bytesRead != sizeof( struct csids_header) ) {
diff --git a/wiretap/i4btrace.c b/wiretap/i4btrace.c
index 12f8aef0eb..52e487ff08 100644
--- a/wiretap/i4btrace.c
+++ b/wiretap/i4btrace.c
@@ -1,6 +1,6 @@
 /* i4btrace.c
  *
- * $Id: i4btrace.c,v 1.9 2000/08/25 21:25:37 gram Exp $
+ * $Id: i4btrace.c,v 1.10 2000/09/07 05:34:08 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
@@ -31,7 +31,7 @@
 #include "buffer.h"
 #include "i4b_trace.h"
 
-static int i4btrace_read(wtap *wth, int *err);
+static gboolean i4btrace_read(wtap *wth, int *err, int *data_offset);
 static int i4btrace_seek_read(wtap *wth, int seek_off,
     union wtap_pseudo_header *pseudo_header, u_char *pd, int length);
 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err);
@@ -110,26 +110,25 @@ int i4btrace_open(wtap *wth, int *err)
 #define V120SABME	"\010\001\177"
 
 /* Read the next packet */
-static int i4btrace_read(wtap *wth, int *err)
+static gboolean i4btrace_read(wtap *wth, int *err, int *data_offset)
 {
-	int	record_offset;
 	int	ret;
 	i4b_trace_hdr_t hdr;
 	guint16 length;
 	void *bufp;
 
 	/* Read record header. */
-	record_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	ret = i4b_read_rec_header(wth->fh, &hdr, err);
 	if (ret <= 0) {
 		/* Read error or EOF */
-		return ret;
+		return FALSE;
 	}
 	wth->data_offset += sizeof hdr;
 	i4b_byte_swap_header(wth, &hdr);
 	length = hdr.length - sizeof(hdr);
 	if (length == 0)
-		return 0;
+		return FALSE;
 
 	wth->phdr.len = length;
 	wth->phdr.caplen = length;
@@ -145,7 +144,7 @@ static int i4btrace_read(wtap *wth, int *err)
 	buffer_assure_space(wth->frame_buffer, length);
 	bufp = buffer_start_ptr(wth->frame_buffer);
 	if (i4b_read_rec_data(wth->fh, bufp, length, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += length;
 
 	/*
@@ -179,17 +178,7 @@ static int i4btrace_read(wtap *wth, int *err)
 			wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 	}
 
-	/*
-	 * XXX - there is no file header for i4btrace files, so the
-	 * first record begins at the beginning of the file, hence
-	 * its offset is 0.
-	 *
-	 * Unfortunately, a return value of 0 means "end of file".
-	 *
-	 * Therefore, we return the record offset + 1, and compensate
-	 * for that in "i4btrace_seek_read()".
-	 */
-	return record_offset + 1;
+	return TRUE;
 }
 
 static int
@@ -200,11 +189,7 @@ i4btrace_seek_read(wtap *wth, int seek_off,
 	int	err;		/* XXX - return this */
 	i4b_trace_hdr_t hdr;
 
-	/*
-	 * We subtract 1 because we added 1 before returning the record
-	 * offset in "i4btrace_read()"; see the comment above.
-	 */
-	file_seek(wth->random_fh, seek_off - 1, SEEK_SET);
+	file_seek(wth->random_fh, seek_off, SEEK_SET);
 
 	/* Read record header. */
 	ret = i4b_read_rec_header(wth->random_fh, &hdr, &err);
diff --git a/wiretap/iptrace.c b/wiretap/iptrace.c
index a1793b6a23..a2bf913b58 100644
--- a/wiretap/iptrace.c
+++ b/wiretap/iptrace.c
@@ -1,6 +1,6 @@
 /* iptrace.c
  *
- * $Id: iptrace.c,v 1.30 2000/08/25 21:25:37 gram Exp $
+ * $Id: iptrace.c,v 1.31 2000/09/07 05:34:09 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -31,12 +31,14 @@
 #include "buffer.h"
 #include "iptrace.h"
 
-static int iptrace_read_1_0(wtap *wth, int *err);
+static gboolean iptrace_read_1_0(wtap *wth, int *err, int *data_offset);
 static int iptrace_seek_read_1_0(wtap *wth, int seek_off,
     union wtap_pseudo_header *pseudo_header, u_char *pd, int packet_size);
-static int iptrace_read_2_0(wtap *wth, int *err);
+
+static gboolean iptrace_read_2_0(wtap *wth, int *err, int *data_offset);
 static int iptrace_seek_read_2_0(wtap *wth, int seek_off,
     union wtap_pseudo_header *pseudo_header, u_char *pd, int packet_size);
+
 static int iptrace_read_rec_header(FILE_T fh, guint8 *header, int header_len,
     int *err);
 static int iptrace_read_rec_data(FILE_T fh, guint8 *data_ptr, int packet_size,
@@ -96,9 +98,8 @@ typedef struct {
 } iptrace_1_0_phdr;
 
 /* Read the next packet */
-static int iptrace_read_1_0(wtap *wth, int *err)
+static gboolean iptrace_read_1_0(wtap *wth, int *err, int *data_offset)
 {
-	int			record_offset;
 	int			ret;
 	guint32			packet_size;
 	guint8			header[30];
@@ -106,11 +107,11 @@ static int iptrace_read_1_0(wtap *wth, int *err)
 	iptrace_1_0_phdr	pkt_hdr;
 
 	/* Read the descriptor data */
-	record_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	ret = iptrace_read_rec_header(wth->fh, header, 30, err);
 	if (ret <= 0) {
 		/* Read error or EOF */
-		return ret;
+		return FALSE;
 	}
 	wth->data_offset += 30;
 
@@ -119,7 +120,7 @@ static int iptrace_read_1_0(wtap *wth, int *err)
 	buffer_assure_space( wth->frame_buffer, packet_size );
 	data_ptr = buffer_start_ptr( wth->frame_buffer );
 	if (iptrace_read_rec_data(wth->fh, data_ptr, packet_size, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += packet_size;
 
 	wth->phdr.len = packet_size;
@@ -139,7 +140,7 @@ static int iptrace_read_1_0(wtap *wth, int *err)
 		g_message("iptrace: interface type IFT=0x%02x unknown or unsupported",
 		    pkt_hdr.if_type);
 		*err = WTAP_ERR_UNSUPPORTED_ENCAP;
-		return -1;
+		return FALSE;
 	}
 
 	if ( wth->phdr.pkt_encap == WTAP_ENCAP_ATM_SNIFFER ) {
@@ -159,7 +160,7 @@ static int iptrace_read_1_0(wtap *wth, int *err)
 			wth->file_encap = WTAP_ENCAP_PER_PACKET;
 	}
 
-	return record_offset;
+	return TRUE;
 }
 
 static int iptrace_seek_read_1_0(wtap *wth, int seek_off,
@@ -205,9 +206,8 @@ typedef struct {
 } iptrace_2_0_phdr;
 
 /* Read the next packet */
-static int iptrace_read_2_0(wtap *wth, int *err)
+static gboolean iptrace_read_2_0(wtap *wth, int *err, int *data_offset)
 {
-	int			record_offset;
 	int			ret;
 	guint32			packet_size;
 	guint8			header[40];
@@ -215,11 +215,11 @@ static int iptrace_read_2_0(wtap *wth, int *err)
 	iptrace_2_0_phdr	pkt_hdr;
 
 	/* Read the descriptor data */
-	record_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	ret = iptrace_read_rec_header(wth->fh, header, 40, err);
 	if (ret <= 0) {
 		/* Read error or EOF */
-		return ret;
+		return FALSE;
 	}
 	wth->data_offset += 40;
 
@@ -228,7 +228,7 @@ static int iptrace_read_2_0(wtap *wth, int *err)
 	buffer_assure_space( wth->frame_buffer, packet_size );
 	data_ptr = buffer_start_ptr( wth->frame_buffer );
 	if (iptrace_read_rec_data(wth->fh, data_ptr, packet_size, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += packet_size;
 
 	/* AIX saves time in nsec, not usec. It's easier to make iptrace
@@ -252,7 +252,7 @@ static int iptrace_read_2_0(wtap *wth, int *err)
 		g_message("iptrace: interface type IFT=0x%02x unknown or unsupported",
 		    pkt_hdr.if_type);
 		*err = WTAP_ERR_UNSUPPORTED_ENCAP;
-		return -1;
+		return FALSE;
 	}
 
 	if ( wth->phdr.pkt_encap == WTAP_ENCAP_ATM_SNIFFER ) {
@@ -272,7 +272,7 @@ static int iptrace_read_2_0(wtap *wth, int *err)
 			wth->file_encap = WTAP_ENCAP_PER_PACKET;
 	}
 
-	return record_offset;
+	return TRUE;
 }
 
 static int iptrace_seek_read_2_0(wtap *wth, int seek_off,
diff --git a/wiretap/lanalyzer.c b/wiretap/lanalyzer.c
index bf2966fc82..4df14843c9 100644
--- a/wiretap/lanalyzer.c
+++ b/wiretap/lanalyzer.c
@@ -1,6 +1,6 @@
 /* lanalyzer.c
  *
- * $Id: lanalyzer.c,v 1.24 2000/08/25 21:25:38 gram Exp $
+ * $Id: lanalyzer.c,v 1.25 2000/09/07 05:34:10 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -47,7 +47,7 @@
 #define BOARD_325		226	/* LANalyzer 325 (Ethernet) */
 #define BOARD_325TR		227	/* LANalyzer 325TR (Token-ring) */
 
-static int lanalyzer_read(wtap *wth, int *err);
+static gboolean lanalyzer_read(wtap *wth, int *err, int *data_offset);
 static void lanalyzer_close(wtap *wth);
 
 int lanalyzer_open(wtap *wth, int *err)
@@ -199,7 +199,7 @@ int lanalyzer_open(wtap *wth, int *err)
 #define DESCRIPTOR_LEN	32
 
 /* Read the next packet */
-static int lanalyzer_read(wtap *wth, int *err)
+static gboolean lanalyzer_read(wtap *wth, int *err, int *data_offset)
 {
 	int		packet_size = 0;
 	int		bytes_read;
@@ -207,7 +207,6 @@ static int lanalyzer_read(wtap *wth, int *err)
 	char		LE_record_length[2];
 	guint16		record_type, record_length;
 	gchar		descriptor[DESCRIPTOR_LEN];
-	int		data_offset;
 	guint16		time_low, time_med, time_high, true_size;
 	double		t;
 
@@ -216,13 +215,10 @@ static int lanalyzer_read(wtap *wth, int *err)
 	bytes_read = file_read(LE_record_type, 1, 2, wth->fh);
 	if (bytes_read != 2) {
 		*err = file_error(wth->fh);
-		if (*err != 0)
-			return -1;
-		if (bytes_read != 0) {
+		if (*err == 0 && bytes_read != 0) {
 			*err = WTAP_ERR_SHORT_READ;
-			return -1;
 		}
-		return 0;
+		return FALSE;
 	}
 	wth->data_offset += 2;
 	bytes_read = file_read(LE_record_length, 1, 2, wth->fh);
@@ -230,7 +226,7 @@ static int lanalyzer_read(wtap *wth, int *err)
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += 2;
 
@@ -244,7 +240,7 @@ static int lanalyzer_read(wtap *wth, int *err)
 		g_message("lanalyzer: record type %u seen after trace summary record",
 		    record_type);
 		*err = WTAP_ERR_BAD_RECORD;
-		return -1;
+		return FALSE;
 	}
 	else {
 		packet_size = record_length - DESCRIPTOR_LEN;
@@ -257,13 +253,13 @@ static int lanalyzer_read(wtap *wth, int *err)
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += DESCRIPTOR_LEN;
 
 	/* Read the packet data */
 	buffer_assure_space(wth->frame_buffer, packet_size);
-	data_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	errno = WTAP_ERR_CANT_READ;
 	bytes_read = file_read(buffer_start_ptr(wth->frame_buffer), 1,
 		packet_size, wth->fh);
@@ -272,7 +268,7 @@ static int lanalyzer_read(wtap *wth, int *err)
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += packet_size;
 
@@ -294,7 +290,7 @@ static int lanalyzer_read(wtap *wth, int *err)
 	wth->phdr.caplen = packet_size;
 	wth->phdr.pkt_encap = wth->file_encap;
 
-	return data_offset;
+	return TRUE;
 }
 
 static void
diff --git a/wiretap/libpcap.c b/wiretap/libpcap.c
index 539ca4c83e..9c52fa4811 100644
--- a/wiretap/libpcap.c
+++ b/wiretap/libpcap.c
@@ -1,6 +1,6 @@
 /* libpcap.c
  *
- * $Id: libpcap.c,v 1.38 2000/08/25 06:25:21 guy Exp $
+ * $Id: libpcap.c,v 1.39 2000/09/07 05:34:11 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -38,7 +38,7 @@
 #define BIT_SWAPPED_MAC_ADDRS
 #endif
 
-static int libpcap_read(wtap *wth, int *err);
+static gboolean libpcap_read(wtap *wth, int *err, int *data_offset);
 static void adjust_header(wtap *wth, struct pcaprec_hdr *hdr);
 static void libpcap_close(wtap *wth);
 static gboolean libpcap_dump(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
@@ -453,12 +453,11 @@ give_up:
 }
 
 /* Read the next packet */
-static int libpcap_read(wtap *wth, int *err)
+static gboolean libpcap_read(wtap *wth, int *err, int *data_offset)
 {
 	guint	packet_size;
 	int	bytes_to_read, bytes_read;
 	struct pcaprec_ss990915_hdr hdr;
-	int	data_offset;
 
 	/* Read record header. */
 	errno = WTAP_ERR_CANT_READ;
@@ -484,13 +483,10 @@ static int libpcap_read(wtap *wth, int *err)
 	bytes_read = file_read(&hdr, 1, bytes_to_read, wth->fh);
 	if (bytes_read != bytes_to_read) {
 		*err = file_error(wth->fh);
-		if (*err != 0)
-			return -1;
-		if (bytes_read != 0) {
+		if (*err == 0 && bytes_read != 0) {
 			*err = WTAP_ERR_SHORT_READ;
-			return -1;
 		}
-		return 0;
+		return FALSE;
 	}
 	wth->data_offset += bytes_read;
 
@@ -505,11 +501,11 @@ static int libpcap_read(wtap *wth, int *err)
 		g_message("pcap: File has %u-byte packet, bigger than maximum of %u",
 		    packet_size, WTAP_MAX_PACKET_SIZE);
 		*err = WTAP_ERR_BAD_RECORD;
-		return -1;
+		return FALSE;
 	}
 
 	buffer_assure_space(wth->frame_buffer, packet_size);
-	data_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	errno = WTAP_ERR_CANT_READ;
 	bytes_read = file_read(buffer_start_ptr(wth->frame_buffer), 1,
 			packet_size, wth->fh);
@@ -518,7 +514,7 @@ static int libpcap_read(wtap *wth, int *err)
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += packet_size;
 
@@ -528,7 +524,7 @@ static int libpcap_read(wtap *wth, int *err)
 	wth->phdr.len = hdr.hdr.orig_len;
 	wth->phdr.pkt_encap = wth->file_encap;
 
-	return data_offset;
+	return TRUE;
 }
 
 static void
diff --git a/wiretap/netmon.c b/wiretap/netmon.c
index 603982d8d0..337c4a8c34 100644
--- a/wiretap/netmon.c
+++ b/wiretap/netmon.c
@@ -1,6 +1,6 @@
 /* netmon.c
  *
- * $Id: netmon.c,v 1.32 2000/08/25 21:25:39 gram Exp $
+ * $Id: netmon.c,v 1.33 2000/09/07 05:34:12 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -93,7 +93,7 @@ struct netmonrec_2_x_hdr {
 	guint32	incl_len;	/* number of octets captured in file */
 };
 
-static int netmon_read(wtap *wth, int *err);
+static gboolean netmon_read(wtap *wth, int *err, int *data_offset);
 static void netmon_close(wtap *wth);
 static gboolean netmon_dump(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
     const union wtap_pseudo_header *pseudo_header, const u_char *pd, int *err);
@@ -277,7 +277,7 @@ int netmon_open(wtap *wth, int *err)
 }
 
 /* Read the next packet */
-static int netmon_read(wtap *wth, int *err)
+static gboolean netmon_read(wtap *wth, int *err, int *data_offset)
 {
 	netmon_t *netmon = wth->capture.netmon;
 	guint32	packet_size = 0;
@@ -287,7 +287,7 @@ static int netmon_read(wtap *wth, int *err)
 		struct netmonrec_2_x_hdr hdr_2_x;
 	}	hdr;
 	int	hdr_size = 0;
-	int	data_offset;
+	int	rec_offset;
 	time_t	secs;
 	guint32	usecs;
 	double	t;
@@ -305,9 +305,9 @@ static int netmon_read(wtap *wth, int *err)
 	   not there already (seeking to the current position
 	   may still cause a seek and a read of the underlying file,
 	   so we don't want to do it unconditionally). */
-	data_offset = netmon->frame_table[netmon->current_frame];
-	if (wth->data_offset != data_offset) {
-		wth->data_offset = data_offset;
+	rec_offset = netmon->frame_table[netmon->current_frame];
+	if (wth->data_offset != rec_offset) {
+		wth->data_offset = rec_offset;
 		file_seek(wth->fh, wth->data_offset, SEEK_SET);
 	}
 	netmon->current_frame++;
@@ -328,13 +328,10 @@ static int netmon_read(wtap *wth, int *err)
 	bytes_read = file_read(&hdr, 1, hdr_size, wth->fh);
 	if (bytes_read != hdr_size) {
 		*err = file_error(wth->fh);
-		if (*err != 0)
-			return -1;
-		if (bytes_read != 0) {
+		if (*err == 0 && bytes_read != 0) {
 			*err = WTAP_ERR_SHORT_READ;
-			return -1;
 		}
-		return 0;
+		return FALSE;
 	}
 	wth->data_offset += hdr_size;
 
@@ -356,10 +353,10 @@ static int netmon_read(wtap *wth, int *err)
 		g_message("netmon: File has %u-byte packet, bigger than maximum of %u",
 		    packet_size, WTAP_MAX_PACKET_SIZE);
 		*err = WTAP_ERR_BAD_RECORD;
-		return -1;
+		return FALSE;
 	}
 	buffer_assure_space(wth->frame_buffer, packet_size);
-	data_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	errno = WTAP_ERR_CANT_READ;
 	bytes_read = file_read(buffer_start_ptr(wth->frame_buffer), 1,
 			packet_size, wth->fh);
@@ -368,7 +365,7 @@ static int netmon_read(wtap *wth, int *err)
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += packet_size;
 
@@ -401,7 +398,7 @@ static int netmon_read(wtap *wth, int *err)
 	}
 	wth->phdr.pkt_encap = wth->file_encap;
 
-	return data_offset;
+	return TRUE;
 }
 
 static void
diff --git a/wiretap/nettl.c b/wiretap/nettl.c
index 3bd86d378e..314ab95a96 100644
--- a/wiretap/nettl.c
+++ b/wiretap/nettl.c
@@ -1,6 +1,6 @@
 /* nettl.c
  *
- * $Id: nettl.c,v 1.15 2000/08/25 21:25:40 gram Exp $
+ * $Id: nettl.c,v 1.16 2000/09/07 05:34:13 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -63,7 +63,7 @@ struct nettlrec_ns_ls_ip_hdr {
 
 /* header is followed by data and once again the total length (2 bytes) ! */
 
-static int nettl_read(wtap *wth, int *err);
+static gboolean nettl_read(wtap *wth, int *err, int *data_offset);
 static int nettl_seek_read(wtap *wth, int seek_off,
 		union wtap_pseudo_header *pseudo_header, u_char *pd, int length);
 static int nettl_read_rec_header(wtap *wth, FILE_T fh,
@@ -122,18 +122,17 @@ int nettl_open(wtap *wth, int *err)
 }
 
 /* Read the next packet */
-static int nettl_read(wtap *wth, int *err)
+static gboolean nettl_read(wtap *wth, int *err, int *data_offset)
 {
-    int record_offset;
     int ret;
 
     /* Read record header. */
-    record_offset = wth->data_offset;
+    *data_offset = wth->data_offset;
     ret = nettl_read_rec_header(wth, wth->fh, &wth->phdr, &wth->pseudo_header,
         err);
     if (ret <= 0) {
 	/* Read error or EOF */
-	return ret;
+	return FALSE;
     }
     wth->data_offset += ret;
 
@@ -143,9 +142,9 @@ static int nettl_read(wtap *wth, int *err)
     buffer_assure_space(wth->frame_buffer, wth->phdr.caplen);
     if (nettl_read_rec_data(wth->fh, buffer_start_ptr(wth->frame_buffer),
 		wth->phdr.caplen, err) < 0)
-	return -1;	/* Read error */
+	return FALSE;	/* Read error */
     wth->data_offset += wth->phdr.caplen;
-    return record_offset;
+    return TRUE;
 }
 
 static int
diff --git a/wiretap/netxray.c b/wiretap/netxray.c
index ed513be5f6..061387ff7e 100644
--- a/wiretap/netxray.c
+++ b/wiretap/netxray.c
@@ -1,6 +1,6 @@
 /* netxray.c
  *
- * $Id: netxray.c,v 1.30 2000/08/25 21:25:40 gram Exp $
+ * $Id: netxray.c,v 1.31 2000/09/07 05:34:14 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -93,7 +93,7 @@ struct netxrayrec_2_x_hdr {
 	guint32	xxx[7];		/* unknown */
 };
 
-static int netxray_read(wtap *wth, int *err);
+static gboolean netxray_read(wtap *wth, int *err, int *data_offset);
 static void netxray_close(wtap *wth);
 static gboolean netxray_dump_1_1(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
 	const union wtap_pseudo_header *pseudo_header, const u_char *pd, int *err);
@@ -219,7 +219,7 @@ int netxray_open(wtap *wth, int *err)
 }
 
 /* Read the next packet */
-static int netxray_read(wtap *wth, int *err)
+static gboolean netxray_read(wtap *wth, int *err, int *data_offset)
 {
 	guint32	packet_size;
 	int	bytes_read;
@@ -228,14 +228,13 @@ static int netxray_read(wtap *wth, int *err)
 		struct netxrayrec_2_x_hdr hdr_2_x;
 	}	hdr;
 	int	hdr_size = 0;
-	int	data_offset;
 	double	t;
 
 reread:
 	/* Have we reached the end of the packet data? */
 	if (wth->data_offset == wth->capture.netxray->end_offset) {
 		/* Yes. */
-		return 0;
+		return FALSE;
 	}
 	/* Read record header. */
 	switch (wth->capture.netxray->version_major) {
@@ -253,10 +252,10 @@ reread:
 	if (bytes_read != hdr_size) {
 		*err = file_error(wth->fh);
 		if (*err != 0)
-			return -1;
+			return FALSE;
 		if (bytes_read != 0) {
 			*err = WTAP_ERR_SHORT_READ;
-			return -1;
+			return FALSE;
 		}
 
 		/* We're at EOF.  Wrap? */
@@ -269,13 +268,13 @@ reread:
 		}
 
 		/* We've already wrapped - don't wrap again. */
-		return 0;
+		return FALSE;
 	}
 	wth->data_offset += hdr_size;
 
 	packet_size = pletohs(&hdr.hdr_1_x.incl_len);
 	buffer_assure_space(wth->frame_buffer, packet_size);
-	data_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	errno = WTAP_ERR_CANT_READ;
 	bytes_read = file_read(buffer_start_ptr(wth->frame_buffer), 1,
 			packet_size, wth->fh);
@@ -284,7 +283,7 @@ reread:
 		*err = file_error(wth->fh);
 		if (*err == 0)
 			*err = WTAP_ERR_SHORT_READ;
-		return -1;
+		return FALSE;
 	}
 	wth->data_offset += packet_size;
 
@@ -299,7 +298,7 @@ reread:
 	wth->phdr.len = pletohs(&hdr.hdr_1_x.orig_len);
 	wth->phdr.pkt_encap = wth->file_encap;
 
-	return data_offset;
+	return TRUE;
 }
 
 static void
diff --git a/wiretap/ngsniffer.c b/wiretap/ngsniffer.c
index bd11b9253c..898806c5fc 100644
--- a/wiretap/ngsniffer.c
+++ b/wiretap/ngsniffer.c
@@ -1,6 +1,6 @@
 /* ngsniffer.c
  *
- * $Id: ngsniffer.c,v 1.50 2000/08/25 21:25:41 gram Exp $
+ * $Id: ngsniffer.c,v 1.51 2000/09/07 05:34:16 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -250,7 +250,7 @@ struct frame4_rec {
 static double Usec[] = { 15.0, 0.838096, 15.0, 0.5, 2.0, 1.0, 0.1 };
 
 static int skip_header_records(wtap *wth, int *err, gint16 version);
-static int ngsniffer_read(wtap *wth, int *err);
+static gboolean ngsniffer_read(wtap *wth, int *err, int *data_offset);
 static int ngsniffer_seek_read(wtap *wth, int seek_off,
     union wtap_pseudo_header *pseudo_header, u_char *pd, int packet_size);
 static int ngsniffer_read_rec_header(wtap *wth, gboolean is_random,
@@ -533,9 +533,8 @@ skip_header_records(wtap *wth, int *err, gint16 version)
 }
 
 /* Read the next packet */
-static int ngsniffer_read(wtap *wth, int *err)
+static gboolean ngsniffer_read(wtap *wth, int *err, int *data_offset)
 {
-	int	record_offset;
 	int	ret;
 	guint16	type, length;
 	struct frame2_rec frame2;
@@ -548,12 +547,12 @@ static int ngsniffer_read(wtap *wth, int *err)
 		/*
 		 * Read the record header.
 		 */
-		record_offset = wth->data_offset;
+		*data_offset = wth->data_offset;
 		ret = ngsniffer_read_rec_header(wth, FALSE, &type, &length,
 		    err);
 		if (ret <= 0) {
 			/* Read error or EOF */
-			return ret;
+			return FALSE;
 		}
 		wth->data_offset += 6;
 
@@ -567,14 +566,14 @@ static int ngsniffer_read(wtap *wth, int *err)
 				 */
 				g_message("ngsniffer: REC_FRAME2 record in an ATM Sniffer file");
 				*err = WTAP_ERR_BAD_RECORD;
-				return -1;
+				return FALSE;
 			}
 
 			/* Read the f_frame2_struct */
 			ret = ngsniffer_read_frame2(wth, FALSE, &frame2, err);
 			if (ret < 0) {
 				/* Read error */
-				return ret;
+				return FALSE;
 			}
 			wth->data_offset += sizeof frame2;
 			time_low = pletohs(&frame2.time_low);
@@ -599,7 +598,7 @@ static int ngsniffer_read(wtap *wth, int *err)
 				 */
 				g_message("ngsniffer: REC_FRAME4 record in a non-ATM Sniffer file");
 				*err = WTAP_ERR_BAD_RECORD;
-				return -1;
+				return FALSE;
 			}
 
 			/* Read the f_frame4_struct */
@@ -627,7 +626,7 @@ static int ngsniffer_read(wtap *wth, int *err)
 			/*
 			 * End of file.  Return an EOF indication.
 			 */
-			return 0;
+			return FALSE;
 
 		default:
 			break;	/* unknown type, skip it */
@@ -652,7 +651,7 @@ found:
 	buffer_assure_space(wth->frame_buffer, length);
 	pd = buffer_start_ptr(wth->frame_buffer);
 	if (ngsniffer_read_rec_data(wth, FALSE, pd, length, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += length;
 
 	if (wth->file_encap == WTAP_ENCAP_UNKNOWN) {
@@ -685,7 +684,7 @@ found:
 	wth->phdr.ts.tv_usec = (unsigned long)((t-(double)(wth->phdr.ts.tv_sec))
 			*1.0e6);
 	wth->phdr.pkt_encap = wth->file_encap;
-	return record_offset;
+	return TRUE;
 }
 
 static int ngsniffer_seek_read(wtap *wth, int seek_off,
diff --git a/wiretap/radcom.c b/wiretap/radcom.c
index 4d559fc4b3..23cb8fdfa9 100644
--- a/wiretap/radcom.c
+++ b/wiretap/radcom.c
@@ -1,6 +1,6 @@
 /* radcom.c
  *
- * $Id: radcom.c,v 1.25 2000/08/25 21:25:42 gram Exp $
+ * $Id: radcom.c,v 1.26 2000/09/07 05:34:18 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -66,7 +66,7 @@ struct radcomrec_hdr {
 	char	xxw[9];		/* unknown */
 };
 
-static int radcom_read(wtap *wth, int *err);
+static gboolean radcom_read(wtap *wth, int *err, int *data_offset);
 static int radcom_seek_read(wtap *wth, int seek_off,
 	union wtap_pseudo_header *pseudo_header, u_char *pd, int length);
 static int radcom_read_rec_header(FILE_T fh, struct radcomrec_hdr *hdr,
@@ -221,9 +221,8 @@ read_error:
 }
 
 /* Read the next packet */
-static int radcom_read(wtap *wth, int *err)
+static gboolean radcom_read(wtap *wth, int *err, int *data_offset)
 {
-	int	record_offset;
 	int	ret;
 	struct radcomrec_hdr hdr;
 	guint16 length;
@@ -233,15 +232,15 @@ static int radcom_read(wtap *wth, int *err)
 	char	fcs[2];
 
 	/* Read record header. */
-	record_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 	ret = radcom_read_rec_header(wth->fh, &hdr, err);
 	if (ret <= 0) {
 		/* Read error or EOF */
-		return ret;
+		return FALSE;
 	}
 	wth->data_offset += sizeof hdr;
 	length = pletohs(&hdr.length);
-	if (length == 0) return 0;
+	if (length == 0) return FALSE;
 
 	if (wth->file_encap == WTAP_ENCAP_LAPB)
 		length -= 2; /* FCS */
@@ -267,7 +266,7 @@ static int radcom_read(wtap *wth, int *err)
 	buffer_assure_space(wth->frame_buffer, length);
 	if (radcom_read_rec_data(wth->fh,
 	    buffer_start_ptr(wth->frame_buffer), length, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += length;
 
 	wth->phdr.pkt_encap = wth->file_encap;
@@ -281,12 +280,12 @@ static int radcom_read(wtap *wth, int *err)
 			*err = file_error(wth->fh);
 			if (*err == 0)
 				*err = WTAP_ERR_SHORT_READ;
-			return -1;
+			return FALSE;
 		}
 		wth->data_offset += sizeof fcs;
 	}
 
-	return record_offset;
+	return TRUE;
 }
 
 static int
diff --git a/wiretap/snoop.c b/wiretap/snoop.c
index 3d247bce21..14a590136a 100644
--- a/wiretap/snoop.c
+++ b/wiretap/snoop.c
@@ -1,6 +1,6 @@
 /* snoop.c
  *
- * $Id: snoop.c,v 1.29 2000/07/26 00:20:06 guy Exp $
+ * $Id: snoop.c,v 1.30 2000/09/07 05:34:19 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -55,7 +55,7 @@ struct snooprec_hdr {
 	guint32	ts_usec;	/* timestamp microseconds */
 };
 
-static int snoop_read(wtap *wth, int *err);
+static gboolean snoop_read(wtap *wth, int *err, int *data_offset);
 static int snoop_seek_read(wtap *wth, int seek_off,
     union wtap_pseudo_header *pseudo_header, u_char *pd, int length);
 static int snoop_read_atm_pseudoheader(FILE_T fh,
@@ -206,12 +206,11 @@ int snoop_open(wtap *wth, int *err)
 }
 
 /* Read the next packet */
-static int snoop_read(wtap *wth, int *err)
+static gboolean snoop_read(wtap *wth, int *err, int *data_offset)
 {
 	guint32 rec_size;
 	guint32	packet_size;
 	guint32 orig_size;
-	int	data_offset;
 	int	bytes_read;
 	struct snooprec_hdr hdr;
 	char	padbuf[4];
@@ -223,13 +222,10 @@ static int snoop_read(wtap *wth, int *err)
 	bytes_read = file_read(&hdr, 1, sizeof hdr, wth->fh);
 	if (bytes_read != sizeof hdr) {
 		*err = file_error(wth->fh);
-		if (*err != 0)
-			return -1;
-		if (bytes_read != 0) {
+		if (*err == 0 && bytes_read != 0) {
 			*err = WTAP_ERR_SHORT_READ;
-			return -1;
 		}
-		return 0;
+		return FALSE;
 	}
 	wth->data_offset += sizeof hdr;
 
@@ -244,10 +240,10 @@ static int snoop_read(wtap *wth, int *err)
 		g_message("snoop: File has %u-byte packet, bigger than maximum of %u",
 		    packet_size, WTAP_MAX_PACKET_SIZE);
 		*err = WTAP_ERR_BAD_RECORD;
-		return -1;
+		return FALSE;
 	}
 
-	data_offset = wth->data_offset;
+	*data_offset = wth->data_offset;
 
 	/*
 	 * If this is an ATM packet, the first four bytes are the
@@ -264,11 +260,11 @@ static int snoop_read(wtap *wth, int *err)
 			g_message("snoop: atmsnoop file has a %u-byte packet, too small to have even an ATM pseudo-header\n",
 			    packet_size);
 			*err = WTAP_ERR_BAD_RECORD;
-			return -1;
+			return FALSE;
 		}
 		if (snoop_read_atm_pseudoheader(wth->fh, &wth->pseudo_header,
 		    err) < 0)
-			return -1;	/* Read error */
+			return FALSE;	/* Read error */
 
 		/*
 		 * Don't count the pseudo-header as part of the packet.
@@ -282,7 +278,7 @@ static int snoop_read(wtap *wth, int *err)
 	buffer_assure_space(wth->frame_buffer, packet_size);
 	if (snoop_read_rec_data(wth->fh, buffer_start_ptr(wth->frame_buffer),
 	    packet_size, err) < 0)
-		return -1;	/* Read error */
+		return FALSE;	/* Read error */
 	wth->data_offset += packet_size;
 
 	wth->phdr.ts.tv_sec = ntohl(hdr.ts_sec);
@@ -309,13 +305,13 @@ static int snoop_read(wtap *wth, int *err)
 			*err = file_error(wth->fh);
 			if (*err == 0)
 				*err = WTAP_ERR_SHORT_READ;
-			return -1;
+			return FALSE;
 		}
 		wth->data_offset += bytes_read;
 		padbytes -= bytes_read;
 	}
 
-	return data_offset;
+	return TRUE;
 }
 
 static int
diff --git a/wiretap/toshiba.c b/wiretap/toshiba.c
index caa0b6c249..407b52dab7 100644
--- a/wiretap/toshiba.c
+++ b/wiretap/toshiba.c
@@ -1,6 +1,6 @@
 /* toshiba.c
  *
- * $Id: toshiba.c,v 1.11 2000/05/19 23:07:03 gram Exp $
+ * $Id: toshiba.c,v 1.12 2000/09/07 05:34:20 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -104,7 +104,7 @@ static const char toshiba_hdr_magic[]  =
 static const char toshiba_rec_magic[]  = { '[', 'N', 'o', '.' };
 #define TOSHIBA_REC_MAGIC_SIZE  (sizeof toshiba_rec_magic  / sizeof toshiba_rec_magic[0])
 
-static int toshiba_read(wtap *wth, int *err);
+static gboolean toshiba_read(wtap *wth, int *err, int *data_offset);
 static int toshiba_seek_read(wtap *wth, int seek_off,
 	union wtap_pseudo_header *pseudo_header, guint8 *pd, int len);
 static gboolean parse_single_hex_dump_line(char* rec, guint8 *buf, int byte_offset);
@@ -200,7 +200,7 @@ int toshiba_open(wtap *wth, int *err)
 }
 
 /* Find the next packet and parse it; called from wtap_loop(). */
-static int toshiba_read(wtap *wth, int *err)
+static gboolean toshiba_read(wtap *wth, int *err, int *data_offset)
 {
 	int	offset = 0;
 	guint8	*buf;
@@ -209,7 +209,7 @@ static int toshiba_read(wtap *wth, int *err)
 	/* Find the next packet */
 	offset = toshiba_seek_next_packet(wth);
 	if (offset < 1) {
-		return 0;
+		return FALSE;
 	}
 
 	/* Parse the header */
@@ -224,7 +224,8 @@ static int toshiba_read(wtap *wth, int *err)
 	parse_toshiba_hex_dump(wth->fh, pkt_len, buf, err);
 
 	wth->data_offset = offset;
-	return offset;
+	*data_offset = offset;
+	return TRUE;
 }
 
 /* Used to read packets in random-access fashion */
diff --git a/wiretap/wtap-int.h b/wiretap/wtap-int.h
index a8742b1c38..44abd47fbb 100644
--- a/wiretap/wtap-int.h
+++ b/wiretap/wtap-int.h
@@ -1,6 +1,6 @@
 /* wtap-int.h
  *
- * $Id: wtap-int.h,v 1.7 2000/08/25 21:25:43 gram Exp $
+ * $Id: wtap-int.h,v 1.8 2000/09/07 05:34:21 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -116,7 +116,7 @@ typedef struct {
 	gboolean byteswapped;
 } csids_t;
 
-typedef int (*subtype_read_func)(struct wtap*, int*);
+typedef int (*subtype_read_func)(struct wtap*, int*, int*);
 typedef int (*subtype_seek_read_func)(struct wtap*, int, union wtap_pseudo_header*,
 					guint8*, int);
 struct wtap {
diff --git a/wiretap/wtap.c b/wiretap/wtap.c
index 4a79760390..dd6a34e39e 100644
--- a/wiretap/wtap.c
+++ b/wiretap/wtap.c
@@ -1,6 +1,6 @@
 /* wtap.c
  *
- * $Id: wtap.c,v 1.46 2000/08/19 18:31:23 deniel Exp $
+ * $Id: wtap.c,v 1.47 2000/09/07 05:34:22 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -30,27 +30,32 @@
 #include "file_wrappers.h"
 #include "buffer.h"
 
-FILE* wtap_file(wtap *wth)
+FILE*
+wtap_file(wtap *wth)
 {
 	return wth->fh;
 }
 
-int wtap_fd(wtap *wth)
+int
+wtap_fd(wtap *wth)
 {
 	return wth->fd;
 }
 
-int wtap_file_type(wtap *wth)
+int
+wtap_file_type(wtap *wth)
 {
 	return wth->file_type;
 }
 
-int wtap_snapshot_length(wtap *wth)
+int
+wtap_snapshot_length(wtap *wth)
 {
 	return wth->snapshot_length;
 }
 
-int wtap_file_encap(wtap *wth)
+int
+wtap_file_encap(wtap *wth)
 {
 	return wth->file_encap;
 }
@@ -113,7 +118,8 @@ const static struct encap_type_info {
 };
 
 /* Name that should be somewhat descriptive. */
-const char *wtap_encap_string(int encap)
+const char
+*wtap_encap_string(int encap)
 {
 	if (encap < 0 || encap >= WTAP_NUM_ENCAP_TYPES)
 		return NULL;
@@ -122,7 +128,8 @@ const char *wtap_encap_string(int encap)
 }
 
 /* Name to use in, say, a command-line flag specifying the type. */
-const char *wtap_encap_short_string(int encap)
+const char
+*wtap_encap_short_string(int encap)
 {
 	if (encap < 0 || encap >= WTAP_NUM_ENCAP_TYPES)
 		return NULL;
@@ -131,7 +138,8 @@ const char *wtap_encap_short_string(int encap)
 }
 
 /* Translate a short name to a capture file type. */
-int wtap_short_string_to_encap(const char *short_name)
+int
+wtap_short_string_to_encap(const char *short_name)
 {
 	int encap;
 
@@ -162,7 +170,8 @@ static const char *wtap_errlist[] = {
 };
 #define	WTAP_ERRLIST_SIZE	(sizeof wtap_errlist / sizeof wtap_errlist[0])
 
-const char *wtap_strerror(int err)
+const char
+*wtap_strerror(int err)
 {
 	static char errbuf[128];
 	int wtap_errlist_index;
@@ -196,7 +205,8 @@ const char *wtap_strerror(int err)
    
    Instead, if the subtype has a "sequential close" function, we call it,
    to free up stuff used only by the sequential side. */
-void wtap_sequential_close(wtap *wth)
+void
+wtap_sequential_close(wtap *wth)
 {
 	if (wth->subtype_sequential_close != NULL)
 		(*wth->subtype_sequential_close)(wth);
@@ -213,7 +223,8 @@ void wtap_sequential_close(wtap *wth)
 	}
 }
 
-void wtap_close(wtap *wth)
+void
+wtap_close(wtap *wth)
 {
 	wtap_sequential_close(wth);
 
@@ -226,47 +237,53 @@ void wtap_close(wtap *wth)
 	g_free(wth);
 }
 
-int wtap_read(wtap *wth, int *err)
+gboolean
+wtap_read(wtap *wth, int *err, int *data_offset)
 {
-	return wth->subtype_read(wth, err);
+	return wth->subtype_read(wth, err, data_offset);
 }
 
-struct wtap_pkthdr *wtap_phdr(wtap *wth)
+struct wtap_pkthdr*
+wtap_phdr(wtap *wth)
 {
 	return &wth->phdr;
 }
 
-union wtap_pseudo_header *wtap_pseudoheader(wtap *wth)
+union wtap_pseudo_header*
+wtap_pseudoheader(wtap *wth)
 {
 	return &wth->pseudo_header;
 }
 
-guint8 *wtap_buf_ptr(wtap *wth)
+guint8*
+wtap_buf_ptr(wtap *wth)
 {
 	return buffer_start_ptr(wth->frame_buffer);
 }
 
-int wtap_loop(wtap *wth, int count, wtap_handler callback, u_char* user,
-	int *err)
+gboolean
+wtap_loop(wtap *wth, int count, wtap_handler callback, u_char* user, int *err)
 {
-	int data_offset, loop = 0;
+	int		data_offset, loop = 0;
 
-	/* Start be clearing error flag */
+	/* Start by clearing error flag */
 	*err = 0;
 
-	while ((data_offset = wtap_read(wth, err)) > 0) {
+	while ( (wtap_read(wth, err, &data_offset)) ) {
 		callback(user, &wth->phdr, data_offset,
 		    &wth->pseudo_header, buffer_start_ptr(wth->frame_buffer));
 		if (count > 0 && ++loop >= count)
 			break;
 	}
-	if (data_offset < 0)
-		return FALSE;	/* failure */
-	else
+
+	if (*err == 0)
 		return TRUE;	/* success */
+	else
+		return FALSE;	/* failure */
 }
 
-int wtap_seek_read(wtap *wth, int seek_off,
+int
+wtap_seek_read(wtap *wth, int seek_off,
 	union wtap_pseudo_header *pseudo_header, guint8 *pd, int len)
 {
 	return wth->subtype_seek_read(wth, seek_off, pseudo_header, pd, len);
diff --git a/wiretap/wtap.h b/wiretap/wtap.h
index 3b248e9ff1..bc429651f8 100644
--- a/wiretap/wtap.h
+++ b/wiretap/wtap.h
@@ -1,6 +1,6 @@
 /* wtap.h
  *
- * $Id: wtap.h,v 1.77 2000/08/11 13:32:37 deniel Exp $
+ * $Id: wtap.h,v 1.78 2000/09/07 05:34:23 gram Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
@@ -273,8 +273,16 @@ typedef struct wtap_dumper wtap_dumper;
  * a negative number, indicating the type of error, on other failures.
  */
 struct wtap* wtap_open_offline(const char *filename, int *err, gboolean do_random);
-int wtap_loop(wtap *wth, int, wtap_handler, u_char*, int*);
-int wtap_read(wtap *wth, int *err);
+
+/* Returns TRUE if entire loop-reading was successful. If read failure
+ * happened, FALSE is returned and err is set. */
+gboolean wtap_loop(wtap *wth, int, wtap_handler, u_char*, int *err);
+
+/* Returns TRUE if read was successful. FALSE if failure. data_offset is
+ * set the the offset in the file where the data for the read packet is
+ * located. */
+gboolean wtap_read(wtap *wth, int *err, int *data_offset);
+
 struct wtap_pkthdr *wtap_phdr(wtap *wth);
 union wtap_pseudo_header *wtap_pseudoheader(wtap *wth);
 guint8 *wtap_buf_ptr(wtap *wth);