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Clean up some things. 

Rename ascend_seek() to ascend_find_next_packet(), to indicate what it
does; it doesn't seek to an arbitrary place, it tries to find the
starting offset of the next packet when reading sequentially.

Don't have it set the header type - that's the job of the parser.

Don't set the "next packet seek start" when doing random access I/O -
that field is only for sequential I/O, and we don't want random I/O
happening at the same time (which can happen in Wireshark) interfering.

Clean up comments.

Change-Id: I2808479eeec074afa16945ffb577b91d8cb356f7
Reviewed-on: https://code.wireshark.org/review/29975
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2018-10-02 04:20:19 -07:00
parent 5df87a5ad7
commit f71f968438
2 changed files with 36 additions and 27 deletions
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4
wiretap/ascend.y
View File

@ -382,8 +382,8 @@ wdd_hdr: WDD_CHUNK hexnum KEYWORD KEYWORD hexnum KEYWORD decnum decnum decnum KE
;
byte: HEXBYTE {
/* remember the position of the data group in the trace, to tip
off ascend_seek() as to where to look for the next header. */
/* remember the position of the data group in the trace, to tip off
ascend_find_next_packet() as to where to look for the next header. */
if (parser_state->first_hexbyte == 0)
parser_state->first_hexbyte = file_tell(fh);

59
wiretap/ascendtext.c
View File

@ -71,12 +71,12 @@ static gboolean ascend_seek_read(wtap *wth, gint64 seek_off,
/* Seeks to the beginning of the next packet, and returns the
byte offset at which the header for that packet begins.
Returns -1 on failure. */
static gint64 ascend_seek(wtap *wth, int *err, gchar **err_info)
static gint64 ascend_find_next_packet(wtap *wth, int *err, gchar **err_info)
{
int byte;
gint64 date_off = -1, cur_off, packet_off;
size_t string_level[ASCEND_MAGIC_STRINGS];
guint string_i = 0, type = 0;
guint string_i = 0;
static const gchar ascend_date[] = ASCEND_DATE;
size_t ascend_date_len = sizeof ascend_date - 1; /* strlen of a constant string */
size_t ascend_date_string_level;
@ -135,7 +135,6 @@ static gint64 ascend_seek(wtap *wth, int *err, gchar **err_info)
packet_off = date_off;
}
type = ascend_magic[string_i].type;
goto found;
}
} else {
@ -200,8 +199,6 @@ found:
if (file_seek(wth->fh, packet_off, SEEK_SET, err) == -1)
return -1;
wth->rec.rec_header.packet_header.pseudo_header.ascend.type = type;
return packet_off;
}
@ -214,11 +211,11 @@ wtap_open_return_val ascend_open(wtap *wth, int *err, gchar **err_info)
ascend_t *ascend;
/* We haven't yet allocated a data structure for our private stuff;
set the pointer to null, so that "ascend_seek()" knows not to
fill it in. */
set the pointer to null, so that "ascend_find_next_packet()" knows
not to fill it in. */
wth->priv = NULL;
offset = ascend_seek(wth, err, err_info);
offset = ascend_find_next_packet(wth, err, err_info);
if (offset == -1) {
if (*err != 0 && *err != WTAP_ERR_SHORT_READ)
return WTAP_OPEN_ERROR;
@ -269,9 +266,9 @@ wtap_open_return_val ascend_open(wtap *wth, int *err, gchar **err_info)
ascend = (ascend_t *)g_malloc(sizeof(ascend_t));
wth->priv = (void *)ascend;
/* The first packet we want to read is the one that "ascend_seek()"
just found; start searching for it at the offset at which it
found it. */
/* The first packet we want to read is the one that
"ascend_find_next_packet()" just found; start searching
for it at the offset at which it found it. */
ascend->next_packet_seek_start = offset;
/* MAXen and Pipelines report the time since reboot. In order to keep
@ -293,7 +290,8 @@ wtap_open_return_val ascend_open(wtap *wth, int *err, gchar **err_info)
Returns TRUE if we got a packet, FALSE otherwise. */
static gboolean
parse_ascend(ascend_t *ascend, FILE_T fh, wtap_rec *rec, Buffer *buf,
guint length, int *err, gchar **err_info)
guint length, gint64 *next_packet_seek_start_ret,
int *err, gchar **err_info)
{
ascend_state_t parser_state;
int retval;
@ -302,19 +300,29 @@ parse_ascend(ascend_t *ascend, FILE_T fh, wtap_rec *rec, Buffer *buf,
retval = run_ascend_parser(fh, rec, ws_buffer_start_ptr(buf), &parser_state,
err, err_info);
/* did we see any data (hex bytes)? if so, tip off ascend_seek()
as to where to look for the next packet, if any. If we didn't,
maybe this record was broken. Advance so we don't get into
an infinite loop reading a broken trace. */
/* Did we see any data (hex bytes)? */
if (parser_state.first_hexbyte) {
ascend->next_packet_seek_start = parser_state.first_hexbyte;
/* Yes. Provide the offset of the first byte so that our caller can
tip off ascend_find_next_packet() as to where to look for the next
packet, if any. */
if (next_packet_seek_start_ret != NULL)
*next_packet_seek_start_ret = parser_state.first_hexbyte;
} else {
/* Sometimes, a header will be printed but the data will be omitted, or
worse -- two headers will be printed, followed by the data for each.
/* No. Maybe this record was broken; sometimes, a header will be
printed but the data will be omitted, or worse -- two headers will
be printed, followed by the data for each.
Because of this, we need to be fairly tolerant of what we accept
here. If we didn't find any hex bytes, skip over what we've read so
far so we can try reading a new packet. */
ascend->next_packet_seek_start = file_tell(fh);
here. Provide our current offset so that our caller can tell
ascend_find_next_packet() to skip over what we've read so far so
we can try reading a new packet.
. That keeps us from getting into an infinite loop reading a broken
trace. */
if (next_packet_seek_start_ret != NULL)
*next_packet_seek_start_ret = file_tell(fh);
/* Don't treat that as a fatal error; pretend the parse succeeded. */
retval = 0;
}
@ -405,11 +413,12 @@ static gboolean ascend_read(wtap *wth, int *err, gchar **err_info,
SEEK_SET, err) == -1)
return FALSE;
offset = ascend_seek(wth, err, err_info);
offset = ascend_find_next_packet(wth, err, err_info);
if (offset == -1)
return FALSE;
if (!parse_ascend(ascend, wth->fh, &wth->rec, wth->rec_data,
wth->snapshot_length, err, err_info))
wth->snapshot_length, &ascend->next_packet_seek_start,
err, err_info))
return FALSE;
/* Flex might have gotten an EOF and caused *err to be set to
@ -434,7 +443,7 @@ 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, rec, buf,
wth->snapshot_length, err, err_info))
wth->snapshot_length, NULL, err, err_info))
return FALSE;
/* Flex might have gotten an EOF and caused *err to be set to