2012-03-02 06:02:28 +00:00
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/* mp2t.c
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*
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* ISO/IEC 13818-1 MPEG2-TS file format decoder for the Wiretap library.
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* Written by Weston Schmidt <weston_schmidt@alumni.purdue.edu>
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* Copyright 2012 Weston Schmidt
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*
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* Wiretap Library
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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2012-06-28 22:56:06 +00:00
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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2012-03-02 06:02:28 +00:00
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*/
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#include "config.h"
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#ifdef HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "mp2t.h"
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#include "wtap-int.h"
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2014-07-15 23:40:46 +00:00
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#include <wsutil/buffer.h>
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2012-03-02 06:02:28 +00:00
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#include "file_wrappers.h"
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#define MP2T_SYNC_BYTE 0x47
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#define MP2T_SIZE 188
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#define MP2T_QAM256_BITRATE 38810700 /* bits per second */
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#define MP2T_QAM64_BITRATE 26970350 /* bits per second */
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2012-03-30 23:19:49 +00:00
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/* we try to detect trailing data up to 40 bytes after each packet */
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#define TRAILER_LEN_MAX 40
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/* number of consecutive packets we must read to decide that a file
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is actually an mpeg2 ts */
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#define SYNC_STEPS 10
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2012-03-02 06:02:28 +00:00
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typedef struct {
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2012-05-05 02:52:41 +00:00
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int start_offset;
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2012-03-30 23:19:49 +00:00
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/* length of trailing data (e.g. FEC) that's appended after each packet */
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guint8 trailer_len;
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2012-03-02 06:02:28 +00:00
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} mp2t_filetype_t;
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2013-06-17 23:43:55 +00:00
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static gboolean
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2013-11-08 17:17:57 +00:00
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mp2t_read_packet(mp2t_filetype_t *mp2t, FILE_T fh, gint64 offset,
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2013-06-17 23:43:55 +00:00
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struct wtap_pkthdr *phdr, Buffer *buf, int *err,
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gchar **err_info)
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2013-05-18 03:42:06 +00:00
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{
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guint64 tmp;
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2013-06-17 23:43:55 +00:00
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2014-08-02 11:00:48 +00:00
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ws_buffer_assure_space(buf, MP2T_SIZE);
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Add some higher-level file-read APIs and use them.
Add wtap_read_bytes(), which takes a FILE_T, a pointer, a byte count, an
error number pointer, and an error string pointer as arguments, and that
treats a short read of any sort, including a read that returns 0 bytes,
as a WTAP_ERR_SHORT_READ error, and that returns the error number and
string through its last two arguments.
Add wtap_read_bytes_or_eof(), which is similar, but that treats a read
that returns 0 bytes as an EOF, supplying an error number of 0 as an EOF
indication.
Use those in file readers; that simplifies the code and makes it less
likely that somebody will fail to supply the error number and error
string on a file read error.
Change-Id: Ia5dba2a6f81151e87b614461349d611cffc16210
Reviewed-on: https://code.wireshark.org/review/4512
Reviewed-by: Guy Harris <guy@alum.mit.edu>
2014-10-07 01:00:57 +00:00
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if (!wtap_read_bytes_or_eof(fh, ws_buffer_start_ptr(buf), MP2T_SIZE, err, err_info))
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2013-06-17 23:43:55 +00:00
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return FALSE;
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2013-05-18 03:42:06 +00:00
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2014-05-24 18:28:30 +00:00
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phdr->rec_type = REC_TYPE_PACKET;
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2013-05-18 03:42:06 +00:00
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/* XXX - relative, not absolute, time stamps */
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phdr->presence_flags = WTAP_HAS_TS;
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/*
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* Every packet in an MPEG2-TS stream is has a fixed size of
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* MP2T_SIZE plus the number of trailer bytes.
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*
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* The bitrate is constant, so the time offset, from the beginning
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* of the stream, of a given packet is the packet offset, in bits,
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* divided by the bitrate.
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*
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* It would be really cool to be able to configure the bitrate...
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*/
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tmp = ((guint64)(offset - mp2t->start_offset) * 8); /* offset, in bits */
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phdr->ts.secs = (time_t)(tmp / MP2T_QAM256_BITRATE);
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phdr->ts.nsecs = (int)((tmp % MP2T_QAM256_BITRATE) * 1000000000 / MP2T_QAM256_BITRATE);
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phdr->caplen = MP2T_SIZE;
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phdr->len = MP2T_SIZE;
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2012-03-02 06:02:28 +00:00
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return TRUE;
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}
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2014-05-23 10:50:02 +00:00
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static gboolean
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2014-05-09 05:18:49 +00:00
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mp2t_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
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2012-03-02 06:02:28 +00:00
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{
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mp2t_filetype_t *mp2t;
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2014-05-09 05:18:49 +00:00
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mp2t = (mp2t_filetype_t*) wth->priv;
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2012-03-02 06:02:28 +00:00
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2014-05-09 05:18:49 +00:00
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*data_offset = file_tell(wth->fh);
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2012-05-05 02:52:41 +00:00
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2014-05-09 05:18:49 +00:00
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if (!mp2t_read_packet(mp2t, wth->fh, *data_offset, &wth->phdr,
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wth->frame_buffer, err, err_info)) {
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2014-05-23 10:50:02 +00:00
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return FALSE;
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2012-03-02 06:02:28 +00:00
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}
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2012-03-30 23:19:49 +00:00
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/* if there's a trailer, skip it and go to the start of the next packet */
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2013-06-17 23:43:55 +00:00
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if (mp2t->trailer_len!=0) {
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2014-05-09 05:18:49 +00:00
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if (-1 == file_seek(wth->fh, mp2t->trailer_len, SEEK_CUR, err)) {
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2014-05-23 10:50:02 +00:00
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return FALSE;
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2013-06-17 23:43:55 +00:00
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}
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2012-03-30 23:19:49 +00:00
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}
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2014-05-23 10:50:02 +00:00
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return TRUE;
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2012-03-02 06:02:28 +00:00
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}
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2014-05-23 10:50:02 +00:00
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static gboolean
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2014-05-09 05:18:49 +00:00
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mp2t_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr,
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2014-01-02 20:47:21 +00:00
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Buffer *buf, int *err, gchar **err_info)
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2012-03-02 06:02:28 +00:00
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{
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2013-05-18 03:42:06 +00:00
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mp2t_filetype_t *mp2t;
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2014-05-09 05:18:49 +00:00
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if (-1 == file_seek(wth->random_fh, seek_off, SEEK_SET, err)) {
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2014-05-23 10:50:02 +00:00
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return FALSE;
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2012-03-02 06:02:28 +00:00
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}
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2014-05-09 05:18:49 +00:00
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mp2t = (mp2t_filetype_t*) wth->priv;
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2013-05-18 03:42:06 +00:00
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2014-05-09 05:18:49 +00:00
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if (!mp2t_read_packet(mp2t, wth->random_fh, seek_off, phdr, buf,
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2013-06-17 23:43:55 +00:00
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err, err_info)) {
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if (*err == 0)
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*err = WTAP_ERR_SHORT_READ;
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2014-05-23 10:50:02 +00:00
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return FALSE;
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2013-06-17 23:43:55 +00:00
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}
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2014-05-23 10:50:02 +00:00
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return TRUE;
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2012-03-02 06:02:28 +00:00
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}
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2014-10-09 23:44:15 +00:00
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wtap_open_return_val
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2014-05-09 05:18:49 +00:00
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mp2t_open(wtap *wth, int *err, gchar **err_info)
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2012-03-02 06:02:28 +00:00
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{
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2012-03-30 23:19:49 +00:00
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guint8 buffer[MP2T_SIZE+TRAILER_LEN_MAX];
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guint8 trailer_len = 0;
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guint sync_steps = 0;
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2012-03-02 06:02:28 +00:00
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int i;
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int first;
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mp2t_filetype_t *mp2t;
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2012-03-30 23:19:49 +00:00
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Add some higher-level file-read APIs and use them.
Add wtap_read_bytes(), which takes a FILE_T, a pointer, a byte count, an
error number pointer, and an error string pointer as arguments, and that
treats a short read of any sort, including a read that returns 0 bytes,
as a WTAP_ERR_SHORT_READ error, and that returns the error number and
string through its last two arguments.
Add wtap_read_bytes_or_eof(), which is similar, but that treats a read
that returns 0 bytes as an EOF, supplying an error number of 0 as an EOF
indication.
Use those in file readers; that simplifies the code and makes it less
likely that somebody will fail to supply the error number and error
string on a file read error.
Change-Id: Ia5dba2a6f81151e87b614461349d611cffc16210
Reviewed-on: https://code.wireshark.org/review/4512
Reviewed-by: Guy Harris <guy@alum.mit.edu>
2014-10-07 01:00:57 +00:00
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if (!wtap_read_bytes(wth->fh, buffer, MP2T_SIZE, err, err_info)) {
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if (*err != WTAP_ERR_SHORT_READ)
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_ERROR;
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return WTAP_OPEN_NOT_MINE;
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2012-03-02 06:02:28 +00:00
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}
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first = -1;
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for (i = 0; i < MP2T_SIZE; i++) {
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if (MP2T_SYNC_BYTE == buffer[i]) {
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first = i;
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break;
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}
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}
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if (-1 == first) {
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_NOT_MINE; /* wrong file type - not an mpeg2 ts file */
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2012-03-02 06:02:28 +00:00
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}
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2014-05-09 05:18:49 +00:00
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if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_ERROR;
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2012-03-05 08:30:39 +00:00
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}
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2012-03-30 23:19:49 +00:00
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/* read some packets and make sure they all start with a sync byte */
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do {
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2014-10-07 22:48:29 +00:00
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if (!wtap_read_bytes(wth->fh, buffer, MP2T_SIZE+trailer_len, err, err_info)) {
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if (*err != WTAP_ERR_SHORT_READ)
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_ERROR; /* read error */
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if(sync_steps<2) return WTAP_OPEN_NOT_MINE; /* wrong file type - not an mpeg2 ts file */
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2012-03-30 23:19:49 +00:00
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break; /* end of file, that's ok if we're still in sync */
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2012-04-18 08:32:12 +00:00
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}
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2012-03-30 23:19:49 +00:00
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if (buffer[0] == MP2T_SYNC_BYTE) {
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sync_steps++;
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}
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else {
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/* no sync byte found, check if trailing data is appended
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and we have to increase the packet size */
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/* if we've already detected a trailer field, we must remain in sync
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another mismatch means we have no mpeg2 ts file */
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if (trailer_len>0)
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_NOT_MINE;
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2012-03-30 23:19:49 +00:00
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/* check if a trailer is appended to the packet */
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for (i=0; i<TRAILER_LEN_MAX; i++) {
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if (buffer[i] == MP2T_SYNC_BYTE) {
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trailer_len = i;
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2014-05-09 05:18:49 +00:00
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if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_ERROR;
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2012-03-30 23:19:49 +00:00
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}
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sync_steps = 0;
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break;
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}
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}
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/* no sync byte found in the vicinity, this is no mpeg2 ts file */
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if (i==TRAILER_LEN_MAX)
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_NOT_MINE;
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2012-03-30 23:19:49 +00:00
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}
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} while (sync_steps < SYNC_STEPS);
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2014-05-09 05:18:49 +00:00
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if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_ERROR;
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2012-03-02 06:02:28 +00:00
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}
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2014-05-09 05:18:49 +00:00
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wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG_2_TS;
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wth->file_encap = WTAP_ENCAP_MPEG_2_TS;
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2014-09-28 18:37:06 +00:00
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wth->file_tsprec = WTAP_TSPREC_NSEC;
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2014-05-09 05:18:49 +00:00
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wth->subtype_read = mp2t_read;
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wth->subtype_seek_read = mp2t_seek_read;
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wth->snapshot_length = 0;
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2012-03-02 06:02:28 +00:00
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mp2t = (mp2t_filetype_t*) g_malloc(sizeof(mp2t_filetype_t));
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2014-05-09 05:18:49 +00:00
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wth->priv = mp2t;
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2012-05-05 02:52:41 +00:00
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mp2t->start_offset = first;
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2012-03-30 23:19:49 +00:00
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mp2t->trailer_len = trailer_len;
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2012-03-02 06:02:28 +00:00
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2014-10-09 23:44:15 +00:00
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return WTAP_OPEN_MINE;
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2012-03-02 06:02:28 +00:00
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}
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