305 lines
7.3 KiB
C
305 lines
7.3 KiB
C
/* mpeg.c
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*
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* MPEG file format decoder for the Wiretap library.
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* Written by Shaun Jackman <sjackman@gmail.com>
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* Copyright 2007 Shaun Jackman
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*
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* $Id$
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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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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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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 "mpeg.h"
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#include "wsutil/mpeg-audio.h"
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#include "wtap-int.h"
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#include "buffer.h"
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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 PES_PREFIX 1
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#define PES_VALID(n) (((n) >> 8 & 0xffffff) == PES_PREFIX)
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static size_t
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mpeg_resync(wtap *wth, int *err, gchar **err_info _U_)
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{
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gint64 offset = file_tell(wth->fh);
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size_t count = 0;
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int byte = file_getc(wth->fh);
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while (byte != EOF) {
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if (byte == 0xff && count > 0) {
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byte = file_getc(wth->fh);
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if (byte != EOF && (byte & 0xe0) == 0xe0)
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break;
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} else
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byte = file_getc(wth->fh);
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count++;
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}
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file_seek(wth->fh, offset, SEEK_SET, err);
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return count;
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}
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static int
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mpeg_read_header(wtap *wth, int *err, gchar **err_info _U_,
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guint32 *n)
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{
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int bytes_read;
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errno = WTAP_ERR_CANT_READ;
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bytes_read = file_read(n, 1, sizeof *n, wth->fh);
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if (bytes_read != sizeof *n) {
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*err = file_error(wth->fh);
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if (*err == 0 && bytes_read != 0)
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*err = WTAP_ERR_SHORT_READ;
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return -1;
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}
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*n = g_ntohl(*n);
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if (file_seek(wth->fh, -(gint64)(sizeof *n), SEEK_CUR, err) == -1)
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return -1;
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return bytes_read;
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}
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static gboolean
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mpeg_read_rec_data(FILE_T fh, guchar *pd, int length, int *err)
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{
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int bytes_read;
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errno = WTAP_ERR_CANT_READ;
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bytes_read = file_read(pd, 1, length, fh);
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if (bytes_read != length) {
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*err = file_error(fh);
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if (*err == 0)
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*err = WTAP_ERR_SHORT_READ;
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return FALSE;
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}
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return TRUE;
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}
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#define SCRHZ 27000000
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static gboolean
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mpeg_read(wtap *wth, int *err, gchar **err_info _U_,
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gint64 *data_offset)
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{
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guint32 n;
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int bytes_read = mpeg_read_header(wth, err, err_info, &n);
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unsigned packet_size;
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struct wtap_nstime ts = wth->capture.mpeg->now;
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if (bytes_read == -1)
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return FALSE;
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if (PES_VALID(n)) {
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gint64 offset = file_tell(wth->fh);
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guint8 stream;
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if (offset == -1)
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return -1;
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if (file_seek(wth->fh, 3, SEEK_CUR, err) == -1)
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return FALSE;
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bytes_read = file_read(&stream, 1, sizeof stream, wth->fh);
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if (bytes_read != sizeof stream) {
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*err = file_error(wth->fh);
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return FALSE;
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}
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if (stream == 0xba) {
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guint32 pack1;
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guint32 pack0;
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guint64 pack;
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guint8 stuffing;
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bytes_read = file_read(&pack1, 1, sizeof pack1, wth->fh);
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if (bytes_read != sizeof pack1) {
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*err = file_error(wth->fh);
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if (*err == 0 && bytes_read != 0)
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*err = WTAP_ERR_SHORT_READ;
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return FALSE;
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}
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bytes_read = file_read(&pack0, 1, sizeof pack0, wth->fh);
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if (bytes_read != sizeof pack0) {
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*err = file_error(wth->fh);
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if (*err == 0 && bytes_read != 0)
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*err = WTAP_ERR_SHORT_READ;
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return FALSE;
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}
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pack = (guint64)g_ntohl(pack1) << 32 | g_ntohl(pack0);
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switch (pack >> 62) {
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case 1:
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if (file_seek(wth->fh, 1, SEEK_CUR, err) == -1)
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return FALSE;
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bytes_read = file_read(&stuffing,
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1, sizeof stuffing, wth->fh);
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if (bytes_read != sizeof stuffing) {
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*err = file_error(wth->fh);
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return FALSE;
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}
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stuffing &= 0x07;
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packet_size = 14 + stuffing;
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{
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guint64 bytes = pack >> 16;
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guint64 ts_val =
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(bytes >> 43 & 0x0007) << 30 |
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(bytes >> 27 & 0x7fff) << 15 |
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(bytes >> 11 & 0x7fff) << 0;
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unsigned ext = (unsigned)((bytes >> 1) & 0x1ff);
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guint64 cr = 300 * ts_val + ext;
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unsigned rem = (unsigned)(cr % SCRHZ);
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wth->capture.mpeg->now.secs
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= wth->capture.mpeg->t0 + (time_t)(cr / SCRHZ);
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wth->capture.mpeg->now.nsecs
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= (int)(G_GINT64_CONSTANT(1000000000) * rem / SCRHZ);
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}
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ts = wth->capture.mpeg->now;
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break;
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default:
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packet_size = 12;
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}
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} else {
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guint16 length;
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bytes_read = file_read(&length, 1, sizeof length, wth->fh);
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if (bytes_read != sizeof length) {
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*err = file_error(wth->fh);
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if (*err == 0 && bytes_read != 0)
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*err = WTAP_ERR_SHORT_READ;
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return FALSE;
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}
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length = g_ntohs(length);
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packet_size = 6 + length;
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}
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if (file_seek(wth->fh, offset, SEEK_SET, err) == -1)
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return FALSE;
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} else {
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struct mpa mpa;
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MPA_UNMARSHAL(&mpa, n);
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if (MPA_VALID(&mpa)) {
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packet_size = MPA_BYTES(&mpa);
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wth->capture.mpeg->now.nsecs += MPA_DURATION_NS(&mpa);
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if (wth->capture.mpeg->now.nsecs >= 1000000000) {
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wth->capture.mpeg->now.secs++;
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wth->capture.mpeg->now.nsecs -= 1000000000;
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}
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} else {
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packet_size = mpeg_resync(wth, err, err_info);
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if (packet_size == 0)
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return FALSE;
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}
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}
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*data_offset = wth->data_offset;
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buffer_assure_space(wth->frame_buffer, packet_size);
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if (!mpeg_read_rec_data(wth->fh, buffer_start_ptr(wth->frame_buffer),
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packet_size, err))
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return FALSE;
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wth->data_offset += packet_size;
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wth->phdr.ts = ts;
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wth->phdr.caplen = packet_size;
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wth->phdr.len = packet_size;
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return TRUE;
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}
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static gboolean
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mpeg_seek_read(wtap *wth, gint64 seek_off,
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union wtap_pseudo_header *pseudo_header _U_, guchar *pd, int length,
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int *err, gchar **err_info _U_)
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{
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if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
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return FALSE;
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return mpeg_read_rec_data(wth->random_fh, pd, length, err);
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}
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static void
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mpeg_close(wtap *wth)
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{
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g_free(wth->capture.mpeg);
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}
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struct _mpeg_magic {
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size_t len;
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const gchar* match;
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} magic[] = {
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{ 3, "TAG" }, /* ID3v1 */
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{ 3, "ID3" }, /* ID3v2 */
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{ 3, "\0\0\1" }, /* MPEG PES */
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/* XXX MPEG audio is missing. */
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{ 0, NULL }
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};
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int
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mpeg_open(wtap *wth, int *err, gchar **err_info _U_)
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{
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int bytes_read;
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char magic_buf[16];
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struct _mpeg_magic* m;
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errno = WTAP_ERR_CANT_READ;
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bytes_read = file_read(magic_buf, 1, sizeof magic_buf, wth->fh);
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if (bytes_read != (int) sizeof magic_buf) {
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*err = file_error(wth->fh);
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if (*err != 0)
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return -1;
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return 0;
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}
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for (m=magic;m->match;m++) {
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if (memcmp(magic_buf,m->match,m->len) == 0)
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goto good_magic;
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}
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return 0;
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good_magic:
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/* This appears to be a file with MPEG data. */
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
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return -1;
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wth->file_type = WTAP_FILE_MPEG;
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wth->file_encap = WTAP_ENCAP_MPEG;
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wth->tsprecision = WTAP_FILE_TSPREC_NSEC;
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wth->subtype_read = mpeg_read;
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wth->subtype_seek_read = mpeg_seek_read;
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wth->subtype_close = mpeg_close;
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wth->snapshot_length = 0;
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wth->capture.mpeg = g_malloc(sizeof(mpeg_t));
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wth->capture.mpeg->now.secs = time(NULL);
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wth->capture.mpeg->now.nsecs = 0;
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wth->capture.mpeg->t0 = wth->capture.mpeg->now.secs;
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return 1;
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}
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