forked from osmocom/wireshark
![Guy Harris](/assets/img/avatar_default.png)
Allow file_read() to take a null pointer as a buffer argument; a null argument means "do everything except copy the bytes from the file to the user buffer". That means that wtap_read_bytes() and wtap_read_bytes_or_eof() also support a null pointer as a buffer argument. Use wtap_read_bytes() with a null buffer argument rather than file_skip() to skip forward over data. This fixes some places where files were mis-identified as ERF files, as the ERF open heuristics now get a short "read" error if they try to skip over more bytes than exist in the file. Change-Id: I4f73499d877c1f582e2bcf9b045034880cb09622 Reviewed-on: https://code.wireshark.org/review/17974 Reviewed-by: Guy Harris <guy@alum.mit.edu>
289 lines
6.9 KiB
C
289 lines
6.9 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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* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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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 "mpeg.h"
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#include "wsutil/mpeg-audio.h"
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#include "wtap-int.h"
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#include <wsutil/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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typedef struct {
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nstime_t now;
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time_t t0;
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} mpeg_t;
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static int
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mpeg_resync(FILE_T fh, int *err)
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{
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gint64 offset = file_tell(fh);
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int count = 0;
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int byte = file_getc(fh);
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while (byte != EOF) {
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if (byte == 0xff && count > 0) {
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byte = file_getc(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(fh);
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count++;
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}
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if (file_seek(fh, offset, SEEK_SET, err) == -1)
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return 0;
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return count;
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}
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#define SCRHZ 27000000
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static gboolean
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mpeg_read_packet(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
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gboolean is_random, int *err, gchar **err_info)
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{
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mpeg_t *mpeg = (mpeg_t *)wth->priv;
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guint32 n;
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unsigned int packet_size;
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nstime_t ts = mpeg->now;
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/*
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* All packets have at least 4 bytes in them. Read the first
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* 4 bytes and determine whether it's a PES packet or not
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* based on that.
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*
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* XXX - can an MPEG file contain a mixture of PES and non-PES
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* packets? If not, can we determine whether the packets will
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* be PES packets or not based on the magic number (i.e., if the
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* file begins with 0x00 0x00 0x01, it contains PES packets,
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* otherwise it doesn't)?
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*/
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if (!wtap_read_bytes_or_eof(fh, &n, sizeof n, err, err_info))
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return FALSE;
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if (file_seek(fh, -(gint64)(sizeof n), SEEK_CUR, err) == -1)
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return FALSE;
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n = g_ntohl(n);
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if (PES_VALID(n)) {
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gint64 offset = file_tell(fh);
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guint8 stream;
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if (!wtap_read_bytes(fh, NULL, 3, err, err_info))
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return FALSE;
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if (!wtap_read_bytes(fh, &stream, sizeof stream, err, err_info))
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return FALSE;
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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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if (!wtap_read_bytes(fh, &pack1, sizeof pack1, err, err_info))
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return FALSE;
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if (!wtap_read_bytes(fh, &pack0, sizeof pack0, err, err_info))
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return FALSE;
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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 (!wtap_read_bytes(fh, NULL, 1, err,
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err_info))
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return FALSE;
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if (!wtap_read_bytes(fh, &stuffing,
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sizeof stuffing, err, err_info))
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return FALSE;
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stuffing &= 0x07;
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packet_size = 14 + stuffing;
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if (!is_random) {
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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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guint ext = (guint)((bytes >> 1) & 0x1ff);
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guint64 cr = 300 * ts_val + ext;
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guint rem = (guint)(cr % SCRHZ);
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mpeg->now.secs
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= mpeg->t0 + (time_t)(cr / SCRHZ);
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mpeg->now.nsecs
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= (int)(G_GINT64_CONSTANT(1000000000) * rem / SCRHZ);
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}
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ts = 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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if (!wtap_read_bytes(fh, &length, sizeof length, err, err_info))
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return FALSE;
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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(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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if (!is_random) {
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mpeg->now.nsecs += MPA_DURATION_NS(&mpa);
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if (mpeg->now.nsecs >= 1000000000) {
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mpeg->now.secs++;
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mpeg->now.nsecs -= 1000000000;
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}
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}
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} else {
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packet_size = mpeg_resync(fh, err);
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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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if (!wtap_read_packet_bytes(fh, buf, packet_size, err, err_info))
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return FALSE;
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phdr->rec_type = REC_TYPE_PACKET;
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/* XXX - relative, not absolute, time stamps */
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if (!is_random) {
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phdr->presence_flags = WTAP_HAS_TS;
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phdr->ts = ts;
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}
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phdr->caplen = packet_size;
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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_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
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{
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*data_offset = file_tell(wth->fh);
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return mpeg_read_packet(wth, wth->fh, &wth->phdr, wth->frame_buffer,
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FALSE, err, err_info);
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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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struct wtap_pkthdr *phdr, Buffer *buf,
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int *err, gchar **err_info)
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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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if (!mpeg_read_packet(wth, wth->random_fh, phdr, buf, TRUE, err,
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err_info)) {
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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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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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{ 2, "\xff\xfb" }, /* MP3, taken from http://en.wikipedia.org/wiki/MP3#File_structure */
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{ 0, NULL }
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};
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wtap_open_return_val
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mpeg_open(wtap *wth, int *err, gchar **err_info)
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{
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char magic_buf[16];
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struct _mpeg_magic* m;
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mpeg_t *mpeg;
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if (!wtap_read_bytes(wth->fh, magic_buf, sizeof magic_buf,
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err, err_info)) {
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if (*err != WTAP_ERR_SHORT_READ)
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return WTAP_OPEN_ERROR;
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return WTAP_OPEN_NOT_MINE;
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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 WTAP_OPEN_NOT_MINE;
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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 WTAP_OPEN_ERROR;
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wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG;
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wth->file_encap = WTAP_ENCAP_MPEG;
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wth->file_tsprec = WTAP_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->snapshot_length = 0;
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mpeg = (mpeg_t *)g_malloc(sizeof(mpeg_t));
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wth->priv = (void *)mpeg;
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mpeg->now.secs = 0;
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mpeg->now.nsecs = 0;
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mpeg->t0 = mpeg->now.secs;
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return WTAP_OPEN_MINE;
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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