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mpv/demux/cue.c
wm4 cbee577d0a cue: tolerate NBSP as whitespace
Apparently such .cue files exist. They fail both probing and parsing. To
make it worse, the sample at hand was encoded as Latin1.

One part of this is replacing bstr_lstrip() with a version that supports
NBSP. One could argue that bstr_lstrip() should always do this, but I
don't want to overdo it. There are many more unicode abomination which
it could be said it's supposed to handle, so it will stay ASCII instead
of going down this rabbit hole. I'm just assuming this cue sheet was
generated by some stupid software that inexplicably liked NBSPs (which
is how we justify a one-off fix). The new lstrip_whitespace() doesn't
look particularly efficient, but it doesn't have to be.

The second part is dealing with the fact that the charset is not
necessarily UTF-8. We don't want to do conversion before probing thinks
it knows it's a cue sheet (would probably make it more fragile all
around), so just make it work with Latin1 by assuming invalid code
points are Latin1. This fallback is part of why lstrip_whitespace() is
sort of roundabout.

(You could still rewrite it as much more efficient state machine,
instead of using a slow and validating UTF-8 parser that is called per
codepoint. Starting to overthink this.)

Multimedia is terrible. Legacy charsets are terrible. Everything is
terrible.

Fixes: #7429
2020-02-03 19:13:44 +01:00

271 lines
7.6 KiB
C

/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <inttypes.h>
#include "mpv_talloc.h"
#include "misc/bstr.h"
#include "common/common.h"
#include "common/tags.h"
#include "cue.h"
#define SECS_PER_CUE_FRAME (1.0/75.0)
enum cue_command {
CUE_ERROR = -1, // not a valid CUE command, or an unknown extension
CUE_EMPTY, // line with whitespace only
CUE_UNUSED, // valid CUE command, but ignored by this code
CUE_FILE,
CUE_TRACK,
CUE_INDEX,
CUE_TITLE,
CUE_PERFORMER,
};
static const struct {
enum cue_command command;
const char *text;
} cue_command_strings[] = {
{ CUE_FILE, "FILE" },
{ CUE_TRACK, "TRACK" },
{ CUE_INDEX, "INDEX" },
{ CUE_TITLE, "TITLE" },
{ CUE_UNUSED, "CATALOG" },
{ CUE_UNUSED, "CDTEXTFILE" },
{ CUE_UNUSED, "FLAGS" },
{ CUE_UNUSED, "ISRC" },
{ CUE_PERFORMER, "PERFORMER" },
{ CUE_UNUSED, "POSTGAP" },
{ CUE_UNUSED, "PREGAP" },
{ CUE_UNUSED, "REM" },
{ CUE_UNUSED, "SONGWRITER" },
{ CUE_UNUSED, "MESSAGE" },
{ -1 },
};
static const uint8_t spaces[] = {' ', '\f', '\n', '\r', '\t', '\v', 0xA0};
static struct bstr lstrip_whitespace(struct bstr data)
{
while (data.len) {
bstr rest = data;
int code = bstr_decode_utf8(data, &rest);
if (code < 0) {
// Tolerate Latin1 => probing works (which doesn't convert charsets).
code = data.start[0];
rest.start += 1;
rest.len -= 1;
}
for (size_t n = 0; n < MP_ARRAY_SIZE(spaces); n++) {
if (spaces[n] == code) {
data = rest;
goto next;
}
}
break;
next: ;
}
return data;
}
static enum cue_command read_cmd(struct bstr *data, struct bstr *out_params)
{
struct bstr line = bstr_strip_linebreaks(bstr_getline(*data, data));
line = lstrip_whitespace(line);
if (line.len == 0)
return CUE_EMPTY;
for (int n = 0; cue_command_strings[n].command != -1; n++) {
struct bstr name = bstr0(cue_command_strings[n].text);
if (bstr_case_startswith(line, name)) {
struct bstr rest = bstr_cut(line, name.len);
struct bstr par = lstrip_whitespace(rest);
if (rest.len && par.len == rest.len)
continue;
if (out_params)
*out_params = par;
return cue_command_strings[n].command;
}
}
return CUE_ERROR;
}
static bool eat_char(struct bstr *data, char ch)
{
if (data->len && data->start[0] == ch) {
*data = bstr_cut(*data, 1);
return true;
} else {
return false;
}
}
static char *read_quoted(void *talloc_ctx, struct bstr *data)
{
*data = lstrip_whitespace(*data);
if (!eat_char(data, '"'))
return NULL;
int end = bstrchr(*data, '"');
if (end < 0)
return NULL;
struct bstr res = bstr_splice(*data, 0, end);
*data = bstr_cut(*data, end + 1);
return bstrto0(talloc_ctx, res);
}
static struct bstr strip_quotes(struct bstr data)
{
bstr s = data;
if (bstr_eatstart0(&s, "\"") && bstr_eatend0(&s, "\""))
return s;
return data;
}
// Read an unsigned decimal integer.
// Optionally check if it is 2 digit.
// Return -1 on failure.
static int read_int(struct bstr *data, bool two_digit)
{
*data = lstrip_whitespace(*data);
if (data->len && data->start[0] == '-')
return -1;
struct bstr s = *data;
int res = (int)bstrtoll(s, &s, 10);
if (data->len == s.len || (two_digit && data->len - s.len > 2))
return -1;
*data = s;
return res;
}
static double read_time(struct bstr *data)
{
struct bstr s = *data;
bool ok = true;
double t1 = read_int(&s, false);
ok = eat_char(&s, ':') && ok;
double t2 = read_int(&s, true);
ok = eat_char(&s, ':') && ok;
double t3 = read_int(&s, true);
ok = ok && t1 >= 0 && t2 >= 0 && t3 >= 0;
return ok ? t1 * 60.0 + t2 + t3 * SECS_PER_CUE_FRAME : 0;
}
static struct bstr skip_utf8_bom(struct bstr data)
{
return bstr_startswith0(data, "\xEF\xBB\xBF") ? bstr_cut(data, 3) : data;
}
// Check if the text in data is most likely CUE data. This is used by the
// demuxer code to check the file type.
// data is the start of the probed file, possibly cut off at a random point.
bool mp_probe_cue(struct bstr data)
{
bool valid = false;
data = skip_utf8_bom(data);
for (;;) {
enum cue_command cmd = read_cmd(&data, NULL);
// End reached. Since the line was most likely cut off, don't use the
// result of the last parsing call.
if (data.len == 0)
break;
if (cmd == CUE_ERROR)
return false;
if (cmd != CUE_EMPTY)
valid = true;
}
return valid;
}
struct cue_file *mp_parse_cue(struct bstr data)
{
struct cue_file *f = talloc_zero(NULL, struct cue_file);
f->tags = talloc_zero(f, struct mp_tags);
data = skip_utf8_bom(data);
char *filename = NULL;
// Global metadata, and copied into new tracks.
struct cue_track proto_track = {0};
struct cue_track *cur_track = NULL;
while (data.len) {
struct bstr param;
int cmd = read_cmd(&data, &param);
switch (cmd) {
case CUE_ERROR:
talloc_free(f);
return NULL;
case CUE_TRACK: {
MP_TARRAY_GROW(f, f->tracks, f->num_tracks);
f->num_tracks += 1;
cur_track = &f->tracks[f->num_tracks - 1];
*cur_track = proto_track;
cur_track->tags = talloc_zero(f, struct mp_tags);
break;
}
case CUE_TITLE:
case CUE_PERFORMER: {
static const char *metanames[] = {
[CUE_TITLE] = "title",
[CUE_PERFORMER] = "performer",
};
struct mp_tags *tags = cur_track ? cur_track->tags : f->tags;
mp_tags_set_bstr(tags, bstr0(metanames[cmd]), strip_quotes(param));
break;
}
case CUE_INDEX: {
int type = read_int(&param, true);
double time = read_time(&param);
if (cur_track) {
if (type == 1) {
cur_track->start = time;
cur_track->filename = filename;
} else if (type == 0) {
cur_track->pregap_start = time;
}
}
break;
}
case CUE_FILE:
// NOTE: FILE comes before TRACK, so don't use cur_track->filename
filename = read_quoted(f, &param);
break;
}
}
return f;
}
int mp_check_embedded_cue(struct cue_file *f)
{
char *fn0 = f->tracks[0].filename;
for (int n = 1; n < f->num_tracks; n++) {
char *fn = f->tracks[n].filename;
// both filenames have the same address (including NULL)
if (fn0 == fn)
continue;
// only one filename is NULL, or the strings don't match
if (!fn0 || !fn || strcmp(fn0, fn) != 0)
return -1;
}
return 0;
}