summaryrefslogtreecommitdiffstats
path: root/input/cmd.c
blob: 64232143f7644fbc696f968b81bac1842326b072 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
/*
 * 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 <stddef.h>

#include "misc/bstr.h"
#include "misc/node.h"
#include "common/common.h"
#include "common/msg.h"
#include "options/m_option.h"

#include "cmd.h"
#include "input.h"
#include "misc/json.h"

#include "libmpv/client.h"

static void destroy_cmd(void *ptr)
{
    struct mp_cmd *cmd = ptr;
    for (int n = 0; n < cmd->nargs; n++) {
        if (cmd->args[n].type)
            m_option_free(cmd->args[n].type, &cmd->args[n].v);
    }
}

struct flag {
    const char *name;
    unsigned int remove, add;
};

static const struct flag cmd_flags[] = {
    {"no-osd",              MP_ON_OSD_FLAGS, MP_ON_OSD_NO},
    {"osd-bar",             MP_ON_OSD_FLAGS, MP_ON_OSD_BAR},
    {"osd-msg",             MP_ON_OSD_FLAGS, MP_ON_OSD_MSG},
    {"osd-msg-bar",         MP_ON_OSD_FLAGS, MP_ON_OSD_MSG | MP_ON_OSD_BAR},
    {"osd-auto",            MP_ON_OSD_FLAGS, MP_ON_OSD_AUTO},
    {"expand-properties",   0,               MP_EXPAND_PROPERTIES},
    {"raw",                 MP_EXPAND_PROPERTIES, 0},
    {"repeatable",          0,               MP_ALLOW_REPEAT},
    {"async",               MP_SYNC_CMD,     MP_ASYNC_CMD},
    {"sync",                MP_ASYNC_CMD,     MP_SYNC_CMD},
    {0}
};

static bool apply_flag(struct mp_cmd *cmd, bstr str)
{
    for (int n = 0; cmd_flags[n].name; n++) {
        if (bstr_equals0(str, cmd_flags[n].name)) {
            cmd->flags = (cmd->flags & ~cmd_flags[n].remove) | cmd_flags[n].add;
            return true;
        }
    }
    return false;
}

static bool find_cmd(struct mp_log *log, struct mp_cmd *cmd, bstr name)
{
    if (name.len == 0) {
        mp_err(log, "Command name missing.\n");
        return false;
    }

    char nname[80];
    snprintf(nname, sizeof(nname), "%.*s", BSTR_P(name));
    for (int n = 0; nname[n]; n++) {
        if (nname[n] == '_')
            nname[n] = '-';
    }

    for (int n = 0; mp_cmds[n].name; n++) {
        if (strcmp(nname, mp_cmds[n].name) == 0) {
            cmd->def = &mp_cmds[n];
            cmd->name = (char *)cmd->def->name;
            return true;
        }
    }
    mp_err(log, "Command '%.*s' not found.\n", BSTR_P(name));
    return false;
}

static bool is_vararg(const struct mp_cmd_def *m, int i)
{
    return m->vararg && (i + 1 >= MP_CMD_DEF_MAX_ARGS || !m->args[i + 1].type);
}

static const struct m_option *get_arg_type(const struct mp_cmd_def *cmd, int i)
{
    const struct m_option *opt = NULL;
    if (is_vararg(cmd, i)) {
        // The last arg in a vararg command sets all vararg types.
        for (int n = MPMIN(i, MP_CMD_DEF_MAX_ARGS - 1); n >= 0; n--) {
            if (cmd->args[n].type) {
                opt = &cmd->args[n];
                break;
            }
        }
    } else if (i < MP_CMD_DEF_MAX_ARGS) {
        opt = &cmd->args[i];
    }
    return opt && opt->type ? opt : NULL;
}

// Return the name of the argument, possibly as stack allocated string (which is
// why this is a macro, and out of laziness). Otherwise as get_arg_type().
#define get_arg_name(cmd, i)                                    \
    ((i) < MP_CMD_DEF_MAX_ARGS && (cmd)->args[(i)].name &&      \
     (cmd)->args[(i)].name[0]                                   \
     ? (cmd)->args[(i)].name : mp_tprintf(10, "%d", (i) + 1))

// Verify that there are no missing args, fill in missing optional args.
static bool finish_cmd(struct mp_log *log, struct mp_cmd *cmd)
{
    for (int i = 0; i < MP_CMD_DEF_MAX_ARGS; i++) {
        // (type==NULL is used for yet unset arguments)
        if (i < cmd->nargs && cmd->args[i].type)
            continue;
        const struct m_option *opt = get_arg_type(cmd->def, i);
        if (i >= cmd->nargs && (!opt || is_vararg(cmd->def, i)))
            break;
        if (!opt->defval && !(opt->flags & MP_CMD_OPT_ARG)) {
            mp_err(log, "Command %s: required argument %s not set.\n",
                   cmd->name, get_arg_name(cmd->def, i));
            return false;
        }
        struct mp_cmd_arg arg = {.type = opt};
        if (opt->defval)
            m_option_copy(opt, &arg.v, opt->defval);
        assert(i <= cmd->nargs);
        if (i == cmd->nargs) {
            MP_TARRAY_APPEND(cmd, cmd->args, cmd->nargs, arg);
        } else {
            cmd->args[i] = arg;
        }
    }

    if (!(cmd->flags & (MP_ASYNC_CMD | MP_SYNC_CMD)))
        cmd->flags |= cmd->def->default_async ? MP_ASYNC_CMD : MP_SYNC_CMD;

    return true;
}

static bool set_node_arg(struct mp_log *log, struct mp_cmd *cmd, int i,
                         mpv_node *val)
{
    const char *name = get_arg_name(cmd->def, i);

    const struct m_option *opt = get_arg_type(cmd->def, i);
    if (!opt) {
        mp_err(log, "Command %s: has only %d arguments.\n", cmd->name, i);
        return false;
    }

    if (i < cmd->nargs && cmd->args[i].type) {
        mp_err(log, "Command %s: argument %s was already set.\n", cmd->name, name);
        return false;
    }

    struct mp_cmd_arg arg = {.type = opt};
    void *dst = &arg.v;
    if (val->format == MPV_FORMAT_STRING) {
        int r = m_option_parse(log, opt, bstr0(cmd->name),
                                bstr0(val->u.string), dst);
        if (r < 0) {
            mp_err(log, "Command %s: argument %s can't be parsed: %s.\n",
                   cmd->name, name, m_option_strerror(r));
            return false;
        }
    } else {
        int r = m_option_set_node(opt, dst, val);
        if (r < 0) {
            mp_err(log, "Command %s: argument %s has incompatible type.\n",
                   cmd->name, name);
            return false;
        }
    }

    // (leave unset arguments blank, to be set later or checked by finish_cmd())
    while (i >= cmd->nargs) {
        struct mp_cmd_arg t = {0};
        MP_TARRAY_APPEND(cmd, cmd->args, cmd->nargs, t);
    }

    cmd->args[i] = arg;
    return true;
}

static bool cmd_node_array(struct mp_log *log, struct mp_cmd *cmd, mpv_node *node)
{
    assert(node->format == MPV_FORMAT_NODE_ARRAY);
    mpv_node_list *args = node->u.list;
    int cur = 0;

    while (cur < args->num) {
        if (args->values[cur].format != MPV_FORMAT_STRING)
            break;
        if (!apply_flag(cmd, bstr0(args->values[cur].u.string)))
            break;
        cur++;
    }

    bstr cmd_name = {0};
    if (cur < args->num && args->values[cur].format == MPV_FORMAT_STRING)
        cmd_name = bstr0(args->values[cur++].u.string);
    if (!find_cmd(log, cmd, cmd_name))
        return false;

    int first = cur;
    for (int i = 0; i < args->num - first; i++) {
        if (!set_node_arg(log, cmd, cmd->nargs, &args->values[cur++]))
            return false;
    }

    return true;
}

static bool cmd_node_map(struct mp_log *log, struct mp_cmd *cmd, mpv_node *node)
{
    assert(node->format == MPV_FORMAT_NODE_MAP);
    mpv_node_list *args = node->u.list;

    mpv_node *name = node_map_get(node, "name");
    if (!name || name->format != MPV_FORMAT_STRING)
        return false;

    if (!find_cmd(log, cmd, bstr0(name->u.string)))
        return false;

    if (cmd->def->vararg) {
        mp_err(log, "Command %s: this command uses a variable number of "
               "arguments, which does not work with named arguments.\n",
               cmd->name);
        return false;
    }

    for (int n = 0; n < args->num; n++) {
        const char *key = args->keys[n];
        mpv_node *val = &args->values[n];

        if (strcmp(key, "name") == 0) {
            // already handled above
        } else if (strcmp(key, "_flags") == 0) {
            if (val->format != MPV_FORMAT_NODE_ARRAY)
                return false;
            mpv_node_list *flags = val->u.list;
            for (int i = 0; i < flags->num; i++) {
                if (flags->values[i].format != MPV_FORMAT_STRING)
                    return false;
                if (!apply_flag(cmd, bstr0(flags->values[i].u.string)))
                    return false;
            }
        } else {
            int arg = -1;

            for (int i = 0; i < MP_CMD_DEF_MAX_ARGS; i++) {
                const char *arg_name = cmd->def->args[i].name;
                if (arg_name && arg_name[0] && strcmp(key, arg_name) == 0) {
                    arg = i;
                    break;
                }
            }

            if (arg < 0) {
                mp_err(log, "Command %s: no argument %s.\n", cmd->name, key);
                return false;
            }

            if (!set_node_arg(log, cmd, arg, val))
                return false;
        }
    }

    return true;
}

struct mp_cmd *mp_input_parse_cmd_node(struct mp_log *log, mpv_node *node)
{
    struct mp_cmd *cmd = talloc_ptrtype(NULL, cmd);
    talloc_set_destructor(cmd, destroy_cmd);
    *cmd = (struct mp_cmd) { .scale = 1, .scale_units = 1 };

    bool res = false;
    if (node->format == MPV_FORMAT_NODE_ARRAY) {
        res = cmd_node_array(log, cmd, node);
    } else if (node->format == MPV_FORMAT_NODE_MAP) {
        res = cmd_node_map(log, cmd, node);
    }

    res = res && finish_cmd(log, cmd);

    if (!res)
        TA_FREEP(&cmd);

    return cmd;
}

static bool read_token(bstr str, bstr *out_rest, bstr *out_token)
{
    bstr t = bstr_lstrip(str);
    int next = bstrcspn(t, WHITESPACE "#;");
    if (!next)
        return false;
    *out_token = bstr_splice(t, 0, next);
    *out_rest = bstr_cut(t, next);
    return true;
}

struct parse_ctx {
    struct mp_log *log;
    void *tmp;
    bstr start, str;
};

static int pctx_read_token(struct parse_ctx *ctx, bstr *out)
{
    *out = (bstr){0};
    ctx->str = bstr_lstrip(ctx->str);
    bstr start = ctx->str;
    if (bstr_eatstart0(&ctx->str, "\"")) {
        if (!mp_append_escaped_string_noalloc(ctx->tmp, out, &ctx->str)) {
            MP_ERR(ctx, "Broken string escapes: ...>%.*s<.\n", BSTR_P(start));
            return -1;
        }
        if (!bstr_eatstart0(&ctx->str, "\"")) {
            MP_ERR(ctx, "Unterminated double quote: ...>%.*s<.\n", BSTR_P(start));
            return -1;
        }
        return 1;
    }
    if (bstr_eatstart0(&ctx->str, "'")) {
        int next = bstrchr(ctx->str, '\'');
        if (next < 0) {
            MP_ERR(ctx, "Unterminated single quote: ...>%.*s<.\n", BSTR_P(start));
            return -1;
        }
        *out = bstr_splice(ctx->str, 0, next);
        ctx->str = bstr_cut(ctx->str, next+1);
        return 1;
    }
    if (ctx->start.len > 1 && bstr_eatstart0(&ctx->str, "`")) {
        char endquote[2] = {ctx->str.start[0], '`'};
        ctx->str = bstr_cut(ctx->str, 1);
        int next = bstr_find(ctx->str, (bstr){endquote, 2});
        if (next < 0) {
            MP_ERR(ctx, "Unterminated custom quote: ...>%.*s<.\n", BSTR_P(start));
            return -1;
        }
        *out = bstr_splice(ctx->str, 0, next);
        ctx->str = bstr_cut(ctx->str, next+2);
        return 1;
    }

    return read_token(ctx->str, &ctx->str, out) ? 1 : 0;
}

static struct mp_cmd *parse_cmd_str(struct mp_log *log, void *tmp,
                                    bstr *str, const char *loc)
{
    struct parse_ctx *ctx = &(struct parse_ctx){
        .log = log,
        .tmp = tmp,
        .str = *str,
        .start = *str,
    };

    struct mp_cmd *cmd = talloc_ptrtype(NULL, cmd);
    talloc_set_destructor(cmd, destroy_cmd);
    *cmd = (struct mp_cmd) {
        .flags = MP_ON_OSD_AUTO | MP_EXPAND_PROPERTIES,
        .scale = 1,
        .scale_units = 1,
    };

    ctx->str = bstr_lstrip(ctx->str);

    bstr cur_token;
    if (pctx_read_token(ctx, &cur_token) < 0)
        goto error;

    while (1) {
        if (!apply_flag(cmd, cur_token))
            break;
        if (pctx_read_token(ctx, &cur_token) < 0)
            goto error;
    }

    if (!find_cmd(ctx->log, cmd, cur_token))
        goto error;

    for (int i = 0; i < MP_CMD_MAX_ARGS; i++) {
        const struct m_option *opt = get_arg_type(cmd->def, i);
        if (!opt)
            break;

        int r = pctx_read_token(ctx, &cur_token);
        if (r < 0) {
            MP_ERR(ctx, "Command %s: error in argument %d.\n", cmd->name, i + 1);
            goto error;
        }
        if (r < 1)
            break;

        struct mp_cmd_arg arg = {.type = opt};
        r = m_option_parse(ctx->log, opt, bstr0(cmd->name), cur_token, &arg.v);
        if (r < 0) {
            MP_ERR(ctx, "Command %s: argument %d can't be parsed: %s.\n",
                   cmd->name, i + 1, m_option_strerror(r));
            goto error;
        }

        MP_TARRAY_APPEND(cmd, cmd->args, cmd->nargs, arg);
    }

    if (!finish_cmd(ctx->log, cmd))
        goto error;

    bstr dummy;
    if (read_token(ctx->str, &dummy, &dummy) && ctx->str.len) {
        MP_ERR(ctx, "Command %s has trailing unused arguments: '%.*s'.\n",
               cmd->name, BSTR_P(ctx->str));
        // Better make it fatal to make it clear something is wrong.
        goto error;
    }

    bstr orig = {ctx->start.start, ctx->str.start - ctx->start.start};
    cmd->original = bstrto0(cmd, bstr_strip(orig));

    *str = ctx->str;
    return cmd;

error:
    MP_ERR(ctx, "Command was defined at %s.\n", loc);
    talloc_free(cmd);
    *str = ctx->str;
    return NULL;
}

mp_cmd_t *mp_input_parse_cmd_str(struct mp_log *log, bstr str, const char *loc)
{
    void *tmp = talloc_new(NULL);
    bstr original = str;
    struct mp_cmd *cmd = parse_cmd_str(log, tmp, &str, loc);
    if (!cmd)
        goto done;

    // Handle "multi" commands
    struct mp_cmd **p_prev = NULL;
    while (1) {
        str = bstr_lstrip(str);
        // read_token just to check whether it's trailing whitespace only
        bstr u1, u2;
        if (!bstr_eatstart0(&str, ";") || !read_token(str, &u1, &u2))
            break;
        // Multi-command. Since other input.c code uses queue_next for its
        // own purposes, a pseudo-command is used to wrap the command list.
        if (!p_prev) {
            struct mp_cmd *list = talloc_ptrtype(NULL, list);
            talloc_set_destructor(list, destroy_cmd);
            *list = (struct mp_cmd) {
                .name = (char *)mp_cmd_list.name,
                .def = &mp_cmd_list,
            };
            talloc_steal(list, cmd);
            struct mp_cmd_arg arg = {0};
            arg.v.p = cmd;
            list->args = talloc_dup(list, &arg);
            p_prev = &cmd->queue_next;
            cmd = list;
        }
        struct mp_cmd *sub = parse_cmd_str(log, tmp, &str, loc);
        if (!sub) {
            talloc_free(cmd);
            cmd = NULL;
            goto done;
        }
        talloc_steal(cmd, sub);
        *p_prev = sub;
        p_prev = &sub->queue_next;
    }

    cmd->original = bstrto0(cmd, bstr_strip(
                        bstr_splice(original, 0, str.start - original.start)));

    str = bstr_strip(str);
    if (bstr_eatstart0(&str, "#") && !bstr_startswith0(str, "#")) {
        str = bstr_strip(str);
        if (str.len)
            cmd->desc = bstrto0(cmd, str);
    }

done:
    talloc_free(tmp);
    return cmd;
}

struct mp_cmd *mp_input_parse_cmd_strv(struct mp_log *log, const char **argv)
{
    int count = 0;
    while (argv[count])
        count++;
    mpv_node *items = talloc_zero_array(NULL, mpv_node, count);
    mpv_node_list list = {.values = items, .num = count};
    mpv_node node = {.format = MPV_FORMAT_NODE_ARRAY, .u = {.list = &list}};
    for (int n = 0; n < count; n++) {
        items[n] = (mpv_node){.format = MPV_FORMAT_STRING,
                              .u = {.string = (char *)argv[n]}};
    }
    struct mp_cmd *res = mp_input_parse_cmd_node(log, &node);
    talloc_free(items);
    return res;
}

void mp_cmd_free(mp_cmd_t *cmd)
{
    talloc_free(cmd);
}

mp_cmd_t *mp_cmd_clone(mp_cmd_t *cmd)
{
    if (!cmd)
        return NULL;

    mp_cmd_t *ret = talloc_dup(NULL, cmd);
    talloc_set_destructor(ret, destroy_cmd);
    ret->name = talloc_strdup(ret, cmd->name);
    ret->args = talloc_zero_array(ret, struct mp_cmd_arg, ret->nargs);
    for (int i = 0; i < ret->nargs; i++) {
        ret->args[i].type = cmd->args[i].type;
        m_option_copy(ret->args[i].type, &ret->args[i].v, &cmd->args[i].v);
    }
    ret->original = talloc_strdup(ret, cmd->original);
    ret->desc = talloc_strdup(ret, cmd->desc);
    ret->sender = NULL;
    ret->key_name = talloc_strdup(ret, ret->key_name);
    ret->key_text = talloc_strdup(ret, ret->key_text);

    if (cmd->def == &mp_cmd_list) {
        struct mp_cmd *prev = NULL;
        for (struct mp_cmd *sub = cmd->args[0].v.p; sub; sub = sub->queue_next) {
            sub = mp_cmd_clone(sub);
            talloc_steal(ret, sub);
            if (prev) {
                prev->queue_next = sub;
            } else {
                struct mp_cmd_arg arg = {0};
                arg.v.p = sub;
                ret->args = talloc_dup(ret, &arg);
            }
            prev = sub;
        }
    }

    return ret;
}

static int get_arg_count(const struct mp_cmd_def *cmd)
{
    for (int i = MP_CMD_DEF_MAX_ARGS - 1; i >= 0; i--) {
        if (cmd->args[i].type)
            return i + 1;
    }
    return 0;
}

void mp_cmd_dump(struct mp_log *log, int msgl, char *header, struct mp_cmd *cmd)
{
    if (!mp_msg_test(log, msgl))
        return;
    if (header)
        mp_msg(log, msgl, "%s ", header);
    if (!cmd) {
        mp_msg(log, msgl, "(NULL)\n");
        return;
    }
    mp_msg(log, msgl, "%s, flags=%d, args=[", cmd->name, cmd->flags);
    int argc = get_arg_count(cmd->def);
    for (int n = 0; n < cmd->nargs; n++) {
        const char *argname = cmd->def->args[MPMIN(n, argc - 1)].name;
        char *s = m_option_print(cmd->args[n].type, &cmd->args[n].v);
        if (n)
            mp_msg(log, msgl, ", ");
        struct mpv_node node = {
            .format = MPV_FORMAT_STRING,
            .u.string = s ? s : "(NULL)",
        };
        char *esc = NULL;
        json_write(&esc, &node);
        mp_msg(log, msgl, "%s=%s", argname, esc ? esc : "<error>");
        talloc_free(esc);
        talloc_free(s);
    }
    mp_msg(log, msgl, "]\n");
}

bool mp_input_is_repeatable_cmd(struct mp_cmd *cmd)
{
    if (cmd->def == &mp_cmd_list && cmd->args[0].v.p)
        cmd = cmd->args[0].v.p;  // list - only 1st cmd is considered

    return (cmd->def->allow_auto_repeat) || (cmd->flags & MP_ALLOW_REPEAT);
}

bool mp_input_is_scalable_cmd(struct mp_cmd *cmd)
{
    return cmd->def->scalable;
}

void mp_print_cmd_list(struct mp_log *out)
{
    for (int i = 0; mp_cmds[i].name; i++) {
        const struct mp_cmd_def *def = &mp_cmds[i];
        mp_info(out, "%-20.20s", def->name);
        for (int j = 0; j < MP_CMD_DEF_MAX_ARGS && def->args[j].type; j++) {
            const struct m_option *arg = &def->args[j];
            bool is_opt = arg->defval || (arg->flags & MP_CMD_OPT_ARG);
            mp_info(out, " %s%s=%s%s", is_opt ? "[" : "", arg->name,
                    arg->type->name, is_opt ? "]" : "");
        }
        if (def->vararg)
            mp_info(out, "..."); // essentially append to last argument
        mp_info(out, "\n");
    }
}

static int parse_cycle_dir(struct mp_log *log, const struct m_option *opt,
                           struct bstr name, struct bstr param, void *dst)
{
    double val;
    if (bstrcmp0(param, "up") == 0) {
        val = +1;
    } else if (bstrcmp0(param, "down") == 0) {
        val = -1;
    } else {
        return m_option_type_double.parse(log, opt, name, param, dst);
    }
    *(double *)dst = val;
    return 1;
}

static char *print_cycle_dir(const m_option_t *opt, const void *val)
{
    return talloc_asprintf(NULL, "%f", *(double *)val);
}

static void copy_opt(const m_option_t *opt, void *dst, const void *src)
{
    if (dst && src)
        memcpy(dst, src, opt->type->size);
}

const struct m_option_type m_option_type_cycle_dir = {
    .name = "up|down",
    .parse = parse_cycle_dir,
    .print = print_cycle_dir,
    .copy = copy_opt,
    .size = sizeof(double),
};