apps/plugin.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 Björn Stenberg
  11  *
  12  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19 #include "plugin.h"
  20 #include <ctype.h>
  21 #include <string.h>
  22 #include <sprintf.h>
  23 #include <atoi.h>
  24 #include "debug.h"
  25 #include "i2c.h"
  26 #include "lang.h"
  27 #include "keyboard.h"
  28 #include "buffer.h"
  29 #include "backlight.h"
  30 #include "sound_menu.h"
  31 #include "mp3data.h"
  32 #include "powermgmt.h"
  33 #include "splash.h"
  34 #include "logf.h"
  35
  36 #if CONFIG_CHARGING
  37 #include "power.h"
  38 #endif
  39
  40 #ifdef HAVE_LCD_BITMAP
  41 #include "scrollbar.h"
  42 #include "peakmeter.h"
  43 #include "bmp.h"
  44 #include "bidi.h"
  45 #endif
  46
  47 #ifdef SIMULATOR
  48 static unsigned char pluginbuf[PLUGIN_BUFFER_SIZE];
  49 void *sim_plugin_load(char *plugin, void **pd);
  50 void sim_plugin_close(void *pd);
  51 void sim_lcd_ex_init(int shades, unsigned long (*getpixel)(int, int));
  52 void sim_lcd_ex_update_rect(int x, int y, int width, int height);
  53 #else
  54 #define sim_plugin_close(x)
  55 extern unsigned char pluginbuf[];
  56 #include "bitswap.h"
  57 #endif
  58
  59 /* for actual plugins only, not for codecs */
  60 static bool plugin_loaded = false;
  61 static int  plugin_size = 0;
  62 static bool (*pfn_tsr_exit)(bool reenter) = NULL; /* TSR exit callback */
  63 static char current_plugin[MAX_PATH];
  64
  65 extern struct thread_entry threads[MAXTHREADS];
  66
  67 static const struct plugin_api rockbox_api = {
  68
  69     /* lcd */
  70     lcd_set_contrast,
  71     lcd_update,
  72     lcd_clear_display,
  73     lcd_setmargins,
  74     lcd_getstringsize,
  75     lcd_putsxy,
  76     lcd_puts,
  77     lcd_puts_scroll,
  78     lcd_stop_scroll,
  79 #ifdef HAVE_LCD_CHARCELLS
  80     lcd_define_pattern,
  81     lcd_get_locked_pattern,
  82     lcd_unlock_pattern,
  83     lcd_putc,
  84     lcd_put_cursor,
  85     lcd_remove_cursor,
  86     lcd_icon,
  87     lcd_double_height,
  88 #else
  89     lcd_set_drawmode,
  90     lcd_get_drawmode,
  91     lcd_setfont,
  92     lcd_drawpixel,
  93     lcd_drawline,
  94     lcd_hline,
  95     lcd_vline,
  96     lcd_drawrect,
  97     lcd_fillrect,
  98     lcd_mono_bitmap_part,
  99     lcd_mono_bitmap,
 100 #if LCD_DEPTH > 1
 101     lcd_set_foreground,
 102     lcd_get_foreground,
 103     lcd_set_background,
 104     lcd_get_background,
 105     lcd_bitmap_part,
 106     lcd_bitmap,
 107     lcd_set_backdrop,
 108 #endif
 109 #if LCD_DEPTH == 16
 110     lcd_bitmap_transparent_part,
 111     lcd_bitmap_transparent,
 112 #endif
 113     bidi_l2v,
 114     font_get_bits,
 115     font_load,
 116     lcd_puts_style,
 117     lcd_puts_scroll_style,
 118     &lcd_framebuffer[0][0],
 119     lcd_blit,
 120     lcd_update_rect,
 121     gui_scrollbar_draw,
 122     font_get,
 123     font_getstringsize,
 124     font_get_width,
 125 #endif
 126     backlight_on,
 127     backlight_off,
 128     backlight_set_timeout,
 129     gui_syncsplash,
 130 #ifdef HAVE_REMOTE_LCD
 131     /* remote lcd */
 132     lcd_remote_set_contrast,
 133     lcd_remote_clear_display,
 134     lcd_remote_puts,
 135     lcd_remote_puts_scroll,
 136     lcd_remote_stop_scroll,
 137     lcd_remote_set_drawmode,
 138     lcd_remote_get_drawmode,
 139     lcd_remote_setfont,
 140     lcd_remote_getstringsize,
 141     lcd_remote_drawpixel,
 142     lcd_remote_drawline,
 143     lcd_remote_hline,
 144     lcd_remote_vline,
 145     lcd_remote_drawrect,
 146     lcd_remote_fillrect,
 147     lcd_remote_mono_bitmap_part,
 148     lcd_remote_mono_bitmap,
 149     lcd_remote_putsxy,
 150     lcd_remote_puts_style,
 151     lcd_remote_puts_scroll_style,
 152     &lcd_remote_framebuffer[0][0],
 153     lcd_remote_update,
 154     lcd_remote_update_rect,
 155
 156     remote_backlight_on,
 157     remote_backlight_off,
 158 #endif
 159 #if NB_SCREENS == 2
 160     {&screens[SCREEN_MAIN], &screens[SCREEN_REMOTE]},
 161 #else
 162     {&screens[SCREEN_MAIN]},
 163 #endif
 164 #if defined(HAVE_REMOTE_LCD) && (LCD_REMOTE_DEPTH > 1)
 165     lcd_remote_set_foreground,
 166     lcd_remote_get_foreground,
 167     lcd_remote_set_background,
 168     lcd_remote_get_background,
 169     lcd_remote_bitmap_part,
 170     lcd_remote_bitmap,
 171 #endif
 172
 173 #if defined(HAVE_LCD_COLOR) && !defined(SIMULATOR)
 174     lcd_yuv_blit,
 175 #endif
 176     /* list */
 177     gui_synclist_init,
 178     gui_synclist_set_nb_items,
 179     gui_synclist_set_icon_callback,
 180     gui_synclist_get_nb_items,
 181     gui_synclist_get_sel_pos,
 182     gui_synclist_draw,
 183     gui_synclist_select_item,
 184     gui_synclist_add_item,
 185     gui_synclist_del_item,
 186     gui_synclist_limit_scroll,
 187     gui_synclist_flash,
 188     gui_synclist_do_button,
 189     gui_synclist_set_title,
 190
 191     /* button */
 192     button_get,
 193     button_get_w_tmo,
 194     button_status,
 195     button_clear_queue,
 196 #ifdef HAS_BUTTON_HOLD
 197     button_hold,
 198 #endif
 199
 200     /* file */
 201     (open_func)PREFIX(open),
 202     close,
 203     (read_func)read,
 204     PREFIX(lseek),
 205     (creat_func)PREFIX(creat),
 206     (write_func)write,
 207     PREFIX(remove),
 208     PREFIX(rename),
 209     PREFIX(ftruncate),
 210     PREFIX(filesize),
 211     fdprintf,
 212     read_line,
 213     settings_parseline,
 214 #ifndef SIMULATOR
 215     ata_sleep,
 216     ata_disk_is_active,
 217 #endif
 218     ata_spindown,
 219     reload_directory,
 220
 221     /* dir */
 222     PREFIX(opendir),
 223     PREFIX(closedir),
 224     PREFIX(readdir),
 225     PREFIX(mkdir),
 226     PREFIX(rmdir),
 227
 228     /* dir, cached */
 229 #ifdef HAVE_DIRCACHE
 230     opendir_cached,
 231     readdir_cached,
 232     closedir_cached,
 233 #endif
 234
 235     /* kernel/ system */
 236     PREFIX(sleep),
 237     yield,
 238 #ifdef HAVE_PRIORITY_SCHEDULING
 239     priority_yield,
 240 #endif
 241     &current_tick,
 242     default_event_handler,
 243     default_event_handler_ex,
 244     create_thread,
 245     remove_thread,
 246     reset_poweroff_timer,
 247 #ifndef SIMULATOR
 248     system_memory_guard,
 249     &cpu_frequency,
 250
 251 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
 252 #ifdef CPU_BOOST_LOGGING
 253     cpu_boost_,
 254 #else
 255     cpu_boost,
 256 #endif
 257 #endif
 258     timer_register,
 259     timer_unregister,
 260     timer_set_period,
 261 #endif
 262     queue_init,
 263     queue_delete,
 264     queue_post,
 265     queue_wait_w_tmo,
 266     usb_acknowledge,
 267 #ifdef RB_PROFILE
 268     profile_thread,
 269     profstop,
 270     profile_func_enter,
 271     profile_func_exit,
 272 #endif
 273
 274 #ifdef SIMULATOR
 275     /* special simulator hooks */
 276 #if defined(HAVE_LCD_BITMAP) && LCD_DEPTH < 8
 277     sim_lcd_ex_init,
 278     sim_lcd_ex_update_rect,
 279 #endif
 280 #endif
 281
 282     /* strings and memory */
 283     snprintf,
 284     vsnprintf,
 285     strcpy,
 286     strncpy,
 287     strlen,
 288     strrchr,
 289     strcmp,
 290     strncmp,
 291     strcasecmp,
 292     strncasecmp,
 293     memset,
 294     memcpy,
 295     memmove,
 296     _ctype_,
 297     atoi,
 298     strchr,
 299     strcat,
 300     memchr,
 301     memcmp,
 302     strcasestr,
 303     strtok_r,
 304     /* unicode stuff */
 305     utf8decode,
 306     iso_decode,
 307     utf16LEdecode,
 308     utf16BEdecode,
 309     utf8encode,
 310     utf8length,
 311     utf8seek,
 312
 313     /* sound */
 314 #if CONFIG_CODEC == SWCODEC
 315     sound_default,
 316 #endif
 317     sound_set,
 318     set_sound,
 319
 320     sound_min,
 321     sound_max,
 322 #ifndef SIMULATOR
 323     mp3_play_data,
 324     mp3_play_pause,
 325     mp3_play_stop,
 326     mp3_is_playing,
 327 #if CONFIG_CODEC != SWCODEC
 328     bitswap,
 329 #endif
 330 #endif
 331 #if CONFIG_CODEC == SWCODEC
 332     &audio_master_sampr_list[0],
 333     &hw_freq_sampr[0],
 334     pcm_apply_settings,
 335     pcm_play_data,
 336     pcm_play_stop,
 337     pcm_set_frequency,
 338     pcm_is_playing,
 339     pcm_is_paused,
 340     pcm_play_pause,
 341     pcm_get_bytes_waiting,
 342     pcm_calculate_peaks,
 343 #ifdef HAVE_RECORDING
 344     &rec_freq_sampr[0],
 345     pcm_init_recording,
 346     pcm_close_recording,
 347     pcm_record_data,
 348     pcm_record_more,
 349     pcm_stop_recording,
 350     pcm_calculate_rec_peaks,
 351     audio_set_recording_gain,
 352 #endif /* HAVE_RECORDING */
 353 #if INPUT_SRC_CAPS != 0
 354     audio_set_output_source,
 355     audio_set_input_source,
 356 #endif
 357 #endif /* CONFIG_CODEC == SWCODEC */
 358
 359     /* playback control */
 360     playlist_amount,
 361     playlist_resume,
 362     playlist_start,
 363     PREFIX(audio_play),
 364     audio_stop,
 365     audio_pause,
 366     audio_resume,
 367     audio_next,
 368     audio_prev,
 369     audio_ff_rewind,
 370     audio_next_track,
 371     audio_status,
 372     audio_has_changed_track,
 373     audio_current_track,
 374     audio_flush_and_reload_tracks,
 375     audio_get_file_pos,
 376 #if !defined(SIMULATOR) && (CONFIG_CODEC != SWCODEC)
 377     mpeg_get_last_header,
 378 #endif
 379 #if (CONFIG_CODEC == MAS3587F) || (CONFIG_CODEC == MAS3539F) || \
 380     (CONFIG_CODEC == SWCODEC)
 381     sound_set_pitch,
 382 #endif
 383
 384 #if !defined(SIMULATOR) && (CONFIG_CODEC != SWCODEC)
 385     /* MAS communication */
 386     mas_readmem,
 387     mas_writemem,
 388     mas_readreg,
 389     mas_writereg,
 390 #if (CONFIG_CODEC == MAS3587F) || (CONFIG_CODEC == MAS3539F)
 391     mas_codec_writereg,
 392     mas_codec_readreg,
 393     i2c_begin,
 394     i2c_end,
 395     i2c_write,
 396 #endif
 397 #endif /* !SIMULATOR && CONFIG_CODEC != SWCODEC */
 398
 399     /* menu */
 400     do_menu,
 401     /* statusbars */
 402     &statusbars,
 403     gui_syncstatusbar_draw,
 404     /* options */
 405     set_option,
 406     set_int,
 407     set_bool,
 408
 409     /* action handling */
 410     get_custom_action,
 411     get_action,
 412     action_signalscreenchange,
 413     action_userabort,
 414
 415     /* power */
 416     battery_level,
 417     battery_level_safe,
 418     battery_time,
 419 #ifndef SIMULATOR
 420     battery_voltage,
 421 #endif
 422 #if CONFIG_CHARGING
 423     charger_inserted,
 424 # if CONFIG_CHARGING == CHARGING_MONITOR
 425     charging_state,
 426 # endif
 427 #endif
 428 #ifdef HAVE_USB_POWER
 429         usb_powered,
 430 #endif
 431
 432     /* misc */
 433     srand,
 434     rand,
 435     (qsort_func)qsort,
 436     kbd_input,
 437     get_time,
 438     set_time,
 439     plugin_get_buffer,
 440     plugin_get_audio_buffer,
 441     plugin_tsr,
 442 #ifdef IRAM_STEAL
 443     plugin_iram_init,
 444 #endif
 445 #if defined(DEBUG) || defined(SIMULATOR)
 446     debugf,
 447 #endif
 448 #ifdef ROCKBOX_HAS_LOGF
 449     _logf,
 450 #endif
 451     &global_settings,
 452     &global_status,
 453     mp3info,
 454     count_mp3_frames,
 455     create_xing_header,
 456     find_next_frame,
 457 #if (CONFIG_CODEC == MAS3587F) || (CONFIG_CODEC == MAS3539F)
 458     peak_meter_scale_value,
 459     peak_meter_set_use_dbfs,
 460     peak_meter_get_use_dbfs,
 461 #endif
 462 #ifdef HAVE_LCD_BITMAP
 463     read_bmp_file,
 464     screen_dump_set_hook,
 465 #endif
 466     show_logo,
 467     tree_get_context,
 468
 469 #ifdef HAVE_WHEEL_POSITION
 470     wheel_status,
 471     wheel_send_events,
 472 #endif
 473 #if LCD_DEPTH > 1
 474     lcd_get_backdrop,
 475 #endif
 476
 477     /* new stuff at the end, sort into place next time
 478        the API gets incompatible */
 479
 480 #ifdef IRIVER_H100_SERIES
 481     /* Routines for the iriver_flash -plugin. */
 482     detect_original_firmware,
 483     detect_flashed_ramimage,
 484     detect_flashed_romimage,
 485 #endif
 486
 487 #if NUM_CORES > 1
 488     spinlock_init,
 489     spinlock_lock,
 490     spinlock_unlock,
 491 #endif
 492
 493 #if (CONFIG_CODEC == SWCODEC)
 494     codec_load_file,
 495     get_metadata,
 496     get_codec_filename,
 497 #endif
 498     threads,
 499     create_numbered_filename,
 500     set_bool_options,
 501 #ifdef HAVE_LCD_COLOR
 502     set_color,
 503 #endif
 504 };
 505
 506 int plugin_load(const char* plugin, void* parameter)
 507 {
 508     int rc;
 509     struct plugin_header *hdr;
 510     const char *p = strrchr(plugin,'/');
 511 #ifdef SIMULATOR
 512     void *pd;
 513 #else
 514     int fd;
 515     ssize_t readsize;
 516 #endif
 517     int xm, ym;
 518 #ifdef HAVE_REMOTE_LCD
 519     int rxm, rym;
 520 #endif
 521
 522 #if LCD_DEPTH > 1
 523     fb_data* old_backdrop;
 524 #endif
 525
 526     if (!p)
 527         p = plugin;
 528     action_signalscreenchange();
 529
 530     if (pfn_tsr_exit != NULL) /* if we have a resident old plugin: */
 531     {
 532         if (pfn_tsr_exit(!strcmp(current_plugin,p)) == false )
 533         {
 534             /* not allowing another plugin to load */
 535             return PLUGIN_OK;
 536         }
 537         pfn_tsr_exit = NULL;
 538         plugin_loaded = false;
 539     }
 540
 541     gui_syncsplash(0, str(LANG_WAIT));
 542     strcpy(current_plugin,p);
 543
 544 #ifdef SIMULATOR
 545     hdr = sim_plugin_load((char *)plugin, &pd);
 546     if (pd == NULL) {
 547         gui_syncsplash(HZ*2, str(LANG_PLUGIN_CANT_OPEN), plugin);
 548         return -1;
 549     }
 550     if (hdr == NULL
 551         || hdr->magic != PLUGIN_MAGIC
 552         || hdr->target_id != TARGET_ID) {
 553         sim_plugin_close(pd);
 554         gui_syncsplash(HZ*2, str(LANG_PLUGIN_WRONG_MODEL));
 555         return -1;
 556     }
 557     if (hdr->api_version > PLUGIN_API_VERSION
 558         || hdr->api_version < PLUGIN_MIN_API_VERSION) {
 559         sim_plugin_close(pd);
 560         gui_syncsplash(HZ*2, str(LANG_PLUGIN_WRONG_VERSION));
 561         return -1;
 562     }
 563 #else
 564     fd = open(plugin, O_RDONLY);
 565     if (fd < 0) {
 566         gui_syncsplash(HZ*2, str(LANG_PLUGIN_CANT_OPEN), plugin);
 567         return fd;
 568     }
 569
 570     readsize = read(fd, pluginbuf, PLUGIN_BUFFER_SIZE);
 571     close(fd);
 572
 573     if (readsize < 0) {
 574         gui_syncsplash(HZ*2, str(LANG_READ_FAILED), plugin);
 575         return -1;
 576     }
 577     hdr = (struct plugin_header *)pluginbuf;
 578
 579     if ((unsigned)readsize <= sizeof(struct plugin_header)
 580         || hdr->magic != PLUGIN_MAGIC
 581         || hdr->target_id != TARGET_ID
 582         || hdr->load_addr != pluginbuf
 583         || hdr->end_addr > pluginbuf + PLUGIN_BUFFER_SIZE) {
 584         gui_syncsplash(HZ*2, str(LANG_PLUGIN_WRONG_MODEL));
 585         return -1;
 586     }
 587     if (hdr->api_version > PLUGIN_API_VERSION
 588         || hdr->api_version < PLUGIN_MIN_API_VERSION) {
 589         gui_syncsplash(HZ*2, str(LANG_PLUGIN_WRONG_VERSION));
 590         return -1;
 591     }
 592     plugin_size = hdr->end_addr - pluginbuf;
 593
 594     /* zero out bss area only, above guards end of pluginbuf */
 595     if (plugin_size > readsize)
 596         memset(pluginbuf + readsize, 0, plugin_size - readsize);
 597 #endif
 598
 599     plugin_loaded = true;
 600
 601     xm = lcd_getxmargin();
 602     ym = lcd_getymargin();
 603     lcd_setmargins(0,0);
 604
 605 #if defined HAVE_LCD_BITMAP && LCD_DEPTH > 1
 606     old_backdrop = lcd_get_backdrop();
 607 #endif
 608     lcd_clear_display();
 609     lcd_update();
 610
 611 #ifdef HAVE_REMOTE_LCD
 612     rxm = lcd_remote_getxmargin();
 613     rym = lcd_remote_getymargin();
 614     lcd_remote_setmargins(0, 0);
 615     lcd_remote_clear_display();
 616     lcd_remote_update();
 617 #endif
 618
 619     invalidate_icache();
 620
 621     rc = hdr->entry_point((struct plugin_api*) &rockbox_api, parameter);
 622     /* explicitly casting the pointer here to avoid touching every plugin. */
 623
 624     action_signalscreenchange();
 625     button_clear_queue();
 626
 627 #ifdef HAVE_LCD_BITMAP
 628 #if LCD_DEPTH > 1
 629     lcd_set_backdrop(old_backdrop);
 630 #ifdef HAVE_LCD_COLOR
 631     lcd_set_drawinfo(DRMODE_SOLID, global_settings.fg_color,
 632                                    global_settings.bg_color);
 633 #else
 634     lcd_set_drawinfo(DRMODE_SOLID, LCD_DEFAULT_FG, LCD_DEFAULT_BG);
 635 #endif
 636 #else /* LCD_DEPTH == 1 */
 637     lcd_set_drawmode(DRMODE_SOLID);
 638 #endif /* LCD_DEPTH */
 639 #endif /* HAVE_LCD_BITMAP */
 640
 641     /* restore margins */
 642     lcd_setmargins(xm,ym);
 643     lcd_clear_display();
 644     lcd_update();
 645
 646 #ifdef HAVE_REMOTE_LCD
 647 #if LCD_REMOTE_DEPTH > 1
 648     lcd_remote_set_drawinfo(DRMODE_SOLID, LCD_REMOTE_DEFAULT_FG,
 649                             LCD_REMOTE_DEFAULT_BG);
 650 #else
 651     lcd_remote_set_drawmode(DRMODE_SOLID);
 652 #endif
 653     lcd_remote_setmargins(rxm, rym);
 654     lcd_remote_clear_display();
 655     lcd_remote_update();
 656 #endif
 657
 658     if (pfn_tsr_exit == NULL)
 659         plugin_loaded = false;
 660
 661     sim_plugin_close(pd);
 662
 663     switch (rc) {
 664         case PLUGIN_OK:
 665             break;
 666
 667         case PLUGIN_USB_CONNECTED:
 668             return PLUGIN_USB_CONNECTED;
 669
 670         default:
 671             gui_syncsplash(HZ*2, str(LANG_PLUGIN_ERROR));
 672             break;
 673     }
 674     return PLUGIN_OK;
 675 }
 676
 677 /* Returns a pointer to the portion of the plugin buffer that is not already
 678    being used.  If no plugin is loaded, returns the entire plugin buffer */
 679 void* plugin_get_buffer(size_t *buffer_size)
 680 {
 681     int buffer_pos;
 682
 683     if (plugin_loaded)
 684     {
 685         if (plugin_size >= PLUGIN_BUFFER_SIZE)
 686             return NULL;
 687
 688         *buffer_size = PLUGIN_BUFFER_SIZE-plugin_size;
 689         buffer_pos = plugin_size;
 690     }
 691     else
 692     {
 693         *buffer_size = PLUGIN_BUFFER_SIZE;
 694         buffer_pos = 0;
 695     }
 696
 697     return &pluginbuf[buffer_pos];
 698 }
 699
 700 /* Returns a pointer to the mp3 buffer.
 701    Playback gets stopped, to avoid conflicts.
 702    Talk buffer is stolen as well.
 703  */
 704 void* plugin_get_audio_buffer(size_t *buffer_size)
 705 {
 706 #if CONFIG_CODEC == SWCODEC
 707     return audio_get_buffer(true, buffer_size);
 708 #else
 709     audio_stop();
 710     talk_buffer_steal(); /* we use the mp3 buffer, need to tell */
 711     *buffer_size = audiobufend - audiobuf;
 712     return audiobuf;
 713 #endif
 714 }
 715
 716 #ifdef IRAM_STEAL
 717 /* Initializes plugin IRAM */
 718 void plugin_iram_init(char *iramstart, char *iramcopy, size_t iram_size,
 719                       char *iedata, size_t iedata_size)
 720 {
 721     audio_iram_steal();
 722     memcpy(iramstart, iramcopy, iram_size);
 723     memset(iedata, 0, iedata_size);
 724     memset(iramcopy, 0, iram_size);
 725 }
 726 #endif /* IRAM_STEAL */
 727
 728 /* The plugin wants to stay resident after leaving its main function, e.g.
 729    runs from timer or own thread. The callback is registered to later
 730    instruct it to free its resources before a new plugin gets loaded. */
 731 void plugin_tsr(bool (*exit_callback)(bool))
 732 {
 733     pfn_tsr_exit = exit_callback; /* remember the callback for later */
 734 }