stream/stream.c

   1 /*
   2  * This file is part of MPlayer.
   3  *
   4  * MPlayer is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * MPlayer is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #ifndef __MINGW32__
  26 #include <sys/ioctl.h>
  27 #include <sys/wait.h>
  28 #endif
  29 #include <fcntl.h>
  30 #include <strings.h>
  31
  32 #include "config.h"
  33
  34 #if HAVE_WINSOCK2_H
  35 #include <winsock2.h>
  36 #endif
  37
  38 #include <libavutil/common.h>
  39
  40 #include "mp_msg.h"
  41 #include "osdep/shmem.h"
  42 #include "osdep/timer.h"
  43 #include "network.h"
  44 #include "stream.h"
  45 #include "libmpdemux/demuxer.h"
  46 #include "ffmpeg_files/intreadwrite.h"
  47
  48 #include "m_option.h"
  49 #include "m_struct.h"
  50
  51 #include "cache2.h"
  52
  53 struct input_ctx;
  54 static int (*stream_check_interrupt_cb)(struct input_ctx *ctx, int time);
  55 static struct input_ctx *stream_check_interrupt_ctx;
  56
  57 extern const stream_info_t stream_info_vcd;
  58 extern const stream_info_t stream_info_cdda;
  59 extern const stream_info_t stream_info_netstream;
  60 extern const stream_info_t stream_info_pnm;
  61 extern const stream_info_t stream_info_asf;
  62 extern const stream_info_t stream_info_rtsp;
  63 extern const stream_info_t stream_info_rtp;
  64 extern const stream_info_t stream_info_udp;
  65 extern const stream_info_t stream_info_http1;
  66 extern const stream_info_t stream_info_http2;
  67 extern const stream_info_t stream_info_dvb;
  68 extern const stream_info_t stream_info_tv;
  69 extern const stream_info_t stream_info_radio;
  70 extern const stream_info_t stream_info_pvr;
  71 extern const stream_info_t stream_info_ftp;
  72 extern const stream_info_t stream_info_vstream;
  73 extern const stream_info_t stream_info_dvdnav;
  74 extern const stream_info_t stream_info_smb;
  75 extern const stream_info_t stream_info_sdp;
  76 extern const stream_info_t stream_info_rtsp_sip;
  77
  78 extern const stream_info_t stream_info_cue;
  79 extern const stream_info_t stream_info_null;
  80 extern const stream_info_t stream_info_mf;
  81 extern const stream_info_t stream_info_ffmpeg;
  82 extern const stream_info_t stream_info_file;
  83 extern const stream_info_t stream_info_ifo;
  84 extern const stream_info_t stream_info_dvd;
  85 extern const stream_info_t stream_info_bluray;
  86
  87 static const stream_info_t* const auto_open_streams[] = {
  88 #ifdef CONFIG_VCD
  89   &stream_info_vcd,
  90 #endif
  91 #ifdef CONFIG_CDDA
  92   &stream_info_cdda,
  93 #endif
  94 #ifdef CONFIG_NETWORKING
  95   &stream_info_netstream,
  96   &stream_info_http1,
  97   &stream_info_asf,
  98   &stream_info_pnm,
  99   &stream_info_rtsp,
 100 #ifdef CONFIG_LIVE555
 101   &stream_info_sdp,
 102   &stream_info_rtsp_sip,
 103 #endif
 104   &stream_info_rtp,
 105   &stream_info_udp,
 106   &stream_info_http2,
 107 #endif
 108 #ifdef CONFIG_DVBIN
 109   &stream_info_dvb,
 110 #endif
 111 #ifdef CONFIG_TV
 112   &stream_info_tv,
 113 #endif
 114 #ifdef CONFIG_RADIO
 115   &stream_info_radio,
 116 #endif
 117 #ifdef CONFIG_PVR
 118   &stream_info_pvr,
 119 #endif
 120 #ifdef CONFIG_FTP
 121   &stream_info_ftp,
 122 #endif
 123 #ifdef CONFIG_VSTREAM
 124   &stream_info_vstream,
 125 #endif
 126 #ifdef CONFIG_LIBSMBCLIENT
 127   &stream_info_smb,
 128 #endif
 129   &stream_info_cue,
 130 #ifdef CONFIG_DVDREAD
 131   &stream_info_ifo,
 132   &stream_info_dvd,
 133 #endif
 134 #ifdef CONFIG_DVDNAV
 135   &stream_info_dvdnav,
 136 #endif
 137 #ifdef CONFIG_LIBBLURAY
 138   &stream_info_bluray,
 139 #endif
 140 #ifdef CONFIG_FFMPEG
 141   &stream_info_ffmpeg,
 142 #endif
 143
 144   &stream_info_null,
 145   &stream_info_mf,
 146   &stream_info_file,
 147   NULL
 148 };
 149
 150 static stream_t *open_stream_plugin(const stream_info_t *sinfo,
 151                                     const char *filename,
 152                                     int mode, struct MPOpts *options,
 153                                     int *file_format, int *ret,
 154                                     char **redirected_url)
 155 {
 156   void* arg = NULL;
 157   stream_t* s;
 158   m_struct_t* desc = (m_struct_t*)sinfo->opts;
 159
 160   // Parse options
 161   if(desc) {
 162     arg = m_struct_alloc(desc);
 163     if(sinfo->opts_url) {
 164       m_option_t url_opt =
 165         { "stream url", arg , CONF_TYPE_CUSTOM_URL, 0, 0 ,0, sinfo->opts };
 166       if(m_option_parse(&url_opt,"stream url",filename,arg,M_CONFIG_FILE) < 0) {
 167         mp_msg(MSGT_OPEN,MSGL_ERR, "URL parsing failed on url %s\n",filename);
 168         m_struct_free(desc,arg);
 169         return NULL;
 170       }
 171     }
 172   }
 173   s = new_stream(-2,-2);
 174   s->opts = options;
 175   s->url=strdup(filename);
 176   s->flags |= mode;
 177   *ret = sinfo->open(s,mode,arg,file_format);
 178   if((*ret) != STREAM_OK) {
 179 #ifdef CONFIG_NETWORKING
 180     if (*ret == STREAM_REDIRECTED && redirected_url) {
 181         if (s->streaming_ctrl && s->streaming_ctrl->url
 182             && s->streaming_ctrl->url->url)
 183           *redirected_url = strdup(s->streaming_ctrl->url->url);
 184         else
 185           *redirected_url = NULL;
 186     }
 187     streaming_ctrl_free(s->streaming_ctrl);
 188 #endif
 189     free(s->url);
 190     free(s);
 191     return NULL;
 192   }
 193   if(s->type <= -2)
 194     mp_msg(MSGT_OPEN,MSGL_WARN, "Warning streams need a type !!!!\n");
 195   if(s->flags & MP_STREAM_SEEK && !s->seek)
 196     s->flags &= ~MP_STREAM_SEEK;
 197   if(s->seek && !(s->flags & MP_STREAM_SEEK))
 198     s->flags |= MP_STREAM_SEEK;
 199
 200   s->mode = mode;
 201
 202   mp_msg(MSGT_OPEN,MSGL_V, "STREAM: [%s] %s\n",sinfo->name,filename);
 203   mp_msg(MSGT_OPEN,MSGL_V, "STREAM: Description: %s\n",sinfo->info);
 204   mp_msg(MSGT_OPEN,MSGL_V, "STREAM: Author: %s\n", sinfo->author);
 205   mp_msg(MSGT_OPEN,MSGL_V, "STREAM: Comment: %s\n", sinfo->comment);
 206
 207   return s;
 208 }
 209
 210
 211 stream_t *open_stream_full(const char *filename, int mode,
 212                            struct MPOpts *options, int *file_format)
 213 {
 214   int i,j,l,r;
 215   const stream_info_t* sinfo;
 216   stream_t* s;
 217   char *redirected_url = NULL;
 218
 219   for(i = 0 ; auto_open_streams[i] ; i++) {
 220     sinfo = auto_open_streams[i];
 221     if(!sinfo->protocols) {
 222       mp_msg(MSGT_OPEN,MSGL_WARN, "Stream type %s has protocols == NULL, it's a bug\n", sinfo->name);
 223       continue;
 224     }
 225     for(j = 0 ; sinfo->protocols[j] ; j++) {
 226       l = strlen(sinfo->protocols[j]);
 227       // l == 0 => Don't do protocol matching (ie network and filenames)
 228       if((l == 0 && !strstr(filename, "://")) ||
 229          ((strncasecmp(sinfo->protocols[j],filename,l) == 0) &&
 230                       (strncmp("://",filename+l,3) == 0))) {
 231         *file_format = DEMUXER_TYPE_UNKNOWN;
 232         s = open_stream_plugin(sinfo,filename,mode,options,file_format,&r,
 233                                 &redirected_url);
 234         if(s) return s;
 235         if(r == STREAM_REDIRECTED && redirected_url) {
 236           mp_msg(MSGT_OPEN,MSGL_V, "[%s] open %s redirected to %s\n",
 237                  sinfo->info, filename, redirected_url);
 238           s = open_stream_full(redirected_url, mode, options, file_format);
 239           free(redirected_url);
 240           return s;
 241         }
 242         else if(r != STREAM_UNSUPPORTED) {
 243           mp_tmsg(MSGT_OPEN,MSGL_ERR, "Failed to open %s.\n",filename);
 244           return NULL;
 245         }
 246         break;
 247       }
 248     }
 249   }
 250
 251   mp_msg(MSGT_OPEN,MSGL_ERR, "No stream found to handle url %s\n",filename);
 252   return NULL;
 253 }
 254
 255 stream_t *open_output_stream(const char *filename, struct MPOpts *options)
 256 {
 257   int file_format; //unused
 258   if(!filename) {
 259     mp_msg(MSGT_OPEN,MSGL_ERR,"open_output_stream(), NULL filename, report this bug\n");
 260     return NULL;
 261   }
 262
 263   return open_stream_full(filename,STREAM_WRITE,options,&file_format);
 264 }
 265
 266 //=================== STREAMER =========================
 267
 268 void stream_capture_do(stream_t *s)
 269 {
 270   if (fwrite(s->buffer, s->buf_len, 1, s->capture_file) < 1) {
 271     mp_tmsg(MSGT_GLOBAL, MSGL_ERR, "Error writing capture file: %s\n",
 272             strerror(errno));
 273     fclose(s->capture_file);
 274     s->capture_file = NULL;
 275   }
 276 }
 277
 278 int stream_fill_buffer(stream_t *s){
 279   int len;
 280   // we will retry even if we already reached EOF previously.
 281   switch(s->type){
 282   case STREAMTYPE_STREAM:
 283 #ifdef CONFIG_NETWORKING
 284     if( s->streaming_ctrl!=NULL && s->streaming_ctrl->streaming_read ) {
 285             len=s->streaming_ctrl->streaming_read(s->fd,s->buffer,STREAM_BUFFER_SIZE, s->streaming_ctrl);
 286     } else
 287 #endif
 288     if (s->fill_buffer)
 289       len = s->fill_buffer(s, s->buffer, STREAM_BUFFER_SIZE);
 290     else
 291       len=read(s->fd,s->buffer,STREAM_BUFFER_SIZE);
 292     break;
 293   case STREAMTYPE_DS:
 294     len = demux_read_data((demux_stream_t*)s->priv,s->buffer,STREAM_BUFFER_SIZE);
 295     break;
 296
 297
 298   default:
 299     len= s->fill_buffer ? s->fill_buffer(s,s->buffer,STREAM_BUFFER_SIZE) : 0;
 300   }
 301   if(len<=0){ s->eof=1; return 0; }
 302   // When reading succeeded we are obviously not at eof.
 303   // This e.g. avoids issues with eof getting stuck when lavf seeks in MPEG-TS
 304   s->eof=0;
 305   s->buf_pos=0;
 306   s->buf_len=len;
 307   s->pos+=len;
 308 //  printf("[%d]",len);fflush(stdout);
 309   if (s->capture_file)
 310     stream_capture_do(s);
 311   return len;
 312 }
 313
 314 int stream_write_buffer(stream_t *s, unsigned char *buf, int len) {
 315   int rd;
 316   if(!s->write_buffer)
 317     return -1;
 318   rd = s->write_buffer(s, buf, len);
 319   if(rd < 0)
 320     return -1;
 321   s->pos += rd;
 322   return rd;
 323 }
 324
 325 int stream_seek_long(stream_t *s,off_t pos){
 326 off_t newpos=0;
 327
 328 //  if( mp_msg_test(MSGT_STREAM,MSGL_DBG3) ) printf("seek_long to 0x%X\n",(unsigned int)pos);
 329
 330   s->buf_pos=s->buf_len=0;
 331
 332   if(s->mode == STREAM_WRITE) {
 333     if(!s->seek || !s->seek(s,pos))
 334       return 0;
 335     return 1;
 336   }
 337
 338   if(s->sector_size)
 339       newpos = (pos/s->sector_size)*s->sector_size;
 340   else
 341       newpos = pos&(~((off_t)STREAM_BUFFER_SIZE-1));
 342
 343 if( mp_msg_test(MSGT_STREAM,MSGL_DBG3) ){
 344   mp_msg(MSGT_STREAM,MSGL_DBG3, "s->pos=%"PRIX64"  newpos=%"PRIX64"  new_bufpos=%"PRIX64"  buflen=%X  \n",
 345     (int64_t)s->pos,(int64_t)newpos,(int64_t)pos,s->buf_len);
 346 }
 347   pos-=newpos;
 348
 349 if(newpos==0 || newpos!=s->pos){
 350   switch(s->type){
 351   case STREAMTYPE_STREAM:
 352     //s->pos=newpos; // real seek
 353     // Some streaming protocol allow to seek backward and forward
 354     // A function call that return -1 can tell that the protocol
 355     // doesn't support seeking.
 356 #ifdef CONFIG_NETWORKING
 357     if(s->seek) { // new stream seek is much cleaner than streaming_ctrl one
 358       if(!s->seek(s,newpos)) {
 359         mp_msg(MSGT_STREAM,MSGL_ERR, "Seek failed\n");
 360         return 0;
 361       }
 362       break;
 363     }
 364
 365     if( s->streaming_ctrl!=NULL && s->streaming_ctrl->streaming_seek ) {
 366       if( s->streaming_ctrl->streaming_seek( s->fd, pos, s->streaming_ctrl )<0 ) {
 367         mp_msg(MSGT_STREAM,MSGL_INFO,"Stream not seekable!\n");
 368         return 1;
 369       }
 370       break;
 371     }
 372 #endif
 373     if(newpos<s->pos){
 374       mp_msg(MSGT_STREAM,MSGL_INFO,"Cannot seek backward in linear streams!\n");
 375       return 1;
 376     }
 377     while(s->pos<newpos){
 378       if(stream_fill_buffer(s)<=0) break; // EOF
 379     }
 380     break;
 381   default:
 382     // This should at the beginning as soon as all streams are converted
 383     if(!s->seek)
 384       return 0;
 385     // Now seek
 386     if(!s->seek(s,newpos)) {
 387       mp_msg(MSGT_STREAM,MSGL_ERR, "Seek failed\n");
 388       return 0;
 389     }
 390   }
 391 //   putchar('.');fflush(stdout);
 392 //} else {
 393 //   putchar('%');fflush(stdout);
 394 }
 395
 396 s->eof = 0; // EOF reset when seek succeeds.
 397 while (stream_fill_buffer(s) > 0) {
 398   if(pos<=s->buf_len){
 399     s->buf_pos=pos; // byte position in sector
 400     return 1;
 401   }
 402   pos -= s->buf_len;
 403 }
 404 // Fill failed, but seek still is a success.
 405 s->pos += pos;
 406 s->buf_pos = 0;
 407 s->buf_len = 0;
 408
 409 mp_msg(MSGT_STREAM,MSGL_V,
 410        "stream_seek: Seek to/past EOF: no buffer preloaded.\n");
 411 return 1;
 412 }
 413
 414
 415 void stream_reset(stream_t *s){
 416   if(s->eof){
 417     s->pos=0;
 418     s->buf_pos=s->buf_len=0;
 419     s->eof=0;
 420   }
 421   if(s->control) s->control(s,STREAM_CTRL_RESET,NULL);
 422   //stream_seek(s,0);
 423 }
 424
 425 int stream_control(stream_t *s, int cmd, void *arg){
 426   if(!s->control) return STREAM_UNSUPPORTED;
 427 #ifdef CONFIG_STREAM_CACHE
 428   if (s->cache_pid)
 429     return cache_do_control(s, cmd, arg);
 430 #endif
 431   return s->control(s, cmd, arg);
 432 }
 433
 434 stream_t* new_memory_stream(unsigned char* data,int len){
 435   stream_t *s;
 436
 437   if(len < 0)
 438     return NULL;
 439   s=calloc(1, sizeof(stream_t)+len);
 440   s->fd=-1;
 441   s->type=STREAMTYPE_MEMORY;
 442   s->buf_pos=0; s->buf_len=len;
 443   s->start_pos=0; s->end_pos=len;
 444   stream_reset(s);
 445   s->pos=len;
 446   memcpy(s->buffer,data,len);
 447   return s;
 448 }
 449
 450 stream_t* new_stream(int fd,int type){
 451   stream_t *s=calloc(1, sizeof(stream_t));
 452   if(s==NULL) return NULL;
 453
 454 #if HAVE_WINSOCK2_H
 455   {
 456     WSADATA wsdata;
 457     int temp = WSAStartup(0x0202, &wsdata); // there might be a better place for this (-> later)
 458     mp_msg(MSGT_STREAM,MSGL_V,"WINSOCK2 init: %i\n", temp);
 459   }
 460 #endif
 461
 462   s->fd=fd;
 463   s->type=type;
 464   s->buf_pos=s->buf_len=0;
 465   s->start_pos=s->end_pos=0;
 466   s->priv=NULL;
 467   s->url=NULL;
 468   s->cache_pid=0;
 469   stream_reset(s);
 470   return s;
 471 }
 472
 473 void free_stream(stream_t *s){
 474 //  printf("\n*** free_stream() called ***\n");
 475 #ifdef CONFIG_STREAM_CACHE
 476     cache_uninit(s);
 477 #endif
 478   if (s->capture_file) {
 479     fclose(s->capture_file);
 480     s->capture_file = NULL;
 481   }
 482
 483   if(s->close) s->close(s);
 484   if(s->fd>0){
 485     /* on unix we define closesocket to close
 486        on windows however we have to distinguish between
 487        network socket and file */
 488     if(s->url && strstr(s->url,"://"))
 489       closesocket(s->fd);
 490     else close(s->fd);
 491   }
 492 #if HAVE_WINSOCK2_H
 493   mp_msg(MSGT_STREAM,MSGL_V,"WINSOCK2 uninit\n");
 494   WSACleanup(); // there might be a better place for this (-> later)
 495 #endif
 496   // Disabled atm, i don't like that. s->priv can be anything after all
 497   // streams should destroy their priv on close
 498   //if(s->priv) free(s->priv);
 499   if(s->url) free(s->url);
 500   free(s);
 501 }
 502
 503 stream_t* new_ds_stream(demux_stream_t *ds) {
 504   stream_t* s = new_stream(-1,STREAMTYPE_DS);
 505   s->priv = ds;
 506   return s;
 507 }
 508
 509 void stream_set_interrupt_callback(int (*cb)(struct input_ctx *, int),
 510                                    struct input_ctx *ctx)
 511 {
 512     stream_check_interrupt_cb = cb;
 513     stream_check_interrupt_ctx = ctx;
 514 }
 515
 516 int stream_check_interrupt(int time) {
 517     if(!stream_check_interrupt_cb) {
 518         usec_sleep(time * 1000);
 519         return 0;
 520     }
 521     return stream_check_interrupt_cb(stream_check_interrupt_ctx, time);
 522 }
 523
 524 /**
 525  * Helper function to read 16 bits little-endian and advance pointer
 526  */
 527 static uint16_t get_le16_inc(const uint8_t **buf)
 528 {
 529   uint16_t v = AV_RL16(*buf);
 530   *buf += 2;
 531   return v;
 532 }
 533
 534 /**
 535  * Helper function to read 16 bits big-endian and advance pointer
 536  */
 537 static uint16_t get_be16_inc(const uint8_t **buf)
 538 {
 539   uint16_t v = AV_RB16(*buf);
 540   *buf += 2;
 541   return v;
 542 }
 543
 544 /**
 545  * Find a newline character in buffer
 546  * \param buf buffer to search
 547  * \param len amount of bytes to search in buffer, may not overread
 548  * \param utf16 chose between UTF-8/ASCII/other and LE and BE UTF-16
 549  *              0 = UTF-8/ASCII/other, 1 = UTF-16-LE, 2 = UTF-16-BE
 550  */
 551 static const uint8_t *find_newline(const uint8_t *buf, int len, int utf16)
 552 {
 553   uint32_t c;
 554   const uint8_t *end = buf + len;
 555   switch (utf16) {
 556   case 0:
 557     return (uint8_t *)memchr(buf, '\n', len);
 558   case 1:
 559     while (buf < end - 1) {
 560       GET_UTF16(c, buf < end - 1 ? get_le16_inc(&buf) : 0, return NULL;)
 561       if (buf <= end && c == '\n')
 562         return buf - 1;
 563     }
 564     break;
 565   case 2:
 566     while (buf < end - 1) {
 567       GET_UTF16(c, buf < end - 1 ? get_be16_inc(&buf) : 0, return NULL;)
 568       if (buf <= end && c == '\n')
 569         return buf - 1;
 570     }
 571     break;
 572   }
 573   return NULL;
 574 }
 575
 576 /**
 577  * Copy a number of bytes, converting to UTF-8 if input is UTF-16
 578  * \param dst buffer to copy to
 579  * \param dstsize size of dst buffer
 580  * \param src buffer to copy from
 581  * \param len amount of bytes to copy from src
 582  * \param utf16 chose between UTF-8/ASCII/other and LE and BE UTF-16
 583  *              0 = UTF-8/ASCII/other, 1 = UTF-16-LE, 2 = UTF-16-BE
 584  */
 585 static int copy_characters(uint8_t *dst, int dstsize,
 586                            const uint8_t *src, int *len, int utf16)
 587 {
 588   uint32_t c;
 589   uint8_t *dst_end = dst + dstsize;
 590   const uint8_t *end = src + *len;
 591   switch (utf16) {
 592   case 0:
 593     if (*len > dstsize)
 594       *len = dstsize;
 595     memcpy(dst, src, *len);
 596     return *len;
 597   case 1:
 598     while (src < end - 1 && dst_end - dst > 8) {
 599       uint8_t tmp;
 600       GET_UTF16(c, src < end - 1 ? get_le16_inc(&src) : 0, ;)
 601       PUT_UTF8(c, tmp, *dst++ = tmp;)
 602     }
 603     *len -= end - src;
 604     return dstsize - (dst_end - dst);
 605   case 2:
 606     while (src < end - 1 && dst_end - dst > 8) {
 607       uint8_t tmp;
 608       GET_UTF16(c, src < end - 1 ? get_be16_inc(&src) : 0, ;)
 609       PUT_UTF8(c, tmp, *dst++ = tmp;)
 610     }
 611     *len -= end - src;
 612     return dstsize - (dst_end - dst);
 613   }
 614   return 0;
 615 }
 616
 617 unsigned char* stream_read_line(stream_t *s,unsigned char* mem, int max, int utf16) {
 618   int len;
 619   const unsigned char *end;
 620   unsigned char *ptr = mem;
 621   if (max < 1) return NULL;
 622   max--; // reserve one for 0-termination
 623   do {
 624     len = s->buf_len-s->buf_pos;
 625     // try to fill the buffer
 626     if(len <= 0 &&
 627        (!cache_stream_fill_buffer(s) ||
 628         (len = s->buf_len-s->buf_pos) <= 0)) break;
 629     end = find_newline(s->buffer+s->buf_pos, len, utf16);
 630     if(end) len = end - (s->buffer+s->buf_pos) + 1;
 631     if(len > 0 && max > 0) {
 632       int l = copy_characters(ptr, max, s->buffer+s->buf_pos, &len, utf16);
 633       max -= l;
 634       ptr += l;
 635       if (!len)
 636         break;
 637     }
 638     s->buf_pos += len;
 639   } while(!end);
 640   ptr[0] = 0;
 641   if(s->eof && ptr == mem) return NULL;
 642   return mem;
 643 }