/* TODO: Check all read calls (in loops, especially!) for return value 0 (EOF)! */

/*
	readers.c: reading input data

	copyright ?-2008 by the mpg123 project - free software under the terms of the LGPL 2.1
	see COPYING and AUTHORS files in distribution or http://mpg123.org
	initially written by Michael Hipp
*/

#include "mpg123lib_intern.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
/* For select(), I need select.h according to POSIX 2001, else: sys/time.h sys/types.h unistd.h */
/* Including these here although it works without on my Linux install... curious about _why_. */
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef _MSC_VER
#include <io.h>
#endif

#include "debug.h"

static int default_init(mpg123_handle *fr);
static off_t get_fileinfo(mpg123_handle *);
static ssize_t posix_read(int fd, void *buf, size_t count){ return read(fd, buf, count); }
static off_t   posix_lseek(int fd, off_t offset, int whence){ return lseek(fd, offset, whence); }

static ssize_t plain_fullread(mpg123_handle *fr,unsigned char *buf, ssize_t count);

/* Bufferchain methods. */
static void bc_init(struct bufferchain *bc);
static void bc_reset(struct bufferchain *bc);
static int bc_append(struct bufferchain *bc, ssize_t size);
#if 0
static void bc_drop(struct bufferchain *bc);
#endif
static int bc_add(struct bufferchain *bc, const unsigned char *data, ssize_t size);
static ssize_t bc_give(struct bufferchain *bc, unsigned char *out, size_t size);
static ssize_t bc_skip(struct bufferchain *bc, ssize_t count);
static ssize_t bc_seekback(struct bufferchain *bc, ssize_t count);
static void bc_forget(struct bufferchain *bc);

/* A normal read and a read with timeout. */
static ssize_t plain_read(mpg123_handle *fr, void *buf, size_t count)
{
	ssize_t ret = fr->rdat.read(fr->rdat.filept, buf, count);
	if(VERBOSE3) debug2("read %li bytes of %li", (long)ret, (long)count);
	return ret;
}
#ifndef WIN32

/* Wait for data becoming available, allowing soft-broken network connection to die
   This is needed for Shoutcast servers that have forgotten about us while connection was temporarily down. */
static ssize_t timeout_read(mpg123_handle *fr, void *buf, size_t count)
{
	struct timeval tv;
	ssize_t ret = 0;
	fd_set fds;
	tv.tv_sec = fr->rdat.timeout_sec;
	tv.tv_usec = 0;
	FD_ZERO(&fds);
	FD_SET(fr->rdat.filept, &fds);
	ret = select(fr->rdat.filept+1, &fds, NULL, NULL, &tv);
	/* This works only with "my" read function. Not user-replaced. */
	if(ret > 0) ret = read(fr->rdat.filept, buf, count);
	else
	{
		ret=-1; /* no activity is the error */
		if(NOQUIET) error("stream timed out");
	}
	return ret;
}
#endif

/* stream based operation  with icy meta data*/
static ssize_t icy_fullread(mpg123_handle *fr, unsigned char *buf, ssize_t count)
{
	ssize_t ret,cnt;
	cnt = 0;
	if(fr->rdat.flags & READER_SEEKABLE)
	{
		if(NOQUIET) error("mpg123 programmer error: I don't do ICY on seekable streams.");
		return -1;
	}
	/*
		We check against READER_ID3TAG instead of rds->filelen >= 0 because if we got the ID3 TAG we know we have the end of the file.
		If we don't have an ID3 TAG, then it is possible the file has grown since we started playing, so we want to keep reading from it if possible.
	*/
	if((fr->rdat.flags & READER_ID3TAG) && fr->rdat.filepos + count > fr->rdat.filelen) count = fr->rdat.filelen - fr->rdat.filepos;

	while(cnt < count)
	{
		/* all icy code is inside this if block, everything else is the plain fullread we know */
		/* debug1("read: %li left", (long) count-cnt); */
		if(fr->icy.next < count-cnt)
		{
			unsigned char temp_buff;
			size_t meta_size;
			ssize_t cut_pos;

			/* we are near icy-metaint boundary, read up to the boundary */
			if(fr->icy.next > 0)
			{
				cut_pos = fr->icy.next;
				ret = fr->rdat.fdread(fr,buf,cut_pos);
				if(ret < 1)
				{
					if(ret == 0) break; /* Just EOF. */
					if(NOQUIET) error("icy boundary read");

					return READER_ERROR;
				}
				fr->rdat.filepos += ret;
				cnt += ret;
				fr->icy.next -= ret;
				if(fr->icy.next > 0)
				{
					debug1("another try... still %li left", (long)fr->icy.next);
					continue;
				}
			}
			/* now off to read icy data */

			/* one byte icy-meta size (must be multiplied by 16 to get icy-meta length) */
			
			ret = fr->rdat.fdread(fr,&temp_buff,1); /* Getting one single byte hast to suceed. */
			if(ret < 0){ if(NOQUIET) error("reading icy size"); return READER_ERROR; }
			if(ret == 0) break;

			debug2("got meta-size byte: %u, at filepos %li", temp_buff, (long)fr->rdat.filepos );
			if(!(fr->rdat.flags & READER_BUFFERED)) fr->rdat.filepos += ret; /* 1... */

			if((meta_size = ((size_t) temp_buff) * 16))
			{
				/* we have got some metadata */
				char *meta_buff;
				meta_buff = malloc(meta_size+1);
				if(meta_buff != NULL)
				{
					ssize_t left = meta_size;
					while(left > 0)
					{
						ret = fr->rdat.fdread(fr,meta_buff+meta_size-left,left);
						/* 0 is error here, too... there _must_ be the ICY data, the server promised! */
						if(ret < 1){ if(NOQUIET) error("reading icy-meta"); return READER_ERROR; }
						left -= ret;
					}
					meta_buff[meta_size] = 0; /* string paranoia */
					if(!(fr->rdat.flags & READER_BUFFERED)) fr->rdat.filepos += ret;

					if(fr->icy.data) free(fr->icy.data);
					fr->icy.data = meta_buff;
					fr->metaflags |= MPG123_NEW_ICY;
					debug2("icy-meta: %s size: %d bytes", fr->icy.data, (int)meta_size);
				}
				else
				{
					if(NOQUIET) error1("cannot allocate memory for meta_buff (%lu bytes) ... trying to skip the metadata!", (unsigned long)meta_size);
					fr->rd->skip_bytes(fr, meta_size);
				}
			}
			fr->icy.next = fr->icy.interval;
		}

		ret = plain_fullread(fr, buf+cnt, count-cnt);
		if(ret < 0){ if(NOQUIET) error1("reading the rest of %li", (long)(count-cnt)); return READER_ERROR; }
		if(ret == 0) break;

		cnt += ret;
		fr->icy.next -= ret;
	}
	/* debug1("done reading, got %li", (long)cnt); */
	return cnt;
}

/* stream based operation */
static ssize_t plain_fullread(mpg123_handle *fr,unsigned char *buf, ssize_t count)
{
	ssize_t ret,cnt=0;

	/*
		We check against READER_ID3TAG instead of rds->filelen >= 0 because if we got the ID3 TAG we know we have the end of the file.
		If we don't have an ID3 TAG, then it is possible the file has grown since we started playing, so we want to keep reading from it if possible.
	*/
	if((fr->rdat.flags & READER_ID3TAG) && fr->rdat.filepos + count > fr->rdat.filelen) count = fr->rdat.filelen - fr->rdat.filepos;
	while(cnt < count)
	{
		ret = fr->rdat.fdread(fr,buf+cnt,count-cnt);
		if(ret < 0) return READER_ERROR;
		if(ret == 0) break;
		if(!(fr->rdat.flags & READER_BUFFERED)) fr->rdat.filepos += ret;
		cnt += ret;
	}
	return cnt;
}

static off_t stream_lseek(mpg123_handle *fr, off_t pos, int whence)
{
	off_t ret;
	ret = fr->rdat.lseek(fr->rdat.filept, pos, whence);
	if (ret >= 0)	fr->rdat.filepos = ret;
	else ret = READER_ERROR; /* not the original value */
	return ret;
}

static void stream_close(mpg123_handle *fr)
{
	if(fr->rdat.flags & READER_FD_OPENED) close(fr->rdat.filept);
	if(fr->rdat.flags & READER_BUFFERED)  bc_reset(&fr->rdat.buffer);
}

static int stream_seek_frame(mpg123_handle *fr, off_t newframe)
{
	if(fr->rdat.flags & READER_SEEKABLE)
	{
		off_t preframe;

		/* two leading frames? hm, doesn't seem to be really needed... */
		/*if(newframe > 1) newframe -= 2;
		else newframe = 0;*/

		/* now seek to nearest leading index position and read from there until newframe is reached */
		if(stream_lseek(fr,frame_index_find(fr, newframe, &preframe),SEEK_SET) < 0)
		return READER_ERROR;
		debug2("going to %lu; just got %lu", (long unsigned)newframe, (long unsigned)preframe);
		fr->num = preframe-1; /* Watch out! I am going to read preframe... fr->num should indicate the frame before! */
		while(fr->num < newframe)
		{
			/* try to be non-fatal now... frameNum only gets advanced on success anyway */
			if(!read_frame(fr)) break;
		}
		/* Now the wanted frame should be ready for decoding. */

		/* I think, I don't want this...
		if(fr->lay == 3) set_pointer(fr, 512); */

		debug1("arrived at %lu", (long unsigned)fr->num);

		return MPG123_OK;
	}
	else return READER_ERROR; /* invalid, no seek happened */
}

/* return FALSE on error, TRUE on success, READER_MORE on occasion */
static int generic_head_read(mpg123_handle *fr,unsigned long *newhead)
{
	unsigned char hbuf[4];
	int ret = fr->rd->fullread(fr,hbuf,4);
	if(ret == READER_MORE) return ret;
	if(ret != 4) return FALSE;

	*newhead = ((unsigned long) hbuf[0] << 24) |
	           ((unsigned long) hbuf[1] << 16) |
	           ((unsigned long) hbuf[2] << 8)  |
	            (unsigned long) hbuf[3];

	return TRUE;
}

/* return FALSE on error, TRUE on success, READER_MORE on occasion */
static int generic_head_shift(mpg123_handle *fr,unsigned long *head)
{
	unsigned char hbuf;
	int ret = fr->rd->fullread(fr,&hbuf,1);
	if(ret == READER_MORE) return ret;
	if(ret != 1) return FALSE;

	*head <<= 8;
	*head |= hbuf;
	*head &= 0xffffffff;
	return TRUE;
}

/* returns reached position... negative ones are bad... */
static off_t stream_skip_bytes(mpg123_handle *fr,off_t len)
{
	if(fr->rdat.flags & READER_SEEKABLE)
	{
		off_t ret = stream_lseek(fr, len, SEEK_CUR);

		return ret<0 ? READER_ERROR : ret;
	}
	else if(len >= 0)
	{
		unsigned char buf[1024]; /* ThOr: Compaq cxx complained and it makes sense to me... or should one do a cast? What for? */
		ssize_t ret;
		while (len > 0)
		{
			ssize_t num = len < (off_t)sizeof(buf) ? (ssize_t)len : (ssize_t)sizeof(buf);
			ret = fr->rd->fullread(fr, buf, num);
			if (ret < 0) return ret;
			else if(ret == 0) break; /* EOF... an error? interface defined to tell the actual position... */
			len -= ret;
		}
		return fr->rd->tell(fr);
	}
	else if(fr->rdat.flags & READER_BUFFERED)
	{ /* Perhaps we _can_ go a bit back. */
		if(fr->rdat.buffer.pos >= -len)
		{
			fr->rdat.buffer.pos += len;
			return fr->rd->tell(fr);
		}
		else return READER_ERROR;
	}
	else return READER_ERROR;
}

/* Return 0 on success... */
static int stream_back_bytes(mpg123_handle *fr, off_t bytes)
{
	off_t want = fr->rd->tell(fr)-bytes;
	if(want < 0) return READER_ERROR;
	if(stream_skip_bytes(fr,-bytes) != want) return READER_ERROR;

	return 0;
}


/* returns size on success... */
static int generic_read_frame_body(mpg123_handle *fr,unsigned char *buf, int size)
{
	long l;

	if((l=fr->rd->fullread(fr,buf,size)) != size)
	{
		long ll = l;
		if(ll <= 0) ll = 0;

		/* This allows partial frames at the end... do we really want to pad and decode these?! */
		memset(buf+ll,0,size-ll);
	}
	return l;
}

static off_t generic_tell(mpg123_handle *fr)
{
	if(fr->rdat.flags & READER_BUFFERED)
	fr->rdat.filepos = fr->rdat.buffer.fileoff+fr->rdat.buffer.pos;

	return fr->rdat.filepos;
}

/* This does not (fully) work for non-seekable streams... You have to check for that flag, pal! */
static void stream_rewind(mpg123_handle *fr)
{
	if(fr->rdat.flags & READER_SEEKABLE)
	fr->rdat.buffer.fileoff = fr->rdat.filepos = stream_lseek(fr,0,SEEK_SET);
	if(fr->rdat.flags & READER_BUFFERED)
	{
		fr->rdat.buffer.pos      = 0;
		fr->rdat.buffer.firstpos = 0;
		fr->rdat.filepos = fr->rdat.buffer.fileoff;
	}
}

/*
 * returns length of a file (if filept points to a file)
 * reads the last 128 bytes information into buffer
 * ... that is not totally safe...
 */
static off_t get_fileinfo(mpg123_handle *fr)
{
	off_t len;

	if((len=fr->rdat.lseek(fr->rdat.filept,0,SEEK_END)) < 0)	return -1;

	if(fr->rdat.lseek(fr->rdat.filept,-128,SEEK_END) < 0) return -1;

	if(fr->rd->fullread(fr,(unsigned char *)fr->id3buf,128) != 128)	return -1;

	if(!strncmp((char*)fr->id3buf,"TAG",3))	len -= 128;

	if(fr->rdat.lseek(fr->rdat.filept,0,SEEK_SET) < 0)	return -1;

	if(len <= 0)	return -1;

	return len;
}

/* Methods for the buffer chain, mainly used for feed reader, but not just that. */

static void bc_init(struct bufferchain *bc)
{
	bc->first = NULL;
	bc->last  = bc->first;
	bc->size  = 0;
	bc->pos   = 0;
	bc->firstpos = 0;
	bc->fileoff  = 0;
}

static void bc_reset(struct bufferchain *bc)
{
	/* free the buffer chain */
	struct buffy *b = bc->first;
	while(b != NULL)
	{
		struct buffy *n = b->next;
		free(b->data);
		free(b);
		b = n;
	}
	bc_init(bc);
}

/* Create a new buffy at the end to be filled. */
static int bc_append(struct bufferchain *bc, ssize_t size)
{
	struct buffy *newbuf;
	if(size < 1) return -1;

	newbuf = malloc(sizeof(struct buffy));
	if(newbuf == NULL) return -2;

	newbuf->data = malloc(size);
	if(newbuf->data == NULL)
	{
		free(newbuf);
		return -3;
	}
	newbuf->size = size;
	newbuf->next = NULL;
	if(bc->last != NULL)  bc->last->next = newbuf;
	else if(bc->first == NULL) bc->first = newbuf;

	bc->last  = newbuf;
	bc->size += size;
	return 0;
}

#if 0
/* Drop the last one (again).
   This is not optimal but should happen on error situations only, anyway. */
static void bc_drop(struct bufferchain *bc)
{
	struct buffy *cur = bc->first;
	if(bc->first == NULL || bc->last == NULL) return;
	/* Special case: only one buffer there. */
	if(cur->next == NULL)
	{
		free(cur->data);
		free(cur);
		bc->first = bc->last = NULL;
		bc->size  = 0;
		return;
	}
	/* Find the pre-last buffy. If chain is consistent, this _will_ succeed. */
	while(cur->next != bc->last){ cur = cur->next; }

	bc->size -= bc->last->size;
	free(bc->last->data);
	free(bc->last);
	cur->next = NULL;
	bc->last  = cur;
}
#endif

/* Append a new buffer and copy content to it. */
static int bc_add(struct bufferchain *bc, const unsigned char *data, ssize_t size)
{
	int ret = 0;
	if((ret = bc_append(bc, size)) == 0)
	memcpy(bc->last->data, data, size);

	return ret;
}

/* Give some data, advancing position but not forgetting yet. */
static ssize_t bc_give(struct bufferchain *bc, unsigned char *out, size_t size)
{
	struct buffy *b = bc->first;
	ssize_t gotcount = 0;
	ssize_t offset = 0;
	if(bc->size - bc->pos < size)
	{
		debug3("hit end, back to beginning (%li - %li < %li)", (long)bc->size, (long)bc->pos, (long)size);
		/* go back to firstpos, undo the previous reads */
		bc->pos = bc->firstpos;
		return READER_MORE;
	}
	/* find the current buffer */
	while(b != NULL && (offset + b->size) <= bc->pos)
	{
		offset += b->size;
		b = b->next;
	}
	/* now start copying from there */
	while(gotcount < size && (b != NULL))
	{
		ssize_t loff = bc->pos - offset;
		ssize_t chunk = size - gotcount; /* amount of bytes to get from here... */
		if(chunk > b->size - loff) chunk = b->size - loff;

#ifdef EXTRA_DEBUG
		debug3("copying %liB from %p+%li",(long)chunk, b->data, (long)loff); */
#endif

		memcpy(out+gotcount, b->data+loff, chunk);
		gotcount += chunk;
		bc->pos  += chunk;
		offset += b->size;
		b = b->next;
	}
#ifdef EXTRA_DEBUG
	debug2("got %li bytes, pos advanced to %li", (long)gotcount, (long)bc->pos);
#endif

	return gotcount;
}

/* Skip some bytes and return the new position.
   The buffers are still there, just the read pointer is moved! */
static ssize_t bc_skip(struct bufferchain *bc, ssize_t count)
{
	if(count >= 0)
	{
		if(bc->size - bc->pos < count) return READER_MORE;
		else return bc->pos += count;
	}
	else return READER_ERROR;
}

static ssize_t bc_seekback(struct bufferchain *bc, ssize_t count)
{
	if(count >= 0 && count <= bc->pos) return bc->pos -= count;
	else return READER_ERROR;
}

/* Throw away buffies that we passed. */
static void bc_forget(struct bufferchain *bc)
{
	struct buffy *b = bc->first;
	/* free all buffers that are def'n'tly outdated */
	/* we have buffers until filepos... delete all buffers fully below it */
#ifdef EXTRA_DEBUG
	if(b) debug2("bc_forget: block %lu pos %lu", (unsigned long)b->size, (unsigned long)bc->pos);
	else debug("forget with nothing there!");
#endif
	while(b != NULL && bc->pos >= b->size)
	{
		struct buffy *n = b->next; /* != NULL or this is indeed the end and the last cycle anyway */
		if(n == NULL) bc->last = NULL; /* Going to delete the last buffy... */
		bc->fileoff += b->size;
		bc->pos  -= b->size;
		bc->size -= b->size;
#ifdef EXTRA_DEBUG
		debug5("bc_forget: forgot %p with %lu, pos=%li, size=%li, fileoff=%li", (void*)b->data, (long)b->size, (long)bc->pos,  (long)bc->size, (long)bc->fileoff);
#endif
		free(b->data);
		free(b);
		b = n;
	}
	bc->first = b;
	bc->firstpos = bc->pos;
}

/* reader for input via manually provided buffers */

static int feed_init(mpg123_handle *fr)
{
	bc_init(&fr->rdat.buffer);
	fr->rdat.filelen = 0;
	fr->rdat.filepos = 0;
	fr->rdat.flags |= READER_BUFFERED;
	return 0;
}

/* externally called function, returns 0 on success, -1 on error */
int feed_more(mpg123_handle *fr, const unsigned char *in, long count)
{
	int ret = 0;
	if(VERBOSE3) debug("feed_more");
	if((ret = bc_add(&fr->rdat.buffer, in, count)) != 0)
	{
		ret = READER_ERROR;
		if(NOQUIET) error1("Failed to add buffer, return: %i", ret);
	}
	else /* Not talking about filelen... that stays at 0. */

	if(VERBOSE3) debug3("feed_more: %p %luB bufsize=%lu", fr->rdat.buffer.last->data,
		(unsigned long)fr->rdat.buffer.last->size, (unsigned long)fr->rdat.buffer.size);
	return ret;
}

static ssize_t feed_read(mpg123_handle *fr, unsigned char *out, ssize_t count)
{
	ssize_t gotcount = bc_give(&fr->rdat.buffer, out, count);
	if(gotcount >= 0 && gotcount != count) return READER_ERROR;
	else return gotcount;
}

/* returns reached position... negative ones are bad... */
static off_t feed_skip_bytes(mpg123_handle *fr,off_t len)
{
	return fr->rdat.buffer.fileoff+bc_skip(&fr->rdat.buffer, (ssize_t)len);
}

static int feed_back_bytes(mpg123_handle *fr, off_t bytes)
{
	if(bytes >=0)
	return bc_seekback(&fr->rdat.buffer, (ssize_t)bytes) >= 0 ? 0 : READER_ERROR;
	else
	return feed_skip_bytes(fr, -bytes) >= 0 ? 0 : READER_ERROR;
}

static int buffered_seek_frame(mpg123_handle *fr, off_t num){ return READER_ERROR; }

/* Not just for feed reader, also for self-feeding buffered reader. */
static void buffered_forget(mpg123_handle *fr)
{
	bc_forget(&fr->rdat.buffer);
	fr->rdat.filepos = fr->rdat.buffer.fileoff + fr->rdat.buffer.pos;
}

off_t feed_set_pos(mpg123_handle *fr, off_t pos)
{
	struct bufferchain *bc = &fr->rdat.buffer;
	if(pos >= bc->fileoff && pos-bc->fileoff < bc->size)
	{ /* We have the position! */
		bc->pos = (ssize_t)(pos - bc->fileoff);
		return pos+bc->size; /* Next input after end of buffer... */
	}
	else
	{ /* I expect to get the specific position on next feed. Forget what I have now. */
		bc_reset(bc);
		bc->fileoff = pos;
		return pos; /* Next input from exactly that position. */
	}
}

/* The specific stuff for buffered stream reader. */

/* Let's work in nice 4K blocks, that may be nicely reusable (by malloc(), even). */
#define BUFFBLOCK 4096
static ssize_t buffered_fullread(mpg123_handle *fr, unsigned char *out, ssize_t count)
{
	struct bufferchain *bc = &fr->rdat.buffer;
	ssize_t gotcount;
	if(bc->size - bc->pos < count)
	{ /* Add more stuff to buffer. If hitting end of file, adjust count. */
		unsigned char readbuf[BUFFBLOCK];
		ssize_t need = count - (bc->size-bc->pos);
		while(need>0)
		{
			int ret;
			ssize_t got = fr->rdat.fullread(fr, readbuf, BUFFBLOCK);
			if(got < 0)
			{
				if(NOQUIET) error("buffer reading");
				return READER_ERROR;
			}

			if(VERBOSE3) debug1("buffered_fullread: buffering %li bytes from stream (if > 0)", (long)got);
			if(got > 0 && (ret=bc_add(bc, readbuf, got)) != 0)
			{
				if(NOQUIET) error1("unable to add to chain, return: %i", ret);
				return READER_ERROR;
			}

			need -= got; /* May underflow here... */
			if(got < BUFFBLOCK) /* That naturally catches got == 0, too. */
			{
				if(VERBOSE3) fprintf(stderr, "Note: Input data end.\n");
				break; /* End. */
			}
		}
		if(bc->size - bc->pos < count)
		count = bc->size - bc->pos; /* We want only what we got. */
	}
	gotcount = bc_give(bc, out, count);

	if(VERBOSE3) debug2("wanted %li, got %li", (long)count, (long)gotcount);

	if(gotcount != count){ if(NOQUIET) error("gotcount != count"); return READER_ERROR; }
	else return gotcount;
}



/*****************************************************************
 * read frame helper
 */

#define bugger_off { mh->err = MPG123_NO_READER; return MPG123_ERR; }
int bad_init(mpg123_handle *mh) bugger_off
void bad_close(mpg123_handle *mh){}
ssize_t bad_fullread(mpg123_handle *mh, unsigned char *data, ssize_t count) bugger_off
int bad_head_read(mpg123_handle *mh, unsigned long *newhead) bugger_off
int bad_head_shift(mpg123_handle *mh, unsigned long *head) bugger_off
off_t bad_skip_bytes(mpg123_handle *mh, off_t len) bugger_off
int bad_read_frame_body(mpg123_handle *mh, unsigned char *data, int size) bugger_off
int bad_back_bytes(mpg123_handle *mh, off_t bytes) bugger_off
int bad_seek_frame(mpg123_handle *mh, off_t num) bugger_off
off_t bad_tell(mpg123_handle *mh) bugger_off
void bad_rewind(mpg123_handle *mh){}
#undef bugger_off

#define READER_STREAM 0
#define READER_ICY_STREAM 1
#define READER_FEED       2
#define READER_BUF_STREAM 3
#define READER_BUF_ICY_STREAM 4
struct reader readers[] =
{
	{ /* READER_STREAM */
		default_init,
		stream_close,
		plain_fullread,
		generic_head_read,
		generic_head_shift,
		stream_skip_bytes,
		generic_read_frame_body,
		stream_back_bytes,
		stream_seek_frame,
		generic_tell,
		stream_rewind,
		NULL
	} ,
	{ /* READER_ICY_STREAM */
		default_init,
		stream_close,
		icy_fullread,
		generic_head_read,
		generic_head_shift,
		stream_skip_bytes,
		generic_read_frame_body,
		stream_back_bytes,
		stream_seek_frame,
		generic_tell,
		stream_rewind,
		NULL
	},
	{ /* READER_FEED */
		feed_init,
		stream_close,
		feed_read,
		generic_head_read,
		generic_head_shift,
		feed_skip_bytes,
		generic_read_frame_body,
		feed_back_bytes,
		buffered_seek_frame,
		generic_tell,
		stream_rewind,
		buffered_forget
	},
	{ /* READER_BUF_STREAM */
		default_init,
		stream_close,
		buffered_fullread,
		generic_head_read,
		generic_head_shift,
		stream_skip_bytes,
		generic_read_frame_body,
		stream_back_bytes,
		buffered_seek_frame,
		generic_tell,
		stream_rewind,
		buffered_forget
	} ,
	{ /* READER_BUF_ICY_STREAM */
		default_init,
		stream_close,
		buffered_fullread,
		generic_head_read,
		generic_head_shift,
		stream_skip_bytes,
		generic_read_frame_body,
		stream_back_bytes,
		buffered_seek_frame,
		generic_tell,
		stream_rewind,
		buffered_forget
	},
#ifdef READ_SYSTEM
	,{
		system_init,
		NULL,	/* filled in by system_init() */
		fullread,
		NULL,
		NULL,
		NULL,
		NULL,
		NULL,
		NULL,
		NULL,
		NULL,
		NULL,
	}
#endif
};

struct reader bad_reader =
{
	bad_init,
	bad_close,
	bad_fullread,
	bad_head_read,
	bad_head_shift,
	bad_skip_bytes,
	bad_read_frame_body,
	bad_back_bytes,
	bad_seek_frame,
	bad_tell,
	bad_rewind,
	NULL
};

static int default_init(mpg123_handle *fr)
{
#ifndef WIN32
	if(fr->p.timeout > 0)
	{
		int flags = fcntl(fr->rdat.filept, F_GETFL);
		flags |= O_NONBLOCK;
		fcntl(fr->rdat.filept, F_SETFL, flags);
		fr->rdat.fdread = timeout_read;
		fr->rdat.timeout_sec = fr->p.timeout;
		fr->rdat.flags |= READER_NONBLOCK;
	}
	else
#endif
	fr->rdat.fdread = plain_read;

	fr->rdat.read  = fr->rdat.r_read  != NULL ? fr->rdat.r_read  : posix_read;
	fr->rdat.lseek = fr->rdat.r_lseek != NULL ? fr->rdat.r_lseek : posix_lseek;
	fr->rdat.filelen = get_fileinfo(fr);
	fr->rdat.filepos = 0;
	if(fr->rdat.filelen >= 0)
	{
		fr->rdat.flags |= READER_SEEKABLE;
		if(!strncmp((char*)fr->id3buf,"TAG",3))
		{
			fr->rdat.flags |= READER_ID3TAG;
			fr->metaflags  |= MPG123_NEW_ID3;
		}
	}
	/* Switch reader to a buffered one, if allowed. */
	else if(fr->p.flags & MPG123_SEEKBUFFER)
	{
		if     (fr->rd == &readers[READER_STREAM])
		{
			fr->rd = &readers[READER_BUF_STREAM];
			fr->rdat.fullread = plain_fullread;
		}
		else if(fr->rd == &readers[READER_ICY_STREAM])
		{
			fr->rd = &readers[READER_BUF_ICY_STREAM];
			fr->rdat.fullread = icy_fullread;
		}
		else
		{
			if(NOQUIET) error("mpg123 Programmer's fault: invalid reader");
			return -1;
		}
		bc_init(&fr->rdat.buffer);
		fr->rdat.filelen = 0; /* We carry the offset, but never know how big the stream is. */
		fr->rdat.flags |= READER_BUFFERED;
	}
	return 0;
}


void open_bad(mpg123_handle *mh)
{
	clear_icy(&mh->icy);
	mh->rd = &bad_reader;
	mh->rdat.flags = 0;
	bc_init(&mh->rdat.buffer);
}

int open_feed(mpg123_handle *fr)
{
	debug("feed reader");
	clear_icy(&fr->icy);
	fr->rd = &readers[READER_FEED];
	fr->rdat.flags = 0;
	if(fr->rd->init(fr) < 0) return -1;
	return 0;
}

int open_stream(mpg123_handle *fr, const char *bs_filenam, int fd)
{
	int filept_opened = 1;
	int filept; /* descriptor of opened file/stream */

	clear_icy(&fr->icy); /* can be done inside frame_clear ...? */
	if(!bs_filenam) /* no file to open, got a descriptor (stdin) */
	{
		filept = fd;
		filept_opened = 0; /* and don't try to close it... */
	}
	#ifndef O_BINARY
	#define O_BINARY (0)
	#endif
	else if((filept = open(bs_filenam, O_RDONLY|O_BINARY)) < 0) /* a plain old file to open... */
	{
		if(NOQUIET) error2("Cannot open file %s: %s", bs_filenam, strerror(errno));
		fr->err = MPG123_BAD_FILE;
		return MPG123_ERR; /* error... */
	}

	/* now we have something behind filept and can init the reader */
	fr->rdat.filelen = -1;
	fr->rdat.filept  = filept;
	fr->rdat.flags = 0;
	if(filept_opened)	fr->rdat.flags |= READER_FD_OPENED;

	if(fr->p.icy_interval > 0)
	{
		debug("ICY reader");
		fr->icy.interval = fr->p.icy_interval;
		fr->icy.next = fr->icy.interval;
		fr->rd = &readers[READER_ICY_STREAM];
	}
	else
	{
		fr->rd = &readers[READER_STREAM];
		debug("stream reader");
	}

	if(fr->rd->init(fr) < 0) return -1;

	return MPG123_OK;
}