C++ read_block函数代码示例

// Read and validate the file system bitmap.
//
// Read all the bitmap blocks into memory.
// Set the "bitmap" pointer to point at the beginning of the first
// bitmap block.
// 
// Check that all reserved blocks -- 0, 1, and the bitmap blocks themselves --
// are all marked as in-use
// (for each block i, assert(!block_is_free(i))).
//
// Hint: Assume that the superblock has already been loaded into
// memory (in variable 'super').  Check out super->s_nblocks.
void
read_bitmap(void)
{
	int r;
	uint32_t i;
	char *blk;

	// Read the bitmap into memory.
	// The bitmap consists of one or more blocks.  A single bitmap block
	// contains the in-use bits for BLKBITSIZE blocks.  There are
	// super->s_nblocks blocks in the disk altogether.
	// Set 'bitmap' to point to the first address in the bitmap.
	// Hint: Use read_block.

	// LAB 5: Your code here.
	uint32_t bitmap_blkno = super->s_nblocks / BLKBITSIZE;
	if(super -> s_nblocks % BLKBITSIZE != 0)
		bitmap_blkno++;

	for(i=0;i<bitmap_blkno;i++){
		if(read_block(2+i,&blk) < 0)
			panic("read_bitmap: read_block fail!\n");
	}

	bitmap = (uint32_t *)diskaddr(2);
	// Make sure the reserved and root blocks are marked in-use.
	assert(!block_is_free(0));
	assert(!block_is_free(1));
	assert(bitmap);

	// Make sure that the bitmap blocks are marked in-use.
	// LAB 5: Your code here.
	for(i=0;i<bitmap_blkno;i++)
		assert(!block_is_free(2+i));
	cprintf("read_bitmap is good\n");
}

boost::string_ref HDFSFileSplitter::fetch_block(bool is_next) {
    int nbytes = 0;
    if (is_next) {
        // directly read the next block using the current file
        nbytes = hdfsRead(fs_, file_, data_, hdfs_block_size);
        if (nbytes == 0)
            return "";
        if (nbytes == -1) {
            throw base::HuskyException("read next block error!");
        }
    } else {
        // Ask the master for a new block
        BinStream question;
        question << url_ << husky::Context::get_param("hostname");
        BinStream answer = husky::Context::get_coordinator()->ask_master(question, husky::TYPE_HDFS_BLK_REQ);
        std::string fn;
        answer >> fn;
        answer >> offset_;

        if (fn == "") {
            // no more files
            return "";
        }

        if (file_ != NULL) {
            int rc = hdfsCloseFile(fs_, file_);
            assert(rc == 0);
            // Notice that "file" will be deleted inside hdfsCloseFile
            file_ = NULL;
        }

        // read block
        nbytes = read_block(fn);
    }
    return boost::string_ref(data_, nbytes);
}

main (int argc, char *argv[])
{
  float block[GULP],copy[GULP];
  int ixnc,kxnc,i,j,k,n,off,nadd,nread,headersize=0;

  input=fopen(argv[1],"rb");
  output=fopen(argv[2],"wb");
  nadd=atoi(argv[3]);

  for (i=0;i<4;i++) ifstream[i]='Y';

  if (!(headersize=read_header(input))) 
    error_message("could not read header parameters!");
  obits=32;
  tsamp*=nadd;
  filterbank_header(output);
  for (i=0;i<GULP;i++) block[i]=copy[i]=0.0;
  nread=GULP/nchans;

  while(n=read_block(input,nbits,block,nread)) {
    k=off=0;
    for (i=0;i<n/nchans;i++) {
      ixnc=i*nchans;
      kxnc=k*nchans;
      for (j=0;j<nchans;j++) copy[off+j]+=block[ixnc+j];
      k++;
      if (k==nadd) {
	off+=nchans;
	k=0;
      }
    }
    for (j=0;j<n/nadd;j++) copy[j]/=(float)nadd;
    fwrite(copy,sizeof(float),n/nadd,output);
    for (j=0;j<n/nadd;j++) copy[j]=0.0;
  }
}

/*
 * Update dedup structure with block's hash and crc
 */
void dedup_calc_block_hash_crc(sector_t block)
{
	size_t block_size = dedup_get_block_size();
	char *block_data;

	if (block >= blocks_count)
		// outside dedup range
		return;

	block_data = (char*)kmalloc(block_size, GFP_KERNEL);
	if (block_data == NULL) {
		printk(KERN_ERR "failed allocating block data buffer.\n");
		return;
	}

	// Read block
	read_block(block_data, block_size, start_block + block);
	// Calc hash
	calc_hash(block_data, block_size, blocksArray.hashes[block]);
	// Calc crc32
	blocksArray.hash_crc[block] = crc32_le(0, blocksArray.hashes[block], SHA256_DIGEST_SIZE);

	kfree(block_data);
}

size_t ext2_read(Ext2_file *file, uint8_t *buf, size_t count)
{
	// Check if we would read past the end of the file
	if (file->pos + count > file->inode.size)
		count = file->inode.size - file->pos;

	size_t bytes_left   = count;

	while (bytes_left > 0) {
		size_t to_copy = bytes_left;

		// Check if this read will go beyond the current buffer
		bool new_block = file->curr_block_pos + to_copy >= block_size;
		if (new_block)
			to_copy = block_size - file->curr_block_pos;

		// Copy across from the buffer in the *file and advance the position
		memcpy(buf + (count - bytes_left),
				file->buf + file->curr_block_pos, to_copy);
		file->curr_block_pos += to_copy;
		file->pos            += to_copy;
		bytes_left           -= to_copy;

		// If we read to the end of the buffer then read the next block
		if (new_block) {
			file->curr_block_pos = 0;
			file->block_index++;
			if (file->block_index >= 12)
				PANIC("Indirect block pointers are currently unsupported");

			read_block(file->inode.dbp[file->block_index], file->buf);
		}
	}

	return count;
}

int sba_reiserfs_find_journal_entries(void)
{
	int i;
	char *data;
	
	if ((data = read_block(REISER_SUPER)) != NULL) {
		struct reiserfs_super_block *rsb = (struct reiserfs_super_block *)data;

		if (sba_reiserfs_is_any_reiserfs_magic_string (rsb)) {
			sba_debug(1,"SUCCESS ! Found reiserfs superblock\n");

			sba_debug(1,"Journal begin = %u Journal size = %u\n", 
			rsb->s_v1.s_journal.jp_journal_1st_block, rsb->s_v1.s_journal.jp_journal_size);

			sba_debug(1,"Trans max = %u Max batch = %u\n", 
			rsb->s_v1.s_journal.jp_journal_trans_max, rsb->s_v1.s_journal.jp_journal_max_batch);

			sba_debug(1,"Commit age = %u Trans age = %u\n", 
			rsb->s_v1.s_journal.jp_journal_max_commit_age, rsb->s_v1.s_journal.jp_journal_max_trans_age);

			reiser_jour_start = rsb->s_v1.s_journal.jp_journal_1st_block;
			reiser_jour_size = rsb->s_v1.s_journal.jp_journal_size;
		}

		free_page((int)data);
	}

	
	for (i = 0; i < reiser_jour_size; i ++) {
		ht_add(h_sba_reiserfs_journal, reiser_jour_start + i);
	}

	sba_debug(1, "Begin = %d End = %d\n", reiser_jour_start, reiser_jour_start + reiser_jour_size - 1);

	return 1;
}

static int comment_43_uncompress(FILE *infp, FILE *outfp, int skip_magic)
{
  block_data_t *block_data = malloc(sizeof(block_data_t));
  size_t work_len = snappy_max_compressed_length(UINT16_MAX); /* length of worst case */
  char *work = malloc(work_len);
  int err = 1;
  stream_state_t state = skip_magic ? PROCESSING_STATE : INITIAL_STATE;

  if (block_data == NULL || work == NULL) {
    print_error("out of memory\n");
    goto cleanup;
  }

  while (state != ERROR_STATE) {
    switch (read_block(infp, block_data)) {
    case EOF:
      if (state == END_OF_STREAM_STATE) {
        err = 0; /* success */
        goto cleanup;
      }
      /* FALLTHROUGH */
    case TOO_SHORT_DATA_BLOCK:
      if (feof_unlocked(infp)) {
        print_error("Unexpected end of file\n");
      } else {
        print_error("Failed to read a file: %s\n", strerror(errno));
      }
      goto cleanup;
    }
    state = process_block(outfp, state, block_data, work, work_len);
  }
 cleanup:
  free(block_data);
  free(work);
  return err;
}

struct compressor *read_super(int fd, struct squashfs_super_block *sBlk, char *source)
{
	int res, bytes = 0;
	char buffer[SQUASHFS_METADATA_SIZE] __attribute__ ((aligned));

	res = read_fs_bytes(fd, SQUASHFS_START, sizeof(struct squashfs_super_block),
		sBlk);
	if(res == 0) {
		ERROR("Can't find a SQUASHFS superblock on %s\n",
				source);
		ERROR("Wrong filesystem or filesystem is corrupted!\n");
		goto failed_mount;
	}

	SQUASHFS_INSWAP_SUPER_BLOCK(sBlk);

	if(sBlk->s_magic != SQUASHFS_MAGIC) {
		if(sBlk->s_magic == SQUASHFS_MAGIC_SWAP)
			ERROR("Pre 4.0 big-endian filesystem on %s, appending"
				" to this is unsupported\n", source);
		else {
			ERROR("Can't find a SQUASHFS superblock on %s\n",
				source);
			ERROR("Wrong filesystem or filesystem is corrupted!\n");
		}
		goto failed_mount;
	}

	/* Check the MAJOR & MINOR versions */
	if(sBlk->s_major != SQUASHFS_MAJOR || sBlk->s_minor > SQUASHFS_MINOR) {
		if(sBlk->s_major < 4)
			ERROR("Filesystem on %s is a SQUASHFS %d.%d filesystem."
				"  Appending\nto SQUASHFS %d.%d filesystems is "
				"not supported.  Please convert it to a "
				"SQUASHFS 4 filesystem\n", source,
				sBlk->s_major,
				sBlk->s_minor, sBlk->s_major, sBlk->s_minor);
		else
			ERROR("Filesystem on %s is %d.%d, which is a later "
				"filesystem version than I support\n",
				source, sBlk->s_major, sBlk->s_minor);
		goto failed_mount;
	}

	/* Check the compression type */
	comp = lookup_compressor_id(sBlk->compression);
	if(!comp->supported) {
		ERROR("Filesystem on %s uses %s compression, this is "
			"unsupported by this version\n", source, comp->name);
		ERROR("Compressors available:\n");
		display_compressors("", "");
		goto failed_mount;
	}

	/*
	 * Read extended superblock information from disk.
	 *
	 * Read compressor specific options from disk if present, and pass
	 * to compressor to set compressor options.
	 *
	 * Note, if there's no compressor options present, the compressor
	 * is still called to set the default options (the defaults may have
	 * been changed by the user specifying options on the command
	 * line which need to be over-ridden).
	 *
	 * Compressor_extract_options is also used to ensure that 
	 * we know how decompress a filesystem compressed with these
	 * compression options.
	 */
	if(SQUASHFS_COMP_OPTS(sBlk->flags)) {
		bytes = read_block(fd, sizeof(*sBlk), NULL, 0, buffer);

		if(bytes == 0) {
			ERROR("Failed to read compressor options from append "
				"filesystem\n");
			ERROR("Filesystem corrupted?\n");
			goto failed_mount;
		}
	}

	res = compressor_extract_options(comp, sBlk->block_size, buffer, bytes);
	if(res == -1) {
		ERROR("Compressor failed to set compressor options\n");
		goto failed_mount;
	}

	printf("Found a valid %sSQUASHFS superblock on %s.\n",
		SQUASHFS_EXPORTABLE(sBlk->flags) ? "exportable " : "", source);
	printf("\tCompression used %s\n", comp->name);
	printf("\tInodes are %scompressed\n",
		SQUASHFS_UNCOMPRESSED_INODES(sBlk->flags) ? "un" : "");
	printf("\tData is %scompressed\n",
		SQUASHFS_UNCOMPRESSED_DATA(sBlk->flags) ? "un" : "");
	printf("\tFragments are %scompressed\n",
		SQUASHFS_UNCOMPRESSED_FRAGMENTS(sBlk->flags) ? "un" : "");
	printf("\tXattrs are %scompressed\n",
		SQUASHFS_UNCOMPRESSED_XATTRS(sBlk->flags) ? "un" : "");
	printf("\tFragments are %spresent in the filesystem\n",
		SQUASHFS_NO_FRAGMENTS(sBlk->flags) ? "not " : "");
	printf("\tAlways-use-fragments option is %sspecified\n",
//.........这里部分代码省略.........

void decode_block(decoder_info_t *decoder_info,int size,int ypos,int xpos){

  int width = decoder_info->width;
  int height = decoder_info->height;
  int xposY = xpos;
  int yposY = ypos;
  int xposC = xpos/2;
  int yposC = ypos/2;
  int sizeY = size;
  int sizeC = size/2;

  block_mode_t mode;
  mv_t mv;
  intra_mode_t intra_mode;

  frame_type_t frame_type = decoder_info->frame_info.frame_type;
  int bipred = decoder_info->bipred;

  int qpY = decoder_info->frame_info.qpb;
  int qpC = chroma_qp[qpY];

  /* Intermediate block variables */
  uint8_t *pblock_y = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock_u = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock_v = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  int16_t *coeff_y = thor_alloc(2*MAX_TR_SIZE*MAX_TR_SIZE, 16);
  int16_t *coeff_u = thor_alloc(2*MAX_TR_SIZE*MAX_TR_SIZE, 16);
  int16_t *coeff_v = thor_alloc(2*MAX_TR_SIZE*MAX_TR_SIZE, 16);

  /* Block variables for bipred */
  uint8_t *pblock0_y = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock0_u = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock0_v = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock1_y = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock1_u = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  uint8_t *pblock1_v = thor_alloc(MAX_BLOCK_SIZE*MAX_BLOCK_SIZE, 16);
  yuv_frame_t *rec = decoder_info->rec;
  yuv_frame_t *ref = decoder_info->ref[0];

  /* Calculate position in padded reference frame */
  int ref_posY = yposY*ref->stride_y+xposY;
  int ref_posC = yposC*ref->stride_c+xposC;

  /* Pointers to current position in reconstructed frame*/
  uint8_t *rec_y = &rec->y[yposY*rec->stride_y+xposY];
  uint8_t *rec_u = &rec->u[yposC*rec->stride_c+xposC];
  uint8_t *rec_v = &rec->v[yposC*rec->stride_c+xposC];

  /* Pointers to colocated block position in reference frame */
  uint8_t *ref_y = ref->y + ref_posY;
  uint8_t *ref_u = ref->u + ref_posC;
  uint8_t *ref_v = ref->v + ref_posC;

  stream_t *stream = decoder_info->stream;

  /* Read data from bitstream */
  block_info_dec_t block_info;
  block_info.block_pos.size = size;
  block_info.block_pos.ypos = ypos;
  block_info.block_pos.xpos = xpos;
  block_info.coeffq_y = coeff_y;
  block_info.coeffq_u = coeff_u;
  block_info.coeffq_v = coeff_v;

  /* Used for rectangular skip blocks */
  int bwidth = min(size,width - xpos);
  int bheight = min(size,height - ypos);
  block_info.block_pos.bwidth = bwidth;
  block_info.block_pos.bheight = bheight;

  read_block(decoder_info,stream,&block_info,frame_type);
  mode = block_info.block_param.mode;

  if (mode == MODE_INTRA){
    /* Dequantize, inverse tranform, predict and reconstruct */
    intra_mode = block_info.block_param.intra_mode;
    int upright_available = get_upright_available(ypos,xpos,size,width);
    int downleft_available = get_downleft_available(ypos,xpos,size,height);
    int tb_split = block_info.block_param.tb_split;
    decode_and_reconstruct_block_intra(rec_y,rec->stride_y,sizeY,qpY,pblock_y,coeff_y,tb_split,upright_available,downleft_available,intra_mode,yposY,xposY,width,0);
    decode_and_reconstruct_block_intra(rec_u,rec->stride_c,sizeC,qpC,pblock_u,coeff_u,tb_split&&size>8,upright_available,downleft_available,intra_mode,yposC,xposC,width/2,1);
    decode_and_reconstruct_block_intra(rec_v,rec->stride_c,sizeC,qpC,pblock_v,coeff_v,tb_split&&size>8,upright_available,downleft_available,intra_mode,yposC,xposC,width/2,2);
  }
  else
  {
    if (mode==MODE_SKIP){
      if (block_info.block_param.dir==2){
        uint8_t *ref0_y,*ref0_u,*ref0_v;
        uint8_t *ref1_y,*ref1_u,*ref1_v;

        int r0 = decoder_info->frame_info.ref_array[block_info.block_param.ref_idx0];
        yuv_frame_t *ref0 = r0>=0 ? decoder_info->ref[r0] : decoder_info->interp_frames[0];
        ref0_y = ref0->y + ref_posY;
        ref0_u = ref0->u + ref_posC;
        ref0_v = ref0->v + ref_posC;

        int r1 = decoder_info->frame_info.ref_array[block_info.block_param.ref_idx1];
        yuv_frame_t *ref1 = r1>=0 ? decoder_info->ref[r1] : decoder_info->interp_frames[0];
        ref1_y = ref1->y + ref_posY;
        ref1_u = ref1->u + ref_posC;
//.........这里部分代码省略.........

static int write_tind_metadata(struct defrag_ctx *c, struct data_extent *e,
                              __u32 tind_block, __u32 *cur_logical,
                              __u32 *cur_block)
{
	struct inode *inode = c->inodes[e->inode_nr];
	__u32 offset = *cur_logical;
	__u32 ind_blocks = EXT2_ADDR_PER_BLOCK(&c->sb);
	__u32 blocks_per_ind = 1 + ind_blocks;
	__u32 blocks_per_dind = 1 + ind_blocks * blocks_per_ind;
	__u32 blocks_per_tind = 1 + ind_blocks * blocks_per_dind;
	__u32 buffer[EXT2_ADDR_PER_BLOCK(&c->sb)];
	int ret;
	char to_sync = 0;

	if (tind_block == 0) {
		*cur_logical += blocks_per_tind;
		return 0;
	}
	ret = read_block(c, buffer, tind_block);
	if (ret)
		return -1;
	offset -= EXT2_TIND_LBLOCK(&c->sb) + 1;
	offset = offset % blocks_per_tind;
	if (offset % blocks_per_dind) {
		offset = offset / blocks_per_dind;
		ret = write_dind_metadata(c, e, buffer[offset], cur_logical,
		                         cur_block);
		if (ret)
			return ret;
		offset++;
	} else {
		offset = offset / blocks_per_dind;
	}
	while (offset < EXT2_ADDR_PER_BLOCK(&c->sb)
	                                        && *cur_block <= e->end_block) {
		__u32 new_block;
		if (is_sparse(inode, *cur_logical))
			new_block = 0;
		else
			new_block = (*cur_block)++;
		(*cur_logical)++;
		if (new_block) {
			ret = write_dind_metadata(c, e, new_block,
			                          cur_logical, cur_block);
			if (ret)
				return ret;
		} else {
			*cur_logical += blocks_per_dind - 1;
		}
		if (buffer[offset] != new_block) {
			to_sync = 1;
			buffer[offset] = new_block;
		}
		offset++;
	}
	if (to_sync) {
		ret = write_block(c, buffer, tind_block);
		return ret;
	}
	return 0;
}

/*
 * Read and return the next packet from the savefile.  Return the header
 * in hdr and a pointer to the contents in data.  Return 0 on success, 1
 * if there were no more packets, and -1 on an error.
 */
static int
pcap_ng_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
{
	struct pcap_ng_sf *ps = p->priv;
	struct block_cursor cursor;
	int status;
	struct enhanced_packet_block *epbp;
	struct simple_packet_block *spbp;
	struct packet_block *pbp;
	bpf_u_int32 interface_id = 0xFFFFFFFF;
	struct interface_description_block *idbp;
	struct section_header_block *shbp;
	FILE *fp = p->rfile;
	u_int64_t t, sec, frac;

	/*
	 * Look for an Enhanced Packet Block, a Simple Packet Block,
	 * or a Packet Block.
	 */
	for (;;) {
		/*
		 * Read the block type and length; those are common
		 * to all blocks.
		 */
		status = read_block(fp, p, &cursor, p->errbuf);
		if (status == 0)
			return (1);	/* EOF */
		if (status == -1)
			return (-1);	/* error */
		switch (cursor.block_type) {

		case BT_EPB:
			/*
			 * Get a pointer to the fixed-length portion of the
			 * EPB.
			 */
			epbp = get_from_block_data(&cursor, sizeof(*epbp),
			    p->errbuf);
			if (epbp == NULL)
				return (-1);	/* error */

			/*
			 * Byte-swap it if necessary.
			 */
			if (p->swapped) {
				/* these were written in opposite byte order */
				interface_id = SWAPLONG(epbp->interface_id);
				hdr->caplen = SWAPLONG(epbp->caplen);
				hdr->len = SWAPLONG(epbp->len);
				t = ((u_int64_t)SWAPLONG(epbp->timestamp_high)) << 32 |
				    SWAPLONG(epbp->timestamp_low);
			} else {
				interface_id = epbp->interface_id;
				hdr->caplen = epbp->caplen;
				hdr->len = epbp->len;
				t = ((u_int64_t)epbp->timestamp_high) << 32 |
				    epbp->timestamp_low;
			}
			goto found;

		case BT_SPB:
			/*
			 * Get a pointer to the fixed-length portion of the
			 * SPB.
			 */
			spbp = get_from_block_data(&cursor, sizeof(*spbp),
			    p->errbuf);
			if (spbp == NULL)
				return (-1);	/* error */

			/*
			 * SPB packets are assumed to have arrived on
			 * the first interface.
			 */
			interface_id = 0;

			/*
			 * Byte-swap it if necessary.
			 */
			if (p->swapped) {
				/* these were written in opposite byte order */
				hdr->len = SWAPLONG(spbp->len);
			} else
				hdr->len = spbp->len;

			/*
			 * The SPB doesn't give the captured length;
			 * it's the minimum of the snapshot length
			 * and the packet length.
			 */
			hdr->caplen = hdr->len;
			if ((int)hdr->caplen > p->snapshot)
				hdr->caplen = p->snapshot;
			t = 0;	/* no time stamps */
			goto found;
//.........这里部分代码省略.........

void
Playback_DS::disk_thread ( void )
{
    _thread.name( "Playback" );

    DMESSAGE( "playback thread running" );

    /* buffer to hold the interleaved data returned by the track reader */
    sample_t *buf = buffer_alloc( _nframes * channels() * _disk_io_blocks );
    sample_t *cbuf = buffer_alloc( _nframes );

    const nframes_t nframes = _nframes;
    nframes_t blocks_written;

    while ( ! _terminate )
    {

    seek:

        blocks_written = 0;
        read_block( buf, nframes * _disk_io_blocks );

        while ( blocks_written < _disk_io_blocks &&
                wait_for_block() )
        {
//        lock(); // for seeking
            
            if ( _pending_seek )
            {
                /* FIXME: non-RT-safe IO */
                DMESSAGE( "performing seek to frame %lu", (unsigned long)_seek_frame );
                
                _frame = _seek_frame;
                _pending_seek = false;

                flush();
                
                goto seek;
            }

            /* might have received terminate signal while waiting for block */
            if ( _terminate )
                goto done;
        
//        unlock(); // for seeking
        
            /* deinterleave the buffer and stuff it into the per-channel ringbuffers */

            const size_t block_size = nframes * sizeof( sample_t );

            for ( int i = 0; i < channels(); i++ )
            {
                buffer_deinterleave_one_channel( cbuf,
                                                 buf + ( blocks_written * nframes * channels() ),
                                                 i,
                                                 channels(), 
                                                 nframes );

                while ( jack_ringbuffer_write_space( _rb[ i ] ) < block_size )
                    usleep( 100 * 1000 );

                jack_ringbuffer_write( _rb[ i ], ((char*)cbuf), block_size );
            }

            blocks_written++;
        }
    }

done:

    DMESSAGE( "playback thread terminating" );

    free(buf);
    free(cbuf);

//    flush();

    _terminate = false;

    _thread.exit();
}

static int do_readpage(struct ubifs_info *c, struct inode *inode,
		       struct page *page, int last_block_size)
{
	void *addr;
	int err = 0, i;
	unsigned int block, beyond;
	struct ubifs_data_node *dn;
	loff_t i_size = inode->i_size;

	dbg_gen("ino %lu, pg %lu, i_size %lld",
		inode->i_ino, page->index, i_size);

	addr = kmap(page);

	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
	beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
	if (block >= beyond) {
		/* Reading beyond inode */
		memset(addr, 0, PAGE_CACHE_SIZE);
		goto out;
	}

	dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS);
	if (!dn)
		return -ENOMEM;

	i = 0;
	while (1) {
		int ret;

		if (block >= beyond) {
			/* Reading beyond inode */
			err = -ENOENT;
			memset(addr, 0, UBIFS_BLOCK_SIZE);
		} else {
			/*
			 * Reading last block? Make sure to not write beyond
			 * the requested size in the destination buffer.
			 */
			if (((block + 1) == beyond) || last_block_size) {
				void *buff;
				int dlen;

				/*
				 * We need to buffer the data locally for the
				 * last block. This is to not pad the
				 * destination area to a multiple of
				 * UBIFS_BLOCK_SIZE.
				 */
				buff = malloc(UBIFS_BLOCK_SIZE);
				if (!buff) {
					printf("%s: Error, malloc fails!\n",
					       __func__);
					err = -ENOMEM;
					break;
				}

				/* Read block-size into temp buffer */
				ret = read_block(inode, buff, block, dn);
				if (ret) {
					err = ret;
					if (err != -ENOENT) {
						free(buff);
						break;
					}
				}

				if (last_block_size)
					dlen = last_block_size;
				else
					dlen = le32_to_cpu(dn->size);

				/* Now copy required size back to dest */
				memcpy(addr, buff, dlen);

				free(buff);
			} else {
				ret = read_block(inode, addr, block, dn);
				if (ret) {
					err = ret;
					if (err != -ENOENT)
						break;
				}
			}
		}
		if (++i >= UBIFS_BLOCKS_PER_PAGE)
			break;
		block += 1;
		addr += UBIFS_BLOCK_SIZE;
	}
	if (err) {
		if (err == -ENOENT) {
			/* Not found, so it must be a hole */
			dbg_gen("hole");
			goto out_free;
		}
		ubifs_err("cannot read page %lu of inode %lu, error %d",
			  page->index, inode->i_ino, err);
		goto error;
	}
//.........这里部分代码省略.........

int fbcopy(     FILE            *fout, 
                CIFBLK          *cif,
                DADSM           *dadsm,
                int             tran, 
                int             verbose) {

        FORMAT1_DSCB    *f1dscb = &dadsm->f1buf;
        DSXTENT         extent[MAX_EXTENTS];
        int     rc, trk = 0, trkconv = 999, rec = 1;
        int     cyl = 0, head = 0, rc_rb, len, offset;
        int     rc_copy = 0;
        int     recs_written = 0, lrecl, num_extents;
        int     lstartrack = 0, lstarrec = 0, lstarvalid = 0;
        BYTE    *buffer;
        char    *pascii = NULL;
        char    zdsn[sizeof(f1dscb->ds1dsnam) + 1];     // ascii dsn

    // Kludge to avoid rewriting this code (for now):
    memcpy(&extent, (void *)&(dadsm->f1ext), sizeof(extent));

    num_extents = f1dscb->ds1noepv;
    lrecl = (f1dscb->ds1lrecl[0] << 8) | (f1dscb->ds1lrecl[1]);
    if (absvalid) {
        strcpy(zdsn, argdsn);
        if (debug) fprintf(stderr, "fbcopy absvalid\n");
    } else {
        make_asciiz(zdsn, sizeof(zdsn), 
                f1dscb->ds1dsnam, sizeof(f1dscb->ds1dsnam));
        if ((f1dscb->ds1lstar[0] !=0) || 
                (f1dscb->ds1lstar[1] != 0) || 
                (f1dscb->ds1lstar[2] != 0)) {
            lstartrack = (f1dscb->ds1lstar[0] << 8) | (f1dscb->ds1lstar[1]);
            lstarrec = f1dscb->ds1lstar[2];
            lstarvalid = 1;     // DS1LSTAR valid
        }
    }
    if (debug) {
        fprintf(stderr, "fbcopy zdsn %s\n", zdsn);
        fprintf(stderr, "fbcopy num_extents %d\n", num_extents);
        fprintf(stderr, "fbcopy lrecl %d\n", lrecl);
        fprintf(stderr, "fbcopy F1 DSCB\n");
        data_dump(f1dscb, sizeof(FORMAT1_DSCB));
        sayext(num_extents, (void *)&extent);
    }   
    if (verbose)                // DS1LSTAR = last block written TTR
        fprintf(stderr, 
                "fbcopy DS1LSTAR %2.2X%2.2X%2.2X lstartrack %d "
                "lstarrec %d lstarvalid %d\n",
                f1dscb->ds1lstar[0], f1dscb->ds1lstar[1], f1dscb->ds1lstar[2],
                lstartrack, lstarrec, lstarvalid);

    if (tran) {                 // need ASCII translation buffer?
        pascii = malloc(lrecl + 1);
        if (pascii == NULL) {
            fprintf(stderr, "fbcopy unable to allocate ascii buffer\n");
            return -1;
        }
    }

    while (1) {                 // output records until something stops us

//  Honor DS1LSTAR when valid

        if ((lstarvalid) && (trk == lstartrack) && (rec > lstarrec)) {
            if (verbose)
                fprintf(stderr, "fbcopy DS1LSTAR indicates EOF\n"
                        "fbcopy DS1LSTAR %2.2X%2.2X%2.2X "
                        "track %d record %d\n",
                        f1dscb->ds1lstar[0], f1dscb->ds1lstar[1], 
                        f1dscb->ds1lstar[2], trk, rec);
            rc_copy = recs_written;
            break;
        }

//  Convert TT to CCHH for upcoming read_block call

        if (trkconv != trk) {           // avoid converting for each block
            trkconv = trk;              // current track converted
            rc = convert_tt(trk, num_extents, extent, cif->heads, &cyl, &head);
            if (rc < 0) {
                fprintf(stderr, 
                        "fbcopy convert_tt track %5.5d, rc %d\n", trk, rc);
                if (absvalid) 
                    rc_copy = recs_written;
                else 
                    rc_copy = -1;
                break;
            }
            if (verbose > 1) 
                fprintf(stderr, "fbcopy convert TT %5.5d CCHH %4.4X %4.4X\n", 
                        trk, cyl, head);
        }

//  Read block from dasd

        if (verbose > 2) 
            fprintf(stderr, "fbcopy reading track %d "
                "record %d CCHHR = %4.4X %4.4X %2.2X\n",
                 trk, rec, cyl, head, rec);
        rc_rb = read_block(cif, cyl, head, rec, NULL, NULL, &buffer, &len);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
  		ASSERT(bp->lmfs_dev != NO_DEV);
 		ASSERT(bp->lmfs_flags & VMMC_BLOCK_LOCKED);
  		ASSERT(bp->data);

		if(ino != VMC_NO_INODE) {
			if(bp->lmfs_inode == VMC_NO_INODE
			|| bp->lmfs_inode != ino
			|| bp->lmfs_inode_offset != ino_off) {
				bp->lmfs_inode = ino;
				bp->lmfs_inode_offset = ino_off;
				bp->lmfs_needsetcache = 1;
			}
		}

  		return(bp);
  	} else {
  		/* This block is not the one sought. */
  		bp = bp->lmfs_hash; /* move to next block on hash chain */
  	}
  }

  /* Desired block is not on available chain. Find a free block to use. */
  if(bp) {
  	ASSERT(bp->lmfs_flags & VMMC_EVICTED);
  } else {
	if ((bp = front) == NULL) panic("all buffers in use: %d", nr_bufs);
  }
  assert(bp);

  rm_lru(bp);

  /* Remove the block that was just taken from its hash chain. */
  b = BUFHASH(bp->lmfs_blocknr);
  prev_ptr = buf_hash[b];
  if (prev_ptr == bp) {
	buf_hash[b] = bp->lmfs_hash;
  } else {
	/* The block just taken is not on the front of its hash chain. */
	while (prev_ptr->lmfs_hash != NULL)
		if (prev_ptr->lmfs_hash == bp) {
			prev_ptr->lmfs_hash = bp->lmfs_hash;	/* found it */
			break;
		} else {
			prev_ptr = prev_ptr->lmfs_hash;	/* keep looking */
		}
  }

  freeblock(bp);

  bp->lmfs_inode = ino;
  bp->lmfs_inode_offset = ino_off;

  bp->lmfs_flags = VMMC_BLOCK_LOCKED;
  bp->lmfs_needsetcache = 0;
  bp->lmfs_dev = dev;		/* fill in device number */
  bp->lmfs_blocknr = block;	/* fill in block number */
  ASSERT(bp->lmfs_count == 0);
  raisecount(bp);
  b = BUFHASH(bp->lmfs_blocknr);
  bp->lmfs_hash = buf_hash[b];

  buf_hash[b] = bp;		/* add to hash list */

  assert(dev != NO_DEV);

  /* Block is not found in our cache, but we do want it
   * if it's in the vm cache.
   */
  assert(!bp->data);
  assert(!bp->lmfs_bytes);
  if(vmcache) {
	if((bp->data = vm_map_cacheblock(dev, dev_off, ino, ino_off,
		&bp->lmfs_flags, fs_block_size)) != MAP_FAILED) {
		bp->lmfs_bytes = fs_block_size;
		ASSERT(!bp->lmfs_needsetcache);
		return bp;
	}
  }
  bp->data = NULL;

  /* Not in the cache; reserve memory for its contents. */

  lmfs_alloc_block(bp);

  assert(bp->data);

  if(only_search == PREFETCH) {
	/* PREFETCH: don't do i/o. */
	bp->lmfs_dev = NO_DEV;
  } else if (only_search == NORMAL) {
	read_block(bp);
  } else if(only_search == NO_READ) {
  	/* This block will be overwritten by new contents. */
  } else
	panic("unexpected only_search value: %d", only_search);

  assert(bp->data);

  return(bp);			/* return the newly acquired block */
}