patch-1.3.72 linux/drivers/char/ftape/ftape-read.c

• Lines: 679
• Date: Wed Mar 6 15:07:20 1996
• Orig file: v1.3.71/linux/drivers/char/ftape/ftape-read.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.71/linux/drivers/char/ftape/ftape-read.c linux/drivers/char/ftape/ftape-read.c
@@ -0,0 +1,678 @@
+/*
+ *      Copyright (C) 1993-1995 Bas Laarhoven.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; see the file COPYING.  If not, write to
+ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ $Source: /home/bas/distr/ftape-2.03b/RCS/ftape-read.c,v $
+ $Author: bas $
+ *
+ $Revision: 1.30 $
+ $Date: 1995/05/27 08:54:21 $
+ $State: Beta $
+ *
+ *      This file contains the reading code
+ *      for the QIC-117 floppy-tape driver for Linux.
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/ftape.h>
+#include <asm/segment.h>
+
+#include "tracing.h"
+#include "ftape-read.h"
+#include "qic117.h"
+#include "ftape-io.h"
+#include "ftape-ctl.h"
+#include "ftape-rw.h"
+#include "ftape-write.h"
+#include "ftape-eof.h"
+#include "ecc.h"
+#include "ftape-bsm.h"
+
+/*      Global vars.
+ */
+
+/*      Local vars.
+ */
+int buf_pos_rd = 0;
+int buf_len_rd = 0;
+
+void ftape_zap_read_buffers(void)
+{
+	int i;
+
+	for (i = 0; i < NR_BUFFERS; ++i) {
+		/*
+		 * changed to "fit" with dynamic allocation of tape_buffer. --khp
+		 */
+		buffer[i].address = tape_buffer[i];
+		buffer[i].status = waiting;
+		buffer[i].bytes = 0;
+		buffer[i].skip = 0;
+		buffer[i].retry = 0;
+	}
+	buf_len_rd = 0;
+	buf_pos_rd = 0;
+	eof_mark = 0;
+	ftape_state = idle;
+}
+
+static unsigned long convert_sector_map(buffer_struct * buff)
+{
+	TRACE_FUN(8, "convert_sector_map");
+	int i = 0;
+	unsigned long bad_map = get_bad_sector_entry(buff->segment_id);
+	unsigned long src_map = buff->soft_error_map | buff->hard_error_map;
+	unsigned long dst_map = 0;
+
+	if (bad_map || src_map) {
+		TRACEx1(5, "bad_map = 0x%08lx", bad_map);
+		TRACEx1(5, "src_map = 0x%08lx", src_map);
+	}
+	while (bad_map) {
+		while ((bad_map & 1) == 0) {
+			if (src_map & 1) {
+				dst_map |= (1 << i);
+			}
+			src_map >>= 1;
+			bad_map >>= 1;
+			++i;
+		}
+		/* (bad_map & 1) == 1 */
+		src_map >>= 1;
+		bad_map >>= 1;
+	}
+	if (src_map) {
+		dst_map |= (src_map << i);
+	}
+	if (dst_map) {
+		TRACEx1(5, "dst_map = 0x%08lx", dst_map);
+	}
+	TRACE_EXIT;
+	return dst_map;
+}
+
+int correct_and_copy(unsigned int tail, byte * destination)
+{
+	TRACE_FUN(8, "correct_and_copy");
+	struct memory_segment mseg;
+	int result;
+	BAD_SECTOR read_bad;
+
+	mseg.read_bad = convert_sector_map(&buffer[tail]);
+	mseg.marked_bad = 0;	/* not used... */
+	mseg.blocks = buffer[tail].bytes / SECTOR_SIZE;
+	mseg.data = buffer[tail].address;
+	/*    If there are no data sectors we can skip this segment.
+	 */
+	if (mseg.blocks <= 3) {
+		TRACE(4, "empty segment");
+		TRACE_EXIT;
+		return 0;
+	}
+	read_bad = mseg.read_bad;
+	history.crc_errors += count_ones(read_bad);
+	result = ecc_correct_data(&mseg);
+	if (read_bad != 0 || mseg.corrected != 0) {
+		TRACElx(4, "crc error map:", read_bad);
+		TRACElx(4, "corrected map:", mseg.corrected);
+		history.corrected += count_ones(mseg.corrected);
+	}
+	if (result == ECC_CORRECTED || result == ECC_OK) {
+		if (result == ECC_CORRECTED) {
+			TRACEi(3, "ecc corrected segment:", buffer[tail].segment_id);
+		}
+		memcpy(destination, mseg.data, (mseg.blocks - 3) * SECTOR_SIZE);
+		if ((read_bad ^ mseg.corrected) & mseg.corrected) {
+			/* sectors corrected without crc errors set */
+			history.crc_failures++;
+		}
+		TRACE_EXIT;
+		return (mseg.blocks - 3) * SECTOR_SIZE;
+	} else {
+		TRACEi(1, "ecc failure on segment", buffer[tail].segment_id);
+		history.ecc_failures++;
+		TRACE_EXIT;
+		return -EAGAIN;	/* should retry */
+	}
+	TRACE_EXIT;
+	return 0;
+}
+
+/*      Read given segment into buffer at address.
+ */
+int read_segment(unsigned segment_id, byte * address, int *eof_mark,
+		 int read_ahead)
+{
+	TRACE_FUN(5, "read_segment");
+	int read_done = 0;
+	int result = 0;
+	int bytes_read = 0;
+	int retry = 0;
+
+	TRACEi(5, "segment_id =", segment_id);
+	if (ftape_state != reading) {
+		if (ftape_state == writing) {
+			ftape_flush_buffers();	/* flush write buffer */
+			TRACE(5, "calling ftape_abort_operation");
+			result = ftape_abort_operation();
+			if (result < 0) {
+				TRACE(1, "ftape_abort_operation failed");
+				TRACE_EXIT;
+				return -EIO;
+			}
+		} else {
+			/* clear remaining read buffers */
+			ftape_zap_read_buffers();
+		}
+		ftape_state = reading;
+	}
+	if (segment_id >= segments_per_track * tracks_per_tape) {
+		TRACE(5, "reading past end of tape");
+		TRACE_EXIT;
+		return -ENOSPC;
+	}
+	for (;;) {
+		/*    Search all full buffers for the first matching the wanted segment.
+		 *    Clear other buffers on the fly.
+		 */
+		while (!read_done && buffer[tail].status == done) {
+			if (buffer[tail].segment_id == segment_id) {
+				unsigned eof_sector;
+				unsigned sector_count = 0;
+				unsigned long bsm = get_bad_sector_entry(segment_id);
+				int i;
+
+				/*        If out buffer is already full, return its contents.
+				 */
+				if (buffer[tail].deleted) {
+					TRACEi(5, "found segment in cache :", segment_id);
+					TRACE_EXIT;
+					/*  Return a value that read_header_segment understands.
+					 *  As this should only occur when searching for the header
+					 *  segments it shouldn't be misinterpreted elsewhere.
+					 */
+					return 0;
+				}
+				TRACEi(5, "found segment in cache :", segment_id);
+				eof_sector = check_for_eof(segment_id);
+				if (eof_sector > 0) {
+					TRACEi(5, "end of file mark in sector:", eof_sector);
+					for (i = 1; i < eof_sector; ++i) {
+						if ((bsm & 1) == 0) {
+							++sector_count;
+						}
+						bsm >>= 1;
+					}
+					*eof_mark = 1;
+				}
+				if (eof_sector != 1) {	/* not found or gt 1 */
+					result = correct_and_copy(tail, address);
+					TRACEi(5, "segment contains (bytes) :", result);
+					if (result < 0) {
+						if (result != -EAGAIN) {
+							TRACE_EXIT;
+							return result;
+						}
+						/* keep read_done == 0, will trigger ftape_abort_operation
+						 * because reading wrong segment.
+						 */
+						TRACE(1, "ecc failed, retry");
+						++retry;
+					} else {
+						read_done = 1;
+					}
+				} else {
+					read_done = 1;
+				}
+				if (eof_sector > 0) {
+					bytes_read = sector_count * SECTOR_SIZE;
+					TRACEi(5, "partial read count:", bytes_read);
+				} else {
+					bytes_read = result;
+				}
+			} else {
+				TRACEi(5, "zapping segment in cache :", buffer[tail].segment_id);
+			}
+			buffer[tail].status = waiting;
+			next_buffer(&tail);
+		}
+		if (!read_done && buffer[tail].status == reading) {
+			if (buffer[tail].segment_id == segment_id) {
+				int result = wait_segment(reading);
+				if (result < 0) {
+					if (result == -EINTR) {
+						TRACE_EXIT;
+						return result;
+					}
+					TRACE(1, "wait_segment failed while reading");
+					ftape_abort_operation();
+				}
+			} else {
+				/*        We're reading the wrong segment, stop runner.
+				 */
+				ftape_abort_operation();
+			}
+		}
+		/*    if just passed the last segment on a track, wait for BOT or EOT mark.
+		 */
+		if (runner_status == logical_eot) {
+			int status;
+			result = ftape_ready_wait(timeout.seek, &status);
+			if (result < 0) {
+				TRACE(1, "ftape_ready_wait waiting for eot/bot failed");
+			}
+			if ((status & (QIC_STATUS_AT_BOT | QIC_STATUS_AT_EOT)) == 0) {
+				TRACE(1, "eot/bot not reached");
+			}
+			runner_status = end_of_tape;
+		}
+		/*    should runner stop ?
+		 */
+		if (runner_status == aborting || runner_status == buffer_overrun ||
+		    runner_status == end_of_tape) {
+			if (runner_status != end_of_tape &&
+			 !(runner_status == aborting && !tape_running)) {
+				ftape_dumb_stop();
+			}
+			if (runner_status == aborting) {
+				if (buffer[head].status == reading || buffer[head].status == error) {
+					if (buffer[head].status == error) {
+						history.defects += count_ones(buffer[head].hard_error_map);
+					}
+					buffer[head].status = waiting;
+				}
+			}
+			runner_status = idle;	/* aborted ? */
+		}
+		/*    If segment to read is empty, do not start runner for it,
+		 *    but wait for next read call.
+		 */
+		if (get_bad_sector_entry(segment_id) == EMPTY_SEGMENT) {
+			bytes_read = 0;		/* flag empty segment */
+			read_done = 1;
+		}
+		/*  Allow escape from this loop on signal !
+		 */
+		if (current->signal & _DONT_BLOCK) {
+			TRACE(2, "interrupted by non-blockable signal");
+			TRACE_EXIT;
+			return -EINTR;
+		}
+		/*    If we got a segment: quit, or else retry up to limit.
+		 */
+		if (read_done) {
+			break;
+		}
+		if (retry > RETRIES_ON_ECC_ERROR) {
+			history.defects++;
+			TRACE(1, "too many retries on ecc failure");
+			TRACE_EXIT;
+			return -ENODATA;
+		}
+		/*    Now at least one buffer is empty !
+		 *    Restart runner & tape if needed.
+		 */
+		TRACEx3(8, "head: %d, tail: %d, runner_status: %d",
+			head, tail, runner_status);
+		TRACEx2(8, "buffer[].status, [head]: %d, [tail]: %d",
+			buffer[head].status, buffer[tail].status);
+		if (buffer[tail].status == waiting) {
+			setup_new_segment(&buffer[head], segment_id, -1);
+			if (!read_ahead) {
+				buffer[head].next_segment = 0;	/* disable read-ahead */
+			}
+			calc_next_cluster(&buffer[head]);
+			if (runner_status == idle) {
+				result = ftape_start_tape(segment_id,
+					     buffer[head].sector_offset);
+				if (result < 0) {
+					TRACEx1(1, "Error: segment %d unreachable", segment_id);
+					TRACE_EXIT;
+					return result;
+				}
+				runner_status = running;
+			}
+			buffer[head].status = reading;
+			setup_fdc_and_dma(&buffer[head], FDC_READ);
+		}
+	}
+	if (read_done) {
+		TRACE_EXIT;
+		return bytes_read;
+	} else {
+		TRACE(1, "too many retries");
+		TRACE_EXIT;
+		return -EIO;
+	}
+}
+
+int read_header_segment(byte * address)
+{
+	TRACE_FUN(5, "read_header_segment");
+	int i;
+	int result;
+	int header_segment = -1;
+	unsigned int max_floppy_side;
+	unsigned int max_floppy_track;
+	unsigned int max_floppy_sector;
+	int first_failed = 0;
+	int status;
+	int new_tape_len;
+
+	result = ftape_report_drive_status(&status);
+	if (result < 0) {
+		TRACE(1, "error: error_status or report failure");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	TRACE(5, "reading...");
+	ftape_last_segment.id = 68;	/* will allow us to read the header ! */
+	/*  We're looking for the first header segment.
+	 *  A header segment cannot contain bad sectors, therefor at the
+	 *  tape start, segments with bad sectors are (according to QIC-40/80)
+	 *  written with deleted data marks and must be skipped.
+	 */
+	used_header_segment = -1;
+	result = 0;
+	for (header_segment = 0;
+	     header_segment < ftape_last_segment.id && result == 0;
+	     ++header_segment) {
+		/*  Set no read-ahead, the isr will force read-ahead whenever
+		 *  it encounters deleted data !
+		 */
+		result = read_segment(header_segment, address, &status, 0);
+		if (result < 0 && !first_failed) {
+			TRACE(1, "header segment damaged, trying backup");
+			first_failed = 1;
+			result = 0;	/* force read of next (backup) segment */
+		}
+	}
+	if (result < 0 || header_segment >= ftape_last_segment.id) {
+		TRACE(1, "no readable header segment found");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	result = ftape_abort_operation();
+	if (result < 0) {
+		TRACE(1, "ftape_abort_operation failed");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	if (GET4(address, 0) != 0xaa55aa55) {
+		TRACE(1, "wrong signature in header segment");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	header_segment_1 = GET2(address, 6);
+	header_segment_2 = GET2(address, 8);
+	TRACEx2(2, "header segments are %d and %d",
+		header_segment_1, header_segment_2);
+	used_header_segment = (first_failed) ? header_segment_2 : header_segment_1;
+
+	/*    Verify tape parameters...
+	 *    QIC-40/80 spec:                 tape_parameters:
+	 *
+	 *    segments-per-track              segments_per_track
+	 *    tracks-per-cartridge            tracks_per_tape
+	 *    max-floppy-side                 (segments_per_track *
+	 *                                    tracks_per_tape - 1) /
+	 *                                    segments_per_head
+	 *    max-floppy-track                segments_per_head /
+	 *                                    segments_per_cylinder - 1
+	 *    max-floppy-sector               segments_per_cylinder *
+	 *                                    SECTORS_PER_SEGMENT
+	 */
+	format_code = (format_type) * (address + 4);
+	segments_per_track = GET2(address, 24);
+	tracks_per_tape = *(address + 26);
+	max_floppy_side = *(address + 27);
+	max_floppy_track = *(address + 28);
+	max_floppy_sector = *(address + 29);
+	TRACEx6(4, "(fmt/spt/tpc/fhm/ftm/fsm) = %d/%d/%d/%d/%d/%d",
+		format_code, segments_per_track, tracks_per_tape,
+		max_floppy_side, max_floppy_track, max_floppy_sector);
+	new_tape_len = tape_len;
+	switch (format_code) {
+	case fmt_425ft:
+		new_tape_len = 425;
+		break;
+	case fmt_normal:
+		if (tape_len == 0) {	/* otherwise 307 ft */
+			new_tape_len = 205;
+		}
+		break;
+	case fmt_1100ft:
+		new_tape_len = 1100;
+		break;
+	case fmt_wide:{
+			int segments_per_1000_inch = 1;		/* non-zero default for switch */
+			switch (qic_std) {
+			case QIC_TAPE_QIC40:
+				segments_per_1000_inch = 332;
+				break;
+			case QIC_TAPE_QIC80:
+				segments_per_1000_inch = 488;
+				break;
+			case QIC_TAPE_QIC3010:
+				segments_per_1000_inch = 730;
+				break;
+			case QIC_TAPE_QIC3020:
+				segments_per_1000_inch = 1430;
+				break;
+			}
+			new_tape_len = (1000 * segments_per_track +
+					(segments_per_1000_inch - 1)) / segments_per_1000_inch;
+			break;
+		}
+	default:
+		TRACE(1, "unknown tape format, please report !");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	if (new_tape_len != tape_len) {
+		tape_len = new_tape_len;
+		TRACEx1(1, "calculated tape length is %d ft", tape_len);
+		ftape_calc_timeouts();
+	}
+	if (segments_per_track == 0 && tracks_per_tape == 0 &&
+	    max_floppy_side == 0 && max_floppy_track == 0 &&
+	    max_floppy_sector == 0) {
+		/*  QIC-40 Rev E and earlier has no values in the header.
+		 */
+		segments_per_track = 68;
+		tracks_per_tape = 20;
+		max_floppy_side = 1;
+		max_floppy_track = 169;
+		max_floppy_sector = 128;
+	}
+	/*  This test will compensate for the wrong parameter on tapes
+	 *  formatted by Conner software.
+	 */
+	if (segments_per_track == 150 &&
+	    tracks_per_tape == 28 &&
+	    max_floppy_side == 7 &&
+	    max_floppy_track == 149 &&
+	    max_floppy_sector == 128) {
+		TRACE(-1, "the famous CONNER bug: max_floppy_side off by one !");
+		max_floppy_side = 6;
+	}
+	/*  This test will compensate for the wrong parameter on tapes
+	 *  formatted by Colorado Windows software.
+	 */
+	if (segments_per_track == 150 &&
+	    tracks_per_tape == 28 &&
+	    max_floppy_side == 6 &&
+	    max_floppy_track == 150 &&
+	    max_floppy_sector == 128) {
+		TRACE(-1, "the famous Colorado bug: max_floppy_track off by one !");
+		max_floppy_track = 149;
+	}
+	segments_per_head = ((max_floppy_sector / SECTORS_PER_SEGMENT) *
+			     (max_floppy_track + 1));
+	/*
+	 *    Verify drive_configuration with tape parameters
+	 */
+	if (segments_per_head == 0 || segments_per_cylinder == 0 ||
+	  ((segments_per_track * tracks_per_tape - 1) / segments_per_head
+	   != max_floppy_side) ||
+	    (segments_per_head / segments_per_cylinder - 1 != max_floppy_track) ||
+	(segments_per_cylinder * SECTORS_PER_SEGMENT != max_floppy_sector)
+#ifdef TESTING
+	    || (format_code == 4 && (max_floppy_track != 254 || max_floppy_sector != 128))
+#endif
+	    ) {
+		TRACE(1, "Tape parameters inconsistency, please report");
+		TRACE_EXIT;
+		return -EIO;
+	}
+	first_data_segment = GET2(address, 10);		/* first data segment */
+	TRACEi(4, "first data segment:", first_data_segment);
+	extract_bad_sector_map(address);
+	/*  Find the highest segment id that allows still one full
+	 *  deblock_buffer to be written to tape.
+	 */
+	ftape_last_segment.size = 0;
+	for (i = segments_per_track * tracks_per_tape - 1; i >= 0; --i) {
+		int space = SECTORS_PER_SEGMENT - 3 - count_ones(get_bad_sector_entry(i));
+		if (space > 0) {
+			ftape_last_segment.size += space;	/* sectors free */
+			ftape_last_segment.free = (ftape_last_segment.size -
+				   sizeof(deblock_buffer) / SECTOR_SIZE);
+			if (ftape_last_segment.free >= 0) {
+				ftape_last_segment.id = i;
+				TRACEx2(4, "`last' segment is %d, %d Kb",
+					ftape_last_segment.id, ftape_last_segment.size);
+				break;
+			}
+		}
+	}
+	/* Copy the failed sector log into our local buffer.
+	 */
+	if (!ftape_validate_label(&deblock_buffer[30])) {
+		TRACE(-1, "This tape has no `Linux raw format' label,\n"
+		      "***** Use `mt' to erase this tape if you want to use file marks !");
+	} else {
+		extract_file_marks(address);
+	}
+	ftape_reset_position();
+	TRACE_EXIT;
+	return 0;
+}
+
+int _ftape_read(char *buff, int req_len)
+{
+	TRACE_FUN(5, "_ftape_read");
+	int result = 0;
+	int cnt;
+	int to_do = req_len;
+	static int remaining;
+	int bytes_read = 0;
+
+	if (ftape_offline || !formatted || no_tape) {
+		TRACEx3(-1, "offline = %d, formatted = %d, no_tape = %d",
+			ftape_offline, formatted, no_tape);
+		result = -EIO;
+	} else {
+		history.used |= 1;
+		if (first_data_segment == -1) {
+			result = read_header_segment(deblock_buffer);
+		}
+	}
+	if (result < 0) {
+		TRACE_EXIT;
+		return result;
+	}
+	/*  As GNU tar doesn't accept partial read counts when the multiple
+	 *  volume flag is set, we make sure to return the requested amount
+	 *  of data. Except, of course, at the end of the tape or file mark.
+	 */
+	while (to_do > 0) {	/* don't return with a partial count ! */
+		/*  If we're reading the `last' segment(s) on tape, make sure we don't
+		 *  get more than 29 Kb from it (As it only contains this much).
+		 *  This works only for sequential access, so random access should
+		 *  stay away from this `last' segment.
+		 *  Note: ftape_seg_pos points to the next segment what will be
+		 *        read, so it's one too hight here!
+		 */
+		if (!eof_mark && ftape_seg_pos - 1 >= ftape_last_segment.id) {
+			TRACEi(5, "remaining of last segment:", remaining);
+			if (to_do > remaining) {
+				to_do = remaining;	/* fake a smaller request */
+				TRACE(5, "clipped request to remaining");
+			}
+		}
+		while (!eof_mark && buf_len_rd == 0) {
+			/*  When starting to read the `last' segment, set remaining
+			 */
+			if (ftape_seg_pos == ftape_last_segment.id) {
+				remaining = sizeof(deblock_buffer);
+				TRACEi(5, "remaining set to:", remaining);
+			}
+			result = read_segment(ftape_seg_pos, deblock_buffer, &eof_mark, 1);
+			if (result < 0) {
+				if (result == -ENODATA) {
+					/*  Unable to recover tape data, return error and skip bad spot.
+					 */
+					++ftape_seg_pos;
+				}
+				TRACEx1(4, "read_segment result: %d", result);
+				TRACE_EXIT;
+				return result;
+			}
+			/*  Allow escape from this loop on signal !
+			 */
+			if (current->signal & _DONT_BLOCK) {
+				TRACE(2, "interrupted by non-blockable signal");
+				TRACE_EXIT;
+				return -EINTR;
+			}
+			buf_pos_rd = 0;
+			buf_len_rd = result;
+			++ftape_seg_pos;
+		}
+		/*  Take as much as we can use
+		 */
+		cnt = (buf_len_rd < to_do) ? buf_len_rd : to_do;
+		TRACEi(7, "nr bytes just read:", cnt);
+		if (cnt > 0) {
+			result = verify_area(VERIFY_WRITE, buff, cnt);
+			if (result) {
+				TRACEx1(1, "verify_area failed, exitcode = %d", result);
+				TRACE_EXIT;
+				return -EIO;
+			}
+			memcpy_tofs(buff, deblock_buffer + buf_pos_rd, cnt);
+			buff += cnt;
+			to_do -= cnt;	/* what's left from req_len */
+			remaining -= cnt;	/* what remains on this tape */
+			bytes_read += cnt;	/* what we got so far */
+			buf_pos_rd += cnt;	/* index in buffer */
+			buf_len_rd -= cnt;	/* remaining bytes in buffer */
+		}
+		if (eof_mark && buf_len_rd == 0) {	/* nothing left */
+			TRACE(5, "partial count because of eof mark");
+			if (bytes_read == 0) {
+				eof_mark = 0;	/* no need for mark next read */
+			}
+			break;
+		}
+	}
+	TRACE_EXIT;
+	return bytes_read;
+}