ftape-read.c

arm平台上的uclinux系统全部源代码

			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 that will be
		 *        read, so it's one too high 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;
}