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

• Lines: 556
• Date: Wed Mar 6 15:07:19 1996
• Orig file: v1.3.71/linux/drivers/char/ftape/ftape-eof.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.71/linux/drivers/char/ftape/ftape-eof.c linux/drivers/char/ftape/ftape-eof.c
@@ -0,0 +1,555 @@
+
+/*
+ *      Copyright (C) 1994-1995 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-eof.c,v $
+ $Author: bas $
+ *
+ $Revision: 1.21 $
+ $Date: 1995/05/27 08:54:21 $
+ $State: Beta $
+ *
+ *      This file contains the eof mark handling code
+ *      for the QIC-40/80 floppy-tape driver for Linux.
+ */
+
+#include <linux/module.h>
+#include <linux/ftape.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+
+#include "tracing.h"
+#include "ftape-eof.h"
+#include "ftape-write.h"
+#include "ftape-read.h"
+#include "ftape-rw.h"
+#include "ftape-ctl.h"
+#include "ftape-bsm.h"
+
+/*      Global vars.
+ */
+int failed_sector_log_changed = 0;
+int eof_mark = 0;
+
+/*      Local vars.
+ */
+static struct failed_sector_entry {
+	unsigned short segment;
+	unsigned short sector;
+} *eof_mark_ptr;
+
+typedef union {
+	struct failed_sector_entry mark;
+	unsigned long entry;
+} eof_mark_union;
+
+/*  a copy of the failed sector log from the header segment.
+ */
+static eof_mark_union eof_map[(2048 - 256) / 4];
+
+/*  index into eof_map table pointing to last found eof mark.
+ */
+static int eof_index;
+
+/*  number of eof marks (entries in bad sector log) on tape.
+ */
+static int nr_of_eof_marks = -1;
+
+static char linux_tape_label[] = "Linux raw format V";
+enum {
+	min_fmt_version = 1, max_fmt_version = 2
+};
+static unsigned ftape_fmt_version = 0;
+
+
+/*  Ftape (mis)uses the bad sector log to record end-of-file marks.
+ *  Initially (when the tape is erased) all entries in the bad sector
+ *  log are added to the tape's bad sector map. The bad sector log
+ *  then is cleared.
+ *
+ *  The bad sector log normally contains entries of the form:
+ *  even 16-bit word: segment number of bad sector
+ *   odd 16-bit word: encoded date
+ *  There can be a total of 448 entries (1792 bytes).
+ *
+ *  My guess is that no program is using this bad sector log (the
+ *  format seems useless as there is no indication of the bad sector
+ *  itself, only the segment)
+ *  However, if any program does use the bad sector log, the format
+ *  used by ftape will let the program think there are some bad sectors
+ *  and no harm is done.
+ *  
+ *  The eof mark entries that ftape stores in the bad sector log:
+ *  even 16-bit word: segment number of eof mark
+ *   odd 16-bit word: sector number of eof mark [1..32]
+ *  
+ *  The eof_map as maintained is a sorted list of eof mark entries.
+ *
+ *
+ *  The tape name field in the header segments is used to store a
+ *  linux tape identification string and a version number.
+ *  This way the tape can be recognized as a Linux raw format
+ *  tape when using tools under other OS's.
+ *
+ *  'Wide' QIC tapes (format code 4) don't have a failed sector list
+ *  anymore. That space is used for the (longer) bad sector map that
+ *  now is a variable length list too.
+ *  We now store our end-of-file marker list after the bad-sector-map
+ *  on tape. The list is delimited by a (long) 0 entry.
+ */
+
+int ftape_validate_label(char *label)
+{
+	TRACE_FUN(8, "ftape_validate_label");
+	int result = 0;
+
+	TRACEx1(4, "tape  label = `%s'", label);
+	ftape_fmt_version = 0;
+	if (memcmp(label, linux_tape_label, strlen(linux_tape_label)) == 0) {
+		int pos = strlen(linux_tape_label);
+		while (label[pos] >= '0' && label[pos] <= '9') {
+			ftape_fmt_version *= 10;
+			ftape_fmt_version = label[pos++] - '0';
+		}
+		result = (ftape_fmt_version >= min_fmt_version &&
+			  ftape_fmt_version <= max_fmt_version);
+	}
+	TRACEx1(4, "format version = %d", ftape_fmt_version);
+	TRACE_EXIT;
+	return result;
+}
+
+static byte *
+ find_end_of_eof_list(byte * ptr, byte * limit)
+{
+	while (ptr + 3 < limit) {
+		if (*(unsigned long *) ptr) {
+			++(unsigned long *) ptr;
+		} else {
+			return ptr;
+		}
+	}
+	return NULL;
+}
+
+void reset_eof_list(void)
+{
+	TRACE_FUN(8, "reset_eof_list");
+
+	eof_mark_ptr = &eof_map[0].mark;
+	eof_index = 0;
+	eof_mark = 0;
+	TRACE_EXIT;
+}
+
+/*  Test if `segment' has an eof mark set (optimized for sequential access).
+ *  return 0 if not eof mark or sector number (> 0) if eof mark set.
+ */
+int check_for_eof(unsigned segment)
+{
+	TRACE_FUN(8, "check_for_eof");
+	static unsigned last_reference = INT_MAX;
+	int result;
+
+	if (segment < last_reference) {
+		reset_eof_list();
+	}
+	last_reference = segment;
+	while (eof_index < nr_of_eof_marks && segment > eof_mark_ptr->segment) {
+		++eof_mark_ptr;
+		++eof_index;
+	}
+	if (eof_index < nr_of_eof_marks && segment == eof_mark_ptr->segment) {
+		TRACEx3(5, "hit mark %d/%d at index %d",
+			eof_map[eof_index].mark.segment, eof_map[eof_index].mark.sector,
+			eof_index);
+		if (eof_mark_ptr->sector >= SECTORS_PER_SEGMENT) {
+			TRACEx2(-1, "Bad file mark detected: %d/%d",
+			    eof_mark_ptr->segment, eof_mark_ptr->sector);
+			result = 0;	/* return bogus (but valid) value */
+		} else {
+			result = eof_mark_ptr->sector;
+		}
+	} else {
+		result = 0;
+	}
+	TRACE_EXIT;
+	return result;
+}
+
+void clear_eof_mark_if_set(unsigned segment, unsigned byte_count)
+{
+	TRACE_FUN(5, "clear_eof_mark_if_set");
+	if (ftape_fmt_version != 0 &&
+	    check_for_eof(segment) > 0 &&
+	    byte_count >= eof_mark_ptr->sector * SECTOR_SIZE) {
+		TRACEx3(5, "clearing mark %d/%d at index %d",
+		 eof_mark_ptr->segment, eof_mark_ptr->sector, eof_index);
+		memmove(&eof_map[eof_index], &eof_map[eof_index + 1],
+			(nr_of_eof_marks - eof_index) * sizeof(*eof_map));
+		--nr_of_eof_marks;
+		failed_sector_log_changed = 1;
+	}
+	TRACE_EXIT;
+}
+
+void put_file_mark_in_map(unsigned segment, unsigned sector)
+{
+	TRACE_FUN(8, "put_file_mark_in_map");
+	eof_mark_union new;
+	int index;
+	eof_mark_union *ptr;
+
+	if (ftape_fmt_version != 0) {
+		new.mark.segment = segment;
+		new.mark.sector = sector;
+		for (index = 0, ptr = &eof_map[0];
+		  index < nr_of_eof_marks && ptr->mark.segment < segment;
+		     ++index, ++ptr) {
+		}
+		if (index < nr_of_eof_marks) {
+			if (ptr->mark.segment == segment) {
+				/* overwrite */
+				if (ptr->mark.sector == sector) {
+					TRACEx2(5, "mark %d/%d already exists",
+						new.mark.segment, new.mark.sector);
+				} else {
+					TRACEx5(5, "overwriting %d/%d at index %d with %d/%d",
+						ptr->mark.segment, ptr->mark.sector, index,
+						new.mark.segment, new.mark.sector);
+					ptr->entry = new.entry;
+					failed_sector_log_changed = 1;
+				}
+			} else {
+				/* insert */
+				TRACEx5(5, "inserting %d/%d at index %d before %d/%d",
+				new.mark.segment, new.mark.sector, index,
+				    ptr->mark.segment, ptr->mark.sector);
+				memmove(ptr + 1, ptr, (nr_of_eof_marks - index) * sizeof(*eof_map));
+				ptr->entry = new.entry;
+				++nr_of_eof_marks;
+				failed_sector_log_changed = 1;
+			}
+		} else {
+			/* append */
+			TRACEx3(5, "appending %d/%d at index %d",
+				new.mark.segment, new.mark.sector, index);
+			ptr->entry = new.entry;
+			++nr_of_eof_marks;
+			failed_sector_log_changed = 1;
+		}
+	}
+	TRACE_EXIT;
+}
+
+/*  Write count file marks to tape starting at first non-bad
+ *  sector following the given segment and sector.
+ *  sector = base 1 !
+ */
+int ftape_weof(unsigned count, unsigned segment, unsigned sector)
+{
+	TRACE_FUN(5, "ftape_weof");
+	int result = 0;
+	unsigned long mask = get_bad_sector_entry(segment);
+	unsigned sector_nr = 0;
+
+	if (ftape_fmt_version != 0) {
+		if (sector < 1 || sector > 29 ||
+		    segment + count >= ftape_last_segment.id) {
+			TRACEx3(5, "parameter out of range: %d, %d, %d", count, segment, sector);
+			result = -EIO;
+		} else {
+			while (count-- > 0) {
+				do {	/* count logical sectors */
+					do {	/* skip until good sector */
+						while (mask & 1) {	/* skip bad sectors */
+							++sector_nr;
+							mask >>= 1;
+						}
+						if (sector_nr >= 29) {
+							if (++segment >= ftape_last_segment.id) {
+								TRACEx1(5, "segment out of range: %d", segment);
+								result = -EIO;
+								break;
+							}
+							mask = get_bad_sector_entry(segment);
+							sector_nr = 0;
+						}
+					} while (mask & 1);
+					++sector_nr;	/* point to good sector */
+					mask >>= 1;
+				} while (--sector);
+				if (result >= 0) {
+					TRACEx2(5, "writing filemark %d/%d", segment, sector_nr);
+					put_file_mark_in_map(segment, sector_nr);
+					++segment;	/* next segment */
+					sector_nr = 0;
+					sector = 1;	/* first sector */
+				}
+			}
+		}
+	} else {
+		result = -EPERM;
+	}
+	TRACE_EXIT;
+	return result;
+}
+
+int ftape_erase(void)
+{
+	TRACE_FUN(5, "ftape_erase");
+	int result = 0;
+	int i;
+	unsigned long now = 0;
+	byte *buffer = deblock_buffer;
+
+	if (write_protected) {
+		result = -EROFS;
+	} else {
+		result = read_header_segment(buffer);
+		if (result >= 0) {
+			/*  Copy entries from bad-sector-log into bad-sector-map
+			 */
+			TRACEx1(5, "old label: `%s'", (char *) (buffer + 30));
+			if (!ftape_validate_label((char *) &buffer[30])) {
+				TRACE(5, "invalid label, overwriting with new");
+				memset(buffer + 30, 0, 44);
+				memcpy(buffer + 30, linux_tape_label, strlen(linux_tape_label));
+				buffer[30 + strlen(linux_tape_label)] = '2';
+				TRACEx1(5, "new label: `%s'", (char *) (buffer + 30));
+				PUT4(buffer, 74, now);
+				if (format_code != 4) {
+					for (i = 0; i < nr_of_eof_marks; ++i) {
+						unsigned failing_segment = eof_map[i].mark.segment;
+
+						if (!valid_segment_no(failing_segment)) {
+							TRACEi(4, "bad entry in failed sector log:", failing_segment);
+						} else {
+							put_bad_sector_entry(failing_segment, EMPTY_SEGMENT);
+							TRACEx2(4, "moved entry %d from failed sector log (%d)",
+								i, failing_segment);
+						}
+					}
+				}
+			}
+			/*  Clear failed sector log: remove all tape marks
+			 */
+			failed_sector_log_changed = 1;
+			memset(eof_map, 0, sizeof(eof_map));
+			nr_of_eof_marks = 0;
+			ftape_fmt_version = max_fmt_version;
+#if 0
+			fix_tape(buffer);	/* see ftape-bsm.c ! */
+#endif
+			result = ftape_update_header_segments(buffer, 1);
+			prevent_flush();	/* prevent flush_buffers writing file marks */
+			reset_eof_list();
+		}
+	}
+	TRACE_EXIT;
+	return result;
+}
+
+void extract_file_marks(byte * address)
+{
+	TRACE_FUN(8, "extract_file_marks");
+	int i;
+
+	if (format_code == 4) {
+		byte *end;
+		byte *start = find_end_of_bsm_list(address + 256,
+					     address + 29 * SECTOR_SIZE);
+
+		memset(eof_map, 0, sizeof(eof_map));
+		nr_of_eof_marks = 0;
+		if (start) {
+			start += 3;	/* skip end of list mark */
+			end = find_end_of_eof_list(start, address + 29 * SECTOR_SIZE);
+			if (end && end - start <= sizeof(eof_map)) {
+				nr_of_eof_marks = (end - start) / sizeof(unsigned long);
+				memcpy(eof_map, start, end - start);
+			} else {
+				TRACE(1, "File Mark List is too long or damaged !");
+			}
+		} else {
+			TRACE(1, "Bad Sector List is too long or damaged !");
+		}
+	} else {
+		memcpy(eof_map, address + 256, sizeof(eof_map));
+		nr_of_eof_marks = GET2(address, 144);
+	}
+	TRACEi(4, "number of file marks:", nr_of_eof_marks);
+	if (ftape_fmt_version == 1) {
+		TRACE(-1, "swapping version 1 fields");
+		/*  version 1 format uses swapped sector and segment fields, correct that !
+		 */
+		for (i = 0; i < nr_of_eof_marks; ++i) {
+			unsigned short tmp = eof_map[i].mark.segment;
+			eof_map[i].mark.segment = eof_map[i].mark.sector;
+			eof_map[i].mark.sector = tmp;
+		}
+	}
+	for (i = 0; i < nr_of_eof_marks; ++i) {
+		TRACEx2(4, "eof mark: %5d/%2d",
+			eof_map[i].mark.segment, eof_map[i].mark.sector);
+	}
+	reset_eof_list();
+	TRACE_EXIT;
+}
+
+int update_failed_sector_log(byte * buffer)
+{
+	TRACE_FUN(8, "update_failed_sector_log");
+
+	if (ftape_fmt_version != 0 && failed_sector_log_changed) {
+		if (ftape_fmt_version == 1) {
+			TRACE(-1, "upgrading version 1 format to version 2");
+			/*  version 1 will be upgraded to version 2 when written.
+			 */
+			buffer[30 + strlen(linux_tape_label)] = '2';
+			ftape_fmt_version = 2;
+			TRACEx1(-1, "new tape label = \"%s\"", &buffer[30]);
+		}
+		if (format_code == 4) {
+			byte *dest = find_end_of_bsm_list(buffer + 256,
+					  buffer + 29 * SECTOR_SIZE) + 3;
+
+			if (dest) {
+				TRACEx2(4, "eof_map at byte offset %6d, size %d",
+					dest - buffer - 256, nr_of_eof_marks * sizeof(unsigned long));
+				memcpy(dest, eof_map, nr_of_eof_marks * sizeof(unsigned long));
+				PUT4(dest, nr_of_eof_marks * sizeof(unsigned long), 0);
+			}
+		} else {
+			memcpy(buffer + 256, eof_map, sizeof(eof_map));
+			PUT2(buffer, 144, nr_of_eof_marks);
+		}
+		failed_sector_log_changed = 0;
+		return 1;
+	}
+	TRACE_EXIT;
+	return 0;
+}
+
+int ftape_seek_eom(void)
+{
+	TRACE_FUN(5, "ftape_seek_eom");
+	int result = 0;
+	unsigned eom;
+
+	if (first_data_segment == -1) {
+		result = read_header_segment(deblock_buffer);
+	}
+	if (result >= 0 && ftape_fmt_version != 0) {
+		eom = first_data_segment;
+		eof_index = 0;
+		eof_mark_ptr = &eof_map[0].mark;
+		/*  If fresh tape, count should be zero but we don't
+		 *  want to worry about the case it's one.
+		 */
+		for (eof_index = 1, eof_mark_ptr = &eof_map[1].mark;
+		     eof_index < nr_of_eof_marks; ++eof_index, ++eof_mark_ptr) {
+			/*  The eom is recorded as two eof marks in succeeding segments
+			 *  where the second one is always at segment number 1.
+			 */
+			if (eof_mark_ptr->sector == 1) {
+				if (eof_mark_ptr->segment == (eof_mark_ptr - 1)->segment + 1) {
+					eom = eof_mark_ptr->segment;
+					break;
+				}
+			}
+		}
+		ftape_seg_pos = eom;
+		TRACEx1(5, "eom found at segment %d", eom);
+	} else {
+		TRACE(5, "Couldn't get eof mark table");
+		result = -EIO;
+	}
+	TRACE_EXIT;
+	return result;
+}
+
+int ftape_seek_eof(unsigned count)
+{
+	TRACE_FUN(5, "ftape_seek_eof");
+	int result = 0;
+	enum {
+		not = 0, begin, end
+	} bad_seek = not;
+
+	if (first_data_segment == -1) {
+		result = read_header_segment(deblock_buffer);
+	}
+	TRACEx1(5, "tape positioned at segment %d", ftape_seg_pos);
+	if (ftape_fmt_version == 0) {
+		result = -1;
+	}
+	if (result >= 0 && count != 0) {
+		for (eof_index = 0; eof_index <= nr_of_eof_marks; ++eof_index) {
+			if (eof_index == nr_of_eof_marks ||	/* start seeking after last mark */
+			    ftape_seg_pos <= eof_map[eof_index].mark.segment) {
+				eof_index += count;
+				if (eof_index < 1) {	/* begin of tape */
+					ftape_seg_pos = first_data_segment;
+					if (eof_index < 0) {	/* `before' begin of tape */
+						eof_index = 0;
+						bad_seek = begin;
+					}
+				} else if (eof_index >= nr_of_eof_marks) {	/* `after' end of tape */
+					ftape_seg_pos = segments_per_track * tracks_per_tape;
+					if (eof_index > nr_of_eof_marks) {
+						eof_index = nr_of_eof_marks;
+						bad_seek = end;
+					}
+				} else {	/* after requested file mark */
+					ftape_seg_pos = eof_map[eof_index - 1].mark.segment + 1;
+				}
+				eof_mark_ptr = &eof_map[eof_index].mark;
+				break;
+			}
+		}
+	}
+	if (result < 0) {
+		TRACE(5, "Couldn't get eof mark table");
+		result = -EIO;
+	} else if (bad_seek != not) {
+		TRACEx1(1, "seek reached %s of tape",
+			(bad_seek == begin) ? "begin" : "end");
+		result = -EIO;
+	} else {
+		TRACEx1(5, "tape repositioned to segment %d", ftape_seg_pos);
+	}
+	TRACE_EXIT;
+	return result;
+}
+
+int ftape_file_no(daddr_t * f_no, daddr_t * b_no)
+{
+	TRACE_FUN(5, "ftape_file_no");
+	int result = 0;
+	int i;
+
+	*f_no = eof_index;
+	*b_no = ftape_seg_pos;
+	TRACEi(4, "number of file marks:", nr_of_eof_marks);
+	for (i = 0; i < nr_of_eof_marks; ++i) {
+		TRACEx2(4, "eof mark: %5d/%2d",
+			eof_map[i].mark.segment, eof_map[i].mark.sector);
+	}
+	TRACE_EXIT;
+	return result;
+}