2019-05-01 06:24:33 -07:00

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/*
* Copyright (C) 2018 John Forecast. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN FORECAST "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Support routines for reading/writing SIMH tape container files.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <sys/stat.h>
#include "fsio.h"
/*++
* t a p e V e r i f y
*
* Verify that the container format is valid, leaving the tape positioned
* at beginning-of-tape.
*
* Inputs:
*
* container - pointer open container file
* eot - return end-of-tape info here, NUL if not needed
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if format is valid, 0 otherwise
*
--*/
int tapeVerify(
FILE *container,
off_t *eot
)
{
int errorCount = 0, tmSeen = 0;
uint32_t meta, header, bc;
off_t position;
struct stat stat;
/*
* Determine the size of the file.
*/
fstat(fileno(container), &stat);
for (;;) {
position = ftello(container);
/*
* If we are positioned at the end-of-file, there is a tape mark or
* end-of-media marker missing. Treat it as though one is present.
*/
if (position == stat.st_size)
break;
if (fread(&meta, sizeof(meta), 1, container) != 1)
return 0;
bc = le32toh(meta);
switch (bc) {
case ST_TM:
if (++tmSeen <= 1)
break;
/* Treat second TM in a row as end of medium */
/* FALLTHROUGH */
case ST_EOM:
if (fseeko(container, -sizeof(meta), SEEK_CUR) != 0)
return 0;
if (errorCount)
printf("mount: Tape contains error records\n");
goto done;
case ST_GAP:
break;
default:
/*
* Record descriptor
*/
tmSeen = 0;
header = bc;
if ((bc & ST_ERROR) != 0)
errorCount++;
if ((bc & ST_MBZ) != 0)
return 0;
bc = RECLEN(bc & ST_LENGTH);
/*
* Check if we are seeking ouside of the file. If so, this is not
* a .tap container file.
*/
if ((position + bc + (2 * sizeof(meta))) > (unsigned long long)stat.st_size)
return 0;
if (fseeko(container, bc, SEEK_CUR) != 0)
return 0;
if (fread(&meta, sizeof(meta), 1, container) != 1)
return 0;
bc = le32toh(meta);
if (header != bc)
return 0;
}
}
done:
if (eot != NULL)
*eot = ftello(container);
/*
* Position at beginning-of-tape.
*/
if (fseeko(container, 0, SEEK_SET) == 0)
return 1;
return 0;
}
/*++
* t a p e G e t P o s i t i o n
*
* Get the current position of the tape.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* Current position of the tape
*
--*/
off_t tapeGetPosition(
FILE *container
)
{
return ftello(container);
}
/*++
* t a p e S e t P o s i t i o n
*
* Position the tape to a position previously obtained by tapeGetPosition().
*
* Inputs:
*
* container - pointer open container file
* pos - requested position
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if successfully positioned, 0 if error
*
--*/
int tapeSetPosition(
FILE *container,
off_t pos
)
{
return fseeko(container, pos, SEEK_SET) == 0 ? 1 : 0;
}
/*++
* t a p e S k i p R e c o r d F
*
* Skip over the next record in the forward direction.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
*
--*/
uint32_t tapeSkipRecordF(
FILE *container
)
{
return tapeReadRecordLength(container);
}
/*++
* t a p e S k i p R e c o r d R
*
* Skip over the next record in the reverse direction.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
*
--*/
uint32_t tapeSkipRecordR(
FILE *container
)
{
return tapeReadRecordLengthReverse(container);
}
/*++
* t a p e P e e k R e c o r d L e n g t h
*
* Get the length of the next record on the tape without actually reading
* the data or changing the current position of the tape.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing the container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
*
--*/
uint32_t tapePeekRecordLength(
FILE *container
)
{
off_t pos = ftello(container);
uint32_t meta;
if ((fread(&meta, sizeof(meta), 1, container) != 1) ||
(fseeko(container, pos, SEEK_SET) != 0))
return ST_FAIL;
return le32toh(meta);
}
/*++
* t a p e R e a d R e c o r d
*
* Read the next record from the tape into the specified buffer. If the
* buffer is smaller than the record, the entire record will be consumed,
* losing data.
*
* Inputs:
*
* container - pointer open container file
* buf - pointer to the buffer to receive the data
* len - length of the buffer
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing the container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
* if the buffer is smaller than the record, the
* length returned will be that of the buffer
*
--*/
uint32_t tapeReadRecord(
FILE *container,
void *buf,
int len
)
{
off_t pos = ftello(container);
uint32_t meta, bc, erflag, length;
if (fread(&meta, sizeof(meta), 1, container) != 1)
return ST_FAIL;
bc = le32toh(meta);
switch (bc) {
case ST_EOM:
case ST_TM:
return bc;
default:
erflag = bc & ST_ERROR;
bc &= ST_LENGTH;
length = (uint32_t)len;
if (bc < length)
length = bc;
if (fread(buf, sizeof(uint8_t), length, container) != length)
return ST_FAIL;
/*
* Now position the file after this record.
*/
pos += RECLEN(bc) + (2 * sizeof(meta));
if (fseeko(container, pos, SEEK_SET) != 0)
return ST_FAIL;
return erflag | length;
}
return ST_FAIL;
}
/*++
* t a p e R e a d R e c o r d L e n g t h
*
* Get the length of the next record on the tape without actually reading
* the data. The tape will be positioned at the start of the next record.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
*
--*/
uint32_t tapeReadRecordLength(
FILE *container
)
{
off_t pos = ftello(container);
uint32_t meta, bc, erflag;
if (fread(&meta, sizeof(meta), 1, container) != 1)
return ST_FAIL;
bc = le32toh(meta);
switch (bc) {
case ST_EOM:
case ST_TM:
return bc;
default:
erflag = bc & ST_ERROR;
bc &= ST_LENGTH;
/*
* Now position the file after this record.
*/
pos += RECLEN(bc) + (2 * sizeof(meta));
if (fseeko(container, pos, SEEK_SET) != 0)
return ST_FAIL;
return erflag | bc;
}
return ST_FAIL;
}
/*++
* t a p e R e a d R e c o r d L e n g t h R e v e r s e
*
* Get the length of the previous record on the tape without actually reading
* the data. The tape will be positioned at the start of the previous record.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* ST_FAIL - error accessing container file
* ST_EOM - end of media detected
* ST_TM - tape mark detected
* Other - record length (including error flag)
*
--*/
uint32_t tapeReadRecordLengthReverse(
FILE *container
)
{
uint32_t meta, bc, erflag;
off_t delta;
if ((fseeko(container, -sizeof(meta), SEEK_CUR) != 0) ||
(fread(&meta, sizeof(meta), 1, container) != 1))
return ST_FAIL;
bc = le32toh(meta);
switch (bc) {
case ST_EOM:
case ST_TM:
if (fseeko(container, -sizeof(meta), SEEK_CUR) != 0)
return ST_FAIL;
return bc;
default:
erflag = bc & ST_ERROR;
bc &= ST_LENGTH;
/*
* Now position the file before this record.
*/
delta = RECLEN(bc) + (2 * sizeof(meta));
if (fseeko(container, -delta, SEEK_CUR) != 0)
return ST_FAIL;
return erflag | bc;
}
return ST_FAIL;
}
/*++
* t a p e W r i t e R e c o r d
*
* Write a record to the tape at it's current position leaving the tape
* positioned after the newly written record.
*
* Inputs:
*
* container - pointer open container file
* buf - pointer to the record to be written
* len - length of the record
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if record was successfully written, 0 otherwise
*
--*/
int tapeWriteRecord(
FILE *container,
void *buf,
int len
)
{
uint32_t meta = htole16(len);
int datalen = (len + 1) & ~1;
if ((fwrite(&meta, sizeof(meta), 1, container) != 1) ||
(fwrite(buf, datalen, 1, container) != 1) ||
(fwrite(&meta, sizeof(meta), 1, container) != 1))
return 0;
return 1;
}
/*++
* t a p e W r i t e E O M
*
* Write an end-of-media record to the tape at it's current position and,
* optionally, backup the tape to before the newly written record.
*
* Inputs:
*
* container - pointer open container file
* backup - if 1, position the tape before the new record
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if EOM record successfully written, 0 otherwise
*
--*/
int tapeWriteEOM(
FILE *container,
int backup
)
{
uint32_t eom = htole32(ST_EOM);
if (fwrite(&eom, sizeof(eom), 1, container) != 1)
return 0;
if (backup)
if (fseeko(container, -sizeof(eom), SEEK_CUR) != 0)
return 0;
return 1;
}
/*++
* t a p e W r i t e T M
*
* Write a tape mark record to the tape at it's current position.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if EOM record successfully written, 0 otherwise
*
--*/
int tapeWriteTM(
FILE *container
)
{
uint32_t tm = htole32(ST_TM);
if (fwrite(&tm, sizeof(tm), 1, container) != 1)
return 0;
return 1;
}
/*++
* t a p e E O M
*
* Position the tape to the end of media so that a subsequent write will
* append a file to the tape.
*
* Inputs:
*
* container - pointer open container file
* eot - pointer to end-of-tape position, NULL if
* not available
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if tape successfully positioned, 0 otherwise
*
--*/
int tapeEOM(
FILE *container,
off_t *eot
)
{
int whence = eot == NULL ? SEEK_END : SEEK_SET;
off_t pos = eot == NULL ? 0 : *eot;
uint32_t bc1, bc2;
/*
* Move to the end of the tape and then look backwards to see how it is
* terminated.
*/
if (fseeko(container, pos, whence) == 0) {
if (ftello(container) == 0) {
/*
* Empty file, we are correctly positioned.
*/
return 1;
}
if ((bc1 = tapeReadRecordLengthReverse(container)) == ST_FAIL)
return 0;
if ((bc1 == ST_EOM) || (bc1 == ST_TM)) {
if (ftello(container) == 0) {
/*
* Only ST_EOM or ST_TM present, we are correctly positioned.
*/
return 1;
}
if ((bc2 = tapeReadRecordLengthReverse(container)) == ST_FAIL)
return 0;
if (bc2 == ST_TM) {
if (ftello(container) == 0) {
/*
* Only ST_TM followed by ST_TM or ST_EOM, we are correctly
* positioned
*/
return 1;
}
/*
* ST_TM followed by ST_TM or ST_EOM with at least one data block
* present, skip over the initial ST_TM.
*/
if (fseeko(container, sizeof(uint32_t), SEEK_CUR) == 0)
return 1;
} else {
/*
* Only a single ST_TM at the end of the container file. This
* indicates that there is a missing ST_TM or ST_EOM. Position
* the tape at the logical end-of-tape so that any subsequent file
* write will fix the problem.
*/
if (fseeko(container, pos, whence) == 0)
return 1;
}
}
}
return 0;
}
/*++
* t a p e R e w i n d
*
* Rewind the tape.
*
* Inputs:
*
* container - pointer open container file
*
* Outputs:
*
* None
*
* Returns:
*
* None
*
--*/
void tapeRewind(
FILE *container
)
{
fseeko(container, 0, SEEK_SET);
}
/*++
* t a p e S k i p F o r w a r d
*
* Skip forward over a number of files. If end-of-media is reached, the skip
* operation will terminate early.
*
* Inputs:
*
* container - pointer open container file
* count - # of files to skip
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if skip was successful, 0 otherwise
*
--*/
int tapeSkipForward(
FILE *container,
unsigned long count
)
{
unsigned long i;
uint32_t bc;
for (i = 0; i < count; i++) {
/*
* Peek at the next record. If it's a tape mark or end-of-media there
* are not more files to skip.
*/
switch (tapePeekRecordLength(container)) {
case ST_FAIL:
return 0;
case ST_TM:
case ST_EOM:
return 1;
}
/*
* Skip forward over 1 file.
*/
do {
switch (bc = tapeReadRecordLength(container)) {
case ST_FAIL:
return 0;
case ST_EOM:
if (fseeko(container, -sizeof(uint32_t), SEEK_CUR) != 0)
return 0;
break;
}
} while ((bc != ST_TM) && (bc != ST_EOM));
}
return 1;
}
/*++
* t a p e S k i p R e v e r s e
*
* Skip backwards over a number of files. If beginning-of-tape is reached,
* the skip operation will terminate early.
*
* Inputs:
*
* container - pointer open container file
* count - # of files to skip
*
* Outputs:
*
* None
*
* Returns:
*
* 1 if skip was successful, 0 otherwise
*
--*/
int tapeSkipReverse(
FILE *container,
unsigned long count
)
{
unsigned long i;
uint32_t bc;
for (i = 0; i < count; i++) {
/*
* If we are at beginning-of-tape, there are no more files to skip.
*/
if (ftello(container) == 0)
return 1;
/*
* If we are not at the beginning of tape, the previous record should
* be a tape mark.
*/
if (tapeReadRecordLengthReverse(container) != ST_TM)
return 0;
/*
* Now skip over the remainder of the file.
*/
do {
if ((bc = tapeReadRecordLengthReverse(container)) == ST_FAIL)
return 0;
} while ((bc != ST_TM) && (ftello(container) != 0));
/*
* Skip over the tape mark since it marks the end of the previous file.
*/
if (bc == ST_TM) {
if (fseeko(container, sizeof(uint32_t), SEEK_CUR) != 0)
return 0;
}
}
return 1;
}