/*
   Bacula(R) - The Network Backup Solution

   Copyright (C) 2000-2016 Kern Sibbald

   The original author of Bacula is Kern Sibbald, with contributions
   from many others, a complete list can be found in the file AUTHORS.

   You may use this file and others of this release according to the
   license defined in the LICENSE file, which includes the Affero General
   Public License, v3.0 ("AGPLv3") and some additional permissions and
   terms pursuant to its AGPLv3 Section 7.

   This notice must be preserved when any source code is 
   conveyed and/or propagated.

   Bacula(R) is a registered trademark of Kern Sibbald.
*/

/*
 * Please note!!! The VTAPE device is for testing only.
 *  It simulates a tape drive, which is useful for testing
 *  without a real drive, but is inefficient for writing
 *  disk volumes. In addition, we do not test for every
 *  possible error condition, so please do not use this
 *  in production.
 */
/*

Device {
  Name = Drive-1                      #
  Maximum File Size = 800M
  Maximum Volume Size = 3G
  Device Type = TAPE
  Archive Device = /tmp/fake
  Media Type = DLT-8000
  AutomaticMount = yes;               # when device opened, read it
  AlwaysOpen = yes;
  RemovableMedia = yes;
  RandomAccess = no;
}

  Block description :

  block {
    int32  size;
    void   *data;
  }

  EOF description :

  EOF {
    int32  size=0;
  }


 */

#include "bacula.h"             /* define 64bit file usage */
#include "stored.h"

#ifdef USE_VTAPE
#include <fcntl.h>

static int dbglevel = 100;
#define FILE_OFFSET 30

void vtape_debug(int level)
{
   dbglevel = level;
}

/* DEVICE virtual that we redefine. */
int vtape::d_ioctl(int fd, ioctl_req_t request, char *op)
{
   int result = 0;

   if (request == MTIOCTOP) {
      result = tape_op((mtop *)op);
   } else if (request == MTIOCGET) {
      result = tape_get((mtget *)op);
   } else if (request == MTIOCPOS) {
      result = tape_pos((mtpos *)op);
   } else {
      errno = ENOTTY;
      result = -1;
   }

   return result;
}

int vtape::tape_op(struct mtop *mt_com)
{
   int result=0;
   int count = mt_com->mt_count;

   if (!online) {
      errno = ENOMEDIUM;
      return -1;
   }

   switch (mt_com->mt_op)
   {
   case MTRESET:
   case MTNOP:
   case MTSETDRVBUFFER:
      break;

   default:
   case MTRAS1:
   case MTRAS2:
   case MTRAS3:
   case MTSETDENSITY:
      errno = ENOTTY;
      result = -1;
      break;

   case MTFSF:                  /* Forward space over mt_count filemarks. */
      do {
         result = fsf();
      } while (--count > 0 && result == 0);
      break;

   case MTBSF:                  /* Backward space over mt_count filemarks. */
      do {
         result = bsf();
      } while (--count > 0 && result == 0);
      break;

   case MTFSR:      /* Forward space over mt_count records (tape blocks). */
/*
    file number = 1
    block number = 0

    file number = 1
    block number = 1

    mt: /dev/lto2: Erreur d'entree/sortie

    file number = 2
    block number = 0
*/
      /* tester si on se trouve a la fin du fichier */
      result = fsr(mt_com->mt_count);
      break;

   case MTBSR:      /* Backward space over mt_count records (tape blocks). */
      result = bsr(mt_com->mt_count);
      break;

   case MTWEOF:                 /* Write mt_count filemarks. */
      do {
         result = weof();
      } while (result == 0 && --count > 0);
      break;

   case MTREW:                  /* Rewind. */
      Dmsg0(dbglevel, "rewind vtape\n");
      check_eof();
      atEOF = atEOD = false;
      atBOT = true;
      current_file = 0;
      current_block = 0;
      lseek(fd, 0, SEEK_SET);
      result = !read_fm(VT_READ_EOF);
      break;

   case MTOFFL:                 /* put tape offline */
      result = offline() ? 0 : -1;
      break;

   case MTRETEN:                /* Re-tension tape. */
      result = 0;
      break;

   case MTBSFM:                 /* not used by bacula */
      errno = EIO;
      result = -1;
      break;

   case MTFSFM:                 /* not used by bacula */
      errno = EIO;
      result = -1;
      break;

   case MTEOM:/* Go to the end of the recorded media (for appending files). */
      while (next_FM) {
         lseek(fd, next_FM, SEEK_SET);
         if (read_fm(VT_READ_EOF)) {
            current_file++;
         }
      }
      boffset_t l;
      while (::read(fd, &l, sizeof(l)) > 0) {
         if (l) {
            lseek(fd, l, SEEK_CUR);
         } else {
            ASSERT(0);
         }
         Dmsg0(dbglevel, "skip 1 block\n");
      }
      current_block = -1;
      atEOF = false;
      atEOD = true;

/*
   file number = 3
   block number = -1
*/
      /* Can be at EOM */
      break;

   case MTERASE:                /* not used by bacula */
      atEOD = true;
      atEOF = false;
      atEOT = false;

      current_file = 0;
      current_block = -1;
      lseek(fd, 0, SEEK_SET);
      read_fm(VT_READ_EOF);
      truncate_file();
      break;

   case MTSETBLK:
      break;

   case MTSEEK:
      break;

   case MTTELL:
      break;

   case MTFSS:
      break;

   case MTBSS:
      break;

   case MTWSM:
      break;

   case MTLOCK:
      break;

   case MTUNLOCK:
      break;

   case MTLOAD:
      break;

   case MTUNLOAD:
      break;

   case MTCOMPRESSION:
      break;

   case MTSETPART:
      break;

   case MTMKPART:
      break;
   }

   return result == 0 ? 0 : -1;
}

int vtape::tape_get(struct mtget *mt_get)
{
   int density = 1;
   int block_size = 1024;

   mt_get->mt_type = MT_ISSCSI2;
   mt_get->mt_blkno = current_block;
   mt_get->mt_fileno = current_file;

   mt_get->mt_resid = -1;
//   pos_info.PartitionBlockValid ? pos_info.Partition : (ULONG)-1;

   /* TODO */
   mt_get->mt_dsreg =
      ((density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK) |
      ((block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK);


   mt_get->mt_gstat = 0x00010000;  /* Immediate report mode.*/

   if (atEOF) {
      mt_get->mt_gstat |= 0x80000000;     // GMT_EOF
   }

   if (atBOT) {
      mt_get->mt_gstat |= 0x40000000;     // GMT_BOT
   }
   if (atEOT) {
      mt_get->mt_gstat |= 0x20000000;     // GMT_EOT
   }

   if (atEOD) {
      mt_get->mt_gstat |= 0x08000000;     // GMT_EOD
   }

   if (0) { //WriteProtected) {
      mt_get->mt_gstat |= 0x04000000;     // GMT_WR_PROT
   }

   if (online) {
      mt_get->mt_gstat |= 0x01000000;     // GMT_ONLINE
   } else {
      mt_get->mt_gstat |= 0x00040000;  // GMT_DR_OPEN
   }
   mt_get->mt_erreg = 0;

   return 0;
}

int vtape::tape_pos(struct mtpos *mt_pos)
{
   if (current_block >= 0) {
      mt_pos->mt_blkno = current_block;
      return 0;
   }

   return -1;
}

/*
 * This function try to emulate the append only behavior
 * of a tape. When you wrote something, data after the
 * current position are discarded.
 */
int vtape::truncate_file()
{
   Dmsg2(dbglevel, "truncate %i:%i\n", current_file, current_block);
   ftruncate(fd, lseek(fd, 0, SEEK_CUR));
   last_file = current_file;
   atEOD=true;
   update_pos();
   return 0;
}

vtape::~vtape()
{
}

vtape::vtape()
{
   lockfd = fd = -1;

   atEOF = false;
   atBOT = false;
   atEOT = false;
   atEOD = false;
   online = false;
   needEOF = false;

   file_block = 0;
   last_file = 0;
   current_file = 0;
   current_block = -1;

   lockfile = NULL;

   max_block = VTAPE_MAX_BLOCK;
}

int vtape::get_fd()
{
   return this->fd;
}

/*
 * DEVICE virtual that we redefine.
 *
 * Write a variable block of count size.
 * block = vtape_header + data
 * vtape_header = sizeof(data)
 * if vtape_header == 0, this is a EOF
 */
ssize_t vtape::d_write(int, const void *buffer, size_t count)
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   ASSERT(count > 0);
   ASSERT(buffer);

   ssize_t nb;
   Dmsg3(dbglevel*2, "write len=%i %i:%i\n",
         count, current_file,current_block);

   if (atEOT) {
      Dmsg0(dbglevel, "write nothing, EOT !\n");
      errno = ENOSPC;
      return -1;
   }

   if (!atEOD) {                /* if not at the end of the data */
      truncate_file();
   }

   if (current_block != -1) {
      current_block++;
   }

   atBOT = false;
   atEOF = false;
   atEOD = true;                /* End of data */

   needEOF = true;              /* next operation need EOF mark */

   uint32_t size = count;
   ::write(fd, &size, sizeof(uint32_t));
   nb = ::write(fd, buffer, count);

   if (nb != (ssize_t)count) {
      atEOT = true;
      Dmsg2(dbglevel,
            "Not enough space writing only %i of %i requested\n",
            nb, count);
   }

   update_pos();

   return nb;
}

/*
 *  +---+---------+---+------------------+---+-------------------+
 *  |00N|  DATA   |0LN|   DATA           |0LC|     DATA          |
 *  +---+---------+---+------------------+---+-------------------+
 *
 *  0 : zero
 *  L : Last FileMark offset
 *  N : Next FileMark offset
 *  C : Current FileMark Offset
 */
int vtape::weof()
{
   ASSERT(online);
   ASSERT(current_file >= 0);

#if 0
   if (atEOT) {
      errno = ENOSPC;
      current_block = -1;
      return -1;
   }
#endif

   if (!atEOD) {
      truncate_file();             /* nothing after this point */
   }

   last_FM = cur_FM;
   cur_FM = lseek(fd, 0, SEEK_CUR); // current position

   /* update previous next_FM  */
   lseek(fd, last_FM + sizeof(uint32_t)+sizeof(boffset_t), SEEK_SET);
   ::write(fd, &cur_FM, sizeof(boffset_t));
   lseek(fd, cur_FM, SEEK_SET);

   next_FM = 0;

   uint32_t c=0;
   ::write(fd, &c,       sizeof(uint32_t)); // EOF
   ::write(fd, &last_FM, sizeof(last_FM));  // F-1
   ::write(fd, &next_FM, sizeof(next_FM));  // F   (will be updated next time)

   current_file++;
   current_block = 0;

   needEOF = false;
   atEOD = false;
   atBOT = false;
   atEOF = true;

   last_file = MAX(current_file, last_file);

   Dmsg4(dbglevel, "Writing EOF %i:%i last=%lli cur=%lli next=0\n",
         current_file, current_block, last_FM, cur_FM);

   return 0;
}

/*
 * Go to next FM
 */
int vtape::fsf()
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   ASSERT(fd >= 0);
/*
 * 1 0 -> fsf -> 2 0 -> fsf -> 2 -1
 */

   int ret=0;
   if (atEOT || atEOD) {
      errno = EIO;
      current_block = -1;
      return -1;
   }

   atBOT = false;
   Dmsg2(dbglevel+1, "fsf %i <= %i\n", current_file, last_file);

   if (next_FM > cur_FM) {      /* not the last file */
      lseek(fd, next_FM, SEEK_SET);
      read_fm(VT_READ_EOF);
      current_file++;
      atEOF = true;
      ret = 0;

   } else if (atEOF) {          /* last file mark */
      current_block=-1;
      errno = EIO;
      atEOF = false;
      atEOD = true;

   } else {                     /* last file, but no at the end */
      fsr(100000);

      Dmsg0(dbglevel, "Try to FSF after EOT\n");
      errno = EIO;
      current_file = last_file ;
      current_block = -1;
      atEOD=true;
      ret = -1;
   }
   return ret;
}

/* /------------\ /---------------\
 * +---+------+---+---------------+-+
 * |OLN|      |0LN|               | |
 * +---+------+---+---------------+-+
 */

bool vtape::read_fm(VT_READ_FM_MODE read_all)
{
   int ret;
   uint32_t c = 0;
   if (read_all == VT_READ_EOF) {
      ::read(fd, &c, sizeof(c));
      if (c != 0) {
         lseek(fd, cur_FM, SEEK_SET);
         return false;
      }
   }

   cur_FM = lseek(fd, 0, SEEK_CUR) - sizeof(c);

   ::read(fd, &last_FM, sizeof(last_FM));
   ret = ::read(fd, &next_FM, sizeof(next_FM));

   current_block=0;

   Dmsg3(dbglevel, "Read FM cur=%lli last=%lli next=%lli\n",
         cur_FM, last_FM, next_FM);

   return (ret == sizeof(next_FM));
}

/*
 * TODO: Check fsr with EOF
 */
int vtape::fsr(int count)
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   ASSERT(fd >= 0);

   int i,nb, ret=0;
// boffset_t where=0;
   uint32_t s;
   Dmsg4(dbglevel, "fsr %i:%i EOF=%i c=%i\n",
         current_file,current_block,atEOF,count);

   check_eof();

   if (atEOT) {
      errno = EIO;
      current_block = -1;
      return -1;
   }

   if (atEOD) {
      errno = EIO;
      return -1;
   }

   atBOT = atEOF = false;

   /* check all block record */
   for(i=0; (i < count) && !atEOF ; i++) {
      nb = ::read(fd, &s, sizeof(uint32_t)); /* get size of next block */
      if (nb == sizeof(uint32_t) && s) {
         current_block++;
         lseek(fd, s, SEEK_CUR);     /* seek after this block */
      } else {
         Dmsg4(dbglevel, "read EOF %i:%i nb=%i s=%i\n",
               current_file, current_block, nb,s);
         errno = EIO;
         ret = -1;
         if (next_FM) {
            current_file++;
            read_fm(VT_SKIP_EOF);
         }
         atEOF = true;          /* stop the loop */
      }
   }

   return ret;
}

/*
 * BSR + EOF => begin of EOF + EIO
 * BSR + BSR + EOF => last block
 * current_block = -1
 */
int vtape::bsr(int count)
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   ASSERT(count == 1);
   ASSERT(fd >= 0);

   check_eof();

   if (!count) {
      return 0;
   }

   int ret=0;
   int last_f=0;
   int last_b=0;

   boffset_t last=-1, last2=-1;
   boffset_t orig = lseek(fd, 0, SEEK_CUR);
   int orig_f = current_file;
   int orig_b = current_block;

   Dmsg4(dbglevel, "bsr(%i) cur_blk=%i orig=%lli cur_FM=%lli\n",
         count, current_block, orig, cur_FM);

   /* begin of tape, do nothing */
   if (atBOT) {
      errno = EIO;
      return -1;
   }

   /* at EOF 0:-1 BOT=0 EOD=0 EOF=0 ERR: Input/output error  */
   if (atEOF) {
      lseek(fd, cur_FM, SEEK_SET);
      atEOF = false;
      if (current_file > 0) {
         current_file--;
      }
      current_block=-1;
      errno = EIO;
      return -1;
   }

   /*
    * First, go to cur/last_FM and read all blocks to find the good one
    */
   if (cur_FM == orig) {        /* already just before  EOF */
      lseek(fd, last_FM, SEEK_SET);

   } else {
      lseek(fd, cur_FM, SEEK_SET);
   }

   ret = read_fm(VT_READ_EOF);

   do {
      if (!atEOF) {
         last2 = last;          /* keep track of the 2 last blocs position */
         last = lseek(fd, 0, SEEK_CUR);
         last_f = current_file;
         last_b = current_block;
         Dmsg6(dbglevel, "EOF=%i last2=%lli last=%lli < orig=%lli %i:%i\n",
               atEOF, last2, last, orig, current_file, current_block);
      }
      ret = fsr(1);
   } while ((lseek(fd, 0, SEEK_CUR) < orig) && (ret == 0));

   if (last2 > 0 && atEOF) {    /* we take the previous position */
      lseek(fd, last2, SEEK_SET);
      current_file = last_f;
      current_block = last_b - 1;
      Dmsg3(dbglevel, "1 set offset2=%lli %i:%i\n",
            last, current_file, current_block);

   } else if (last > 0) {
      lseek(fd, last, SEEK_SET);
      current_file = last_f;
      current_block = last_b;
      Dmsg3(dbglevel, "2 set offset=%lli %i:%i\n",
            last, current_file, current_block);
   } else {
      lseek(fd, orig, SEEK_SET);
      current_file = orig_f;
      current_block = orig_b;
      return -1;
   }

   Dmsg2(dbglevel, "bsr %i:%i\n", current_file, current_block);
   errno=0;
   atEOT = atEOF = atEOD = false;
   atBOT = (lseek(fd, 0, SEEK_CUR) - (sizeof(uint32_t)+2*sizeof(boffset_t))) == 0;

   if (orig_b == -1) {
      current_block = orig_b;
   }

   return 0;
}

/* BSF => just before last EOF
 * EOF + BSF => just before EOF
 * file 0 + BSF => BOT + errno
 */
int vtape::bsf()
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   Dmsg2(dbglevel, "bsf %i:%i count=%i\n", current_file, current_block);
   int ret = 0;

   check_eof();

   atBOT = atEOF = atEOT = atEOD = false;

   if (current_file == 0) {/* BOT + errno */
      lseek(fd, 0, SEEK_SET);
      read_fm(VT_READ_EOF);
      current_file = 0;
      current_block = 0;
      atBOT = true;
      errno = EIO;
      ret = -1;
   } else {
      Dmsg1(dbglevel, "bsf last=%lli\n", last_FM);
      lseek(fd, cur_FM, SEEK_SET);
      current_file--;
      current_block=-1;
   }
   return ret;
}

/*
 * DEVICE virtual that we redefine.
 *
 * Put vtape in offline mode
 */
bool vtape::offline()
{
   close();

   atEOF = false;               /* End of file */
   atEOT = false;               /* End of tape */
   atEOD = false;               /* End of data */
   atBOT = false;               /* Begin of tape */
   online = false;

   file_block = 0;
   current_file = -1;
   current_block = -1;
   last_file = -1;
   return true;
}

/*
 * DEVICE virtual that we redefine.
 *
 * A filemark is automatically written to tape if the last tape operation
 * before close was a write.
 */
int vtape::d_close(int)
{
   struct flock lock;

   check_eof();

   if (lockfd >= 0) {
      lock.l_type   = F_UNLCK;
      lock.l_start = 0;
      lock.l_whence = SEEK_SET;
      lock.l_len = 0;
      lock.l_pid = getpid();

      ASSERT(fcntl(fd, F_SETLK, &lock) != -1);
      ::close(lockfd);
      free(lockfile);
   }

   ::close(fd);
   lockfd = fd = -1;
   return 0;
}

/*
 * DEVICE virtual that we redefine.
 *
 * When a filemark is encountered while reading, the following happens.  If
 * there are data remaining in the buffer when the filemark is found, the
 * buffered data is returned.  The next read returns zero bytes.  The following
 * read returns data from the next file.  The end of recorded data is signaled
 * by returning zero bytes for two consecutive read calls.  The third read
 * returns an error.
 */
ssize_t vtape::d_read(int, void *buffer, size_t count)
{
   ASSERT(online);
   ASSERT(current_file >= 0);
   ssize_t nb;
   uint32_t s;

   Dmsg2(dbglevel*2, "read %i:%i\n", current_file, current_block);

   if (atEOT || atEOD) {
      errno = EIO;
      return -1;
   }

   if (atEOF) {
      if (!next_FM) {
         atEOD = true;
         atEOF = false;
         current_block=-1;
         return 0;
      }
      atEOF=false;
   }

   check_eof();

   atEOD = atBOT = false;

   /* reading size of data */
   nb = ::read(fd, &s, sizeof(uint32_t));
   if (nb <= 0) {
      atEOF = true;             /* TODO: check this */
      return 0;
   }

   if (s > count) {             /* not enough buffer to read block */
      Dmsg2(dbglevel, "Need more buffer to read next block %i > %i\n",s,count);
      lseek(fd, s, SEEK_CUR);
      errno = ENOMEM;
      return -1;
   }

   if (!s) {                    /* EOF */
      atEOF = true;
      if (read_fm(VT_SKIP_EOF)) {
         current_file++;
      }

      return 0;
   }

   /* reading data itself */
   nb = ::read(fd, buffer, s);
   if (nb != (ssize_t)s) { /* read error */
      errno=EIO;
      atEOT=true;
      current_block = -1;
      Dmsg0(dbglevel, "EOT during reading\n");
      return -1;
   }                    /* read ok */

   if (current_block >= 0) {
      current_block++;
   }

   return nb;
}

/* Redefine DEVICE virtual function */
int vtape::d_open(const char *pathname, int uflags)
{
   Dmsg2(dbglevel, "vtape::d_open(%s, %i)\n", pathname, uflags);

   online = true;               /* assume that drive contains a tape */
   struct flock lock;
   struct stat statp;

   if (stat(pathname, &statp) != 0) {
      fd = -1;
      Dmsg1(dbglevel, "Can't stat on %s\n", pathname);
      if (uflags & O_NONBLOCK) {
         online = false;
         fd = ::open("/dev/null", O_RDWR | O_LARGEFILE, 0600);
      }
   } else {
      fd = ::open(pathname, O_RDWR | O_LARGEFILE, 0600);
   }

   if (fd < 0) {
      berrno be;
      Dmsg2(0, "Unable to open vtape device %s ERR=%s\n", pathname, be.bstrerror());
      errno = ENOMEDIUM;
      return -1;
   }

   lockfile = (char *)malloc(strlen(pathname) + 3);
   strcpy(lockfile, pathname);
   strcat(lockfile, ".l");

   lockfd = ::open(lockfile, O_CREAT | O_RDWR | O_LARGEFILE, 0600);
   if (lockfd < 0) {
      berrno be;
      Dmsg2(0, "Unable to open vtape device lock %s ERR=%s\n", lockfile, be.bstrerror());

   } else {
      lock.l_type = F_WRLCK;
      lock.l_start = 0;
      lock.l_whence = SEEK_SET;
      lock.l_len = 0;
      lock.l_pid = getpid();

      ASSERT(fcntl(lockfd, F_SETLK, &lock) != -1);
   }

   file_block = 0;
   current_block = 0;
   current_file = 0;
   cur_FM = next_FM = last_FM = 0;
   needEOF = false;
   atBOT = true;
   atEOT = atEOD = false;

   /* If the vtape is empty, start by writing a EOF */
   if (online && !read_fm(VT_READ_EOF)) {
      lseek(fd, 0, SEEK_SET);          /* rewind */
      cur_FM = next_FM = last_FM = 0;  /* reset */
      weof();                          /* write the first EOF */
      last_file = current_file=0;
   }

   return fd;
}

/* use this to track file usage */
void vtape::update_pos()
{
   ASSERT(online);
   struct stat statp;
   if (fstat(fd, &statp) == 0) {
      file_block = statp.st_blocks;
   }

   Dmsg1(dbglevel*2, "update_pos=%i\n", file_block);

   if (file_block > max_block) {
      atEOT = true;
   } else {
      atEOT = false;
   }
}

void vtape::dump()
{
   Dmsg0(dbglevel+1, "===================\n");
   Dmsg2(dbglevel, "file:block = %i:%i\n", current_file, current_block);
   Dmsg1(dbglevel+1, "last_file=%i\n", last_file);
   Dmsg1(dbglevel+1, "file_block=%i\n", file_block);
   Dmsg4(dbglevel+1, "EOF=%i EOT=%i EOD=%i BOT=%i\n",
         atEOF, atEOT, atEOD, atBOT);
}

#endif  /* ! USE_VTAPE */
