/* virtual.c
Copyright (c) 2000-2012 Craig Condit, Stefan Huelswitt.

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. 

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 REGENTS OR CONTRIBUTORS 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.
*/

#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include "virtual.h"
#include "cdbackup.h"
#include "cdrom.h"
#include "misc.h"
#include "debug.h"

int fd=-1;
struct toc_entry *toc=0;
long long cd_used, cd_avail;

static struct cd_header cd_header;

static unsigned char virt_buffer[VIRT_HEADER_LEN];
struct virt_header *virt_header=(struct virt_header *)virt_buffer;
int virtualMissing=0, virt_off=-1, virt_regular=0;
char *real_virt_name=0;

extern int virtual;
extern int disknum;
extern char *virt_name, *cd_dev;

/****************************************************************************/

void Vopen(int ro)
{
  Vclose();
  if(!virtual) {
    if((fd=open64(cd_dev,O_RDONLY|O_NONBLOCK))<0)
      error("Open failed (device)");
    }
  else {
    free(real_virt_name);
    if(disknum==1 || !virt_regular) {
      real_virt_name=strdup(virt_name);
      }
    else if(virt_off>0) {
      char *strip=strdup(virt_name);
      char *dot=rindex(strip,'.');
      if(dot) {
        *dot=0;
        if(asprintf(&real_virt_name,"%s.%d",strip,disknum+virt_off)<0)
          error("error making virtual name");
        }
      else serror("Bad filename format");
      free(strip);
      }
    else {
      if(asprintf(&real_virt_name,"%s.%d",virt_name,disknum)<0)
        error("error making virtual name");
      }
    DEBUG("Vopen: real filename is '%s' disknum=%d virt_off=%d\n",
          real_virt_name,disknum,virt_off);
    virtualMissing=0; virt_regular=0;
    if((fd=open64(real_virt_name,ro ? O_RDONLY:O_RDWR))<0) {
      if(errno==EACCES || errno==ENOENT || errno==ENOTDIR) {
        virtualMissing=1; virt_regular=1;
        DEBUG("Vopen: missing virtual image, assuming an empty one\n");
        }
      else error("Open failed (virtual)");
      }
    else {
      struct stat64 st;
      if(fstat64(fd,&st)<0) error("Stat failed (virtual)");
      if(S_ISREG(st.st_mode)) virt_regular=1;
      }
    }
}

/****************************************************************************/

void Vclose(void)
{
  if(fd>=0) {
    close(fd);
    fd=-1;
    }
}

/****************************************************************************/

int VisRegular(void)
{
  return virt_regular;
}

/****************************************************************************/

static int VgetCdHeader(struct cd_header *cd)
{
  if(virtualMissing) {
    if(verbose) 
      fprintf(stderr,"%s: Unable to get virtual image header, assuming new virtual image\n",prg_name);
    memset(virt_buffer,0,VIRT_HEADER_LEN);
    virt_header->magic=VIRT_MAGIC;
    virt_header->version=VIRT_VERSION;
    virt_header->leadout=1;
    virt_header->count=disknum + (virt_off>0 ? virt_off:0);
    }
  else {
    int n;
    if((n=read(fd,virt_buffer,VIRT_HEADER_LEN))<0) 
      error("Read failed (virtual header)");
    if(n!=VIRT_HEADER_LEN) 
      serror("Short read on virtual header");
    if(virt_header->magic!=VIRT_MAGIC) 
      serror("Missing magic value in virtual header. Really a virtual image?");
    if(virt_header->version>VIRT_VERSION) 
      serror("Don't know how to handle this virtual image version");
    }

  if(virt_off<0 && disknum==1) {
    virt_off=virt_header->count-1;
    DEBUG("VgetCdHeader: setting virt_off=%d\n",virt_off);
    }
  cd->start_track=1; cd->end_track=virt_header->tracks;
  cd->used=virt_header->leadout;
  return cd->end_track;
}

/****************************************************************************/

static void VgetCdTrack(int num, struct cd_track *cd)
{
  cd->start_sec=virt_header->start[num-1];
  cd->leadout_size=0;
  cd->is_data=1;
}

/****************************************************************************/

int VreadToc(int trackInfos)
{
  struct cd_track cd_track;
  int i, tracks;

  tracks=virtual ? VgetCdHeader(&cd_header) : getCdHeader(&cd_header);
  if(!tracks) {
    cd_used=0; cd_avail=(long long)cd_len*CD_FRAMESIZE;
    DEBUG("Vreadtoc: empty media\n");
    return 0;
    }
  DEBUG("Vreadtoc: starttrack=%d endtrack=%d tracks=%d\n",
        cd_header.start_track,cd_header.end_track,tracks);

  cd_used  =(long long)cd_header.used*CD_FRAMESIZE;
  cd_avail =(long long)cd_len*CD_FRAMESIZE-cd_used;
  if(cd_avail<0) cd_avail=0;
  DEBUG("Vreadtoc: cd_used=%lld (%lld secs) cd_avail=%lld (%lld secs)\n",
        cd_used,cd_used/CD_FRAMESIZE,cd_avail,cd_avail/CD_FRAMESIZE);

  free(toc);
  if(!(toc=calloc(tracks,sizeof(struct toc_entry)))) serror("No memory for TOC");

  cd_track.start_track=cd_header.start_track;
  for(i=tracks-1; i>=0; i--) {
    int t=cd_header.start_track+i;
    if(virtual) VgetCdTrack(t,&cd_track); else getCdTrack(t,&cd_track);
    toc[i].track_no=t;
    toc[i].sec_start=cd_track.start_sec;
    toc[i].sec_end=((i==tracks-1) ? cd_header.used : toc[i+1].sec_start)-1-cd_track.leadout_size; 
    toc[i].is_data=cd_track.is_data;
    DEBUG("Vreadtoc: index=%d track=%d sec_start=%d sec_end=%d data=%d\n",
          i,t,toc[i].sec_start,toc[i].sec_end,toc[i].is_data);
    }

  if(trackInfos) {
    for(i=0; i<tracks; i++) {
      char inbuffer[CD_FRAMESIZE];
      struct header_block *track_header=(struct header_block *)inbuffer;

      if(toc[i].is_data) {
        Vseek(i);
        Vread(inbuffer);
        if(!strncmp(SHORT_HDR,track_header->id_str,strlen(SHORT_HDR))) {
          toc[i].is_cdbackup=1;
          strncpy(toc[i].id_str,track_header->id_str,32); toc[i].id_str[32]=0;
          strncpy(toc[i].vol_id, track_header->vol_id,32); toc[i].vol_id[32]=0;
          strncpy(toc[i].t_stamp, track_header->t_stamp,12); toc[i].t_stamp[12]=0;
          toc[i].disk_set = track_header->disk_set;
          toc[i].flags = track_header->flags;
          }
        }
      }
    }

  return tracks;
}

/****************************************************************************/

const char *VdevName(void)
{
  static char buff[80];
  if(virtual) snprintf(buff,sizeof(buff),"image %s",virt_name);
  else snprintf(buff,sizeof(buff),"device %s",cd_dev);
  return buff;
}

/****************************************************************************/

void VprintSpace(void)
{
  if(verbose) {
    char flex1[16], flex2[16], flex3[16];
    fprintf(stderr,
      "Disk size:  %s (%7ld blocks)\n"
      "Space used: %s (%7lld blocks)\n"
      "Space avail:%s (%7lld blocks)\n",
      FlexSize(flex1,(long long)cd_len*CD_FRAMESIZE),cd_len,
      FlexSize(flex2,cd_used), cd_used/CD_FRAMESIZE,
      FlexSize(flex3,cd_avail), cd_avail/CD_FRAMESIZE);
    }
}

/****************************************************************************/

long long Vseek(int trackNum)
{
  long long pos=0;
  if(trackNum>=0) pos=(long long)toc[trackNum].sec_start*CD_FRAMESIZE;
  DEBUG("Vseek: seeking to index %d, track %d, offset %lld (%s)\n",
        trackNum,toc[trackNum].track_no,pos,virtual ? "virtual":"real");
  if(lseek64(fd,pos,SEEK_SET)<0) error("Seek failed");
  return pos;
}

/****************************************************************************/

void Vread(void *buf)
{
  if(full_read(fd,buf,CD_FRAMESIZE)!=CD_FRAMESIZE)
    serror("Unexpected EOF reading data");
}

/****************************************************************************/

static unsigned long r_ahead, r_fahead;

void VgetAhead(void)
{
  if(!virtual) get_param(fd,&r_ahead,&r_fahead);
}

/****************************************************************************/

void VsetAhead(int restore)
{
  if(!virtual) {
    if(restore) set_param(fd,r_ahead,r_fahead);
    else set_param(fd,0,0);
    }
}