/* Copyright (C) 2022-2023  Patrick H. E. Foubet - e2li.org
         Ecole du Logiciel Libre d'Ivry - FRANCE

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 3 of the License, or 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.  If not, see <http://www.gnu.org/licenses/>
*******************************************************************/
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <memory.h>
#include <string.h>
#include <getopt.h>

#define VERSION "0.4"
typedef uint32_t loc_t;
typedef uint8_t byte;
#define CD_SECTOR_SIZE 0x800 /* 2048 */
#define ISO_PADSIZE 0x10     /*  16  */

#ifndef __cplusplus
typedef uint8_t bool;
#define true (uint8_t)1
#define false (uint8_t)0
#endif

#define ALIGN(x,y) (((x) + ((y)-1)) & (~((y)-1)))

static char *isofilename, *targetfilename, *targetdirname, *hostfilename;
static bool ecrase = false;

struct iso_rep_t {
  uint8_t len;
  uint8_t ex_len;
  uint32_t lba;
  uint32_t big_lba;
  uint32_t file_len;
  uint32_t big_file_len;
  byte time_date[7];
  byte file_flags;
  byte file_unit_size;
  byte interleave_gap_size;
  uint16_t volseq_num;
  uint16_t big_volseq_num;
  uint8_t fileid_len;
  char fileid[0];
} __attribute__((packed));
typedef struct iso_rep_t iso_rep_t;

int getfilesize(FILE *f) {
  int spos = ftell(f);
  fseek(f, 0, SEEK_END);
  int len = ftell(f);
  fseek(f, spos, SEEK_SET);
  return len;
}
static int Verbose;
static int Mode=-2; /* 0=list, 1=put, -1=get */

void CdSetloc(FILE *f, loc_t newpos) {
  fseeko(f, newpos * CD_SECTOR_SIZE, SEEK_SET);
}

void CdRead(void *buf, loc_t nsectors, FILE *f) {
  fread(buf, nsectors, CD_SECTOR_SIZE, f);
}

void CdWrite(void *buf, loc_t nsectors, FILE *f) {
  fwrite(buf, nsectors, CD_SECTOR_SIZE, f);
}

bool ispvd(byte *sec) {
  return( (sec[0] == 1) && (memcmp(sec+1, "CD001", 5) == 0));
}

bool streq(const char *s1, const char *s2) {
  return (strcasecmp(s1,s2) == 0);
}

bool scmplen(const char *s1, const char *s2, int len) {
  for(int i = 0; i < len; i += 1) {
    if(tolower(s1[i]) != tolower(s2[i])) return false;
  }
  return true;
}

loc_t CdTell(FILE *fdi) {
  loc_t s = ftell(fdi);
  return (s & (~(0x7FF))) / 0x800;
}

bool CdFindFileInDir(iso_rep_t *out_dir, FILE* fdi, const char *filename, int filename_len, loc_t *out_secnum, loc_t *out_offset) {
  byte sec[CD_SECTOR_SIZE];
  iso_rep_t *dir = (iso_rep_t*)(sec);
  int slen = filename_len;
  int dirp = 0;

  CdRead(sec, 1, fdi);

  if (Verbose) printf("FFID %s %d\n", filename, slen);
 
  while(dir->len != 0) {
    int dlen = dir->fileid_len;
    if(!(dir->file_flags & 2)) dlen -= 2;
    if ((Mode == 0)&&((strcmp(filename,"*")==0)||(strcmp(filename,"/*")==0))){
      if (dlen>0) {
          dir->fileid[dlen] = '\0';
          if ((dlen==1) && (dir->fileid[0] <= ' ')) {
             if (Verbose) printf(" + 0x%x %d\n",(int)dir->fileid[0], dlen);
          } else printf(" - %s %d\n",dir->fileid, dlen);
      }
    } else {
     if(dlen == slen) {
      if (Verbose) printf(" + %s\n",dir->fileid);
      if(scmplen(dir->fileid, filename, slen)) {
        *out_dir = *dir;
        if(out_secnum != NULL) *out_secnum = CdTell(fdi) - 1;
        if(out_offset != NULL) *out_offset = dirp;
        return true;
      }
     }
    }
    dirp += dir->len;
    if(dirp >= 0x800) {
      CdRead(sec, 1, fdi);
      dirp = dirp % 0x800;
    }
    dir = (iso_rep_t*)(sec + dirp);
  }
  return false;
}

bool CdFindFile(iso_rep_t *outdir, FILE *fdi, const char *filename, loc_t *out_secnum, loc_t *out_offset)
{
  const char *next;
  const char *cur = filename;
  int slen;
  if (Verbose) printf("> %s\n",filename);
  do {
    next = strchr(cur, '/');
    if(next == NULL) slen = strlen(cur);
    else             slen = (int)(next - cur);
    if (!CdFindFileInDir(outdir, fdi, cur, slen, out_secnum, out_offset))
        return false;
    if (next != NULL) {
        CdSetloc(fdi, outdir->lba);
        next++; cur = next;
    } else break;
  } while(next != NULL);
  return true;
}

/* options definitions */
static int help_flag;
static struct option long_options[] = {
    {"verbose", no_argument,       &Verbose, 1},
    {"help",    no_argument,       &help_flag, 1},
    {"list",    no_argument,       0, 'l'},
    {"put",     no_argument,       0, 'p'},
    {"get",     no_argument,       0, 'g'},
    {"host",    required_argument, 0, 'h'},
    {"file",    required_argument, 0, 'f'},
    {"dir",     required_argument, 0, 'd'},
    {0, 0, 0, 0}
};

void explain(void)
{
   puts("Utilisation : isoupd [options] fichier.iso");
   puts("  -l, --list     liste d'un repertoire (defaut)");
   puts("  -p, --put      modifie un fichier de l'iso");
   puts("  -g, --get      extrait un fichier de l'iso");
   puts("  -v, --verbose  mode verbeux, avec trace de la recherche");
   puts("  -f, --file     chemin du fichier dans l'iso");
   puts("  -h, --host     nom du fichier host. Obligatoire pour -p et -g");
   puts("  -d, --dir      nom du repertoire a lister dans l'iso");
   puts("      --help     affiche cette aide !");
}
void messerr(char * m, int err)
{
  fprintf(stderr,"ERREUR : %s !!\n", m);
  if (err) {
     explain();
     exit(err);
  }
}
static int mode_contrad=0;
void errmode(char * o)
{
   fprintf(stderr,"Option %s en contradiction avec une autre !\n",o);
   mode_contrad=1;
}

int main(int N, char *P[])
{
int c, l, opt_ind = 0;
FILE *fdh, *fdi;
char etoile[2] = "*";

  if(sizeof(iso_rep_t) != 33) {
    fprintf(stderr, "Mauvaise compilation : tid=%lu\n",sizeof(iso_rep_t));
    return 9;
  }
  while (1) {
    if ((c=getopt_long(N,P,"vlpgd:h:f:",long_options,&opt_ind))==-1) break;
    switch (c) {
        case 0:
          if (long_options[opt_ind].flag != 0) break;
          printf ("option %s", long_options[opt_ind].name);
          if (optarg) printf (" avec arg %s", optarg);
          printf ("\n");
          break;

        case 'l':
          if (Mode != -2) errmode(P[opt_ind]);
          Mode=0;
          break;
        case 'p':
          if (Mode != -2) errmode(P[opt_ind]);
          Mode=1;
          break;
        case 'g':
          if (Mode != -2) errmode(P[opt_ind]);
          Mode=-1;
          break;
        case 'v':
          Verbose=1;
          break;
        case 'h':
          hostfilename = optarg;
          break;
        case 'f':
          targetfilename = optarg;
          break;
        case 'd':
          l = strlen(optarg);
          if (optarg[l-1]=='/') { l--; optarg[l]='\0'; }
          targetdirname = (char*) malloc(l+3);
          if (targetdirname == NULL) { perror("malloc"); return 4; }
          sprintf(targetdirname, "%s/%s", optarg,etoile);
          break;
        case '?': /* getopt_long already printed an error message. */
          explain();
          return 1;
        default:
          abort ();
      }
    }
    if (help_flag) {
       printf("isoupd version %s (c) E2L 2023\n",VERSION);
       explain();
       return 0;
    }
    if (optind < N) {
      isofilename = P[optind++];
      if (optind < N) {
         fprintf (stderr, "Non pris en compte : ");
         while (optind < N) fprintf (stderr, "%s ", P[optind++]);
         fprintf(stderr, "\n");
         messerr("parametre(s) inutile(s)",3);
      }
    }
    /* verifications */
    if (! isofilename) messerr("Fichier ISO absent",2);
    if (Mode == -2) Mode = 0; /* defaut */
    switch(Mode) {
      case 0 : /* list */
        if (targetfilename) messerr("option -f inutile",2);
        if (hostfilename) messerr("option -h inutile",2);
        if (!targetdirname) targetdirname = etoile;
        if (Verbose) printf("Liste de %s dans %s\n",targetdirname,isofilename);
        targetfilename = targetdirname;
        break;
      case 1 : /* put */
        if (targetdirname) messerr("option -d inutile",2);
        if (!targetfilename) messerr("Chemin du fichier dans l'ISO absent",2);
        if (!hostfilename) messerr("fichier host source absent",2);
        if (Verbose) printf("PUT de %s vers %s dans %s\n",hostfilename,targetfilename,isofilename);
        break;
      case -1 : /* get */
        if (targetdirname) messerr("option -d inutile",2);
        if (!targetfilename) messerr("Chemin du fichier dans l'ISO absent",2);
        if (!hostfilename) messerr("fichier host destination absent",2);
        if (Verbose) printf("GET de %s dans %s vers %s\n",targetfilename,isofilename,hostfilename);
        break;
    }
    if (Verbose) printf("Verbose : mode = %d\n",Mode);

    if ((fdi = fopen(isofilename, "r+")) == NULL) {
      fprintf(stderr, "Erreur ouverture ISO %s\n", isofilename);
      return 1;
    }
    if(hostfilename != NULL) {
      if ((fdh = fopen(hostfilename, "r")) == NULL) {
        if (Mode == 1) { /* put */
          fprintf(stderr, "Erreur ouverture fichier %s\n", hostfilename);
          return 1;
        }
      } else {
        if (Mode == -1) { /* get */
          fprintf(stderr,"Erreur : le fichier %s existe deja !\n",hostfilename);
          return 1;
        }
      }
      if (Mode == -1) { /* get */
        if ((fdh = fopen(hostfilename, "w")) == NULL) {
          fprintf(stderr, "Erreur creation fichier %s\n", hostfilename);
          return 1;
        }
      }
    }
    byte sec[CD_SECTOR_SIZE];
    iso_rep_t *dir = (iso_rep_t*)(sec);
    CdSetloc(fdi, ISO_PADSIZE);
    CdRead(sec, 1, fdi);
    if(!ispvd(sec)) {
      fprintf(stderr, "%s n'est pas un fichier ISO\n", isofilename);
      return 1;
    }
    loc_t root_lba = *(loc_t*)(sec+158);
    if (Verbose) printf("root lba = %x\n", root_lba);
    CdSetloc(fdi, root_lba);
    loc_t dir_lba, dir_offset;
    bool s = CdFindFile(dir, fdi, targetfilename, &dir_lba, &dir_offset);
    if (!Mode) { /* list */
       fclose(fdi);
       return 0;
    }
    if(!s) {
      fprintf(stderr, "Fichier %s absent de l'ISO %s\n", targetfilename, isofilename);
      return 1;
    }
    CdSetloc(fdi, dir_lba);
    CdRead(sec, 1, fdi);
    dir = (iso_rep_t*)(sec + dir_offset);
    int maxsize = ALIGN(dir->file_len, 0x800);
    printf("Taille du fichier sur l'ISO : %d\n", dir->file_len);
    if (Mode == -1) { /* get */
       byte *filedata = (byte*)(malloc(maxsize));
       CdSetloc(fdi, dir->lba);
       CdRead(filedata, (maxsize / CD_SECTOR_SIZE), fdi);
       fwrite(filedata, 1, dir->file_len, fdh);
       fclose(fdh);
       fclose(fdi);
       printf("Extraction faite dans %s.\n",hostfilename);
       return 0;
    }
    int len = getfilesize(fdh);
    int aligned_len = ALIGN(len, 0x800);
    printf("Taille du fichier local : %d\n", len);
    if(!ecrase) {
      if(len > maxsize) {
        fprintf(stderr, "Le fichier %s depasse de %d octets (%d > %d)\n",
           hostfilename, len - maxsize, len, maxsize);
        fclose(fdh);
        fclose(fdi);
       return 1;
      }
      if((uint32_t)len != dir->file_len) {
        if((uint32_t)aligned_len < dir->file_len) {
          printf("ATTENTION: La mise en place de ce fichier\n va retrecir l'espace d'allocation disponible !\n");
          printf(" (il sera de %d octets)\n", aligned_len);
        }
        printf("Les tailles sont differentes mais compatibles.\n");
      }
    }
    printf("AVERTISSEMENT : Version %s de test !!!\n",VERSION);
    printf("============= Il faut faire une sauvegarde de l'ISO avant.\n");
    printf("Modification ? [o/N]\n");
    int ch = getchar();
    if((ch != 'o') && (ch != 'O')) {
      printf("Annulation !!\n");
      return 1;
    }
    byte *filedata = (byte*)(malloc(aligned_len));
    memset(filedata, 0, aligned_len);
    fread(filedata, 1, len, fdh);
    fclose(fdh);

    printf("Ecriture de %d octets sur le secteur %u\n", len, dir->lba);
    CdSetloc(fdi, dir->lba);
    CdWrite(filedata, (aligned_len / CD_SECTOR_SIZE), fdi);

    dir->file_len = len;
    printf("Ecriture d'un nouveau repertoire sur %u\n", dir_lba);
    CdSetloc(fdi, dir_lba);
    CdWrite(sec, 1, fdi);

    printf("OK !\n");

    fclose(fdi);
    return 0;
}