FUSEISO/vtoy_fuse_iso.c

   1 /******************************************************************************
   2  * vtoy_fuse_iso.c
   3  *
   4  * Copyright (c) 2020, longpanda <admin@ventoy.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 3 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #define FUSE_USE_VERSION 26
  22
  23 #include <fuse.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30
  31 typedef unsigned int uint32_t;
  32
  33 typedef struct dmtable_entry
  34 {
  35     uint32_t isoSector;
  36     uint32_t sectorNum;
  37     unsigned long long diskSector;
  38 }dmtable_entry;
  39
  40 #define MAX_ENTRY_NUM  (1024 * 1024 / sizeof(dmtable_entry))
  41
  42 static int verbose = 0;
  43 #define debug(fmt, ...) if(verbose) printf(fmt, ##__VA_ARGS__)
  44
  45 static int g_disk_fd = -1;
  46 static uint64_t g_iso_file_size;
  47 static char g_mnt_point[512];
  48 static char g_iso_file_name[512];
  49 static dmtable_entry *g_disk_entry_list = NULL;
  50 static int g_disk_entry_num = 0;
  51
  52 static int ventoy_iso_getattr(const char *path, struct stat *statinfo)
  53 {
  54     int ret = -ENOENT;
  55
  56     if (path && statinfo)
  57     {
  58         memset(statinfo, 0, sizeof(struct stat));
  59
  60         if (path[0] == '/' && path[1] == 0)
  61         {
  62             statinfo->st_mode  = S_IFDIR | 0755;
  63             statinfo->st_nlink = 2;
  64             ret = 0;
  65         }
  66         else if (strcmp(path, g_iso_file_name) == 0)
  67         {
  68             statinfo->st_mode  = S_IFREG | 0444;
  69             statinfo->st_nlink = 1;
  70             statinfo->st_size  = g_iso_file_size;
  71             ret = 0;
  72         }
  73     }
  74
  75     return ret;
  76 }
  77
  78 static int ventoy_iso_readdir
  79 (
  80     const char *path,
  81     void *buf,
  82     fuse_fill_dir_t filler,
  83     off_t offset,
  84     struct fuse_file_info *file
  85 )
  86 {
  87     (void)offset;
  88     (void)file;
  89
  90     if (path[0] != '/' || path[1] != 0)
  91     {
  92         return -ENOENT;
  93     }
  94
  95     filler(buf, ".", NULL, 0);
  96     filler(buf, "..", NULL, 0);
  97     filler(buf, g_iso_file_name + 1, NULL, 0);
  98
  99     return 0;
 100 }
 101
 102 static int ventoy_iso_open(const char *path, struct fuse_file_info *file)
 103 {
 104     if (strcmp(path, g_iso_file_name) != 0)
 105     {
 106         return -ENOENT;
 107     }
 108
 109     if ((file->flags & 3) != O_RDONLY)
 110     {
 111         return -EACCES;
 112     }
 113
 114     return 0;
 115 }
 116
 117 static int ventoy_read_iso_sector(uint32_t sector, uint32_t num, void *buf)
 118 {
 119     uint32_t i = 0;
 120     uint32_t leftSec = 0;
 121     uint32_t readSec = 0;
 122     dmtable_entry *entry = NULL;
 123
 124     for (i = 0; i < g_disk_entry_num && num > 0; i++)
 125     {
 126         entry = g_disk_entry_list + i;
 127
 128         if (sector >= entry->isoSector && sector < entry->isoSector + entry->sectorNum)
 129         {
 130             lseek(g_disk_fd, (entry->diskSector + (sector - entry->isoSector)) * 512, SEEK_SET);
 131
 132             leftSec = entry->sectorNum - (sector - entry->isoSector);
 133             readSec = (leftSec > num) ? num : leftSec;
 134
 135             read(g_disk_fd, buf, readSec * 512);
 136
 137             sector += readSec;
 138             num -= readSec;
 139         }
 140     }
 141
 142     return 0;
 143 }
 144
 145 static int ventoy_iso_read
 146 (
 147     const char *path, char *buf,
 148     size_t size, off_t offset,
 149     struct fuse_file_info *file
 150 )
 151 {
 152     uint32_t mod = 0;
 153     uint32_t align = 0;
 154     uint32_t sector = 0;
 155     uint32_t number = 0;
 156     size_t leftsize = 0;
 157     char secbuf[512];
 158
 159     (void)file;
 160
 161     if(strcmp(path, g_iso_file_name) != 0)
 162     {
 163         return -ENOENT;
 164     }
 165
 166     if (offset >= g_iso_file_size)
 167     {
 168         return 0;
 169     }
 170
 171     if (offset + size > g_iso_file_size)
 172     {
 173         size = g_iso_file_size - offset;
 174     }
 175
 176     leftsize = size;
 177     sector = offset / 512;
 178
 179     mod = offset % 512;
 180     if (mod > 0)
 181     {
 182         align = 512 - mod;
 183         ventoy_read_iso_sector(sector, 1, secbuf);
 184
 185         if (leftsize > align)
 186         {
 187             memcpy(buf, secbuf + mod, align);
 188             buf += align;
 189             offset += align;
 190             sector++;
 191             leftsize -= align;
 192         }
 193         else
 194         {
 195             memcpy(buf, secbuf + mod, leftsize);
 196             return size;
 197         }
 198     }
 199
 200     number = leftsize / 512;
 201     ventoy_read_iso_sector(sector, number, buf);
 202     buf += number * 512;
 203
 204     mod = leftsize % 512;
 205     if (mod > 0)
 206     {
 207         ventoy_read_iso_sector(sector + number, 1, secbuf);
 208         memcpy(buf, secbuf, mod);
 209     }
 210
 211     return size;
 212 }
 213
 214 static struct fuse_operations ventoy_op =
 215 {
 216     .getattr    = ventoy_iso_getattr,
 217     .readdir    = ventoy_iso_readdir,
 218     .open       = ventoy_iso_open,
 219     .read       = ventoy_iso_read,
 220 };
 221
 222 static int ventoy_parse_dmtable(const char *filename)
 223 {
 224     FILE *fp = NULL;
 225     char diskname[128] = {0};
 226     char line[256] = {0};
 227     dmtable_entry *entry= g_disk_entry_list;
 228
 229     fp = fopen(filename, "r");
 230     if (NULL == fp)
 231     {
 232         printf("Failed to open file %s\n", filename);
 233         return 1;
 234     }
 235
 236     /* read untill the last line */
 237     while (fgets(line, sizeof(line), fp) && g_disk_entry_num < MAX_ENTRY_NUM)
 238     {
 239         sscanf(line, "%u %u linear %s %llu",
 240                &entry->isoSector, &entry->sectorNum,
 241                diskname, &entry->diskSector);
 242
 243         g_iso_file_size += (uint64_t)entry->sectorNum * 512ULL;
 244         g_disk_entry_num++;
 245         entry++;
 246     }
 247     fclose(fp);
 248
 249     if (g_disk_entry_num >= MAX_ENTRY_NUM)
 250     {
 251         fprintf(stderr, "ISO file has too many fragments ( more than %u )\n", MAX_ENTRY_NUM);
 252         return 1;
 253     }
 254
 255     debug("iso file size: %llu disk name %s\n", g_iso_file_size, diskname);
 256
 257     g_disk_fd = open(diskname, O_RDONLY);
 258     if (g_disk_fd < 0)
 259     {
 260         debug("Failed to open %s\n", diskname);
 261         return 1;
 262     }
 263
 264     return 0;
 265 }
 266
 267 int main(int argc, char **argv)
 268 {
 269     int rc;
 270     int ch;
 271     char filename[512] = {0};
 272
 273     /* Avoid to be killed by systemd */
 274     if (access("/etc/initrd-release", F_OK) >= 0)
 275     {
 276         argv[0][0] = '@';
 277     }
 278
 279     g_iso_file_name[0] = '/';
 280
 281     while ((ch = getopt(argc, argv, "f:s:m:v::t::")) != -1)
 282     {
 283         if (ch == 'f')
 284         {
 285             strncpy(filename, optarg, sizeof(filename) - 1);
 286         }
 287         else if (ch == 'm')
 288         {
 289             strncpy(g_mnt_point, optarg, sizeof(g_mnt_point) - 1);
 290         }
 291         else if (ch == 's')
 292         {
 293             strncpy(g_iso_file_name + 1, optarg, sizeof(g_iso_file_name) - 2);
 294         }
 295         else if (ch == 'v')
 296         {
 297             verbose = 1;
 298         }
 299         else if (ch == 't') // for test
 300         {
 301             return 0;
 302         }
 303     }
 304
 305     if (filename[0] == 0)
 306     {
 307         fprintf(stderr, "Must input dmsetup table file with -f\n");
 308         return 1;
 309     }
 310
 311     if (g_mnt_point[0] == 0)
 312     {
 313         fprintf(stderr, "Must input mount point with -m\n");
 314         return 1;
 315     }
 316
 317     if (g_iso_file_name[1] == 0)
 318     {
 319         strncpy(g_iso_file_name + 1, "ventoy.iso", sizeof(g_iso_file_name) - 2);
 320     }
 321
 322     debug("ventoy fuse iso: %s %s %s\n", filename, g_iso_file_name, g_mnt_point);
 323
 324     g_disk_entry_list = malloc(MAX_ENTRY_NUM * sizeof(dmtable_entry));
 325     if (NULL == g_disk_entry_list)
 326     {
 327         return 1;
 328     }
 329
 330     rc = ventoy_parse_dmtable(filename);
 331     if (rc)
 332     {
 333         free(g_disk_entry_list);
 334         return rc;
 335     }
 336
 337     argv[1] = g_mnt_point;
 338     argv[2] = NULL;
 339     rc = fuse_main(2, argv, &ventoy_op, NULL);
 340
 341     close(g_disk_fd);
 342
 343     free(g_disk_entry_list);
 344     return rc;
 345 }
 346