fs.c

   1 #include <stdio.h>
   2 #include <unistd.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <error.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9
  10 #include "include/fs.h"
  11
  12 typedef int (*dfunc)(int);
  13
  14 unsigned short
  15 get_le_short(void *from)
  16 {
  17         unsigned char *p = from;
  18         return ((unsigned short)(p[1]) << 8) +
  19                 (unsigned short)p[0];
  20 }
  21
  22 unsigned int get_le_long(void *from)
  23 {
  24         unsigned char *p = from;
  25         return ((unsigned int)(p[3]) << 24) +
  26                 ((unsigned int)(p[2]) << 16) +
  27                 ((unsigned int)(p[1]) << 8) +
  28                 (unsigned int)p[0];
  29 }
  30
  31 unsigned short get_be_short(void *from)
  32 {
  33         unsigned char *p = from;
  34         return ((unsigned short)(p[0]) << 8) +
  35                 (unsigned short)p[1];
  36 }
  37
  38 unsigned int get_be_long(void *from)
  39 {
  40         unsigned char *p = from;
  41         return ((unsigned int)(p[0]) << 24) +
  42                 ((unsigned int)(p[1]) << 16) +
  43                 ((unsigned int)(p[2]) << 8) +
  44                 (unsigned int)p[3];
  45 }
  46
  47 int get_buffer(int fd, unsigned char *b, int offset, int len)
  48 {
  49         if(lseek(fd, offset, SEEK_SET) != offset)
  50                 return -1;
  51         if(read(fd, b, len) != len)
  52                 return -1;
  53         return 0;
  54 }
  55
  56 #define MBR_BUF_SIZE    512
  57 int detect_mbr(int fd)
  58 {
  59         int ret = NONE;
  60         unsigned char *buffer = (unsigned char*)malloc(MBR_BUF_SIZE);
  61         if(get_buffer(fd, buffer, 0, MBR_BUF_SIZE) != 0)
  62                 goto out;
  63         if((buffer[510] == 0x55) && (buffer[511] == 0xAA))
  64                 ret = MBR;
  65 out:
  66         free(buffer);
  67         return ret;
  68 }
  69
  70 #define EFI_BUF_OFFSET  512
  71 #define EFI_BUF_SIZE    512
  72 int detect_efi(int fd)
  73 {
  74         int ret = NONE;
  75         unsigned char *buffer = (unsigned char*)malloc(EFI_BUF_SIZE);
  76         if(get_buffer(fd, buffer, EFI_BUF_OFFSET, EFI_BUF_SIZE) != 0)
  77                 goto out;
  78         if(!memcmp(buffer, "EFI PART", 8))
  79                 ret = EFI;
  80 out:
  81         free(buffer);
  82         return ret;
  83 }
  84
  85 #define EXT2_BUF_SIZE   1024
  86 int detect_ext23(int fd)
  87 {
  88         int ret = NONE;
  89         unsigned char *buffer = (unsigned char*)malloc(EXT2_BUF_SIZE);
  90         if(get_buffer(fd, buffer, 1024, EXT2_BUF_SIZE) != 0)
  91                 goto out;
  92         if(get_le_short(buffer + 56) == 0xEF53)
  93         {
  94                 if((get_le_long(buffer + 96) & 0x0008)
  95                         || (get_le_long(buffer + 92) & 0x0004))
  96                         ret = EXT3;
  97                 else
  98                         ret = EXT2;
  99         }
 100 out:
 101         free(buffer);
 102         return ret;
 103 }
 104
 105 #define FAT_BUF_SIZE    512
 106 int detect_fat(int fd)
 107 {
 108         int ret = NONE;
 109         unsigned char *buffer = (unsigned char*)malloc(FAT_BUF_SIZE);
 110         if(get_buffer(fd, buffer, 0, FAT_BUF_SIZE) != 0)
 111                 goto out;
 112
 113         if (((((buffer[0] & 0xff) == 0xEB) && ((buffer[2] & 0xff) == 0x90)) || ((buffer[0] & 0xff) == 0xE9))
 114                 && ((buffer[510] & 0xff) == 0x55) /*&& ((buffer[511] & 0xff == 0xAA))*/
 115                 && (memcmp(buffer + 3, "NTFS    ", 8)))
 116                 ret = FAT;
 117 out:
 118         free(buffer);
 119         return ret;
 120 }
 121
 122 #define HFSPLUS_VOL_JOURNALED   (1 << 13)
 123 #define HFSPLUS_BUF_SIZE                        512
 124 int detect_hfsplus(int fd)
 125 {
 126         int ret = NONE;
 127         unsigned short magic;
 128         unsigned int journal;
 129         unsigned char *buffer = (unsigned char*)malloc(HFSPLUS_BUF_SIZE);
 130         if(get_buffer(fd, buffer, 1024, HFSPLUS_BUF_SIZE) != 0)
 131                 goto out;
 132         magic = get_be_short(buffer);
 133         journal = get_be_long(buffer + 4) & HFSPLUS_VOL_JOURNALED;
 134         if(magic == 0x482B)
 135         {
 136                 if(!journal)
 137                         ret = HFSPLUS;
 138         //      else
 139         //              ret = HFSPLUSJOURNAL;
 140         }
 141 out:
 142         free(buffer);
 143         return ret;
 144 }
 145
 146 #define NTFS_BUF_SIZE   512
 147 int detect_ntfs(int fd)
 148 {
 149         int ret = NONE;
 150         unsigned char *buffer = (unsigned char*)malloc(NTFS_BUF_SIZE);
 151         if(get_buffer(fd, buffer, 0, NTFS_BUF_SIZE) != 0)
 152                 goto out;
 153         if(!memcmp(buffer + 3, "NTFS    ", 8))
 154                 ret = NTFS;
 155 out:
 156         free(buffer);
 157         return ret;
 158 }
 159
 160 #define EXTENDED_BUF_SIZE       512
 161 int detect_extended(int fd)
 162 {
 163         int ret = NONE;
 164         unsigned char *buffer = (unsigned char*)malloc(MBR_BUF_SIZE);
 165         if(get_buffer(fd, buffer, 0, 512) != 0)
 166                 goto out;
 167         if((((buffer[0] & 0xff) == 0xEB) && ((buffer[2] & 0xff) == 0x90)) || ((buffer[0] & 0xff) == 0xE9))
 168                 goto out;
 169         if(((buffer[510] & 0xff) == 0x55) && ((buffer[511] & 0xff) == 0xAA))
 170                 ret = EXTENDED;
 171 out:
 172         free(buffer);
 173         return ret;
 174 }
 175
 176 dfunc funcs[] = {
 177         detect_ext23,
 178         detect_fat,
 179         detect_ntfs,
 180         detect_hfsplus,
 181         detect_extended,
 182         detect_efi,
 183         detect_mbr,
 184 };
 185
 186 int detect_fs(char *device)
 187 {
 188         int i = 0;
 189         int ret = NONE;
 190         int fd;
 191
 192         fd = open(device, O_RDONLY);
 193         if(!fd)
 194                 return NONE;
 195
 196         while((i < 6) && (ret == NONE))
 197                 ret = funcs[i++](fd);
 198
 199         close(fd);
 200
 201         return ret;
 202 }