fs.c

   1 #include <stdio.h>
   2 #include <unistd.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <sys/types.h>
   6 #include <sys/stat.h>
   7 #include <fcntl.h>
   8
   9 #include "include/fs.h"
  10
  11 typedef int (*dfunc)(int);
  12
  13 static unsigned short
  14 get_le_short(void *from)
  15 {
  16         unsigned char *p = from;
  17         return ((unsigned short)(p[1]) << 8) +
  18                 (unsigned short)p[0];
  19 }
  20
  21 static unsigned int get_le_long(void *from)
  22 {
  23         unsigned char *p = from;
  24         return ((unsigned int)(p[3]) << 24) +
  25                 ((unsigned int)(p[2]) << 16) +
  26                 ((unsigned int)(p[1]) << 8) +
  27                 (unsigned int)p[0];
  28 }
  29
  30 static unsigned short get_be_short(void *from)
  31 {
  32         unsigned char *p = from;
  33         return ((unsigned short)(p[0]) << 8) +
  34                 (unsigned short)p[1];
  35 }
  36
  37 static unsigned int get_be_long(void *from)
  38 {
  39         unsigned char *p = from;
  40         return ((unsigned int)(p[0]) << 24) +
  41                 ((unsigned int)(p[1]) << 16) +
  42                 ((unsigned int)(p[2]) << 8) +
  43                 (unsigned int)p[3];
  44 }
  45
  46 static int get_buffer(int fd, unsigned char *b, int offset, int len)
  47 {
  48         if(lseek(fd, offset, SEEK_SET) != offset)
  49                 return -1;
  50         if(read(fd, b, len) != len)
  51                 return -1;
  52         return 0;
  53 }
  54
  55 #define MBR_BUF_SIZE    512
  56 static int detect_mbr(int fd)
  57 {
  58         int ret = NONE;
  59         unsigned char *buffer = (unsigned char*)malloc(MBR_BUF_SIZE);
  60         if(get_buffer(fd, buffer, 0, MBR_BUF_SIZE) != 0)
  61                 goto out;
  62         if((buffer[510] == 0x55) && (buffer[511] == 0xAA))
  63                 ret = MBR;
  64 out:
  65         free(buffer);
  66         return ret;
  67 }
  68
  69 #define EFI_BUF_OFFSET  512
  70 #define EFI_BUF_SIZE    512
  71 static int detect_efi(int fd)
  72 {
  73         int ret = NONE;
  74         unsigned char *buffer = (unsigned char*)malloc(EFI_BUF_SIZE);
  75         if(get_buffer(fd, buffer, EFI_BUF_OFFSET, EFI_BUF_SIZE) != 0)
  76                 goto out;
  77         if(!memcmp(buffer, "EFI PART", 8))
  78                 ret = EFI;
  79 out:
  80         free(buffer);
  81         return ret;
  82 }
  83
  84 #define EXT2_BUF_SIZE   1024
  85 static int detect_ext23(int fd)
  86 {
  87         int ret = NONE;
  88         unsigned char *buffer = (unsigned char*)malloc(EXT2_BUF_SIZE);
  89         if(get_buffer(fd, buffer, 1024, EXT2_BUF_SIZE) != 0)
  90                 goto out;
  91         if(get_le_short(buffer + 56) == 0xEF53)
  92         {
  93                 if(get_le_long(buffer + 92) & 0x0004)
  94                 {
  95                         if ((get_le_long(buffer + 96) < 0x0000040)
  96                                 && (get_le_long(buffer + 100) < 0x0000008))
  97                                 ret = EXT3;
  98                         else
  99                                 ret = EXT4;
 100                 }
 101                 else
 102                         ret = EXT2;
 103         }
 104 out:
 105         free(buffer);
 106         return ret;
 107 }
 108
 109 #define FAT_BUF_SIZE    512
 110 static int detect_fat(int fd)
 111 {
 112         int ret = NONE;
 113         unsigned char *buffer = (unsigned char*)malloc(FAT_BUF_SIZE);
 114         if(get_buffer(fd, buffer, 0, FAT_BUF_SIZE) != 0)
 115                 goto out;
 116
 117         if (((((buffer[0] & 0xff) == 0xEB) && ((buffer[2] & 0xff) == 0x90)) || ((buffer[0] & 0xff) == 0xE9))
 118                 && ((buffer[510] & 0xff) == 0x55) /*&& ((buffer[511] & 0xff == 0xAA))*/
 119                 && (memcmp(buffer + 3, "NTFS    ", 8)))
 120                 ret = FAT;
 121 out:
 122         free(buffer);
 123         return ret;
 124 }
 125
 126 #define HFSPLUS_VOL_JOURNALED   (1 << 13)
 127 #define HFSPLUS_BUF_SIZE                        512
 128 static int detect_hfsplus(int fd)
 129 {
 130         int ret = NONE;
 131         unsigned short magic;
 132         unsigned int journal;
 133         unsigned char *buffer = (unsigned char*)malloc(HFSPLUS_BUF_SIZE);
 134         if(get_buffer(fd, buffer, 1024, HFSPLUS_BUF_SIZE) != 0)
 135                 goto out;
 136         magic = get_be_short(buffer);
 137         journal = get_be_long(buffer + 4) & HFSPLUS_VOL_JOURNALED;
 138         if(magic == 0x482B)
 139         {
 140                 if(!journal)
 141                         ret = HFSPLUS;
 142         //      else
 143         //              ret = HFSPLUSJOURNAL;
 144         }
 145 out:
 146         free(buffer);
 147         return ret;
 148 }
 149
 150 #define NTFS_BUF_SIZE   512
 151 static int detect_ntfs(int fd)
 152 {
 153         int ret = NONE;
 154         unsigned char *buffer = (unsigned char*)malloc(NTFS_BUF_SIZE);
 155         if(get_buffer(fd, buffer, 0, NTFS_BUF_SIZE) != 0)
 156                 goto out;
 157         if(!memcmp(buffer + 3, "NTFS    ", 8))
 158                 ret = NTFS;
 159 out:
 160         free(buffer);
 161         return ret;
 162 }
 163
 164 #define EXTENDED_BUF_SIZE       512
 165 static int detect_extended(int fd)
 166 {
 167         int ret = NONE;
 168         unsigned char *buffer = (unsigned char*)malloc(MBR_BUF_SIZE);
 169         if(get_buffer(fd, buffer, 0, 512) != 0)
 170                 goto out;
 171         if((((buffer[0] & 0xff) == 0xEB) && ((buffer[2] & 0xff) == 0x90)) || ((buffer[0] & 0xff) == 0xE9))
 172                 goto out;
 173         if(((buffer[510] & 0xff) == 0x55) && ((buffer[511] & 0xff) == 0xAA))
 174                 ret = EXTENDED;
 175 out:
 176         free(buffer);
 177         return ret;
 178 }
 179
 180 dfunc funcs[] = {
 181         detect_ext23,
 182         detect_fat,
 183         detect_ntfs,
 184         detect_hfsplus,
 185         detect_extended,
 186         detect_efi,
 187         detect_mbr,
 188 };
 189
 190 int detect_fs(char *device)
 191 {
 192         int i = 0;
 193         int ret = NONE;
 194         int fd;
 195
 196         fd = open(device, O_RDONLY);
 197         if(!fd)
 198                 return NONE;
 199
 200         while((i < 6) && (ret == NONE))
 201                 ret = funcs[i++](fd);
 202
 203         close(fd);
 204
 205         return ret;
 206 }