GRUB2/MOD_SRC/grub-2.04/grub-core/kern/file.c

   1 /* file.c - file I/O functions */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2006,2007,2009  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/misc.h>
  21 #include <grub/err.h>
  22 #include <grub/file.h>
  23 #include <grub/net.h>
  24 #include <grub/mm.h>
  25 #include <grub/fs.h>
  26 #include <grub/device.h>
  27 #include <grub/i18n.h>
  28
  29 void (*EXPORT_VAR (grub_grubnet_fini)) (void);
  30
  31 grub_file_filter_t grub_file_filters[GRUB_FILE_FILTER_MAX];
  32
  33 /* Get the device part of the filename NAME. It is enclosed by parentheses.  */
  34 char *
  35 grub_file_get_device_name (const char *name)
  36 {
  37   if (name[0] == '(')
  38     {
  39       char *p = grub_strchr (name, ')');
  40       char *ret;
  41
  42       if (! p)
  43         {
  44           grub_error (GRUB_ERR_BAD_FILENAME, N_("missing `%c' symbol"), ')');
  45           return 0;
  46         }
  47
  48       ret = (char *) grub_malloc (p - name);
  49       if (! ret)
  50         return 0;
  51
  52       grub_memcpy (ret, name + 1, p - name - 1);
  53       ret[p - name - 1] = '\0';
  54       return ret;
  55     }
  56
  57   return 0;
  58 }
  59
  60 /* Support mem:xxx:size:xxx format in chainloader */
  61 grub_file_t grub_memfile_open(const char *name);
  62 #define GRUB_MEMFILE_MEM     "mem:"
  63 #define GRUB_MEMFILE_SIZE    "size:"
  64
  65 grub_file_t grub_memfile_open(const char *name)
  66 {
  67     char *size = NULL;
  68     grub_file_t file = 0;
  69
  70     file = (grub_file_t)grub_zalloc(sizeof(*file));
  71     if (NULL == file)
  72     {
  73         return 0;
  74     }
  75
  76     file->name = grub_strdup(name);
  77     file->data = (void *)grub_strtoul(name + grub_strlen(GRUB_MEMFILE_MEM), NULL, 0);
  78
  79     size = grub_strstr(name, GRUB_MEMFILE_SIZE);
  80     file->size = (grub_off_t)grub_strtoul(size + grub_strlen(GRUB_MEMFILE_SIZE), NULL, 0);
  81
  82     grub_errno = GRUB_ERR_NONE;
  83     return file;
  84 }
  85
  86 grub_file_t
  87 grub_file_open (const char *name, enum grub_file_type type)
  88 {
  89   grub_device_t device = 0;
  90   grub_file_t file = 0, last_file = 0;
  91   char *device_name;
  92   const char *file_name;
  93   grub_file_filter_id_t filter;
  94
  95   /* <DESC> : mem:xxx:size:xxx format in chainloader */
  96   if (grub_strncmp(name, GRUB_MEMFILE_MEM, grub_strlen(GRUB_MEMFILE_MEM)) == 0) {
  97       return grub_memfile_open(name);
  98   }
  99
 100   device_name = grub_file_get_device_name (name);
 101   if (grub_errno)
 102     goto fail;
 103
 104   /* Get the file part of NAME.  */
 105   file_name = (name[0] == '(') ? grub_strchr (name, ')') : NULL;
 106   if (file_name)
 107     file_name++;
 108   else
 109     file_name = name;
 110
 111   device = grub_device_open (device_name);
 112   grub_free (device_name);
 113   if (! device)
 114     goto fail;
 115
 116   file = (grub_file_t) grub_zalloc (sizeof (*file));
 117   if (! file)
 118     goto fail;
 119
 120   file->device = device;
 121
 122   /* In case of relative pathnames and non-Unix systems (like Windows)
 123    * name of host files may not start with `/'. Blocklists for host files
 124    * are meaningless as well (for a start, host disk does not allow any direct
 125    * access - it is just a marker). So skip host disk in this case.
 126    */
 127   if (device->disk && file_name[0] != '/'
 128 #if defined(GRUB_UTIL) || defined(GRUB_MACHINE_EMU)
 129       && grub_strcmp (device->disk->name, "host")
 130 #endif
 131      )
 132     /* This is a block list.  */
 133     file->fs = &grub_fs_blocklist;
 134   else
 135     {
 136       file->fs = grub_fs_probe (device);
 137       if (! file->fs)
 138         goto fail;
 139     }
 140
 141   if ((file->fs->fs_open) (file, file_name) != GRUB_ERR_NONE)
 142     goto fail;
 143
 144   file->name = grub_strdup (name);
 145   grub_errno = GRUB_ERR_NONE;
 146
 147   for (filter = 0; file && filter < ARRAY_SIZE (grub_file_filters);
 148        filter++)
 149     if (grub_file_filters[filter])
 150       {
 151         last_file = file;
 152         file = grub_file_filters[filter] (file, type);
 153         if (file && file != last_file)
 154           {
 155             file->name = grub_strdup (name);
 156             grub_errno = GRUB_ERR_NONE;
 157           }
 158       }
 159   if (!file)
 160     grub_file_close (last_file);
 161
 162   return file;
 163
 164  fail:
 165   if (device)
 166     grub_device_close (device);
 167
 168   /* if (net) grub_net_close (net);  */
 169
 170   grub_free (file);
 171
 172   return 0;
 173 }
 174
 175 grub_disk_read_hook_t grub_file_progress_hook;
 176
 177 grub_ssize_t
 178 grub_file_read (grub_file_t file, void *buf, grub_size_t len)
 179 {
 180   grub_ssize_t res;
 181   grub_disk_read_hook_t read_hook;
 182   void *read_hook_data;
 183
 184   if (file->offset > file->size)
 185     {
 186       grub_error (GRUB_ERR_OUT_OF_RANGE,
 187                   N_("attempt to read past the end of file"));
 188       return -1;
 189     }
 190
 191   if (len == 0)
 192     return 0;
 193
 194   if (len > file->size - file->offset)
 195     len = file->size - file->offset;
 196
 197   /* Prevent an overflow.  */
 198   if ((grub_ssize_t) len < 0)
 199     len >>= 1;
 200
 201   if (len == 0)
 202     return 0;
 203
 204   if (grub_strncmp(file->name, GRUB_MEMFILE_MEM, grub_strlen(GRUB_MEMFILE_MEM)) == 0) {
 205       grub_memcpy(buf, (grub_uint8_t *)(file->data) + file->offset, len);
 206       file->offset += len;
 207       return len;
 208   }
 209
 210   read_hook = file->read_hook;
 211   read_hook_data = file->read_hook_data;
 212   if (!file->read_hook)
 213     {
 214       file->read_hook = grub_file_progress_hook;
 215       file->read_hook_data = file;
 216       file->progress_offset = file->offset;
 217     }
 218   res = (file->fs->fs_read) (file, buf, len);
 219   file->read_hook = read_hook;
 220   file->read_hook_data = read_hook_data;
 221   if (res > 0)
 222     file->offset += res;
 223
 224   return res;
 225 }
 226
 227 grub_err_t
 228 grub_file_close (grub_file_t file)
 229 {
 230   if (file->fs && file->fs->fs_close)
 231     (file->fs->fs_close) (file);
 232
 233   if (file->device)
 234     grub_device_close (file->device);
 235   grub_free (file->name);
 236   grub_free (file);
 237   return grub_errno;
 238 }
 239
 240 grub_off_t
 241 grub_file_seek (grub_file_t file, grub_off_t offset)
 242 {
 243   grub_off_t old;
 244
 245   if (offset > file->size)
 246     {
 247       grub_error (GRUB_ERR_OUT_OF_RANGE,
 248                   N_("attempt to seek outside of the file"));
 249       return -1;
 250     }
 251
 252   old = file->offset;
 253   file->offset = offset;
 254
 255   return old;
 256 }