Theodore Ts'o | 583a1ce | 2002-05-11 13:00:22 -0400 | [diff] [blame] | 1 | /* |
| 2 | |
| 3 | /usr/src/ext2ed/disk.c |
| 4 | |
| 5 | A part of the extended file system 2 disk editor. |
| 6 | |
| 7 | ------------------------------------------------- |
| 8 | The filesystem's disk activity pass through here. |
| 9 | ------------------------------------------------- |
| 10 | |
| 11 | This file is acting as a filter - Before we pass an actual read or write request to the operating system, we |
| 12 | double check the various permissions and possible errors here. |
| 13 | |
| 14 | The major update which needs to be done here is switching to the use of the llseek system call, so that we will |
| 15 | be able to support ext2 filesystems up to 4 TB. Currently, due to the standard fseek usage, we can't handle |
| 16 | filesystems bigger than 4 GB. The limit is actually 2 GB because I used long rather than unsigned long long at too |
| 17 | many places in the program. To conclude - This upgrade needs to be done carefuly; There are many places to change. |
| 18 | |
| 19 | First written on: April 9 1995 |
| 20 | |
| 21 | Copyright (C) 1995 Gadi Oxman |
| 22 | |
| 23 | */ |
| 24 | |
| 25 | #include <stdio.h> |
| 26 | #include <stdlib.h> |
| 27 | #include <string.h> |
| 28 | #include <time.h> |
| 29 | |
| 30 | #include "ext2ed.h" |
| 31 | |
| 32 | int write_access; |
| 33 | |
| 34 | int low_read (unsigned char *buffer,unsigned long length,unsigned long offset) |
| 35 | |
| 36 | /* |
| 37 | |
| 38 | This function is used when we need to read something from the filesystem. |
| 39 | |
| 40 | */ |
| 41 | |
| 42 | { |
| 43 | |
| 44 | #ifdef DEBUG |
| 45 | |
| 46 | char temp [80]; |
| 47 | |
| 48 | if (device_handle==NULL) { /* Check that a device is indeed open */ |
| 49 | internal_error ("No device opened yet read requested","disk","low_read"); |
| 50 | return (0); |
| 51 | } |
| 52 | if (offset > file_system_info.file_system_size) { /* Check that the offset is within limits */ |
| 53 | sprintf (temp,"Seek offset %ld is out of range",offset); |
| 54 | internal_error (temp,"disk","low_read"); |
| 55 | return (0); |
| 56 | } |
| 57 | |
| 58 | #endif |
| 59 | |
| 60 | if ( (fseek (device_handle,offset,SEEK_SET))==-1) { /* Seek to the required offset */ |
| 61 | wprintw (command_win,"Error - Failed to seek to offset %ld in device %s\n",offset,device_name); |
| 62 | refresh_command_win (); |
| 63 | return (0); |
| 64 | }; |
| 65 | |
| 66 | if ( (fread (buffer,1,length,device_handle))==-1) { /* And do the actual reading */ |
| 67 | wprintw (command_win,"Error - Failed to read from offset %ld in device %s\n",offset,device_name); |
| 68 | refresh_command_win ();return (0); |
| 69 | }; |
| 70 | |
| 71 | return (1); |
| 72 | } |
| 73 | |
| 74 | int low_write (unsigned char *buffer,unsigned long length,unsigned long offset) |
| 75 | |
| 76 | /* |
| 77 | |
| 78 | This is used to change something in the filesystem. |
| 79 | write_access is checked to see if we are allowed to do the actual writing. |
| 80 | As a double safety measure, AllowChanges is rechecked here. |
| 81 | If logging is enabled, we log the change before writing it to the device. |
| 82 | |
| 83 | */ |
| 84 | { |
| 85 | char temp [80]; |
| 86 | |
| 87 | if (!write_access) { |
| 88 | wprintw (command_win,"Error - Write access not aviable (use enablewrite)\n"); |
| 89 | return (0); |
| 90 | } |
| 91 | |
| 92 | #ifdef DEBUG |
| 93 | |
| 94 | if (!AllowChanges) { |
| 95 | internal_error ("AllowChanges=0 yet enablewrite succeeded","disk","low_write"); |
| 96 | return (0); |
| 97 | } |
| 98 | |
| 99 | if (device_handle==NULL) { |
| 100 | internal_error ("No device opened yet read requested","disk","low_write"); |
| 101 | return (0); |
| 102 | } |
| 103 | |
| 104 | if (offset > file_system_info.file_system_size) { |
| 105 | sprintf (temp,"Seek offset %ld is out of range",offset); |
| 106 | internal_error (temp,"disk","low_write"); |
| 107 | return (0); |
| 108 | } |
| 109 | |
| 110 | #endif |
| 111 | |
| 112 | if (LogChanges) |
| 113 | if (!log_changes (buffer,length,offset)) |
| 114 | return (0); |
| 115 | |
| 116 | if ( (fseek (device_handle,offset,SEEK_SET))==-1) { |
| 117 | wprintw (command_win,"Error - Failed to seek to offset %ld in device %s\n",offset,device_name); |
| 118 | refresh_command_win ();return (0); |
| 119 | }; |
| 120 | |
| 121 | |
| 122 | if ( (fwrite (buffer,1,length,device_handle))==-1) { |
| 123 | wprintw (command_win,"Error - Failed to write to offset %ld in device %s\n",offset,device_name); |
| 124 | refresh_command_win ();return (0); |
| 125 | }; |
| 126 | |
| 127 | wprintw (command_win,"Data written");refresh_command_win (); |
| 128 | return (1); |
| 129 | } |
| 130 | |
| 131 | int log_changes (unsigned char *buffer,unsigned long length,unsigned long offset) |
| 132 | |
| 133 | /* |
| 134 | |
| 135 | Log the change in a primitive form - An hex dump of the data before the change and after the change. |
| 136 | The hex bytes are converted to text, so that they will be readable with a standard text editor. |
| 137 | |
| 138 | */ |
| 139 | |
| 140 | { |
| 141 | unsigned char *original; |
| 142 | |
| 143 | int i; |
| 144 | time_t current_time; |
| 145 | FILE *fp; |
| 146 | |
| 147 | if ((fp=fopen (LogFile,"a+"))==NULL) { |
| 148 | wprintw (command_win,"Error - Unable to open log file %s\n",LogFile); |
| 149 | refresh_command_win ();return (0); |
| 150 | }; |
| 151 | |
| 152 | current_time=time (NULL); |
| 153 | |
| 154 | fprintf (fp,"\n----- EXT2ED log begin -----\n\n"); |
| 155 | fprintf (fp,"Time: %s\nDevice: %s\n",ctime ((time_t *) ¤t_time),device_name); |
| 156 | fprintf (fp,"Offset: %lu\nLength: %lu\n",offset,length); |
| 157 | |
| 158 | original=(unsigned char *) malloc (length*sizeof (unsigned char)); |
| 159 | |
| 160 | if (original==NULL) { |
| 161 | wprintw (command_win,"Fatal error - Can\'t allocate %lu bytes !"); |
| 162 | refresh_command_win ();fclose (fp);return (0); |
| 163 | } |
| 164 | |
| 165 | if (!low_read (original,length,offset)) { |
| 166 | fclose (fp);return (0); |
| 167 | } |
| 168 | |
| 169 | fprintf (fp,"\nOriginal data:\n\n"); |
| 170 | |
| 171 | for (i=0;i<length;i++) { |
| 172 | if (i%16==0 && i!=0) fprintf (fp,"\n"); |
| 173 | fprintf (fp,"%02x ",original [i]); |
| 174 | } |
| 175 | |
| 176 | fprintf (fp,"\n\nNew data:\n\n"); |
| 177 | |
| 178 | for (i=0;i<length;i++) { |
| 179 | if (i%16==0 && i!=0) fprintf (fp,"\n"); |
| 180 | fprintf (fp,"%02x ",buffer [i]); |
| 181 | } |
| 182 | |
| 183 | fprintf (fp,"\n----- EXT2ED log end -----\n"); |
| 184 | |
| 185 | fclose (fp); |
| 186 | return (1); |
| 187 | } |
| 188 | |
| 189 | int load_type_data (void) |
| 190 | |
| 191 | /* |
| 192 | |
| 193 | Just read from the current position into type data. |
| 194 | |
| 195 | */ |
| 196 | |
| 197 | { |
| 198 | if (device_handle==NULL) { |
| 199 | printf ("Error - No device opened\n"); |
| 200 | return (0); |
| 201 | } |
| 202 | |
| 203 | if (device_offset==-1) { |
| 204 | printf ("Error - No offset set\n"); |
| 205 | return (0); |
| 206 | } |
| 207 | |
| 208 | if (low_read (type_data.u.buffer,EXT2_MAX_BLOCK_SIZE,device_offset)==0) |
| 209 | return (0); |
| 210 | |
| 211 | if (current_type!=NULL) |
| 212 | if (strcmp (current_type->name,"ext2_dir_entry")==0) |
| 213 | current_type->length=type_data.u.t_ext2_dir_entry.rec_len; |
| 214 | |
| 215 | return (1); |
| 216 | } |
| 217 | |
| 218 | int write_type_data (void) |
| 219 | |
| 220 | { |
| 221 | if (device_handle==NULL) { |
| 222 | wprintw (command_win,"Error - No device opened\n"); |
| 223 | refresh_command_win (); |
| 224 | return (0); |
| 225 | } |
| 226 | |
| 227 | if (device_offset==-1) { |
| 228 | wprintw (command_win,"Error - No offset set\n"); |
| 229 | refresh_command_win (); |
| 230 | return (0); |
| 231 | } |
| 232 | |
| 233 | if (low_write (type_data.u.buffer,file_system_info.block_size,device_offset)==0) |
| 234 | return (0); |
| 235 | |
| 236 | return (1); |
| 237 | } |
| 238 | |