5 A part of the extended file system 2 disk editor.
7 -------------------------------------------------
8 The filesystem's disk activity pass through here.
9 -------------------------------------------------
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.
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.
19 First written on: April 9 1995
21 Copyright (C) 1995 Gadi Oxman
34 int low_read (unsigned char *buffer,unsigned long length,unsigned long offset)
38 This function is used when we need to read something from the filesystem.
48 if (device_handle==NULL) { /* Check that a device is indeed open */
49 internal_error ("No device opened yet read requested","disk","low_read");
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");
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 ();
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);
74 int low_write (unsigned char *buffer,unsigned long length,unsigned long offset)
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.
88 wprintw (command_win,"Error - Write access not aviable (use enablewrite)\n");
95 internal_error ("AllowChanges=0 yet enablewrite succeeded","disk","low_write");
99 if (device_handle==NULL) {
100 internal_error ("No device opened yet read requested","disk","low_write");
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");
113 if (!log_changes (buffer,length,offset))
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);
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);
127 wprintw (command_win,"Data written");refresh_command_win ();
131 int log_changes (unsigned char *buffer,unsigned long length,unsigned long offset)
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.
141 unsigned char *original;
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);
152 current_time=time (NULL);
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);
158 original=(unsigned char *) malloc (length*sizeof (unsigned char));
160 if (original==NULL) {
161 wprintw (command_win,"Fatal error - Can\'t allocate %lu bytes !");
162 refresh_command_win ();fclose (fp);return (0);
165 if (!low_read (original,length,offset)) {
166 fclose (fp);return (0);
169 fprintf (fp,"\nOriginal data:\n\n");
171 for (i=0;i<length;i++) {
172 if (i%16==0 && i!=0) fprintf (fp,"\n");
173 fprintf (fp,"%02x ",original [i]);
176 fprintf (fp,"\n\nNew data:\n\n");
178 for (i=0;i<length;i++) {
179 if (i%16==0 && i!=0) fprintf (fp,"\n");
180 fprintf (fp,"%02x ",buffer [i]);
183 fprintf (fp,"\n----- EXT2ED log end -----\n");
189 int load_type_data (void)
193 Just read from the current position into type data.
198 if (device_handle==NULL) {
199 printf ("Error - No device opened\n");
203 if (device_offset==-1) {
204 printf ("Error - No offset set\n");
208 if (low_read (type_data.u.buffer,EXT2_MAX_BLOCK_SIZE,device_offset)==0)
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;
218 int write_type_data (void)
221 if (device_handle==NULL) {
222 wprintw (command_win,"Error - No device opened\n");
223 refresh_command_win ();
227 if (device_offset==-1) {
228 wprintw (command_win,"Error - No offset set\n");
229 refresh_command_win ();
233 if (low_write (type_data.u.buffer,file_system_info.block_size,device_offset)==0)