1 //
2 // C++ Interface: diskio (Windows-specific components)
3 //
4 // Description: Class to handle low-level disk I/O for GPT fdisk
5 //
6 //
7 // Author: Rod Smith <rodsmith@rodsbooks.com>, (C) 2009
8 //
9 // Copyright: See COPYING file that comes with this distribution
10 //
11 //
12 // This program is copyright (c) 2009, 2010 by Roderick W. Smith. It is distributed
13 // under the terms of the GNU GPL version 2, as detailed in the COPYING file.
14 
15 #define __STDC_LIMIT_MACROS
16 #define __STDC_CONSTANT_MACROS
17 
18 #include <windows.h>
19 #include <winioctl.h>
20 #define fstat64 fstat
21 #define stat64 stat
22 #define S_IRGRP 0
23 #define S_IROTH 0
24 #include <stdio.h>
25 #include <string>
26 #include <stdint.h>
27 #include <errno.h>
28 #include <fcntl.h>
29 #include <sys/stat.h>
30 #include <iostream>
31 
32 #include "support.h"
33 #include "diskio.h"
34 
35 using namespace std;
36 
37 // Returns the official Windows name for a shortened version of same.
38 void DiskIO::MakeRealName(void) {
39    size_t colonPos;
40 
41    colonPos = userFilename.find(':', 0);
42    if ((colonPos != string::npos) && (colonPos <= 3)) {
43       realFilename = "\\\\.\\physicaldrive";
44       realFilename += userFilename.substr(0, colonPos);
45    } else {
46       realFilename = userFilename;
47    } // if/else
48 } // DiskIO::MakeRealName()
49 
50 // Open the currently on-record file for reading
51 int DiskIO::OpenForRead(void) {
52    int shouldOpen = 1;
53 
54    if (isOpen) { // file is already open
55       if (openForWrite) {
56          Close();
57       } else {
58          shouldOpen = 0;
59       } // if/else
60    } // if
61 
62    if (shouldOpen) {
63       fd = CreateFile(realFilename.c_str(),GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE,
64                       NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
65       if (fd == INVALID_HANDLE_VALUE) {
66          CloseHandle(fd);
67          cerr << "Problem opening " << realFilename << " for reading!\n";
68          realFilename = "";
69          userFilename = "";
70          isOpen = 0;
71          openForWrite = 0;
72       } else {
73          isOpen = 1;
74          openForWrite = 0;
75       } // if/else
76    } // if
77 
78    return isOpen;
79 } // DiskIO::OpenForRead(void)
80 
81 // An extended file-open function. This includes some system-specific checks.
82 // Returns 1 if the file is open, 0 otherwise....
83 int DiskIO::OpenForWrite(void) {
84    if ((isOpen) && (openForWrite))
85       return 1;
86 
87    // Close the disk, in case it's already open for reading only....
88    Close();
89 
90    // try to open the device; may fail....
91    fd = CreateFile(realFilename.c_str(), GENERIC_READ | GENERIC_WRITE,
92                    FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
93                    FILE_ATTRIBUTE_NORMAL, NULL);
94    // Preceding call can fail when creating backup files; if so, try
95    // again with different option...
96    if (fd == INVALID_HANDLE_VALUE) {
97       CloseHandle(fd);
98       fd = CreateFile(realFilename.c_str(), GENERIC_READ | GENERIC_WRITE,
99                       FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_ALWAYS,
100                       FILE_ATTRIBUTE_NORMAL, NULL);
101    } // if
102    if (fd == INVALID_HANDLE_VALUE) {
103       CloseHandle(fd);
104       isOpen = 0;
105       openForWrite = 0;
106       errno = GetLastError();
107    } else {
108       isOpen = 1;
109       openForWrite = 1;
110    } // if/else
111    return isOpen;
112 } // DiskIO::OpenForWrite(void)
113 
114 // Close the disk device. Note that this does NOT erase the stored filenames,
115 // so the file can be re-opened without specifying the filename.
116 void DiskIO::Close(void) {
117    if (isOpen)
118       CloseHandle(fd);
119    isOpen = 0;
120    openForWrite = 0;
121 } // DiskIO::Close()
122 
123 // Returns block size of device pointed to by fd file descriptor. If the ioctl
124 // returns an error condition, assume it's a disk file and return a value of
125 // SECTOR_SIZE (512). If the disk can't be opened at all, return a value of 0.
126 int DiskIO::GetBlockSize(void) {
127    DWORD blockSize = 0, retBytes;
128    DISK_GEOMETRY_EX geom;
129 
130    // If disk isn't open, try to open it....
131    if (!isOpen) {
132       OpenForRead();
133    } // if
134 
135    if (isOpen) {
136       if (DeviceIoControl(fd, IOCTL_DISK_GET_DRIVE_GEOMETRY_EX, NULL, 0,
137                           &geom, sizeof(geom), &retBytes, NULL)) {
138          blockSize = geom.Geometry.BytesPerSector;
139       } else { // was probably an ordinary file; set default value....
140          blockSize = SECTOR_SIZE;
141       } // if/else
142    } // if (isOpen)
143 
144    return (blockSize);
145 } // DiskIO::GetBlockSize()
146 
147 // In theory, returns the physical block size. In practice, this is only
148 // supported in Linux, as of yet.
149 // TODO: Get this working in Windows.
150 int DiskIO::GetPhysBlockSize(void) {
151    return 0;
152 } // DiskIO::GetPhysBlockSize()
153 
154 // Returns the number of heads, according to the kernel, or 255 if the
155 // correct value can't be determined.
156 uint32_t DiskIO::GetNumHeads(void) {
157    return UINT32_C(255);
158 } // DiskIO::GetNumHeads();
159 
160 // Returns the number of sectors per track, according to the kernel, or 63
161 // if the correct value can't be determined.
162 uint32_t DiskIO::GetNumSecsPerTrack(void) {
163    return UINT32_C(63);
164 } // DiskIO::GetNumSecsPerTrack()
165 
166 // Resync disk caches so the OS uses the new partition table. This code varies
167 // a lot from one OS to another.
168 // Returns 1 on success, 0 if the kernel continues to use the old partition table.
169 int DiskIO::DiskSync(void) {
170    DWORD i;
171    GET_LENGTH_INFORMATION buf;
172    int retval = 0;
173 
174    // If disk isn't open, try to open it....
175    if (!openForWrite) {
176       OpenForWrite();
177    } // if
178 
179    if (isOpen) {
180       if (DeviceIoControl(fd, IOCTL_DISK_UPDATE_PROPERTIES, NULL, 0, &buf, sizeof(buf), &i, NULL) == 0) {
181          cout << "Disk synchronization failed! The computer may use the old partition table\n"
182               << "until you reboot or remove and re-insert the disk!\n";
183       } else {
184          cout << "Disk synchronization succeeded! The computer should now use the new\n"
185               << "partition table.\n";
186          retval = 1;
187       } // if/else
188    } else {
189       cout << "Unable to open the disk for synchronization operation! The computer will\n"
190            << "continue to use the old partition table until you reboot or remove and\n"
191            << "re-insert the disk!\n";
192    } // if (isOpen)
193    return retval;
194 } // DiskIO::DiskSync()
195 
196 // Seek to the specified sector. Returns 1 on success, 0 on failure.
197 int DiskIO::Seek(uint64_t sector) {
198    int retval = 1;
199    LARGE_INTEGER seekTo;
200 
201    // If disk isn't open, try to open it....
202    if (!isOpen) {
203       retval = OpenForRead();
204    } // if
205 
206    if (isOpen) {
207       seekTo.QuadPart = sector * (uint64_t) GetBlockSize();
208       retval = SetFilePointerEx(fd, seekTo, NULL, FILE_BEGIN);
209       if (retval == 0) {
210          errno = GetLastError();
211          cerr << "Error when seeking to " << seekTo.QuadPart << "! Error is " << errno << "\n";
212          retval = 0;
213       } // if
214    } // if
215    return retval;
216 } // DiskIO::Seek()
217 
218 // A variant on the standard read() function. Done to work around
219 // limitations in FreeBSD concerning the matching of the sector
220 // size with the number of bytes read.
221 // Returns the number of bytes read into buffer.
222 int DiskIO::Read(void* buffer, int numBytes) {
223    int blockSize = 512, i, numBlocks;
224    char* tempSpace;
225    DWORD retval = 0;
226 
227    // If disk isn't open, try to open it....
228    if (!isOpen) {
229       OpenForRead();
230    } // if
231 
232    if (isOpen) {
233       // Compute required space and allocate memory
234       blockSize = GetBlockSize();
235       if (numBytes <= blockSize) {
236          numBlocks = 1;
237          tempSpace = new char [blockSize];
238       } else {
239          numBlocks = numBytes / blockSize;
240          if ((numBytes % blockSize) != 0)
241             numBlocks++;
242          tempSpace = new char [numBlocks * blockSize];
243       } // if/else
244       if (tempSpace == NULL) {
245          cerr << "Unable to allocate memory in DiskIO::Read()! Terminating!\n";
246          exit(1);
247       } // if
248 
249       // Read the data into temporary space, then copy it to buffer
250       ReadFile(fd, tempSpace, numBlocks * blockSize, &retval, NULL);
251       for (i = 0; i < numBytes; i++) {
252          ((char*) buffer)[i] = tempSpace[i];
253       } // for
254 
255       // Adjust the return value, if necessary....
256       if (((numBlocks * blockSize) != numBytes) && (retval > 0))
257          retval = numBytes;
258 
259       delete[] tempSpace;
260    } // if (isOpen)
261    return retval;
262 } // DiskIO::Read()
263 
264 // A variant on the standard write() function.
265 // Returns the number of bytes written.
266 int DiskIO::Write(void* buffer, int numBytes) {
267    int blockSize = 512, i, numBlocks, retval = 0;
268    char* tempSpace;
269    DWORD numWritten;
270 
271    // If disk isn't open, try to open it....
272    if ((!isOpen) || (!openForWrite)) {
273       OpenForWrite();
274    } // if
275 
276    if (isOpen) {
277       // Compute required space and allocate memory
278       blockSize = GetBlockSize();
279       if (numBytes <= blockSize) {
280          numBlocks = 1;
281          tempSpace = new char [blockSize];
282       } else {
283          numBlocks = numBytes / blockSize;
284          if ((numBytes % blockSize) != 0) numBlocks++;
285          tempSpace = new char [numBlocks * blockSize];
286       } // if/else
287       if (tempSpace == NULL) {
288          cerr << "Unable to allocate memory in DiskIO::Write()! Terminating!\n";
289          exit(1);
290       } // if
291 
292       // Copy the data to my own buffer, then write it
293       for (i = 0; i < numBytes; i++) {
294          tempSpace[i] = ((char*) buffer)[i];
295       } // for
296       for (i = numBytes; i < numBlocks * blockSize; i++) {
297          tempSpace[i] = 0;
298       } // for
299       WriteFile(fd, tempSpace, numBlocks * blockSize, &numWritten, NULL);
300       retval = (int) numWritten;
301 
302       // Adjust the return value, if necessary....
303       if (((numBlocks * blockSize) != numBytes) && (retval > 0))
304          retval = numBytes;
305 
306       delete[] tempSpace;
307    } // if (isOpen)
308    return retval;
309 } // DiskIO:Write()
310 
311 // Returns the size of the disk in blocks.
312 uint64_t DiskIO::DiskSize(int *err) {
313    uint64_t sectors = 0; // size in sectors
314    DWORD bytes, moreBytes; // low- and high-order bytes of file size
315    GET_LENGTH_INFORMATION buf;
316    DWORD i;
317 
318    // If disk isn't open, try to open it....
319    if (!isOpen) {
320       OpenForRead();
321    } // if
322 
323    if (isOpen) {
324       // Note to self: I recall testing a simplified version of
325       // this code, similar to what's in the __APPLE__ block,
326       // on Linux, but I had some problems. IIRC, it ran OK on 32-bit
327       // systems but not on 64-bit. Keep this in mind in case of
328       // 32/64-bit issues on MacOS....
329       if (DeviceIoControl(fd, IOCTL_DISK_GET_LENGTH_INFO, NULL, 0, &buf, sizeof(buf), &i, NULL)) {
330          sectors = (uint64_t) buf.Length.QuadPart / GetBlockSize();
331          *err = 0;
332       } else { // doesn't seem to be a disk device; assume it's an image file....
333          bytes = GetFileSize(fd, &moreBytes);
334          sectors = ((uint64_t) bytes + ((uint64_t) moreBytes) * UINT32_MAX) / GetBlockSize();
335          *err = 0;
336       } // if
337    } else {
338       *err = -1;
339       sectors = 0;
340    } // if/else (isOpen)
341 
342    return sectors;
343 } // DiskIO::DiskSize()
344