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gpt.cc
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/* gpt.cc -- Functions for loading, saving, and manipulating legacy MBR and GPT partition
data. */
/* By Rod Smith, initial coding January to February, 2009 */
/* This program is copyright (c) 2009-2024 by Roderick W. Smith. It is distributed
under the terms of the GNU GPL version 2, as detailed in the COPYING file. */
#define __STDC_LIMIT_MACROS
#define __STDC_CONSTANT_MACROS
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <fcntl.h>
#include <string.h>
#include <math.h>
#include <time.h>
#include <sys/stat.h>
#include <errno.h>
#include <iostream>
#include <algorithm>
#include "crc32.h"
#include "gpt.h"
#include "bsd.h"
#include "support.h"
#include "parttypes.h"
#include "attributes.h"
#include "diskio.h"
using namespace std;
#ifdef __FreeBSD__
#define log2(x) (log(x) / M_LN2)
#endif // __FreeBSD__
#ifdef _MSC_VER
#define log2(x) (log((double) x) / log(2.0))
#endif // Microsoft Visual C++
#ifdef EFI
// in UEFI mode MMX registers are not yet available so using the
// x86_64 ABI to move "double" values around is not an option.
#ifdef log2
#undef log2
#endif
#define log2(x) log2_32( x )
static inline uint32_t log2_32(uint32_t v) {
int r = -1;
while (v >= 1) {
r++;
v >>= 1;
}
return r;
}
#endif
/****************************************
* *
* GPTData class and related structures *
* *
****************************************/
// Default constructor
GPTData::GPTData(void) {
blockSize = SECTOR_SIZE; // set a default
physBlockSize = 0; // 0 = can't be determined
diskSize = 0;
partitions = NULL;
state = gpt_valid;
device = "";
justLooking = 0;
mainCrcOk = 0;
secondCrcOk = 0;
mainPartsCrcOk = 0;
secondPartsCrcOk = 0;
apmFound = 0;
bsdFound = 0;
sectorAlignment = MIN_AF_ALIGNMENT; // Align partitions on 4096-byte boundaries by default
beQuiet = 0;
whichWasUsed = use_new;
mainHeader.numParts = 0;
mainHeader.firstUsableLBA = 0;
mainHeader.lastUsableLBA = 0;
numParts = 0;
SetGPTSize(NUM_GPT_ENTRIES);
// Initialize CRC functions...
chksum_crc32gentab();
} // GPTData default constructor
GPTData::GPTData(const GPTData & orig) {
uint32_t i;
if (&orig != this) {
mainHeader = orig.mainHeader;
numParts = orig.numParts;
secondHeader = orig.secondHeader;
protectiveMBR = orig.protectiveMBR;
device = orig.device;
blockSize = orig.blockSize;
physBlockSize = orig.physBlockSize;
diskSize = orig.diskSize;
state = orig.state;
justLooking = orig.justLooking;
mainCrcOk = orig.mainCrcOk;
secondCrcOk = orig.secondCrcOk;
mainPartsCrcOk = orig.mainPartsCrcOk;
secondPartsCrcOk = orig.secondPartsCrcOk;
apmFound = orig.apmFound;
bsdFound = orig.bsdFound;
sectorAlignment = orig.sectorAlignment;
beQuiet = orig.beQuiet;
whichWasUsed = orig.whichWasUsed;
myDisk.OpenForRead(orig.myDisk.GetName());
delete[] partitions;
partitions = new GPTPart [numParts];
if (partitions == NULL) {
cerr << "Error! Could not allocate memory for partitions in GPTData::operator=()!\n"
<< "Terminating!\n";
exit(1);
} // if
for (i = 0; i < numParts; i++) {
partitions[i] = orig.partitions[i];
} // for
} // if
} // GPTData copy constructor
// The following constructor loads GPT data from a device file
GPTData::GPTData(string filename) {
blockSize = SECTOR_SIZE; // set a default
diskSize = 0;
partitions = NULL;
state = gpt_invalid;
device = "";
justLooking = 0;
mainCrcOk = 0;
secondCrcOk = 0;
mainPartsCrcOk = 0;
secondPartsCrcOk = 0;
apmFound = 0;
bsdFound = 0;
sectorAlignment = MIN_AF_ALIGNMENT; // Align partitions on 4096-byte boundaries by default
beQuiet = 0;
whichWasUsed = use_new;
mainHeader.numParts = 0;
mainHeader.lastUsableLBA = 0;
numParts = 0;
// Initialize CRC functions...
chksum_crc32gentab();
if (!LoadPartitions(filename))
exit(2);
} // GPTData(string filename) constructor
// Destructor
GPTData::~GPTData(void) {
delete[] partitions;
} // GPTData destructor
// Assignment operator
GPTData & GPTData::operator=(const GPTData & orig) {
uint32_t i;
if (&orig != this) {
mainHeader = orig.mainHeader;
numParts = orig.numParts;
secondHeader = orig.secondHeader;
protectiveMBR = orig.protectiveMBR;
device = orig.device;
blockSize = orig.blockSize;
physBlockSize = orig.physBlockSize;
diskSize = orig.diskSize;
state = orig.state;
justLooking = orig.justLooking;
mainCrcOk = orig.mainCrcOk;
secondCrcOk = orig.secondCrcOk;
mainPartsCrcOk = orig.mainPartsCrcOk;
secondPartsCrcOk = orig.secondPartsCrcOk;
apmFound = orig.apmFound;
bsdFound = orig.bsdFound;
sectorAlignment = orig.sectorAlignment;
beQuiet = orig.beQuiet;
whichWasUsed = orig.whichWasUsed;
myDisk.OpenForRead(orig.myDisk.GetName());
delete[] partitions;
partitions = new GPTPart [numParts];
if (partitions == NULL) {
cerr << "Error! Could not allocate memory for partitions in GPTData::operator=()!\n"
<< "Terminating!\n";
exit(1);
} // if
for (i = 0; i < numParts; i++) {
partitions[i] = orig.partitions[i];
} // for
} // if
return *this;
} // GPTData::operator=()
/*********************************************************************
* *
* Begin functions that verify data, or that adjust the verification *
* information (compute CRCs, rebuild headers) *
* *
*********************************************************************/
// Perform detailed verification, reporting on any problems found, but
// do *NOT* recover from these problems. Returns the total number of
// problems identified.
int GPTData::Verify(void) {
int problems = 0, alignProbs = 0;
uint32_t i, numSegments, testAlignment = sectorAlignment;
uint64_t totalFree, largestSegment;
// First, check for CRC errors in the GPT data....
if (!mainCrcOk) {
problems++;
cout << "\nProblem: The CRC for the main GPT header is invalid. The main GPT header may\n"
<< "be corrupt. Consider loading the backup GPT header to rebuild the main GPT\n"
<< "header ('b' on the recovery & transformation menu). This report may be a false\n"
<< "alarm if you've already corrected other problems.\n";
} // if
if (!mainPartsCrcOk) {
problems++;
cout << "\nProblem: The CRC for the main partition table is invalid. This table may be\n"
<< "corrupt. Consider loading the backup partition table ('c' on the recovery &\n"
<< "transformation menu). This report may be a false alarm if you've already\n"
<< "corrected other problems.\n";
} // if
if (!secondCrcOk) {
problems++;
cout << "\nProblem: The CRC for the backup GPT header is invalid. The backup GPT header\n"
<< "may be corrupt. Consider using the main GPT header to rebuild the backup GPT\n"
<< "header ('d' on the recovery & transformation menu). This report may be a false\n"
<< "alarm if you've already corrected other problems.\n";
} // if
if (!secondPartsCrcOk) {
problems++;
cout << "\nCaution: The CRC for the backup partition table is invalid. This table may\n"
<< "be corrupt. This program will automatically create a new backup partition\n"
<< "table when you save your partitions.\n";
} // if
// Now check that the main and backup headers both point to themselves....
if (mainHeader.currentLBA != 1) {
problems++;
cout << "\nProblem: The main header's self-pointer doesn't point to itself. This problem\n"
<< "is being automatically corrected, but it may be a symptom of more serious\n"
<< "problems. Think carefully before saving changes with 'w' or using this disk.\n";
mainHeader.currentLBA = 1;
} // if
if (secondHeader.currentLBA != (diskSize - UINT64_C(1))) {
problems++;
cout << "\nProblem: The secondary header's self-pointer indicates that it doesn't reside\n"
<< "at the end of the disk. If you've added a disk to a RAID array, use the 'e'\n"
<< "option on the experts' menu to adjust the secondary header's and partition\n"
<< "table's locations.\n";
} // if
// Now check that critical main and backup GPT entries match each other
if (mainHeader.currentLBA != secondHeader.backupLBA) {
problems++;
cout << "\nProblem: main GPT header's current LBA pointer (" << mainHeader.currentLBA
<< ") doesn't\nmatch the backup GPT header's alternate LBA pointer("
<< secondHeader.backupLBA << ").\n";
} // if
if (mainHeader.backupLBA != secondHeader.currentLBA) {
problems++;
cout << "\nProblem: main GPT header's backup LBA pointer (" << mainHeader.backupLBA
<< ") doesn't\nmatch the backup GPT header's current LBA pointer ("
<< secondHeader.currentLBA << ").\n"
<< "The 'e' option on the experts' menu may fix this problem.\n";
} // if
if (mainHeader.firstUsableLBA != secondHeader.firstUsableLBA) {
problems++;
cout << "\nProblem: main GPT header's first usable LBA pointer (" << mainHeader.firstUsableLBA
<< ") doesn't\nmatch the backup GPT header's first usable LBA pointer ("
<< secondHeader.firstUsableLBA << ")\n";
} // if
if (mainHeader.lastUsableLBA != secondHeader.lastUsableLBA) {
problems++;
cout << "\nProblem: main GPT header's last usable LBA pointer (" << mainHeader.lastUsableLBA
<< ") doesn't\nmatch the backup GPT header's last usable LBA pointer ("
<< secondHeader.lastUsableLBA << ")\n"
<< "The 'e' option on the experts' menu can probably fix this problem.\n";
} // if
if ((mainHeader.diskGUID != secondHeader.diskGUID)) {
problems++;
cout << "\nProblem: main header's disk GUID (" << mainHeader.diskGUID
<< ") doesn't\nmatch the backup GPT header's disk GUID ("
<< secondHeader.diskGUID << ")\n"
<< "You should use the 'b' or 'd' option on the recovery & transformation menu to\n"
<< "select one or the other header.\n";
} // if
if (mainHeader.numParts != secondHeader.numParts) {
problems++;
cout << "\nProblem: main GPT header's number of partitions (" << mainHeader.numParts
<< ") doesn't\nmatch the backup GPT header's number of partitions ("
<< secondHeader.numParts << ")\n"
<< "Resizing the partition table ('s' on the experts' menu) may help.\n";
} // if
if (mainHeader.sizeOfPartitionEntries != secondHeader.sizeOfPartitionEntries) {
problems++;
cout << "\nProblem: main GPT header's size of partition entries ("
<< mainHeader.sizeOfPartitionEntries << ") doesn't\n"
<< "match the backup GPT header's size of partition entries ("
<< secondHeader.sizeOfPartitionEntries << ")\n"
<< "You should use the 'b' or 'd' option on the recovery & transformation menu to\n"
<< "select one or the other header.\n";
} // if
// Now check for a few other miscellaneous problems...
// Check that the disk size will hold the data...
if (mainHeader.backupLBA >= diskSize) {
problems++;
cout << "\nProblem: Disk is too small to hold all the data!\n"
<< "(Disk size is " << diskSize << " sectors, needs to be "
<< mainHeader.backupLBA + UINT64_C(1) << " sectors.)\n"
<< "The 'e' option on the experts' menu may fix this problem.\n";
} // if
// Check the main and backup partition tables for overlap with things and unusual gaps
if (mainHeader.partitionEntriesLBA + GetTableSizeInSectors() > mainHeader.firstUsableLBA) {
problems++;
cout << "\nProblem: Main partition table extends past the first usable LBA.\n"
<< "Using 'j' on the experts' menu may enable fixing this problem.\n";
} // if
if (mainHeader.partitionEntriesLBA < 2) {
problems++;
cout << "\nProblem: Main partition table appears impossibly early on the disk.\n"
<< "Using 'j' on the experts' menu may enable fixing this problem.\n";
} // if
if (secondHeader.partitionEntriesLBA + GetTableSizeInSectors() > secondHeader.currentLBA) {
problems++;
cout << "\nProblem: The backup partition table overlaps the backup header.\n"
<< "Using 'e' on the experts' menu may fix this problem.\n";
} // if
if (mainHeader.partitionEntriesLBA != 2) {
cout << "\nWarning: There is a gap between the main metadata (sector 1) and the main\n"
<< "partition table (sector " << mainHeader.partitionEntriesLBA
<< "). This is helpful in some exotic configurations,\n"
<< "but is generally ill-advised. Using 'j' on the experts' menu can adjust this\n"
<< "gap.\n";
} // if
if (secondHeader.partitionEntriesLBA != diskSize - GetTableSizeInSectors() - 1) {
cout << "\nWarning: There is a gap between the secondary partition table (ending at sector\n"
<< secondHeader.partitionEntriesLBA + GetTableSizeInSectors() - 1
<< ") and the secondary metadata (sector " << mainHeader.backupLBA << ").\n"
<< "This is helpful in some exotic configurations, but is generally ill-advised.\n"
<< "Using 'k' on the experts' menu can adjust this gap.\n";
} // if
if (mainHeader.partitionEntriesLBA + GetTableSizeInSectors() != mainHeader.firstUsableLBA) {
cout << "\nWarning: There is a gap between the main partition table (ending sector "
<< mainHeader.partitionEntriesLBA + GetTableSizeInSectors() - 1 << ")\n"
<< "and the first usable sector (" << mainHeader.firstUsableLBA << "). This is helpful in some exotic configurations,\n"
<< "but is unusual. The util-linux fdisk program often creates disks like this.\n"
<< "Using 'j' on the experts' menu can adjust this gap.\n";
} // if
if (mainHeader.sizeOfPartitionEntries * mainHeader.numParts < 16384) {
cout << "\nWarning: The size of the partition table (" << mainHeader.sizeOfPartitionEntries * mainHeader.numParts
<< " bytes) is less than the minimum\n"
<< "required by the GPT specification. Most OSes and tools seem to work fine on\n"
<< "such disks, but this is a violation of the GPT specification and so may cause\n"
<< "problems.\n";
} // if
if ((mainHeader.lastUsableLBA >= diskSize) || (mainHeader.lastUsableLBA > mainHeader.backupLBA)) {
problems++;
cout << "\nProblem: GPT claims the disk is larger than it is! (Claimed last usable\n"
<< "sector is " << mainHeader.lastUsableLBA << ", but backup header is at\n"
<< mainHeader.backupLBA << " and disk size is " << diskSize << " sectors.\n"
<< "The 'e' option on the experts' menu will probably fix this problem\n";
}
// Check for overlapping partitions....
problems += FindOverlaps();
// Check for insane partitions (start after end, hugely big, etc.)
problems += FindInsanePartitions();
// Check for mismatched MBR and GPT partitions...
problems += FindHybridMismatches();
// Check for MBR-specific problems....
problems += VerifyMBR();
// Check for a 0xEE protective partition that's marked as active....
if (protectiveMBR.IsEEActive()) {
cout << "\nWarning: The 0xEE protective partition in the MBR is marked as active. This is\n"
<< "technically a violation of the GPT specification, and can cause some EFIs to\n"
<< "ignore the disk, but it is required to boot from a GPT disk on some BIOS-based\n"
<< "computers. You can clear this flag by creating a fresh protective MBR using\n"
<< "the 'n' option on the experts' menu.\n";
}
// Verify that partitions don't run into GPT data areas....
problems += CheckGPTSize();
if (!protectiveMBR.DoTheyFit()) {
cout << "\nPartition(s) in the protective MBR are too big for the disk! Creating a\n"
<< "fresh protective or hybrid MBR is recommended.\n";
problems++;
}
// Check that partitions are aligned on proper boundaries (for WD Advanced
// Format and similar disks)....
if ((physBlockSize != 0) && (blockSize != 0))
testAlignment = physBlockSize / blockSize;
testAlignment = max(testAlignment, sectorAlignment);
if (testAlignment == 0) // Should not happen; just being paranoid.
testAlignment = sectorAlignment;
for (i = 0; i < numParts; i++) {
if ((partitions[i].IsUsed()) && (partitions[i].GetFirstLBA() % testAlignment) != 0) {
cout << "\nCaution: Partition " << i + 1 << " doesn't begin on a "
<< testAlignment << "-sector boundary. This may\nresult "
<< "in degraded performance on some modern (2009 and later) hard disks.\n";
alignProbs++;
} // if
if ((partitions[i].IsUsed()) && ((partitions[i].GetLastLBA() + 1) % testAlignment) != 0) {
cout << "\nCaution: Partition " << i + 1 << " doesn't end on a "
<< testAlignment << "-sector boundary. This may\nresult "
<< "in problems with some disk encryption tools.\n";
} // if
} // for
if (alignProbs > 0)
cout << "\nConsult http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/\n"
<< "for information on disk alignment.\n";
// Now compute available space, but only if no problems found, since
// problems could affect the results
if (problems == 0) {
totalFree = FindFreeBlocks(&numSegments, &largestSegment);
cout << "\nNo problems found. " << totalFree << " free sectors ("
<< BytesToIeee(totalFree, blockSize) << ") available in "
<< numSegments << "\nsegments, the largest of which is "
<< largestSegment << " (" << BytesToIeee(largestSegment, blockSize)
<< ") in size.\n";
} else {
cout << "\nIdentified " << problems << " problems!\n";
} // if/else
return (problems);
} // GPTData::Verify()
// Checks to see if the GPT tables overrun existing partitions; if they
// do, issues a warning but takes no action. Returns number of problems
// detected (0 if OK, 1 to 2 if problems).
int GPTData::CheckGPTSize(void) {
uint64_t overlap, firstUsedBlock, lastUsedBlock;
uint32_t i;
int numProbs = 0;
// first, locate the first & last used blocks
firstUsedBlock = UINT64_MAX;
lastUsedBlock = 0;
for (i = 0; i < numParts; i++) {
if (partitions[i].IsUsed()) {
if (partitions[i].GetFirstLBA() < firstUsedBlock)
firstUsedBlock = partitions[i].GetFirstLBA();
if (partitions[i].GetLastLBA() > lastUsedBlock) {
lastUsedBlock = partitions[i].GetLastLBA();
} // if
} // if
} // for
// If the disk size is 0 (the default), then it means that various
// variables aren't yet set, so the below tests will be useless;
// therefore we should skip everything
if (diskSize != 0) {
if (mainHeader.firstUsableLBA > firstUsedBlock) {
overlap = mainHeader.firstUsableLBA - firstUsedBlock;
cout << "Warning! Main partition table overlaps the first partition by "
<< overlap << " blocks!\n";
if (firstUsedBlock > 2) {
cout << "Try reducing the partition table size by " << overlap * 4
<< " entries.\n(Use the 's' item on the experts' menu.)\n";
} else {
cout << "You will need to delete this partition or resize it in another utility.\n";
} // if/else
numProbs++;
} // Problem at start of disk
if (mainHeader.lastUsableLBA < lastUsedBlock) {
overlap = lastUsedBlock - mainHeader.lastUsableLBA;
cout << "\nWarning! Secondary partition table overlaps the last partition by\n"
<< overlap << " blocks!\n";
if (lastUsedBlock > (diskSize - 2)) {
cout << "You will need to delete this partition or resize it in another utility.\n";
} else {
cout << "Try reducing the partition table size by " << overlap * 4
<< " entries.\n(Use the 's' item on the experts' menu.)\n";
} // if/else
numProbs++;
} // Problem at end of disk
} // if (diskSize != 0)
return numProbs;
} // GPTData::CheckGPTSize()
// Check the validity of the GPT header. Returns 1 if the main header
// is valid, 2 if the backup header is valid, 3 if both are valid, and
// 0 if neither is valid. Note that this function checks the GPT signature,
// revision value, and CRCs in both headers.
int GPTData::CheckHeaderValidity(void) {
int valid = 3;
cout.setf(ios::uppercase);
cout.fill('0');
// Note: failed GPT signature checks produce no error message because
// a message is displayed in the ReversePartitionBytes() function
if ((mainHeader.signature != GPT_SIGNATURE) || (!CheckHeaderCRC(&mainHeader, 1))) {
valid -= 1;
} else if ((mainHeader.revision != 0x00010000) && valid) {
valid -= 1;
cout << "Unsupported GPT version in main header; read 0x";
cout.width(8);
cout << hex << mainHeader.revision << ", should be\n0x";
cout.width(8);
cout << UINT32_C(0x00010000) << dec << "\n";
} // if/else/if
if ((secondHeader.signature != GPT_SIGNATURE) || (!CheckHeaderCRC(&secondHeader))) {
valid -= 2;
} else if ((secondHeader.revision != 0x00010000) && valid) {
valid -= 2;
cout << "Unsupported GPT version in backup header; read 0x";
cout.width(8);
cout << hex << secondHeader.revision << ", should be\n0x";
cout.width(8);
cout << UINT32_C(0x00010000) << dec << "\n";
} // if/else/if
// Check for an Apple disk signature
if (((mainHeader.signature << 32) == APM_SIGNATURE1) ||
(mainHeader.signature << 32) == APM_SIGNATURE2) {
apmFound = 1; // Will display warning message later
} // if
cout.fill(' ');
return valid;
} // GPTData::CheckHeaderValidity()
// Check the header CRC to see if it's OK...
// Note: Must be called with header in platform-ordered byte order.
// Returns 1 if header's computed CRC matches the stored value, 0 if the
// computed and stored values don't match
int GPTData::CheckHeaderCRC(struct GPTHeader* header, int warn) {
uint32_t oldCRC, newCRC, hSize;
uint8_t *temp;
// Back up old header CRC and then blank it, since it must be 0 for
// computation to be valid
oldCRC = header->headerCRC;
header->headerCRC = UINT32_C(0);
hSize = header->headerSize;
if (IsLittleEndian() == 0)
ReverseHeaderBytes(header);
if ((hSize > blockSize) || (hSize < HEADER_SIZE)) {
if (warn) {
cerr << "\aWarning! Header size is specified as " << hSize << ", which is invalid.\n";
cerr << "Setting the header size for CRC computation to " << HEADER_SIZE << "\n";
} // if
hSize = HEADER_SIZE;
} else if ((hSize > sizeof(GPTHeader)) && warn) {
cout << "\aCaution! Header size for CRC check is " << hSize << ", which is greater than " << sizeof(GPTHeader) << ".\n";
cout << "If stray data exists after the header on the header sector, it will be ignored,\n"
<< "which may result in a CRC false alarm.\n";
} // if/elseif
temp = new uint8_t[hSize];
if (temp != NULL) {
memset(temp, 0, hSize);
if (hSize < sizeof(GPTHeader))
memcpy(temp, header, hSize);
else
memcpy(temp, header, sizeof(GPTHeader));
newCRC = chksum_crc32((unsigned char*) temp, hSize);
delete[] temp;
} else {
cerr << "Could not allocate memory in GPTData::CheckHeaderCRC()! Aborting!\n";
exit(1);
}
if (IsLittleEndian() == 0)
ReverseHeaderBytes(header);
header->headerCRC = oldCRC;
return (oldCRC == newCRC);
} // GPTData::CheckHeaderCRC()
// Recompute all the CRCs. Must be called before saving if any changes have
// been made. Must be called on platform-ordered data (this function reverses
// byte order and then undoes that reversal.)
void GPTData::RecomputeCRCs(void) {
uint32_t crc, hSize;
int littleEndian;
// If the header size is bigger than the GPT header data structure, reset it;
// otherwise, set both header sizes to whatever the main one is....
if (mainHeader.headerSize > sizeof(GPTHeader))
hSize = secondHeader.headerSize = mainHeader.headerSize = HEADER_SIZE;
else
hSize = secondHeader.headerSize = mainHeader.headerSize;
if ((littleEndian = IsLittleEndian()) == 0) {
ReversePartitionBytes();
ReverseHeaderBytes(&mainHeader);
ReverseHeaderBytes(&secondHeader);
} // if
// Compute CRC of partition tables & store in main and secondary headers
crc = chksum_crc32((unsigned char*) partitions, numParts * GPT_SIZE);
mainHeader.partitionEntriesCRC = crc;
secondHeader.partitionEntriesCRC = crc;
if (littleEndian == 0) {
ReverseBytes(&mainHeader.partitionEntriesCRC, 4);
ReverseBytes(&secondHeader.partitionEntriesCRC, 4);
} // if
// Zero out GPT headers' own CRCs (required for correct computation)
mainHeader.headerCRC = 0;
secondHeader.headerCRC = 0;
crc = chksum_crc32((unsigned char*) &mainHeader, hSize);
if (littleEndian == 0)
ReverseBytes(&crc, 4);
mainHeader.headerCRC = crc;
crc = chksum_crc32((unsigned char*) &secondHeader, hSize);
if (littleEndian == 0)
ReverseBytes(&crc, 4);
secondHeader.headerCRC = crc;
if (littleEndian == 0) {
ReverseHeaderBytes(&mainHeader);
ReverseHeaderBytes(&secondHeader);
ReversePartitionBytes();
} // if
} // GPTData::RecomputeCRCs()
// Rebuild the main GPT header, using the secondary header as a model.
// Typically called when the main header has been found to be corrupt.
void GPTData::RebuildMainHeader(void) {
mainHeader.signature = GPT_SIGNATURE;
mainHeader.revision = secondHeader.revision;
mainHeader.headerSize = secondHeader.headerSize;
mainHeader.headerCRC = UINT32_C(0);
mainHeader.reserved = secondHeader.reserved;
mainHeader.currentLBA = secondHeader.backupLBA;
mainHeader.backupLBA = secondHeader.currentLBA;
mainHeader.firstUsableLBA = secondHeader.firstUsableLBA;
mainHeader.lastUsableLBA = secondHeader.lastUsableLBA;
mainHeader.diskGUID = secondHeader.diskGUID;
mainHeader.numParts = secondHeader.numParts;
mainHeader.partitionEntriesLBA = secondHeader.firstUsableLBA - GetTableSizeInSectors();
mainHeader.sizeOfPartitionEntries = secondHeader.sizeOfPartitionEntries;
mainHeader.partitionEntriesCRC = secondHeader.partitionEntriesCRC;
memcpy(mainHeader.reserved2, secondHeader.reserved2, sizeof(mainHeader.reserved2));
mainCrcOk = secondCrcOk;
SetGPTSize(mainHeader.numParts, 0);
} // GPTData::RebuildMainHeader()
// Rebuild the secondary GPT header, using the main header as a model.
void GPTData::RebuildSecondHeader(void) {
secondHeader.signature = GPT_SIGNATURE;
secondHeader.revision = mainHeader.revision;
secondHeader.headerSize = mainHeader.headerSize;
secondHeader.headerCRC = UINT32_C(0);
secondHeader.reserved = mainHeader.reserved;
secondHeader.currentLBA = mainHeader.backupLBA;
secondHeader.backupLBA = mainHeader.currentLBA;
secondHeader.firstUsableLBA = mainHeader.firstUsableLBA;
secondHeader.lastUsableLBA = mainHeader.lastUsableLBA;
secondHeader.diskGUID = mainHeader.diskGUID;
secondHeader.partitionEntriesLBA = secondHeader.lastUsableLBA + UINT64_C(1);
secondHeader.numParts = mainHeader.numParts;
secondHeader.sizeOfPartitionEntries = mainHeader.sizeOfPartitionEntries;
secondHeader.partitionEntriesCRC = mainHeader.partitionEntriesCRC;
memcpy(secondHeader.reserved2, mainHeader.reserved2, sizeof(secondHeader.reserved2));
secondCrcOk = mainCrcOk;
SetGPTSize(secondHeader.numParts, 0);
} // GPTData::RebuildSecondHeader()
// Search for hybrid MBR entries that have no corresponding GPT partition.
// Returns number of such mismatches found
int GPTData::FindHybridMismatches(void) {
int i, found, numFound = 0;
uint32_t j;
uint64_t mbrFirst, mbrLast;
for (i = 0; i < 4; i++) {
if ((protectiveMBR.GetType(i) != 0xEE) && (protectiveMBR.GetType(i) != 0x00)) {
j = 0;
found = 0;
mbrFirst = (uint64_t) protectiveMBR.GetFirstSector(i);
mbrLast = mbrFirst + (uint64_t) protectiveMBR.GetLength(i) - UINT64_C(1);
do {
if ((j < numParts) && (partitions[j].GetFirstLBA() == mbrFirst) &&
(partitions[j].GetLastLBA() == mbrLast) && (partitions[j].IsUsed()))
found = 1;
j++;
} while ((!found) && (j < numParts));
if (!found) {
numFound++;
cout << "\nWarning! Mismatched GPT and MBR partition! MBR partition "
<< i + 1 << ", of type 0x";
cout.fill('0');
cout.setf(ios::uppercase);
cout.width(2);
cout << hex << (int) protectiveMBR.GetType(i) << ",\n"
<< "has no corresponding GPT partition! You may continue, but this condition\n"
<< "might cause data loss in the future!\a\n" << dec;
cout.fill(' ');
} // if
} // if
} // for
return numFound;
} // GPTData::FindHybridMismatches
// Find overlapping partitions and warn user about them. Returns number of
// overlapping partitions.
// Returns number of overlapping segments found.
int GPTData::FindOverlaps(void) {
int problems = 0;
uint32_t i, j;
for (i = 1; i < numParts; i++) {
for (j = 0; j < i; j++) {
if ((partitions[i].IsUsed()) && (partitions[j].IsUsed()) &&
(partitions[i].DoTheyOverlap(partitions[j]))) {
problems++;
cout << "\nProblem: partitions " << i + 1 << " and " << j + 1 << " overlap:\n";
cout << " Partition " << i + 1 << ": " << partitions[i].GetFirstLBA()
<< " to " << partitions[i].GetLastLBA() << "\n";
cout << " Partition " << j + 1 << ": " << partitions[j].GetFirstLBA()
<< " to " << partitions[j].GetLastLBA() << "\n";
} // if
} // for j...
} // for i...
return problems;
} // GPTData::FindOverlaps()
// Find partitions that are insane -- they start after they end or are too
// big for the disk. (The latter should duplicate detection of overlaps
// with GPT backup data structures, but better to err on the side of
// redundant tests than to miss something....)
// Returns number of problems found.
int GPTData::FindInsanePartitions(void) {
uint32_t i;
int problems = 0;
for (i = 0; i < numParts; i++) {
if (partitions[i].IsUsed()) {
if (partitions[i].GetFirstLBA() > partitions[i].GetLastLBA()) {
problems++;
cout << "\nProblem: partition " << i + 1 << " ends before it begins.\n";
} // if
if (partitions[i].GetLastLBA() >= diskSize) {
problems++;
cout << "\nProblem: partition " << i + 1 << " is too big for the disk.\n";
} // if
} // if
} // for
return problems;
} // GPTData::FindInsanePartitions(void)
/******************************************************************
* *
* Begin functions that load data from disk or save data to disk. *
* *
******************************************************************/
// Change the filename associated with the GPT. Used for duplicating
// the partition table to a new disk and saving backups.
// Returns 1 on success, 0 on failure.
int GPTData::SetDisk(const string & deviceFilename) {
int err, allOK = 1;
device = deviceFilename;
if (allOK && myDisk.OpenForRead(deviceFilename)) {
// store disk information....
diskSize = myDisk.DiskSize(&err);
blockSize = (uint32_t) myDisk.GetBlockSize();
physBlockSize = (uint32_t) myDisk.GetPhysBlockSize();
} // if
protectiveMBR.SetDisk(&myDisk);
protectiveMBR.SetDiskSize(diskSize);
protectiveMBR.SetBlockSize(blockSize);
return allOK;
} // GPTData::SetDisk()
// Scan for partition data. This function loads the MBR data (regular MBR or
// protective MBR) and loads BSD disklabel data (which is probably invalid).
// It also looks for APM data, forces a load of GPT data, and summarizes
// the results.
void GPTData::PartitionScan(void) {
BSDData bsdDisklabel;
// Read the MBR & check for BSD disklabel
protectiveMBR.ReadMBRData(&myDisk);
bsdDisklabel.ReadBSDData(&myDisk, 0, diskSize - 1);
// Load the GPT data, whether or not it's valid
ForceLoadGPTData();
// Some tools create a 0xEE partition that's too big. If this is detected,
// normalize it....
if ((state == gpt_valid) && !protectiveMBR.DoTheyFit() && (protectiveMBR.GetValidity() == gpt)) {
if (!beQuiet) {
cerr << "\aThe protective MBR's 0xEE partition is oversized! Auto-repairing.\n\n";
} // if
protectiveMBR.MakeProtectiveMBR();
} // if
if (!beQuiet) {
cout << "Partition table scan:\n";
protectiveMBR.ShowState();
bsdDisklabel.ShowState();
ShowAPMState(); // Show whether there's an Apple Partition Map present
ShowGPTState(); // Show GPT status
cout << "\n";
} // if
if (apmFound) {
cout << "\n*******************************************************************\n"
<< "This disk appears to contain an Apple-format (APM) partition table!\n";
if (!justLooking) {
cout << "It will be destroyed if you continue!\n";
} // if
cout << "*******************************************************************\n\n\a";
} // if
} // GPTData::PartitionScan()
// Read GPT data from a disk.
int GPTData::LoadPartitions(const string & deviceFilename) {
BSDData bsdDisklabel;
int err, allOK = 1;
MBRValidity mbrState;
if (!justLooking) {
if (myDisk.OpenForRead(deviceFilename)) {
err = myDisk.OpenForWrite(deviceFilename);
if (err == 0) {
cout << "\aNOTE: Write test failed with error number " << errno
<< ". It will be impossible to save\nchanges to this disk's partition table!\n";
#if defined (__FreeBSD__) || defined (__FreeBSD_kernel__)
cout << "You may be able to enable writes by exiting this program, typing\n"
<< "'sysctl kern.geom.debugflags=16' at a shell prompt, and re-running this\n"
<< "program.\n";
#endif
#if defined (__APPLE__)
cout << "You may need to deactivate System Integrity Protection to use this program. See\n"
<< "https://www.quora.com/How-do-I-turn-off-the-rootless-in-OS-X-El-Capitan-10-11\n"
<< "for more information.\n";
#endif
cout << "\n";
} // if
myDisk.Close(); // Close and re-open read-only in case of bugs
} else allOK = 0; // if
}
if (allOK && myDisk.OpenForRead(deviceFilename)) {
// store disk information....
diskSize = myDisk.DiskSize(&err);
blockSize = (uint32_t) myDisk.GetBlockSize();
physBlockSize = (uint32_t) myDisk.GetPhysBlockSize();
device = deviceFilename;
PartitionScan(); // Check for partition types, load GPT, & print summary
whichWasUsed = UseWhichPartitions();
switch (whichWasUsed) {
case use_mbr:
XFormPartitions();
break;
case use_bsd:
bsdDisklabel.ReadBSDData(&myDisk, 0, diskSize - 1);
// bsdDisklabel.DisplayBSDData();
ClearGPTData();
protectiveMBR.MakeProtectiveMBR(1); // clear boot area (option 1)
XFormDisklabel(&bsdDisklabel);
break;
case use_gpt:
mbrState = protectiveMBR.GetValidity();
if ((mbrState == invalid) || (mbrState == mbr))
protectiveMBR.MakeProtectiveMBR();
break;
case use_new:
ClearGPTData();
protectiveMBR.MakeProtectiveMBR();
break;
case use_abort:
allOK = 0;
cerr << "Invalid partition data!\n";
break;
} // switch
if (allOK) {
CheckGPTSize();
// Below is unlikely to happen on real disks, but could happen if
// the user is manipulating a truncated image file....
if (diskSize <= GetTableSizeInSectors() * 2 + 3) {
allOK = 0;
cout << "Disk is too small to hold GPT data (" << diskSize
<< " sectors)! Aborting!\n";
}
}
myDisk.Close();
ComputeAlignment();
} else {
allOK = 0;
} // if/else
return (allOK);
} // GPTData::LoadPartitions()
// Loads the GPT, as much as possible. Returns 1 if this seems to have
// succeeded, 0 if there are obvious problems....
int GPTData::ForceLoadGPTData(void) {
int allOK, validHeaders, loadedTable = 1;
allOK = LoadHeader(&mainHeader, myDisk, 1, &mainCrcOk);
if (mainCrcOk && (mainHeader.backupLBA < diskSize)) {
allOK = LoadHeader(&secondHeader, myDisk, mainHeader.backupLBA, &secondCrcOk) && allOK;
} else {
allOK = LoadHeader(&secondHeader, myDisk, diskSize - UINT64_C(1), &secondCrcOk) && allOK;
if (mainCrcOk && (mainHeader.backupLBA >= diskSize))
cout << "Warning! Disk size is smaller than the main header indicates! Loading\n"
<< "secondary header from the last sector of the disk! You should use 'v' to\n"
<< "verify disk integrity, and perhaps options on the experts' menu to repair\n"
<< "the disk.\n";
} // if/else
if (!allOK)
state = gpt_invalid;
// Return valid headers code: 0 = both headers bad; 1 = main header
// good, backup bad; 2 = backup header good, main header bad;
// 3 = both headers good. Note these codes refer to valid GPT
// signatures, version numbers, and CRCs.
validHeaders = CheckHeaderValidity();
// Read partitions (from primary array)
if (validHeaders > 0) { // if at least one header is OK....
// GPT appears to be valid....
state = gpt_valid;
// We're calling the GPT valid, but there's a possibility that one
// of the two headers is corrupt. If so, use the one that seems to
// be in better shape to regenerate the bad one
if (validHeaders == 1) { // valid main header, invalid backup header
cerr << "\aCaution: invalid backup GPT header, but valid main header; regenerating\n"
<< "backup header from main header.\n\n";
RebuildSecondHeader();
state = gpt_corrupt;
secondCrcOk = mainCrcOk; // Since regenerated, use CRC validity of main
} else if (validHeaders == 2) { // valid backup header, invalid main header
cerr << "\aCaution: invalid main GPT header, but valid backup; regenerating main header\n"
<< "from backup!\n\n";
RebuildMainHeader();
state = gpt_corrupt;
mainCrcOk = secondCrcOk; // Since copied, use CRC validity of backup
} // if/else/if
// Figure out which partition table to load....
// Load the main partition table, if its header's CRC is OK
if (validHeaders != 2) {
if (LoadMainTable() == 0)
allOK = 0;
} else { // bad main header CRC and backup header CRC is OK
state = gpt_corrupt;
if (LoadSecondTableAsMain()) {
loadedTable = 2;
cerr << "\aWarning: Invalid CRC on main header data; loaded backup partition table.\n";
} else { // backup table bad, bad main header CRC, but try main table in desperation....
if (LoadMainTable() == 0) {
allOK = 0;
loadedTable = 0;
cerr << "\a\aWarning! Unable to load either main or backup partition table!\n";
} // if
} // if/else (LoadSecondTableAsMain())
} // if/else (load partition table)
if (loadedTable == 1)
secondPartsCrcOk = CheckTable(&secondHeader);
else if (loadedTable == 2)
mainPartsCrcOk = CheckTable(&mainHeader);
else
mainPartsCrcOk = secondPartsCrcOk = 0;
// Problem with main partition table; if backup is OK, use it instead....
if (secondPartsCrcOk && secondCrcOk && !mainPartsCrcOk) {
state = gpt_corrupt;
allOK = allOK && LoadSecondTableAsMain();
mainPartsCrcOk = 0; // LoadSecondTableAsMain() resets this, so re-flag as bad
cerr << "\aWarning! Main partition table CRC mismatch! Loaded backup "
<< "partition table\ninstead of main partition table!\n\n";
} // if */