1 /* mbr.cc -- Functions for loading, saving, and manipulating legacy MBR partition
2    data. */
3 
4 /* Initial coding by Rod Smith, January to February, 2009 */
5 
6 /* This program is copyright (c) 2009-2013 by Roderick W. Smith. It is distributed
7   under the terms of the GNU GPL version 2, as detailed in the COPYING file. */
8 
9 #define __STDC_LIMIT_MACROS
10 #define __STDC_CONSTANT_MACROS
11 
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <stdint.h>
15 #include <fcntl.h>
16 #include <string.h>
17 #include <time.h>
18 #include <sys/stat.h>
19 #include <errno.h>
20 #include <iostream>
21 #include "mbr.h"
22 
23 using namespace std;
24 
25 /****************************************
26  *                                      *
27  * MBRData class and related structures *
28  *                                      *
29  ****************************************/
30 
31 /* // Assignment operator -- copy entire set of MBR data.
32 MBRData & MBRData::operator=(const MBRData & orig) {
33    BasicMBRData::operator=(orig);
34    return *this;
35 } // MBRData::operator=() */
36 
37 // Assignment operator -- copy entire set of MBR data.
operator =(const BasicMBRData & orig)38 MBRData & MBRData::operator=(const BasicMBRData & orig) {
39    BasicMBRData::operator=(orig);
40    return *this;
41 } // MBRData::operator=()
42 
43 /*****************************************************
44  *                                                   *
45  * Functions to create, delete, or change partitions *
46  *                                                   *
47  *****************************************************/
48 
49 // Create a protective MBR. Clears the boot loader area if clearBoot > 0.
MakeProtectiveMBR(int clearBoot)50 void MBRData::MakeProtectiveMBR(int clearBoot) {
51 
52    EmptyMBR(clearBoot);
53 
54    // Initialize variables
55    nulls = 0;
56    MBRSignature = MBR_SIGNATURE;
57    diskSignature = UINT32_C(0);
58 
59    partitions[0].SetStatus(0); // Flag the protective part. as unbootable
60 
61    partitions[0].SetType(UINT8_C(0xEE));
62    if (diskSize < UINT32_MAX) { // If the disk is under 2TiB
63       partitions[0].SetLocation(UINT32_C(1), (uint32_t) diskSize - UINT32_C(1));
64    } else { // disk is too big to represent, so fake it...
65       partitions[0].SetLocation(UINT32_C(1), UINT32_MAX);
66    } // if/else
67    partitions[0].SetInclusion(PRIMARY);
68 
69    state = gpt;
70 } // MBRData::MakeProtectiveMBR()
71 
72 // Optimizes the size of the 0xEE (EFI GPT) partition
OptimizeEESize(void)73 void MBRData::OptimizeEESize(void) {
74    int i, typeFlag = 0;
75    uint64_t after;
76 
77    for (i = 0; i < 4; i++) {
78       // Check for non-empty and non-0xEE partitions
79       if ((partitions[i].GetType() != 0xEE) && (partitions[i].GetType() != 0x00))
80          typeFlag++;
81       if (partitions[i].GetType() == 0xEE) {
82          // Blank space before this partition; fill it....
83          if (SectorUsedAs(partitions[i].GetStartLBA() - 1, 4) == NONE) {
84             partitions[i].SetStartLBA(FindFirstInFree(partitions[i].GetStartLBA() - 1));
85          } // if
86          // Blank space after this partition; fill it....
87          after = partitions[i].GetStartLBA() + partitions[i].GetLengthLBA();
88          if (SectorUsedAs(after, 4) == NONE) {
89             partitions[i].SetLengthLBA(FindLastInFree(after) - partitions[i].GetStartLBA() + 1);
90          } // if free space after
91          if (after > diskSize) {
92             if (diskSize < UINT32_MAX) { // If the disk is under 2TiB
93                partitions[i].SetLengthLBA((uint32_t) diskSize - partitions[i].GetStartLBA());
94             } else { // disk is too big to represent, so fake it...
95                partitions[i].SetLengthLBA(UINT32_MAX - partitions[i].GetStartLBA());
96             } // if/else
97          } // if protective partition is too big
98          RecomputeCHS(i);
99       } // if partition is 0xEE
100    } // for partition loop
101    if (typeFlag == 0) { // No non-hybrid partitions found
102       MakeProtectiveMBR(); // ensure it's a fully compliant protective MBR.
103    } // if
104 } // MBRData::OptimizeEESize()
105 
106 // Delete a partition if one exists at the specified location.
107 // Returns 1 if a partition was deleted, 0 otherwise....
108 // Used to help keep GPT & hybrid MBR partitions in sync....
DeleteByLocation(uint64_t start64,uint64_t length64)109 int MBRData::DeleteByLocation(uint64_t start64, uint64_t length64) {
110    uint32_t start32, length32;
111    int i, deleted = 0;
112 
113    if ((start64 < UINT32_MAX) && (length64 < UINT32_MAX)) {
114       start32 = (uint32_t) start64;
115       length32 = (uint32_t) length64;
116       for (i = 0; i < MAX_MBR_PARTS; i++) {
117          if ((partitions[i].GetType() != 0xEE) && (partitions[i].GetStartLBA() == start32)
118              && (partitions[i].GetLengthLBA() == length32)) {
119             DeletePartition(i);
120          if (state == hybrid)
121             OptimizeEESize();
122          deleted = 1;
123          } // if (match found)
124       } // for i (partition scan)
125    } // if (hybrid & GPT partition < 2TiB)
126    return deleted;
127 } // MBRData::DeleteByLocation()
128 
129 /******************************************************
130  *                                                    *
131  * Functions that extract data on specific partitions *
132  *                                                    *
133  ******************************************************/
134 
135 // Return the MBR data as a GPT partition....
AsGPT(int i)136 GPTPart MBRData::AsGPT(int i) {
137    MBRPart* origPart;
138    GPTPart newPart;
139    uint8_t origType;
140    uint64_t firstSector, lastSector;
141 
142    newPart.BlankPartition();
143    origPart = GetPartition(i);
144    if (origPart != NULL) {
145       origType = origPart->GetType();
146 
147       // don't convert extended, hybrid protective, or null (non-existent)
148       // partitions (Note similar protection is in GPTData::XFormPartitions(),
149       // but I want it here too in case I call this function in another
150       // context in the future....)
151       if ((origType != 0x05) && (origType != 0x0f) && (origType != 0x85) &&
152           (origType != 0x00) && (origType != 0xEE)) {
153          firstSector = (uint64_t) origPart->GetStartLBA();
154          newPart.SetFirstLBA(firstSector);
155          lastSector = (uint64_t) origPart->GetLastLBA();
156          newPart.SetLastLBA(lastSector);
157          newPart.SetType(((uint16_t) origType) * 0x0100);
158          newPart.RandomizeUniqueGUID();
159          newPart.SetAttributes(0);
160          newPart.SetName(newPart.GetTypeName());
161       } // if not extended, protective, or non-existent
162    } // if (origPart != NULL)
163    return newPart;
164 } // MBRData::AsGPT()
165 
166