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From 49ed9305afae9865d9b748ef419b4f923ae4e86d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nikola=20Forr=C3=B3?= <nforro@redhat.com>
Date: Wed, 29 Sep 2021 15:46:37 +0200
Subject: [PATCH] Fix incorrect byte order of partition names on big-endian
systems
---
gdisk.8 | 8 ++++++++
gptcl.cc | 11 +++++++++++
gptpart.cc | 13 +++++++------
gptpart.h | 1 +
gpttext.cc | 20 ++++++++++++++++++++
gpttext.h | 1 +
sgdisk.8 | 8 ++++++++
7 files changed, 56 insertions(+), 6 deletions(-)
diff --git a/gdisk.8 b/gdisk.8
index 62f6bd2..0029b75 100644
--- a/gdisk.8
+++ b/gdisk.8
@@ -419,6 +419,14 @@ set features for each partition. \fBgdisk\fR supports four attributes:
aren't translated into anything useful. In practice, most OSes seem to
ignore these attributes.
+.TP
+.B b
+Swap the byte order for the name of the specified partition. Some
+partitioning tools, including GPT fdisk 1.0.7 and earlier, can write the
+partition name in the wrong byte order on big-endian computers, such as the
+IBM s390 mainframes and PowerPC-based Macs. This feature corrects this
+problem.
+
.TP
.B c
Change partition GUID. You can enter a custom unique GUID for a partition
diff --git a/gptcl.cc b/gptcl.cc
index 2304091..65a99e9 100644
--- a/gptcl.cc
+++ b/gptcl.cc
@@ -64,6 +64,7 @@ int GPTDataCL::DoOptions(int argc, char* argv[]) {
GPTData secondDevice;
int opt, numOptions = 0, saveData = 0, neverSaveData = 0;
int partNum = 0, newPartNum = -1, saveNonGPT = 1, retval = 0, pretend = 0;
+ int byteSwapPartNum = 0;
uint64_t low, high, startSector, endSector, sSize, mainTableLBA;
uint64_t temp; // temporary variable; free to use in any case
char *device;
@@ -76,6 +77,7 @@ int GPTDataCL::DoOptions(int argc, char* argv[]) {
"list|[partnum:show|or|nand|xor|=|set|clear|toggle|get[:bitnum|hexbitmask]]"},
{"set-alignment", 'a', POPT_ARG_INT, &alignment, 'a', "set sector alignment", "value"},
{"backup", 'b', POPT_ARG_STRING, &backupFile, 'b', "backup GPT to file", "file"},
+ {"byte-swap-name", 'B', POPT_ARG_INT, &byteSwapPartNum, 'B', "byte-swap partition's name", "partnum"},
{"change-name", 'c', POPT_ARG_STRING, &partName, 'c', "change partition's name", "partnum:name"},
{"recompute-chs", 'C', POPT_ARG_NONE, NULL, 'C', "recompute CHS values in protective/hybrid MBR", ""},
{"delete", 'd', POPT_ARG_INT, &deletePartNum, 'd', "delete a partition", "partnum"},
@@ -191,6 +193,15 @@ int GPTDataCL::DoOptions(int argc, char* argv[]) {
case 'a':
SetAlignment(alignment);
break;
+ case 'B':
+ if (IsUsedPartNum(byteSwapPartNum - 1)) {
+ partitions[byteSwapPartNum - 1].ReverseNameBytes();
+ cout << "Changed partition " << byteSwapPartNum << "'s name to "
+ << partitions[byteSwapPartNum - 1].GetDescription() << "\n";
+ JustLooking(0);
+ saveData = 1;
+ }
+ break;
case 'b':
SaveGPTBackup(backupFile);
free(backupFile);
diff --git a/gptpart.cc b/gptpart.cc
index b268cf0..b83254d 100644
--- a/gptpart.cc
+++ b/gptpart.cc
@@ -242,7 +242,6 @@ void GPTPart::SetName(const string & theName) {
// then to utf16le
if ( uni < 0x10000 ) {
name[ pos ] = (uint16_t) uni ;
- if ( ! IsLittleEndian() ) ReverseBytes( name + pos , 2 ) ;
pos ++ ;
} // if
else {
@@ -252,10 +251,8 @@ void GPTPart::SetName(const string & theName) {
} // if
uni -= 0x10000 ;
name[ pos ] = (uint16_t)( uni >> 10 ) | 0xd800 ;
- if ( ! IsLittleEndian() ) ReverseBytes( name + pos , 2 ) ;
pos ++ ;
name[ pos ] = (uint16_t)( uni & 0x3ff ) | 0xdc00 ;
- if ( ! IsLittleEndian() ) ReverseBytes( name + pos , 2 ) ;
pos ++ ;
}
} // for
@@ -415,14 +412,18 @@ int GPTPart::DoTheyOverlap(const GPTPart & other) {
// Reverse the bytes of integral data types and of the UTF-16LE name;
// used on big-endian systems.
void GPTPart::ReversePartBytes(void) {
- int i;
-
ReverseBytes(&firstLBA, 8);
ReverseBytes(&lastLBA, 8);
ReverseBytes(&attributes, 8);
+ ReverseNameBytes();
+} // GPTPart::ReversePartBytes()
+
+void GPTPart::ReverseNameBytes(void) {
+ int i;
+
for (i = 0; i < NAME_SIZE; i ++ )
ReverseBytes(name + i, 2);
-} // GPTPart::ReverseBytes()
+} // GPTPart::ReverseNameBytes()
/****************************************
* Functions requiring user interaction *
diff --git a/gptpart.h b/gptpart.h
index fac514e..51bfb38 100644
--- a/gptpart.h
+++ b/gptpart.h
@@ -94,6 +94,7 @@ class GPTPart {
void BlankPartition(void); // empty partition of data
int DoTheyOverlap(const GPTPart & other); // returns 1 if there's overlap
void ReversePartBytes(void); // reverse byte order of all integer fields
+ void ReverseNameBytes(void); // reverse byte order of partition's name field
// Functions requiring user interaction
void ChangeType(void); // Change the type code
diff --git a/gpttext.cc b/gpttext.cc
index ea34444..a5f0fd8 100644
--- a/gpttext.cc
+++ b/gpttext.cc
@@ -341,6 +341,22 @@ int GPTDataTextUI::SetName(uint32_t partNum) {
return retval;
} // GPTDataTextUI::SetName()
+// Enable the user to byte-swap the name of the partition. Used to correct
+// partition names damaged by incorrect byte order, as could be created by
+// GPT fdisk 1.0.7 and earlier on big-endian systems, and perhaps other tools.
+void GPTDataTextUI::ReverseName(uint32_t partNum) {
+ int swapBytes;
+
+ cout << "Current name is: " << partitions[partNum].GetDescription() << "\n";
+ partitions[partNum].ReverseNameBytes();
+ cout << "Byte-swapped name is: " << partitions[partNum].GetDescription() << "\n";
+ cout << "Do you want to byte-swap the name? ";
+ swapBytes = (GetYN() == 'Y');
+ // Already swapped for display, so undo if necessary....
+ if (!swapBytes)
+ partitions[partNum].ReverseNameBytes();
+} // GPTDataTextUI::ReverseName()
+
// Ask user for two partition numbers and swap them in the table. Note that
// this just reorders table entries; it doesn't adjust partition layout on
// the disk.
@@ -799,6 +815,9 @@ void GPTDataTextUI::ExpertsMenu(string filename) {
else
cout << "No partitions\n";
break;
+ case 'b': case 'B':
+ ReverseName(GetPartNum());
+ break;
case 'c': case 'C':
ChangeUniqueGuid();
break;
@@ -896,6 +915,7 @@ void GPTDataTextUI::ExpertsMenu(string filename) {
void GPTDataTextUI::ShowExpertCommands(void) {
cout << "a\tset attributes\n";
+ cout << "b\tbyte-swap a partition's name\n";
cout << "c\tchange partition GUID\n";
cout << "d\tdisplay the sector alignment value\n";
cout << "e\trelocate backup data structures to the end of the disk\n";
diff --git a/gpttext.h b/gpttext.h
index afe4651..6bd22cf 100644
--- a/gpttext.h
+++ b/gpttext.h
@@ -49,6 +49,7 @@ class GPTDataTextUI : public GPTData {
void ChangeUniqueGuid(void);
void SetAttributes(uint32_t partNum);
int SetName(uint32_t partNum);
+ void ReverseName(uint32_t partNum);
int SwapPartitions(void);
int DestroyGPTwPrompt(void); // Returns 1 if user proceeds
void ShowDetails(void);
diff --git a/sgdisk.8 b/sgdisk.8
index 59a3d3c..3fb7ae6 100644
--- a/sgdisk.8
+++ b/sgdisk.8
@@ -182,6 +182,14 @@ backup will reflect your changes. If the GPT data structures are damaged,
the backup may not accurately reflect the damaged state; instead, they
will reflect GPT fdisk's first\-pass interpretation of the GPT.
+.TP
+.B \-B, \-\-byte\-swap\-name=partnum
+Swap the byte order for the name of the specified partition. Some
+partitioning tools, including GPT fdisk 1.0.7 and earlier, can write the
+partition name in the wrong byte order on big-endian computers, such as the
+IBM s390 mainframes and PowerPC-based Macs. This feature corrects this
+problem.
+
.TP
.B \-c, \-\-change\-name=partnum:name
Change the GPT name of a partition. This name is encoded as a UTF\-16
--
2.32.0
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