path: root/debian/patches/gptsync.patch

From aa55572c980da038e675fc963d98a90964a2ce33 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg59@srcf.ucam.org>
Date: Fri, 28 Mar 2014 17:10:01 +0000
Subject: GPT syncing for Intel Macs

On Intel Mac systems, write a synced MBR rather than a protective MBR.

From: Colin Watson <cjwatson@ubuntu.com>
Forwarded: no
Last-Update: 2022-04-19

Patch-Name: gptsync.patch
---
 libparted/labels/gpt.c | 205 +++++++++++++++++++++++++++++++++++++++--
 tests/Makefile.am      |   1 +
 tests/t0290-gptsync.sh | 175 +++++++++++++++++++++++++++++++++++
 3 files changed, 371 insertions(+), 10 deletions(-)
 create mode 100644 tests/t0290-gptsync.sh

diff --git a/libparted/labels/gpt.c b/libparted/labels/gpt.c
index 130b9bd1..bebedb47 100644
--- a/libparted/labels/gpt.c
+++ b/libparted/labels/gpt.c
@@ -369,6 +369,40 @@ typedef struct _GPTPartitionData
 
 static PedDiskType gpt_disk_type;
 
+
+#if (defined(__i386__) || defined(__x86_64__)) && defined(__linux__)
+# define USE_DMI
+#endif
+
+#define APPLE_DMI "Apple Computer, Inc."
+#define APPLE_DMI_2 "Apple Inc."
+static int is_apple = 0;
+
+static char *
+dmi_system_manufacturer (void)
+{
+#ifdef USE_DMI
+  FILE *dmidecode;
+  char *manufacturer = NULL;
+  size_t manufacturer_len = 0;
+
+  dmidecode = popen ("dmidecode -s system-manufacturer 2>/dev/null", "r");
+  if (getline (&manufacturer, &manufacturer_len, dmidecode) < 0) {
+    /* ignore; will return NULL */
+  }
+  pclose (dmidecode);
+  if (manufacturer) {
+    char *newline = strchr (manufacturer, '\n');
+    if (newline)
+      *newline = '\0';
+  }
+  return manufacturer;
+#else /* !USE_DMI */
+  return NULL;
+#endif /* USE_DMI */
+}
+
+
 static inline uint32_t
 pth_get_size (const PedDevice *dev)
 {
@@ -544,16 +578,19 @@ gpt_probe (const PedDevice *dev)
   if (dev->length <= 1)
     return 0;
 
-  void *label;
-  if (!ptt_read_sector (dev, 0, &label))
-    return 0;
-
-  if (!_pmbr_is_valid (label))
+  if (!is_apple)
     {
+      void *label;
+      if (!ptt_read_sector (dev, 0, &label))
+        return 0;
+
+      if (!_pmbr_is_valid (label))
+        {
+          free (label);
+          return 0;
+        }
       free (label);
-      return 0;
     }
-  free (label);
 
   void *pth_raw = ped_malloc (pth_get_size (dev));
   if (ped_device_read (dev, pth_raw, 1, GPT_HEADER_SECTORS)
@@ -973,6 +1010,10 @@ gpt_read_headers (PedDisk const *disk,
  *  warn if it's not there, and treat the disk as MSDOS, with a note
  *  for users to use Parted to "fix up" their disk if they
  *  really want it to be considered GPT.
+ *
+ *  Of course, this is incompatible with how Apple handle things. For
+ *  legacy BIOS compatibility on Apple machines, we need a valid legacy MBR
+ *  rather than a protective one. Aren't standards wonderful?
  ************************************************************/
 static int
 gpt_read (PedDisk *disk)
@@ -1181,6 +1222,129 @@ _write_pmbr (PedDevice *dev, bool pmbr_boot)
   return write_ok;
 }
 
+static void
+fill_raw_part (PartitionRecord_t* raw_part, PedPartition *part, PedSector offset, int number)
+{
+  GPTPartitionData* gpt_part_data = part->disk_specific;
+
+  if (part->fs_type) {
+    if (strncmp (part->fs_type->name, "fat", 3) == 0)
+      raw_part->OSType = 0x0b;
+    else if (strncmp (part->fs_type->name, "ntfs", 4) == 0)
+      raw_part->OSType = 0x07;
+    else if (strncmp (part->fs_type->name, "hfs", 3) == 0)
+      raw_part->OSType = 0xaf;
+    else if (strncmp (part->fs_type->name, "linux-swap", 10) == 0)
+      raw_part->OSType = 0x82;
+    else
+      raw_part->OSType = 0x83;
+  } else
+    raw_part->OSType = 0xda;
+
+  /* Apple's firmware appears to become unhappy if the second partition
+     isn't bootable */
+
+  if (number == 2)
+    raw_part->BootIndicator = 0x80;
+
+  raw_part->StartingLBA = PED_CPU_TO_LE32 ((part->geom.start - offset)
+                            / (part->disk->dev->sector_size / 512));
+
+  raw_part->SizeInLBA = PED_CPU_TO_LE32 (part->geom.length
+                            / (part->disk->dev->sector_size / 512));
+
+  /* EFI system partitions will have a FAT filesystem and
+     PARTITION_SYSTEM_GUID; however, it is not wise to rely on filesystem
+     probing */
+
+  if (number == 1) {
+    if (!guid_cmp (gpt_part_data->type, PARTITION_SYSTEM_GUID) ||
+        !guid_cmp (gpt_part_data->type, PARTITION_BIOS_GRUB_GUID)) {
+      raw_part->OSType = EFI_PMBR_OSTYPE_EFI;
+      raw_part->OSType = EFI_PMBR_OSTYPE_EFI;
+    }
+  }
+
+  /* Apple's firmware also appears to be unhappy if the EFI system
+     partition doesn't extend all the way to the start of the disk */
+
+  if (number == 1 && raw_part->OSType == EFI_PMBR_OSTYPE_EFI) {
+    raw_part->StartSector = 1;
+    raw_part->SizeInLBA += raw_part->StartingLBA - 1;
+    raw_part->StartingLBA = 1;
+  } else {
+    raw_part->StartHead = 0xfe;
+    raw_part->StartSector = 0xff;
+    raw_part->StartTrack = 0xff;
+  }
+
+  raw_part->EndHead = 0xfe;
+  raw_part->EndSector = 0xff;
+  raw_part->EndTrack = 0xff;
+}
+
+static int
+_gptsync (const PedDisk *disk)
+{
+  void *s0;
+  PedPartition* part;
+  int i;
+
+  if (!ptt_read_sector (disk->dev, GPT_PMBR_LBA, &s0))
+    return 0;
+  LegacyMBR_t *pmbr = s0;
+
+  int ok = 0;
+
+  memset(&pmbr->PartitionRecord, 0, sizeof(pmbr->PartitionRecord));
+  pmbr->Signature = PED_CPU_TO_LE16(MSDOS_MBR_SIGNATURE);
+
+  bool prot = false; /* have we found a protective partition? */
+  for (i=1; i<=4; i++) {
+    part = ped_disk_get_partition (disk, i);
+    if (!part)
+      continue;
+
+    fill_raw_part (&pmbr->PartitionRecord [i - 1], part, 0, i);
+    if (pmbr->PartitionRecord[i - 1].OSType == EFI_PMBR_OSTYPE_EFI)
+      prot = true;
+  }
+
+  if (!prot) { /* create one covering the gpt entries */
+    uint32_t prot_size;
+    for (i=2; i>=0; i--)
+      pmbr->PartitionRecord[i + 1] = pmbr->PartitionRecord[i];
+    memset (&pmbr->PartitionRecord[0], 0, sizeof pmbr->PartitionRecord[0]);
+    pmbr->PartitionRecord[0].OSType = EFI_PMBR_OSTYPE_EFI;
+    pmbr->PartitionRecord[0].StartSector = 1;
+    pmbr->PartitionRecord[0].EndHead = 0xfe;
+    pmbr->PartitionRecord[0].EndSector = 0xff;
+    pmbr->PartitionRecord[0].EndTrack = 0xff;
+    pmbr->PartitionRecord[0].StartingLBA = PED_CPU_TO_LE32 (1);
+    if ((disk->dev->length - 1ULL) > 0xFFFFFFFFULL)
+      prot_size = 0xFFFFFFFF;
+    else
+      prot_size = disk->dev->length - 1UL;
+    for (i=1; i<=3; i++) {
+      if (pmbr->PartitionRecord[i].StartingLBA) {
+        uint32_t starting_lba =
+          PED_LE32_TO_CPU (pmbr->PartitionRecord[i].StartingLBA);
+        if (starting_lba - 1 < prot_size)
+          prot_size = starting_lba - 1;
+      }
+    }
+    pmbr->PartitionRecord[0].SizeInLBA = PED_CPU_TO_LE32 (prot_size);
+  }
+
+  if (!ped_device_write (disk->dev, pmbr, GPT_PMBR_LBA, GPT_PMBR_SECTORS))
+    goto error;
+
+  ok = ped_device_sync (disk->dev);
+error:
+  free (s0);
+  return ok;
+}
+
 static int
 _generate_header (const PedDisk *disk, int alternate, uint32_t ptes_crc,
                   GuidPartitionTableHeader_t **gpt_p)
@@ -1287,9 +1451,15 @@ gpt_write (const PedDisk *disk)
 
   ptes_crc = efi_crc32 (ptes, ptes_bytes);
 
-  /* Write protective MBR */
-  if (!_write_pmbr (disk->dev, gpt_disk_data->pmbr_boot))
-    goto error_free_ptes;
+  if (is_apple) {
+    /* Write synced MBR */
+    if (!_gptsync (disk))
+      goto error_free_ptes;
+  } else {
+    /* Write protective MBR */
+    if (!_write_pmbr (disk->dev, gpt_disk_data->pmbr_boot))
+      goto error_free_ptes;
+  }
 
   /* Write PTH and PTEs */
   /* FIXME: Caution: this code is nearly identical to what's just below. */
@@ -1938,6 +2108,21 @@ void
 ped_disk_gpt_init ()
 {
   ped_disk_type_register (&gpt_disk_type);
+
+  char *force_gpt_apple = getenv ("PARTED_GPT_APPLE");
+  if (force_gpt_apple) {
+    if (strcmp (force_gpt_apple, "1") == 0)
+      is_apple = 1;
+  } else {
+    char *manufacturer = dmi_system_manufacturer ();
+    if (manufacturer &&
+        (strncasecmp (APPLE_DMI, manufacturer,
+                      strlen (APPLE_DMI)) == 0 ||
+         strncasecmp (APPLE_DMI_2, manufacturer,
+                      strlen (APPLE_DMI_2)) == 0))
+      is_apple = 1;
+    free (manufacturer);
+  }
 }
 
 void
diff --git a/tests/Makefile.am b/tests/Makefile.am
index da093119..3c1f929a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -32,6 +32,7 @@ TESTS = \
   t0282-gpt-move-backup.sh \
   t0283-overlap-partitions.sh \
   t0290-gpt-name.sh \
+  t0290-gptsync.sh \
   t0300-dos-on-gpt.sh \
   t0301-overwrite-gpt-pmbr.sh \
   t0350-mac-PT-increases-sector-size.sh \
diff --git a/tests/t0290-gptsync.sh b/tests/t0290-gptsync.sh
new file mode 100644
index 00000000..367d61bd
--- /dev/null
+++ b/tests/t0290-gptsync.sh
@@ -0,0 +1,175 @@
+#!/bin/sh
+# test GPT -> hybrid MBR syncing for Apple systems
+# http://www.rodsbooks.com/gdisk/hybrid.html
+
+# Copyright (C) 2012 Canonical Ltd.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  parted --version
+fi
+
+: ${srcdir=.}
+. $srcdir/t-lib.sh
+
+require_root_
+require_scsi_debug_module_
+
+ss=$sector_size_
+# must be big enough for a 32MiB partition in order to be big enough for FAT16
+n_sectors=131072
+bootcode_size=446
+mbr_table_size=$((512 - $bootcode_size))
+
+dump_mbr_table () {
+  dd if=$dev bs=1 skip=$bootcode_size count=$mbr_table_size 2>/dev/null | od -v -An -tx1
+}
+
+# create memory-backed device
+sectors_per_MiB=$((1024 * 1024 / $ss))
+n_MiB=$((($n_sectors + $sectors_per_MiB - 1) / $sectors_per_MiB))
+scsi_debug_setup_ dev_size_mb=$n_MiB > dev-name ||
+  skip_test_ 'failed to create scsi_debug device'
+dev=$(cat dev-name)
+
+# force Apple mode
+export PARTED_GPT_APPLE=1
+
+# create gpt label
+parted -s $dev mklabel gpt > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+
+# print the empty table
+parted -m -s $dev unit s print > t 2>&1 || fail=1
+sed "s,.*/$dev:,$dev:," t > out || fail=1
+
+# check for expected output
+printf "BYT;\n$dev:${n_sectors}s:scsi:$sector_size_:$sector_size_:gpt:Linux scsi_debug;\n" \
+  > exp || fail=1
+compare exp out || fail=1
+
+# the empty table should have a MBR containing only a protective entry
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff ff 01 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# create a 32MiB FAT16 EFI System Partition
+parted -s $dev mkpart p1 fat16 2048s 67583s set 1 boot on > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+mkfs.vfat -F 16 ${dev}1 >/dev/null || skip_ "mkfs.vfat failed"
+
+# this is represented as a protective partition, but now it only extends as
+# far as the end of the first partition rather than covering the whole disk
+# (matching refit gptsync's strategy); it still starts at sector one
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff 07 01 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# add a 2MiB ext3 partition
+parted -s $dev mkpart p2 ext3 67584s 71679s > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+mkfs.ext3 ${dev}2 >/dev/null 2>&1 || skip_ "mkfs.ext3 failed"
+
+# this should have an MBR representing both partitions; the second partition
+# should be marked bootable
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff 07 01 00
+ 80 fe ff ff 83 fe ff ff 00 08 01 00 00 10 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# add a 1MiB partition with no filesystem
+parted -s $dev mkpart p3 71680s 73727s > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+
+# the new partition should be represented as 0xda (Non-FS data)
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff 07 01 00
+ 80 fe ff ff 83 fe ff ff 00 08 01 00 00 10 00 00
+ 00 fe ff ff da fe ff ff 00 18 01 00 00 08 00 00
+ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# add two more 1MiB partitions
+parted -s $dev mkpart p4 73728s 75775s > empty 2>&1 || fail=1
+parted -s $dev mkpart p5 75776s 77823s > empty 2>&1 || fail=1
+
+# only the first four partitions will be represented
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff 07 01 00
+ 80 fe ff ff 83 fe ff ff 00 08 01 00 00 10 00 00
+ 00 fe ff ff da fe ff ff 00 18 01 00 00 08 00 00
+ 00 fe ff ff da fe ff ff 00 20 01 00 00 08 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# convert first partition to a BIOS Boot Partition
+parted -s $dev set 1 boot off set 1 bios_grub on > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+
+# this should be represented in the same way as an EFI System Partition
+dump_mbr_table > out || fail=1
+compare exp out || fail=1
+
+# convert first partition to an ordinary FAT partition
+parted -s $dev set 1 bios_grub off > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+
+# this should result in a protective partition covering the GPT data up to
+# the start of the first partition, and then representations of the first
+# three partitions
+dump_mbr_table > out || fail=1
+cat <<EOF > exp || fail=1
+ 00 00 01 00 ee fe ff ff 01 00 00 00 ff 07 00 00
+ 00 fe ff ff 0b fe ff ff 00 08 00 00 00 00 01 00
+ 80 fe ff ff 83 fe ff ff 00 08 01 00 00 10 00 00
+ 00 fe ff ff da fe ff ff 00 18 01 00 00 08 00 00
+ 55 aa
+EOF
+compare exp out || fail=1
+
+# convert third partition to a BIOS Boot Partition
+parted -s $dev set 3 bios_grub on > empty 2>&1 || fail=1
+compare /dev/null empty || fail=1
+
+# since this isn't the first partition, it shouldn't become a protective
+# partition or have its starting LBA address set to 1 (and GRUB doesn't care
+# whether it's in the hybrid MBR anyway)
+dump_mbr_table > out || fail=1
+compare exp out || fail=1
+
+Exit $fail