[Libguestfs] [PATCH nbdkit v2 1/4] partitioning plugin: Support MBR logical partitions.

--- .../nbdkit-partitioning-plugin.pod | 29 ++-- plugins/partitioning/virtual-disk.h | 12 +- plugins/partitioning/partition-mbr.c | 132 +++++++++++++++--- plugins/partitioning/partitioning.c | 28 ++-- plugins/partitioning/virtual-disk.c | 42 +++++- tests/Makefile.am | 4 +- tests/test-partitioning5.sh | 96 +++++++++++++ 7 files changed, 281 insertions(+), 62 deletions(-) diff --git a/plugins/partitioning/nbdkit-partitioning-plugin.pod b/plugins/partitioning/nbdkit-partitioning-plugin.pod index 57a1133..49436d9 100644 --- a/plugins/partitioning/nbdkit-partitioning-plugin.pod +++ b/plugins/partitioning/nbdkit-partitioning-plugin.pod @@ -27,23 +27,12 @@ access use the I<-r> flag. =head2 Partition table type -You can choose either an MBR partition table, which is limited to 4 -partitions, or a GPT partition table. In theory GPT supports an -unlimited number of partitions. - -The rule for selecting the partition table type is: +Using the C<partition-type> parameter you can choose either an MBR or +a GPT partition table. If this parameter is I<not> present then: =over 4 -=item C<partition-type=mbr> parameter on the command line - -⇒ MBR is selected - -=item C<partition-type=gpt> parameter on the command line - -⇒ GPT is selected - -=item else, number of files E<gt> 4 +=item number of files E<gt> 4 ⇒ GPT @@ -131,7 +120,13 @@ C<./> (absolute paths do not need modification). =item B<partition-type=mbr> Add an MBR (DOS-style) partition table. The MBR format is maximally -compatible with all clients, but only supports up to 4 partitions. +compatible with all clients. + +If there are E<gt> 4 partitions then the first three files are mapped +to primary partitions, an extended partition +(L<https://en.wikipedia.org/wiki/Extended_boot_record>) is created as +partition 4, and the files starting from the 4th will appear as +partition 5 and upwards. =item B<partition-type=gpt> @@ -163,10 +158,6 @@ a Linux filesystem. =head1 LIMITS -This plugin only supports B<primary> MBR partitions, hence the limit -of 4 partitions with MBR. This might be increased in future if we -implement support for logical/extended MBR partitions. - Although this plugin can create GPT partition tables containing more than 128 GPT partitions (in fact, unlimited numbers of partitions), some clients will not be able to handle this. diff --git a/plugins/partitioning/virtual-disk.h b/plugins/partitioning/virtual-disk.h index 8b798a1..f59df70 100644 --- a/plugins/partitioning/virtual-disk.h +++ b/plugins/partitioning/virtual-disk.h @@ -104,7 +104,7 @@ extern struct file *files; extern size_t nr_files; extern struct regions regions; -extern unsigned char *primary, *secondary; +extern unsigned char *primary, *secondary, **ebr; /* Main entry point called after files array has been populated. */ extern int create_virtual_disk_layout (void); @@ -115,16 +115,16 @@ extern int create_virtual_disk_layout (void); extern int parse_guid (const char *str, char *out) __attribute__((__nonnull__ (1, 2))); -/* Internal functions for creating MBR and GPT layouts. These are - * published here because the GPT code calls into the MBR code, but - * are not meant to be called from the main plugin. +/* Internal function for creating a single MBR PTE. The GPT code + * calls this for creating the protective MBR. */ -extern void create_mbr_partition_table (unsigned char *out) - __attribute__((__nonnull__ (1))); extern void create_mbr_partition_table_entry (const struct region *, bool bootable, int partition_id, unsigned char *) __attribute__((__nonnull__ (1, 4))); + +/* Create MBR or GPT layout. */ +extern void create_mbr_layout (void); extern void create_gpt_layout (void); #endif /* NBDKIT_VIRTUAL_DISK_H */ diff --git a/plugins/partitioning/partition-mbr.c b/plugins/partitioning/partition-mbr.c index 0e72cf0..9f4efc8 100644 --- a/plugins/partitioning/partition-mbr.c +++ b/plugins/partitioning/partition-mbr.c @@ -50,27 +50,125 @@ #include "regions.h" #include "virtual-disk.h" -/* Create the partition table. */ +static const struct region *find_file_region (size_t i, size_t *j); +static const struct region *find_ebr_region (size_t i, size_t *j); + +/* Create the MBR and optionally EBRs. */ void -create_mbr_partition_table (unsigned char *out) +create_mbr_layout (void) { - size_t i, j; - - for (j = 0; j < nr_regions (&regions); ++j) { - const struct region *region = get_region (&regions, j); - - if (region->type == region_file) { - i = region->u.i; - assert (i < 4); - create_mbr_partition_table_entry (region, i == 0, - files[i].mbr_id, - &out[0x1be + 16*i]); - } - } + size_t i, j = 0; /* Boot signature. */ - out[0x1fe] = 0x55; - out[0x1ff] = 0xaa; + primary[0x1fe] = 0x55; + primary[0x1ff] = 0xaa; + + if (nr_files <= 4) { + /* Basic MBR with no extended partition. */ + for (i = 0; i < nr_files; ++i) { + const struct region *region = find_file_region (i, &j); + + create_mbr_partition_table_entry (region, i == 0, files[i].mbr_id, + &primary[0x1be + 16*i]); + } + } + else { + struct region region; + const struct region *rptr, *eptr0, *eptr; + + /* The first three primary partitions correspond to the first + * three files. + */ + for (i = 0; i < 3; ++i) { + rptr = find_file_region (i, &j); + create_mbr_partition_table_entry (rptr, i == 0, files[i].mbr_id, + &primary[0x1be + 16*i]); + } + + /* The fourth partition is an extended PTE and does not correspond + * to any file. This partition starts with the first EBR, so find + * it. The partition extends to the end of the disk. + */ + eptr0 = find_ebr_region (3, &j); + region.start = eptr0->start; + region.end = virtual_size (&regions) - 1; /* to end of disk */ + region.len = region.end - region.start + 1; + create_mbr_partition_table_entry (&region, false, 0xf, &primary[0x1ee]); + + /* The remaining files are mapped to logical partitions living in + * the fourth extended partition. + */ + for (i = 3; i < nr_files; ++i) { + if (i == 3) + eptr = eptr0; + else + eptr = find_ebr_region (i, &j); + rptr = find_file_region (i, &j); + + /* Signature. */ + ebr[i-3][0x1fe] = 0x55; + ebr[i-3][0x1ff] = 0xaa; + + /* First entry in EBR contains: + * offset from EBR sector to the first sector of the logical partition + * total count of sectors in the logical partition + */ + region.start = rptr->start - eptr->start; + region.len = rptr->len; + create_mbr_partition_table_entry (&region, false, files[i].mbr_id, + &ebr[i-3][0x1be]); + + if (i < nr_files-1) { + size_t j2 = j; + const struct region *enext = find_ebr_region (i+1, &j2); + const struct region *rnext = find_file_region (i+1, &j2); + + /* Second entry in the EBR contains: + * address of next EBR relative to extended partition + * total count of sectors in the next logical partition including + * next EBR + */ + region.start = enext->start - eptr0->start; + region.len = rnext->end - enext->start + 1; + create_mbr_partition_table_entry (&region, false, 0xf, + &ebr[i-3][0x1ce]); + } + } + } +} + +/* Find the region corresponding to file[i]. + * j is a scratch register ensuring we only do a linear scan. + */ +static const struct region * +find_file_region (size_t i, size_t *j) +{ + const struct region *region; + + for (; *j < nr_regions (&regions); ++(*j)) { + region = get_region (&regions, *j); + if (region->type == region_file && region->u.i == i) + return region; + } + abort (); +} + +/* Find the region corresponding to EBR of file[i] (i >= 3). + * j is a scratch register ensuring we only do a linear scan. + */ +static const struct region * +find_ebr_region (size_t i, size_t *j) +{ + const struct region *region; + + assert (i >= 3); + + for (; *j < nr_regions (&regions); ++(*j)) { + region = get_region (&regions, *j); + if (region->type == region_data && region->u.data == ebr[i-3]) + return region; + } + abort (); } static void diff --git a/plugins/partitioning/partitioning.c b/plugins/partitioning/partitioning.c index 3992bef..689cb24 100644 --- a/plugins/partitioning/partitioning.c +++ b/plugins/partitioning/partitioning.c @@ -82,8 +82,11 @@ size_t nr_files = 0; /* Virtual disk layout. */ struct regions regions; -/* Primary and secondary partition tables (secondary is only used for GPT). */ -unsigned char *primary = NULL, *secondary = NULL; +/* Primary and secondary partition tables and extended boot records. + * Secondary PT is only used for GPT. EBR array of sectors is only + * used for MBR with > 4 partitions and has length equal to nr_files-3. + */ +unsigned char *primary = NULL, *secondary = NULL, **ebr = NULL; /* Used to generate random unique partition GUIDs for GPT. */ static struct random_state random_state; @@ -106,12 +109,17 @@ partitioning_unload (void) free (files); /* We don't need to free regions.regions[].u.data because it points - * to either primary or secondary which we free here. + * to primary, secondary or ebr which we free here. */ free_regions (&regions); free (primary); free (secondary); + if (ebr) { + for (i = 0; i < nr_files-3; ++i) + free (ebr[i]); + free (ebr); + } } static int @@ -237,17 +245,11 @@ partitioning_config_complete (void) total_size = 0; for (i = 0; i < nr_files; ++i) total_size += files[i].statbuf.st_size; - - if (nr_files > 4) - needs_gpt = true; - else if (total_size > MAX_MBR_DISK_SIZE) - needs_gpt = true; - else - needs_gpt = false; + needs_gpt = total_size > MAX_MBR_DISK_SIZE; /* Choose default parttype if not set. */ if (parttype == PARTTYPE_UNSET) { - if (needs_gpt) { + if (needs_gpt || nr_files > 4) { parttype = PARTTYPE_GPT; nbdkit_debug ("picking partition type GPT"); } @@ -257,8 +259,8 @@ partitioning_config_complete (void) } } else if (parttype == PARTTYPE_MBR && needs_gpt) { - nbdkit_error ("MBR partition table type supports a maximum of 4 partitions " - "and a maximum virtual disk size of about 2 TB, " + nbdkit_error ("MBR partition table type supports " + "a maximum virtual disk size of about 2 TB, " "but you requested %zu partition(s) " "and a total size of %" PRIu64 " bytes (> %" PRIu64 "). " "Try using: partition-type=gpt", diff --git a/plugins/partitioning/virtual-disk.c b/plugins/partitioning/virtual-disk.c index e2d72bc..4fe186e 100644 --- a/plugins/partitioning/virtual-disk.c +++ b/plugins/partitioning/virtual-disk.c @@ -69,6 +69,25 @@ create_virtual_disk_layout (void) nbdkit_error ("malloc: %m"); return -1; } + + if (nr_files > 4) { + /* The first 3 primary partitions will be real partitions, the + * 4th will be an extended partition, and so we need to store + * EBRs for nr_files-3 logical partitions. + */ + ebr = malloc (sizeof (unsigned char *) * (nr_files-3)); + if (ebr == NULL) { + nbdkit_error ("malloc: %m"); + return -1; + } + for (i = 0; i < nr_files-3; ++i) { + ebr[i] = calloc (1, SECTOR_SIZE); + if (ebr[i] == NULL) { + nbdkit_error ("malloc: %m"); + return -1; + } + } + } } else /* PARTTYPE_GPT */ { /* Protective MBR + PT header + PTA = 2 + GPT_PTA_LBAs */ @@ -117,6 +136,20 @@ create_virtual_disk_layout (void) */ assert (IS_ALIGNED (offset, SECTOR_SIZE)); + /* Logical partitions are preceeded by an EBR. */ + if (parttype == PARTTYPE_MBR && nr_files > 4 && i >= 3) { + region.start = offset; + region.len = SECTOR_SIZE; + region.end = region.start + region.len - 1; + region.type = region_data; + region.u.data = ebr[i-3]; + region.description = "EBR"; + if (append_region (&regions, region) == -1) + return -1; + + offset = virtual_size (&regions); + } + /* Make sure each partition is aligned for best performance. */ if (!IS_ALIGNED (offset, files[i].alignment)) { region.start = offset; @@ -207,13 +240,10 @@ create_partition_table (void) if (parttype == PARTTYPE_GPT) assert (secondary != NULL); - if (parttype == PARTTYPE_MBR) { - assert (nr_files <= 4); - create_mbr_partition_table (primary); - } - else /* parttype == PARTTYPE_GPT */ { + if (parttype == PARTTYPE_MBR) + create_mbr_layout (); + else /* parttype == PARTTYPE_GPT */ create_gpt_layout (); - } return 0; } diff --git a/tests/Makefile.am b/tests/Makefile.am index 420cb45..27abbaf 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -83,6 +83,7 @@ EXTRA_DIST = \ test-partitioning2.sh \ test-partitioning3.sh \ test-partitioning4.sh \ + test-partitioning5.sh \ test-pattern.sh \ test-pattern-largest.sh \ test-pattern-largest-for-qemu.sh \ @@ -456,7 +457,8 @@ TESTS += \ if HAVE_GUESTFISH TESTS += \ test-partitioning2.sh \ - test-partitioning3.sh + test-partitioning3.sh \ + test-partitioning5.sh endif HAVE_GUESTFISH # pattern plugin test. diff --git a/tests/test-partitioning5.sh b/tests/test-partitioning5.sh new file mode 100755 index 0000000..b4cb6bf --- /dev/null +++ b/tests/test-partitioning5.sh @@ -0,0 +1,96 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright (C) 2018-2019 Red Hat Inc. +# All rights reserved. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +# Test the partitioning plugin. +# +# Test 5: Create a filesystem and embed it in an MBR logical +# partition. libguestfs uses virtio-scsi so the practical limit here +# is about 15 partitions. + +source ./functions.sh +set -e +set -x + +files="partitioning5.pid partitioning5.sock + partitioning5.fs + partitioning5.p1 partitioning5.p2 partitioning5.p3 partitioning5.p5 partitioning5.p6 partitioning5.p7 partitioning5.p8 partitioning5.p9 partitioning5.p10 partitioning5.p11 partitioning5.p13" +rm -f $files +cleanup_fn rm -f $files + +# Test that mke2fs works +if ! mke2fs -V; then + echo "$0: missing or broken mke2fs" + exit 77 +fi + +# Create partitions before and after. +truncate -s 1 partitioning5.p1 +truncate -s 10M partitioning5.p2 +truncate -s 512 partitioning5.p3 +# partition 4 = extended partition +truncate -s 1 partitioning5.p5 +truncate -s 512 partitioning5.p6 +truncate -s 1 partitioning5.p7 +truncate -s 1 partitioning5.p8 +truncate -s 10M partitioning5.p9 +truncate -s 512 partitioning5.p10 +truncate -s 1 partitioning5.p11 +# partition 12 = naked filesystem +truncate -s 10M partitioning5.p13 + +# Create the naked filesystem. +truncate -s 20M partitioning5.fs +mke2fs -F -t ext2 partitioning5.fs + +# Run nbdkit. +start_nbdkit -P partitioning5.pid -U partitioning5.sock \ + partitioning \ + partitioning5.p1 partitioning5.p2 \ + partitioning5.p3 \ + partitioning5.p5 partitioning5.p6 \ + partitioning5.p7 partitioning5.p8 \ + partitioning5.p9 partitioning5.p10 \ + partitioning5.p11 partitioning5.fs \ + partitioning5.p13 \ + partition-type=mbr + +# Connect with guestfish and read/write stuff to partition 12. +guestfish --format=raw -a "nbd://?socket=$PWD/partitioning5.sock" <<'EOF' + run + mount /dev/sda12 / + touch /hello + fill-pattern "abc" 10000 /pattern + ll / + umount /dev/sda12 + sync +EOF -- 2.20.1