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repart: Some fixes for --copy-from= (#42976)

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A bunch of things I noticed that aren't correct about `--copy-from` and
grain sizes + paddings.
This commit is contained in:
Luca Boccassi
2026-07-13 13:33:24 +01:00
committed by GitHub
parent 755efbe410 71d20a990e
commit 061490432e
3 changed files with 154 additions and 12 deletions
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man/systemd-repart.xml
+6 -5
View File
@@ -609,11 +609,12 @@
<listitem><para>Instructs <command>systemd-repart</command> to synthesize partition definitions from
the partition table in the given image or device. This option can be specified multiple times to
synthesize definitions from each of the given images or devices. The generated definitions will copy
the partitions into the destination partition table. The copied partitions will have the same size,
metadata and contents but might have a different partition number and might be located at a different
offset in the destination partition table. These definitions can be combined with partition
definitions read from regular partition definition files. The synthesized definitions take precedence
over the definitions read from partition definition files.</para>
the partitions into the destination partition table. The copied partitions will have the same or a
slightly larger size (partitions may be enlarged to align to the new grain or sector size), metadata
and contents but might have a different partition number and might be located at a different offset
in the destination partition table. These definitions can be combined with partition definitions read
from regular partition definition files. The synthesized definitions take precedence over the
definitions read from partition definition files.</para>
<xi:include href="version-info.xml" xpointer="v255"/></listitem>
</varlistentry>
src/repart/repart.c
+31 -7
View File
@@ -3287,10 +3287,12 @@ static int determine_current_padding(
struct fdisk_partition *p,
uint64_t secsz,
uint64_t grainsz,
uint64_t *ret) {
uint64_t *ret,
bool *ret_is_last_partition) {
size_t n_partitions;
uint64_t offset, next = UINT64_MAX;
bool is_last_partition = false;
assert(c);
assert(t);
@@ -3330,6 +3332,8 @@ static int determine_current_padding(
}
if (next == UINT64_MAX) {
is_last_partition = true;
/* No later partition? In that case check the end of the usable area */
next = sym_fdisk_get_last_lba(c);
assert(next < UINT64_MAX);
@@ -3346,6 +3350,9 @@ static int determine_current_padding(
offset = round_up_size(offset, grainsz);
next = round_down_size(next, grainsz);
if (ret_is_last_partition)
*ret_is_last_partition = is_last_partition;
*ret = LESS_BY(next, offset); /* Saturated subtraction, rounding might have fucked things up */
return 0;
}
@@ -3355,7 +3362,7 @@ static int context_copy_from_one(Context *context, const char *src) {
_cleanup_(fdisk_unref_contextp) struct fdisk_context *c = NULL;
_cleanup_(fdisk_unref_tablep) struct fdisk_table *t = NULL;
Partition *last = NULL;
unsigned long secsz, grainsz;
unsigned long secsz;
size_t n_partitions;
int r;
@@ -3374,7 +3381,6 @@ static int context_copy_from_one(Context *context, const char *src) {
return log_error_errno(r, "Failed to create fdisk context: %m");
secsz = sym_fdisk_get_sector_size(c);
grainsz = sym_fdisk_get_grain_size(c);
/* Insist on a power of two, and that it's a multiple of 512, i.e. the traditional sector size. */
if (secsz < 512 || !ISPOWEROF2(secsz))
@@ -3396,6 +3402,7 @@ static int context_copy_from_one(Context *context, const char *src) {
uint64_t sz, start, padding;
sd_id128_t ptid, id;
GptPartitionType type;
bool is_last_partition;
p = sym_fdisk_table_get_partition(t, i);
if (!p)
@@ -3455,11 +3462,14 @@ static int context_copy_from_one(Context *context, const char *src) {
if (!np->split_name_format)
return log_oom();
r = determine_current_padding(c, t, p, secsz, grainsz, &padding);
/* Pass grain size of 1 to disable rounding by grain as we don't know the grain size
* of the old image. We'll round paddings to the grain size of the new image later. */
r = determine_current_padding(c, t, p, secsz, /* grainsz= */ 1, &padding, &is_last_partition);
if (r < 0)
return r;
np->padding_min = np->padding_max = padding;
if (!is_last_partition)
np->padding_min = np->padding_max = padding;
np->copy_blocks_path = strdup(src);
if (!np->copy_blocks_path)
@@ -4055,7 +4065,14 @@ static int context_load_partition_table(Context *context) {
pp->current_partition = p;
sym_fdisk_ref_partition(p);
r = determine_current_padding(c, t, p, secsz, grainsz, &pp->current_padding);
r = determine_current_padding(
c,
t,
p,
secsz,
grainsz,
&pp->current_padding,
/* ret_is_last_partition= */ NULL);
if (r < 0)
return r;
@@ -4088,7 +4105,14 @@ static int context_load_partition_table(Context *context) {
np->current_partition = p;
sym_fdisk_ref_partition(p);
r = determine_current_padding(c, t, p, secsz, grainsz, &np->current_padding);
r = determine_current_padding(
c,
t,
p,
secsz,
grainsz,
&np->current_padding,
/* ret_is_last_partition= */ NULL);
if (r < 0)
return r;
test/units/TEST-58-REPART.sh
+117
View File
@@ -451,6 +451,123 @@ $imgs/zzz8 : start= 6422488, size= 131072, type=4D21B016-B534-45C2-A9FB
losetup -d "$loop"
}
testcase_copy_from_grain_padding() {
local defs imgs output
defs="$(mktemp --directory "/tmp/test-repart.defs.XXXXXXXXXX")"
imgs="$(mktemp --directory "/var/tmp/test-repart.imgs.XXXXXXXXXX")"
# shellcheck disable=SC2064
trap "rm -rf '$defs' '$imgs'" RETURN
chmod 0755 "$defs"
truncate -s 80MiB "$imgs/copy_from"
sfdisk "$imgs/copy_from" <<EOF
label: gpt
grain: 4194304
size=40961, type=${root_guid}, uuid=837c3d67-21b3-478e-be82-7e7f83bf96d3
size=10240, type=${xbootldr_guid}, uuid=4985c03e-eecb-4fe0-9f65-3f6345782214
EOF
output=$(sfdisk --dump "$imgs/copy_from")
# Padding between partition 1 and 2 is 8191 sectors
assert_in "$imgs/copy_from1 : start= 8192, size= 40961, type=${root_guid}," "$output"
assert_in "$imgs/copy_from2 : start= 57344, size= 10240, type=${xbootldr_guid}," "$output"
truncate -s 100MiB "$imgs/copy_to"
output=$(systemd-repart --offline="$OFFLINE" \
--empty=allow \
--definitions="$defs" \
--seed="$seed" \
--dry-run=no \
--json=pretty \
--copy-from="$imgs/copy_from" \
--grain-size=512 \
"$imgs/copy_to")
output=$(sfdisk --dump "$imgs/copy_to")
assert_in "$imgs/copy_to1 : start= 2048, size= 40961, type=${root_guid}," "$output"
# We set new grain-size to 1 sector, so padding now should be 8191 sectors again
assert_in "$imgs/copy_to2 : start= 51200, size= 10240, type=${xbootldr_guid}," "$output"
}
testcase_copy_from_respects_new_grain() {
local defs imgs output
defs="$(mktemp --directory "/tmp/test-repart.defs.XXXXXXXXXX")"
imgs="$(mktemp --directory "/var/tmp/test-repart.imgs.XXXXXXXXXX")"
# shellcheck disable=SC2064
trap "rm -rf '$defs' '$imgs'" RETURN
chmod 0755 "$defs"
truncate -s 80MiB "$imgs/copy_from"
sfdisk "$imgs/copy_from" <<EOF
label: gpt
size=20480, type=${root_guid}, uuid=837c3d67-21b3-478e-be82-7e7f83bf96d3
size=10240, type=${xbootldr_guid}, uuid=4985c03e-eecb-4fe0-9f65-3f6345782214
EOF
truncate -s 100MiB "$imgs/copy_to"
output=$(systemd-repart --offline="$OFFLINE" \
--empty=allow \
--definitions="$defs" \
--seed="$seed" \
--dry-run=no \
--json=pretty \
--copy-from="$imgs/copy_from" \
--grain-size=4194304 \
"$imgs/copy_to")
output=$(sfdisk --dump "$imgs/copy_to")
assert_in "$imgs/copy_to1 : start= 8192, size= 24576, type=${root_guid}," "$output"
assert_in "$imgs/copy_to2 : start= 32768, size= 16384, type=${xbootldr_guid}," "$output"
}
testcase_copy_from_no_padding_at_beginning_and_end() {
local defs imgs output
defs="$(mktemp --directory "/tmp/test-repart.defs.XXXXXXXXXX")"
imgs="$(mktemp --directory "/var/tmp/test-repart.imgs.XXXXXXXXXX")"
# shellcheck disable=SC2064
trap "rm -rf '$defs' '$imgs'" RETURN
chmod 0755 "$defs"
tee "$defs/03-esp.conf" <<EOF
[Partition]
Type=esp
EOF
truncate -s 80MiB "$imgs/copy_from"
sfdisk "$imgs/copy_from" <<EOF
label: gpt
start=2280, size=20480, type=${root_guid}, uuid=837c3d67-21b3-478e-be82-7e7f83bf96d3
start=22760, size=10240, type=${xbootldr_guid}, uuid=4985c03e-eecb-4fe0-9f65-3f6345782214
EOF
truncate -s 60MiB "$imgs/copy_to"
output=$(systemd-repart --offline="$OFFLINE" \
--empty=allow \
--definitions="$defs" \
--seed="$seed" \
--dry-run=no \
--json=pretty \
--copy-from="$imgs/copy_from" \
"$imgs/copy_to")
output=$(sfdisk --dump "$imgs/copy_to")
assert_in "first-lba: 2048" "$output"
assert_in "last-lba: 122846" "$output"
assert_in "$imgs/copy_to1 : start= 2048, size= 20480, type=${root_guid}," "$output"
assert_in "$imgs/copy_to2 : start= 22528, size= 10240, type=${xbootldr_guid}," "$output"
assert_in "$imgs/copy_to3 : start= 32768, size= 90072, type=${esp_guid}," "$output"
}
testcase_dropin() {
local defs imgs output