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repart: add --image= switch

Browse source 
This is similar to the --image= switch in the other tools, like
systemd-sysusers or systemd-tmpfiles, i.e. it apply the configuration
from the image to the image.

This is particularly useful for downloading minimized GPT image, and
then extending it to the desired size via:

   # systemd-repart --image=foo.image --size=5G
This commit is contained in:
Lennart Poettering 2021-03-19 11:19:00 +01:00
parent 8e5f3cecdf
commit 252d626711
3 changed files with 189 additions and 63 deletions
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6
man/repart.d.xml
View file

@ -486,7 +486,11 @@
<para>The copy operation is executed before the file system is registered in the partition table,
thus ensuring that a file system populated this way only ever exists fully initialized.</para>
<para>This option cannot be combined with <varname>CopyBlocks=</varname>.</para></listitem>
<para>This option cannot be combined with <varname>CopyBlocks=</varname>.</para>
<para>When <command>systemd-repart</command> is invoked with the <option>--image=</option> or
<option>--root=</option> command line switches the source paths specified are taken relative to the
specified root directory or disk image root.</para></listitem>
</varlistentry>
<varlistentry>

33
man/systemd-repart.xml
View file

@ -40,16 +40,17 @@
<citerefentry><refentrytitle>repart.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>If invoked with no arguments, it operates on the block device backing the root file system partition
of the OS, thus growing and adding partitions of the booted OS image itself. When called in the initial
RAM disk it operates on the block device backing <filename>/sysroot/</filename> instead, i.e. on the
block device the system will soon transition into. The <filename>systemd-repart.service</filename>
service is generally run at boot in the initial RAM disk, in order to augment the partition table of the
OS before its partitions are mounted. <command>systemd-repart</command> (mostly) operates in a purely
incremental mode: it only grows existing and adds new partitions; it does not shrink, delete or move
existing partitions. The service is intended to be run on every boot, but when it detects that the
partition table already matches the installed <filename>repart.d/*.conf</filename> configuration
files, it executes no operation.</para>
<para>If invoked with no arguments, it operates on the block device backing the root file system
partition of the running OS, thus growing and adding partitions of the booted OS image itself. If
<varname>--image=</varname> is used it will operate on the specified image file. When called in the
<literal>initrd</literal> it operates on the block device backing <filename>/sysroot/</filename> instead,
i.e. on the block device the system will soon transition into. The
<filename>systemd-repart.service</filename> service is generally run at boot in the initial RAM disk, in
order to augment the partition table of the OS before its partitions are
mounted. <command>systemd-repart</command> (mostly) operates in a purely incremental mode: it only grows
existing and adds new partitions; it does not shrink, delete or move existing partitions. The service is
intended to be run on every boot, but when it detects that the partition table already matches the
installed <filename>repart.d/*.conf</filename> configuration files, it executes no operation.</para>
<para><command>systemd-repart</command> is intended to be used when deploying OS images, to automatically
adjust them to the system they are running on, during first boot. This way the deployed image can be
@ -251,13 +252,21 @@
<term><option>--root=</option></term>
<listitem><para>Takes a path to a directory to use as root file system when searching for
<filename>repart.d/*.conf</filename> files and for the machine ID file to use as seed. By default
when invoked on the regular system this defaults to the host's root file system
<filename>repart.d/*.conf</filename> files, for the machine ID file to use as seed and for the
<varname>CopyFiles=</varname> and <varname>CopyBlocks=</varname> source files and directories. By
default when invoked on the regular system this defaults to the host's root file system
<filename>/</filename>. If invoked from the initial RAM disk this defaults to
<filename>/sysroot/</filename>, so that the tool operates on the configuration and machine ID stored
in the root file system later transitioned into itself.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--image=</option></term>
<listitem><para>Takes a path to a disk image file or device to mount and use in a similar fashion to
<option>--root=</option>, see above.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--seed=</option></term>

213
src/partition/repart.c
View file

@ -92,6 +92,7 @@ static enum {
static bool arg_dry_run = true;
static const char *arg_node = NULL;
static char *arg_root = NULL;
static char *arg_image = NULL;
static char *arg_definitions = NULL;
static bool arg_discard = true;
static bool arg_can_factory_reset = false;
@ -110,6 +111,7 @@ static char *arg_tpm2_device = NULL;
static uint32_t arg_tpm2_pcr_mask = UINT32_MAX;
STATIC_DESTRUCTOR_REGISTER(arg_root, freep);
STATIC_DESTRUCTOR_REGISTER(arg_image, freep);
STATIC_DESTRUCTOR_REGISTER(arg_definitions, freep);
STATIC_DESTRUCTOR_REGISTER(arg_key, erase_and_freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_device, freep);
@ -3483,6 +3485,7 @@ static int help(void) {
" them\n"
" --can-factory-reset Test whether factory reset is defined\n"
" --root=PATH Operate relative to root path\n"
" --image=PATH Operate relative to image file\n"
" --definitions=DIR Find partition definitions in specified directory\n"
" --key-file=PATH Key to use when encrypting partitions\n"
" --tpm2-device=PATH Path to TPM2 device node to use\n"
@ -3513,6 +3516,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_FACTORY_RESET,
ARG_CAN_FACTORY_RESET,
ARG_ROOT,
ARG_IMAGE,
ARG_SEED,
ARG_PRETTY,
ARG_DEFINITIONS,
@ -3534,6 +3538,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "factory-reset", required_argument, NULL, ARG_FACTORY_RESET },
{ "can-factory-reset", no_argument, NULL, ARG_CAN_FACTORY_RESET },
{ "root", required_argument, NULL, ARG_ROOT },
{ "image", required_argument, NULL, ARG_IMAGE },
{ "seed", required_argument, NULL, ARG_SEED },
{ "pretty", required_argument, NULL, ARG_PRETTY },
{ "definitions", required_argument, NULL, ARG_DEFINITIONS },
@ -3613,7 +3618,13 @@ static int parse_argv(int argc, char *argv[]) {
break;
case ARG_ROOT:
r = parse_path_argument(optarg, false, &arg_root);
r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_root);
if (r < 0)
return r;
break;
case ARG_IMAGE:
r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_image);
if (r < 0)
return r;
break;
@ -3763,9 +3774,18 @@ static int parse_argv(int argc, char *argv[]) {
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"If --empty=create is specified, --size= must be specified, too.");
if (arg_image && arg_root)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Please specify either --root= or --image=, the combination of both is not supported.");
else if (!arg_image && !arg_root && in_initrd()) {
/* Default to operation on /sysroot when invoked in the initrd! */
arg_root = strdup("/sysroot");
if (!arg_root)
return log_oom();
}
arg_node = argc > optind ? argv[optind] : NULL;
if (IN_SET(arg_empty, EMPTY_FORCE, EMPTY_REQUIRE, EMPTY_CREATE) && !arg_node)
if (IN_SET(arg_empty, EMPTY_FORCE, EMPTY_REQUIRE, EMPTY_CREATE) && !arg_node && !arg_image)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"A path to a device node or loopback file must be specified when --empty=force, --empty=require or --empty=create are used.");
@ -3838,39 +3858,44 @@ static int remove_efi_variable_factory_reset(void) {
return 0;
}
static int acquire_root_devno(const char *p, int mode, char **ret, int *ret_fd) {
static int acquire_root_devno(
const char *p,
const char *root,
int mode,
char **ret,
int *ret_fd) {
_cleanup_free_ char *found_path = NULL;
dev_t devno, fd_devno = MODE_INVALID;
_cleanup_close_ int fd = -1;
struct stat st;
dev_t devno, fd_devno = MODE_INVALID;
int r;
assert(p);
assert(ret);
assert(ret_fd);
fd = open(p, mode);
fd = chase_symlinks_and_open(p, root, CHASE_PREFIX_ROOT, mode, &found_path);
if (fd < 0)
return -errno;
return fd;
if (fstat(fd, &st) < 0)
return -errno;
if (S_ISREG(st.st_mode)) {
char *s;
s = strdup(p);
if (!s)
return log_oom();
*ret = s;
*ret = TAKE_PTR(found_path);
*ret_fd = TAKE_FD(fd);
return 0;
}
if (S_ISBLK(st.st_mode))
if (S_ISBLK(st.st_mode)) {
/* Refuse referencing explicit block devices if a root dir is specified, after all we should
* be able to leave the image the root path constraints us to. */
if (root)
return -EPERM;
fd_devno = devno = st.st_rdev;
else if (S_ISDIR(st.st_mode)) {
} else if (S_ISDIR(st.st_mode)) {
devno = st.st_dev;
if (major(devno) == 0) {
@ -3930,7 +3955,9 @@ static int find_root(char **ret, int *ret_fd) {
return 0;
}
r = acquire_root_devno(arg_node, O_RDONLY|O_CLOEXEC, ret, ret_fd);
/* Note that we don't specify a root argument here: if the user explicitly configured a node
* we'll take it relative to the host, not the image */
r = acquire_root_devno(arg_node, NULL, O_RDONLY|O_CLOEXEC, ret, ret_fd);
if (r == -EUCLEAN)
return btrfs_log_dev_root(LOG_ERR, r, arg_node);
if (r < 0)
@ -3958,7 +3985,7 @@ static int find_root(char **ret, int *ret_fd) {
} else
p = t;
r = acquire_root_devno(p, O_RDONLY|O_DIRECTORY|O_CLOEXEC, ret, ret_fd);
r = acquire_root_devno(p, arg_root, O_RDONLY|O_DIRECTORY|O_CLOEXEC, ret, ret_fd);
if (r < 0) {
if (r == -EUCLEAN)
return btrfs_log_dev_root(LOG_ERR, r, p);
@ -4005,9 +4032,15 @@ static int resize_pt(int fd) {
return 1;
}
static int resize_backing_fd(const char *node, int *fd) {
static int resize_backing_fd(
const char *node, /* The primary way we access the disk image to operate on */
int *fd, /* An O_RDONLY fd referring to that inode */
const char *backing_file, /* If the above refers to a loopback device, the backing regular file for that, which we can grow */
LoopDevice *loop_device) {
char buf1[FORMAT_BYTES_MAX], buf2[FORMAT_BYTES_MAX];
_cleanup_close_ int writable_fd = -1;
uint64_t current_size;
struct stat st;
int r;
@ -4028,25 +4061,64 @@ static int resize_backing_fd(const char *node, int *fd) {
if (fstat(*fd, &st) < 0)
return log_error_errno(errno, "Failed to stat '%s': %m", node);
r = stat_verify_regular(&st);
if (r < 0)
return log_error_errno(r, "Specified path '%s' is not a regular file, cannot resize: %m", node);
if (S_ISBLK(st.st_mode)) {
if (!backing_file)
return log_error_errno(SYNTHETIC_ERRNO(EBADF), "Cannot resize block device '%s'.", node);
assert_se(format_bytes(buf1, sizeof(buf1), st.st_size));
assert(loop_device);
if (ioctl(*fd, BLKGETSIZE64, &current_size) < 0)
return log_error_errno(errno, "Failed to determine size of block device %s: %m", node);
} else {
r = stat_verify_regular(&st);
if (r < 0)
return log_error_errno(r, "Specified path '%s' is not a regular file or loopback block device, cannot resize: %m", node);
assert(!backing_file);
assert(!loop_device);
current_size = st.st_size;
}
assert_se(format_bytes(buf1, sizeof(buf1), current_size));
assert_se(format_bytes(buf2, sizeof(buf2), arg_size));
if ((uint64_t) st.st_size >= arg_size) {
if (current_size >= arg_size) {
log_info("File '%s' already is of requested size or larger, not growing. (%s >= %s)", node, buf1, buf2);
return 0;
}
/* The file descriptor is read-only. In order to grow the file we need to have a writable fd. We
* reopen the file for that temporarily. We keep the writable fd only open for this operation though,
* as fdisk can't accept it anyway. */
if (S_ISBLK(st.st_mode)) {
assert(backing_file);
writable_fd = fd_reopen(*fd, O_WRONLY|O_CLOEXEC);
if (writable_fd < 0)
return log_error_errno(writable_fd, "Failed to reopen backing file '%s' writable: %m", node);
/* This is a loopback device. We can't really grow those directly, but we can grow the
* backing file, hence let's do that. */
writable_fd = open(backing_file, O_WRONLY|O_CLOEXEC|O_NONBLOCK);
if (writable_fd < 0)
return log_error_errno(errno, "Failed to open backing file '%s': %m", backing_file);
if (fstat(writable_fd, &st) < 0)
return log_error_errno(errno, "Failed to stat() backing file '%s': %m", backing_file);
r = stat_verify_regular(&st);
if (r < 0)
return log_error_errno(r, "Backing file '%s' of block device is not a regular file: %m", backing_file);
if ((uint64_t) st.st_size != current_size)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Size of backing file '%s' of loopback block device '%s' don't match, refusing.", node, backing_file);
} else {
assert(S_ISREG(st.st_mode));
assert(!backing_file);
/* The file descriptor is read-only. In order to grow the file we need to have a writable fd. We
* reopen the file for that temporarily. We keep the writable fd only open for this operation though,
* as fdisk can't accept it anyway. */
writable_fd = fd_reopen(*fd, O_WRONLY|O_CLOEXEC);
if (writable_fd < 0)
return log_error_errno(writable_fd, "Failed to reopen backing file '%s' writable: %m", node);
}
if (!arg_discard) {
if (fallocate(writable_fd, 0, 0, arg_size) < 0) {
@ -4057,16 +4129,12 @@ static int resize_backing_fd(const char *node, int *fd) {
/* Fallback to truncation, if fallocate() is not supported. */
log_debug("Backing file system does not support fallocate(), falling back to ftruncate().");
} else {
r = resize_pt(writable_fd);
if (r < 0)
return r;
if (st.st_size == 0) /* Likely regular file just created by us */
if (current_size == 0) /* Likely regular file just created by us */
log_info("Allocated %s for '%s'.", buf2, node);
else
log_info("File '%s' grown from %s to %s by allocation.", node, buf1, buf2);
return 1;
goto done;
}
}
@ -4074,14 +4142,21 @@ static int resize_backing_fd(const char *node, int *fd) {
return log_error_errno(errno, "Failed to grow '%s' from %s to %s by truncation: %m",
node, buf1, buf2);
if (current_size == 0) /* Likely regular file just created by us */
log_info("Sized '%s' to %s.", node, buf2);
else
log_info("File '%s' grown from %s to %s by truncation.", node, buf1, buf2);
done:
r = resize_pt(writable_fd);
if (r < 0)
return r;
if (st.st_size == 0) /* Likely regular file just created by us */
log_info("Sized '%s' to %s.", node, buf2);
else
log_info("File '%s' grown from %s to %s by truncation.", node, buf1, buf2);
if (loop_device) {
r = loop_device_refresh_size(loop_device, UINT64_MAX, arg_size);
if (r < 0)
return log_error_errno(r, "Failed to update loop device size: %m");
}
return 1;
}
@ -4116,23 +4191,19 @@ static int determine_auto_size(Context *c) {
}
static int run(int argc, char *argv[]) {
_cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
_cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
_cleanup_(umount_and_rmdir_and_freep) char *mounted_dir = NULL;
_cleanup_(context_freep) Context* context = NULL;
_cleanup_free_ char *node = NULL;
_cleanup_close_ int backing_fd = -1;
bool from_scratch;
bool from_scratch, node_is_our_loop = false;
int r;
log_show_color(true);
log_parse_environment();
log_open();
if (in_initrd()) {
/* Default to operation on /sysroot when invoked in the initrd! */
arg_root = strdup("/sysroot");
if (!arg_root)
return log_oom();
}
r = parse_argv(argc, argv);
if (r <= 0)
return r;
@ -4145,6 +4216,40 @@ static int run(int argc, char *argv[]) {
if (r < 0)
return r;
if (arg_image) {
assert(!arg_root);
/* Mount this strictly read-only: we shall modify the partition table, not the file
* systems */
r = mount_image_privately_interactively(
arg_image,
DISSECT_IMAGE_MOUNT_READ_ONLY |
(arg_node ? DISSECT_IMAGE_DEVICE_READ_ONLY : 0) | /* If a different node to make changes to is specified let's open the device in read-only mode) */
DISSECT_IMAGE_GPT_ONLY |
DISSECT_IMAGE_RELAX_VAR_CHECK |
DISSECT_IMAGE_USR_NO_ROOT |
DISSECT_IMAGE_REQUIRE_ROOT,
&mounted_dir,
&loop_device,
&decrypted_image);
if (r < 0)
return r;
arg_root = strdup(mounted_dir);
if (!arg_root)
return log_oom();
if (!arg_node) {
arg_node = strdup(loop_device->node);
if (!arg_node)
return log_oom();
/* Remember that the the device we are about to manipulate is actually the one we
* allocated here, and thus to increase its backing file we know what to do */
node_is_our_loop = true;
}
}
context = context_new(arg_seed);
if (!context)
return log_oom();
@ -4163,7 +4268,11 @@ static int run(int argc, char *argv[]) {
return r;
if (arg_size != UINT64_MAX) {
r = resize_backing_fd(node, &backing_fd);
r = resize_backing_fd(
node,
&backing_fd,
node_is_our_loop ? arg_image : NULL,
node_is_our_loop ? loop_device : NULL);
if (r < 0)
return r;
}
@ -4225,7 +4334,11 @@ static int run(int argc, char *argv[]) {
context_unload_partition_table(context);
assert_se(arg_size != UINT64_MAX);
r = resize_backing_fd(node, &backing_fd);
r = resize_backing_fd(
node,
&backing_fd,
node_is_our_loop ? arg_image : NULL,
node_is_our_loop ? loop_device : NULL);
if (r < 0)
return r;