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gpt-auto-generator: automatically find the root disk of the system
When run in an initrd and no root= argument is set (or is set to
root=gpt-auto) we will automatically look for the root partition on the
same disk the EFI ESP is located on.
Since we look for swap, /home and /srv on the disk the root partition is
located on, we hence have a fully discoverable chain:
Firmware discovers the EFI ESP partition → the initrd discovers the
root partition → the host OS discovers swap, /home, and /srv.
Note that this requires an EFI boot loader that sets the
LoaderDevicePartUUID EFI variable, such as Gummiboot.
This commit is contained in:
Lennart Poettering
parent
329f7803ee
commit
73b80ec2d9
@ -43,7 +43,8 @@
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<refnamediv>
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<refname>systemd-gpt-auto-generator</refname>
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<refpurpose>Generator for automatically discovering
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and mounting <filename>/home</filename> and <filename>/srv</filename>, as well as
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and mounting root, <filename>/home</filename> and
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<filename>/srv</filename> partitions, as well as
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discovering and enabling swap partitions, based on GPT
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partition type GUIDs.</refpurpose>
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</refnamediv>
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@ -56,7 +57,7 @@
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<title>Description</title>
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<para><filename>systemd-gpt-auto-generator</filename>
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is a unit generator that automatically discovers
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is a unit generator that automatically discovers root,
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<filename>/home</filename>, <filename>/srv</filename>
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and swap partitions and creates mount and swap units
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for them, based on the the partition type GUIDs of
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@ -67,11 +68,14 @@
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<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
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or where the mount points are non-empty.</para>
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<para>This generator will only look for partitions on
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the same physical disk the root file system is stored
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on. This generator has no effect on systems where the
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root file system is distributed on multiple disks, for
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example via btrfs RAID.</para>
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<para>This generator will only look for root
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partitions on the same physical disk the EFI System
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Partition (ESP) is located on. It will only look for
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the other partitions on the same physical disk the
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root file system is located on. These partitions will
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not be search on systems where the root file system is
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distributed on multiple disks, for example via btrfs
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RAID.</para>
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<para><filename>systemd-gpt-auto-generator</filename>
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is useful for centralizing file system configuration
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@ -87,30 +91,40 @@
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<title>Partition Type GUIDs</title>
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<tgroup cols='3' align='left' colsep='1' rowsep='1'>
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<colspec colname="guid" />
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<colspec colname="location" />
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<colspec colname="name" />
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<colspec colname="explanation" />
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<thead>
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<row>
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<entry>Partition Type GUID</entry>
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<entry>Location</entry>
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<entry>Name</entry>
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<entry>Explanation</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>0657fd6d-a4ab-43c4-84e50933c84b4f4f</entry>
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<entry>Swap</entry>
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<entry>All swap partitions are enabled.</entry>
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<entry>44479540-f297-41b2-9af7d131d5f0458a</entry>
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<entry><filename>Root Partition (x86)</filename></entry>
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<entry>On 32bit x86 systems the first x86 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
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</row>
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<row>
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<entry>4f68bce3-e8cd-4db1-96e7fbcaf984b709</entry>
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<entry><filename>Root Partition (x86-64)</filename></entry>
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<entry>On 64bit x86 systems the first x86-64 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
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</row>
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<row>
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<entry>933ac7e1-2eb4-4f13-b8440e14e2aef915</entry>
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<entry><filename>/home</filename></entry>
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<entry>The first home partition on the disk is mounted to <filename>/home</filename>.</entry>
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<entry>Home Partition</entry>
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<entry>The first home partition on the disk the root partition is located on is mounted to <filename>/home</filename>.</entry>
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</row>
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<row>
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<entry>3b8f8425-20e0-4f3b-907f1a25a76f98e8</entry>
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<entry><filename>/srv</filename></entry>
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<entry>The first server data partition on the disk is mounted to <filename>/srv</filename>.</entry>
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<entry>Server Data Partition</entry>
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<entry>The first server data partition on the disk the root partition is located on is mounted to <filename>/srv</filename>.</entry>
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</row>
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<row>
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<entry>0657fd6d-a4ab-43c4-84e50933c84b4f4f</entry>
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<entry>Swap</entry>
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<entry>All swap partitions located on the disk the root partition is located on are enabled.</entry>
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</row>
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</tbody>
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</tgroup>
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@ -128,8 +142,13 @@
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<para>Also note that
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<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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will mount the EFI System Partition to
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<filename>/boot</filename> is not otherwise mounted.</para>
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will mount the EFI System Partition (ESP) to
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<filename>/boot</filename> if not otherwise mounted.</para>
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<para>When using this generator in conjunction with
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btrfs file systems make sure to set the correct
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default subvolumes on them, using <command>btrfs
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subvolume set-default</command>.</para>
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<para><filename>systemd-gpt-auto-generator</filename>
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implements the <ulink
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@ -147,7 +166,8 @@
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<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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@ -374,6 +374,7 @@ static int parse_proc_cmdline_item(const char *key, const char *value) {
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log_warning("Environment variable name '%s' is not valid. Ignoring.", value);
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} else if (!streq(key, "systemd.restore_state") &&
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!streq(key, "systemd.gpt_auto") &&
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(startswith(key, "systemd.") || startswith(key, "rd.systemd."))) {
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const char *c;
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@ -43,8 +43,12 @@
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#include "generator.h"
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#include "gpt.h"
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#include "fileio.h"
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#include "efivars.h"
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static const char *arg_dest = "/tmp";
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static bool arg_enabled = true;
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static bool arg_root_enabled = true;
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static bool arg_root_rw = false;
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DEFINE_TRIVIAL_CLEANUP_FUNC(blkid_probe, blkid_free_probe);
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#define _cleanup_blkid_freep_probe_ _cleanup_(blkid_free_probep)
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@ -287,7 +291,15 @@ static int add_cryptsetup(const char *id, const char *what, char **device) {
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return 0;
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}
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static int add_mount(const char *id, const char *what, const char *where, const char *fstype, const char *description) {
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static int add_mount(
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const char *id,
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const char *what,
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const char *where,
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const char *fstype,
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const char *options,
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const char *description,
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const char *post) {
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_cleanup_free_ char *unit = NULL, *lnk = NULL, *crypto_what = NULL, *p = NULL;
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_cleanup_fclose_ FILE *f = NULL;
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int r;
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@ -295,7 +307,6 @@ static int add_mount(const char *id, const char *what, const char *where, const
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assert(id);
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assert(what);
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assert(where);
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assert(fstype);
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assert(description);
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if (path_is_mount_point(where, true) <= 0 &&
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@ -304,9 +315,9 @@ static int add_mount(const char *id, const char *what, const char *where, const
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return 0;
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}
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log_debug("Adding %s: %s %s", where, what, fstype);
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log_debug("Adding %s: %s %s", where, what, strna(fstype));
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if (streq(fstype, "crypto_LUKS")) {
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if (streq_ptr(fstype, "crypto_LUKS")) {
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r = add_cryptsetup(id, what, &crypto_what);
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if (r < 0)
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@ -337,6 +348,9 @@ static int add_mount(const char *id, const char *what, const char *where, const
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"Documentation=man:systemd-gpt-auto-generator(8)\n",
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description);
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if (post)
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fprintf(f, "Before=%s\n", post);
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r = generator_write_fsck_deps(f, arg_dest, what, where, fstype);
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if (r < 0)
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return r;
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@ -348,26 +362,28 @@ static int add_mount(const char *id, const char *what, const char *where, const
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"Where=%s\n",
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what, where);
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if (fstype) {
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fprintf(f,
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"Type=%s\n",
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fstype);
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}
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if (fstype)
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fprintf(f, "Type=%s\n", fstype);
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if (options)
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fprintf(f, "Options=%s\n", options);
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fflush(f);
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if (ferror(f)) {
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log_error("Failed to write unit file %s: %m", unit);
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log_error("Failed to write unit file %s: %m", p);
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return -errno;
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}
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lnk = strjoin(arg_dest, "/" SPECIAL_LOCAL_FS_TARGET ".requires/", unit, NULL);
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if (!lnk)
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return log_oom();
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if (post) {
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lnk = strjoin(arg_dest, "/", post, ".requires/", unit, NULL);
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if (!lnk)
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return log_oom();
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mkdir_parents_label(lnk, 0755);
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if (symlink(unit, lnk) < 0) {
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log_error("Failed to create symlink %s: %m", lnk);
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return -errno;
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mkdir_parents_label(lnk, 0755);
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if (symlink(p, lnk) < 0) {
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log_error("Failed to create symlink %s: %m", lnk);
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return -errno;
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}
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}
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return 0;
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@ -380,7 +396,7 @@ static int enumerate_partitions(struct udev *udev, dev_t dev) {
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unsigned home_nr = (unsigned) -1, srv_nr = (unsigned )-1;
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struct udev_list_entry *first, *item;
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struct udev_device *parent = NULL;
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int r;
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int r, k;
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e = udev_enumerate_new(udev);
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if (!e)
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@ -408,6 +424,8 @@ static int enumerate_partitions(struct udev *udev, dev_t dev) {
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return r;
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}
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r = 0;
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first = udev_enumerate_get_list_entry(e);
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udev_list_entry_foreach(item, first) {
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_cleanup_udev_device_unref_ struct udev_device *q;
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@ -430,21 +448,26 @@ static int enumerate_partitions(struct udev *udev, dev_t dev) {
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if (!node)
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return log_oom();
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r = verify_gpt_partition(node, &type_id, &nr, &fstype);
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if (r < 0) {
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k = verify_gpt_partition(node, &type_id, &nr, &fstype);
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if (k < 0) {
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/* skip child devices which are not detected properly */
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if (r == -EBADSLT)
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if (k == -EBADSLT)
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continue;
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log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
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return r;
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log_error("Failed to verify GPT partition %s: %s", node, strerror(-k));
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r = k;
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continue;
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}
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if (r == 0)
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if (k == 0)
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continue;
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if (sd_id128_equal(type_id, GPT_SWAP))
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add_swap(node, fstype);
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if (sd_id128_equal(type_id, GPT_SWAP)) {
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else if (sd_id128_equal(type_id, GPT_HOME)) {
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k = add_swap(node, fstype);
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if (k < 0)
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r = k;
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} else if (sd_id128_equal(type_id, GPT_HOME)) {
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/* We only care for the first /home partition */
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if (home && nr >= home_nr)
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@ -480,11 +503,17 @@ static int enumerate_partitions(struct udev *udev, dev_t dev) {
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}
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}
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if (home && home_fstype)
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add_mount("home", home, "/home", home_fstype, "Home Partition");
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if (home && home_fstype) {
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k = add_mount("home", home, "/home", home_fstype, NULL, "Home Partition", SPECIAL_LOCAL_FS_TARGET);
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if (k < 0)
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r = k;
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}
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if (srv && srv_fstype)
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add_mount("srv", srv, "/srv", srv_fstype, "Server Data Partition");
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if (srv && srv_fstype) {
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k = add_mount("srv", srv, "/srv", srv_fstype, NULL, "Server Data Partition", SPECIAL_LOCAL_FS_TARGET);
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if (k < 0)
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r = k;
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}
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return r;
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}
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@ -582,10 +611,113 @@ static int devno_to_devnode(struct udev *udev, dev_t devno, char **ret) {
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return 0;
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}
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int main(int argc, char *argv[]) {
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static int parse_proc_cmdline_item(const char *key, const char *value) {
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int r;
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assert(key);
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if (STR_IN_SET(key, "systemd.gpt_auto", "rd.systemd.gpt_auto") && value) {
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r = parse_boolean(value);
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if (r < 0)
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log_warning("Failed to parse gpt-auto switch %s. Ignoring.", value);
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arg_enabled = r;
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} else if (streq(key, "root") && value) {
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/* Disable root disk logic if there's a root= value
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* specified (unless it happens to be "gpt-auto") */
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arg_root_enabled = streq(value, "gpt-auto");
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} else if (streq(key, "rw") && !value)
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arg_root_rw = true;
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else if (streq(key, "ro") && !value)
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arg_root_rw = false;
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else if (startswith(key, "systemd.gpt-auto.") || startswith(key, "rd.systemd.gpt-auto."))
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log_warning("Unknown kernel switch %s. Ignoring.", key);
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return 0;
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}
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static int add_root_mount(void) {
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#ifdef ENABLE_EFI
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int r;
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if (!is_efi_boot()) {
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log_debug("Not a EFI boot, not creating root mount.");
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return 0;
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}
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r = efi_loader_get_device_part_uuid(NULL);
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if (r == -ENOENT) {
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log_debug("EFI loader partition unknown, exiting.");
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return 0;
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} else if (r < 0) {
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log_error("Failed to read ESP partition UUID: %s", strerror(-r));
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return r;
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}
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/* OK, we have an ESP partition, this is fantastic, so let's
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* wait for a root device to show up. A udev rule will create
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* the link for us under the right name. */
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return add_mount(
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"root",
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"/dev/disk/by-id/gpt-auto-root",
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in_initrd() ? "/sysroot" : "/",
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NULL,
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arg_root_rw ? "rw" : "ro",
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"Root Partition",
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in_initrd() ? SPECIAL_INITRD_ROOT_FS_TARGET : SPECIAL_LOCAL_FS_TARGET);
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#else
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return 0;
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#endif
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}
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static int add_mounts(void) {
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_cleanup_udev_unref_ struct udev *udev = NULL;
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_cleanup_free_ char *node = NULL;
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dev_t devno;
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int r;
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r = get_block_device("/", &devno);
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if (r < 0) {
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log_error("Failed to determine block device of root file system: %s", strerror(-r));
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return r;
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} else if (r == 0) {
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log_debug("Root file system not on a (single) block device.");
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return 0;
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}
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udev = udev_new();
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if (!udev)
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return log_oom();
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r = devno_to_devnode(udev, devno, &node);
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if (r < 0) {
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log_error("Failed to determine block device node from major/minor: %s", strerror(-r));
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return r;
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}
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log_debug("Root device %s.", node);
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r = verify_gpt_partition(node, NULL, NULL, NULL);
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if (r < 0) {
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log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
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return r;
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}
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if (r == 0) {
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log_debug("Not a GPT disk, exiting.");
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return 0;
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}
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return enumerate_partitions(udev, devno);
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}
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int main(int argc, char *argv[]) {
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int r = 0;
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if (argc > 1 && argc != 4) {
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@ -602,52 +734,29 @@ int main(int argc, char *argv[]) {
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umask(0022);
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if (in_initrd()) {
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log_debug("In initrd, exiting.");
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return EXIT_SUCCESS;
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}
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if (detect_container(NULL) > 0) {
|
||||
log_debug("In a container, exiting.");
|
||||
return EXIT_SUCCESS;
|
||||
}
|
||||
|
||||
r = get_block_device("/", &devno);
|
||||
if (r < 0) {
|
||||
log_error("Failed to determine block device of root file system: %s", strerror(-r));
|
||||
if (parse_proc_cmdline(parse_proc_cmdline_item) < 0)
|
||||
return EXIT_FAILURE;
|
||||
} else if (r == 0) {
|
||||
log_debug("Root file system not on a (single) block device.");
|
||||
|
||||
if (!arg_enabled) {
|
||||
log_debug("Disabled, exiting.");
|
||||
return EXIT_SUCCESS;
|
||||
}
|
||||
|
||||
udev = udev_new();
|
||||
if (!udev) {
|
||||
log_oom();
|
||||
return EXIT_FAILURE;
|
||||
if (arg_root_enabled)
|
||||
r = add_root_mount();
|
||||
|
||||
if (!in_initrd()) {
|
||||
int k;
|
||||
|
||||
k = add_mounts();
|
||||
if (k < 0)
|
||||
r = k;
|
||||
}
|
||||
|
||||
r = devno_to_devnode(udev, devno, &node);
|
||||
if (r < 0) {
|
||||
log_error("Failed to determine block device node from major/minor: %s", strerror(-r));
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
|
||||
log_debug("Root device %s.", node);
|
||||
|
||||
r = verify_gpt_partition(node, NULL, NULL, NULL);
|
||||
if (r < 0) {
|
||||
log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
if (r == 0) {
|
||||
log_debug("Not a GPT disk, exiting.");
|
||||
return EXIT_SUCCESS;
|
||||
}
|
||||
|
||||
r = enumerate_partitions(udev, devno);
|
||||
if (r < 0)
|
||||
return EXIT_FAILURE;
|
||||
|
||||
return EXIT_SUCCESS;
|
||||
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
|
||||
}
|
||||
|
||||
@ -440,9 +440,6 @@ int efi_loader_get_boot_usec(usec_t *firmware, usec_t *loader) {
|
||||
int efi_loader_get_device_part_uuid(sd_id128_t *u) {
|
||||
_cleanup_free_ char *p = NULL;
|
||||
int r, parsed[16];
|
||||
unsigned i;
|
||||
|
||||
assert(u);
|
||||
|
||||
r = efi_get_variable_string(EFI_VENDOR_LOADER, "LoaderDevicePartUUID", &p);
|
||||
if (r < 0)
|
||||
@ -455,8 +452,12 @@ int efi_loader_get_device_part_uuid(sd_id128_t *u) {
|
||||
&parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
|
||||
return -EIO;
|
||||
|
||||
for (i = 0; i < ELEMENTSOF(parsed); i++)
|
||||
u->bytes[i] = parsed[i];
|
||||
if (u) {
|
||||
unsigned i;
|
||||
|
||||
for (i = 0; i < ELEMENTSOF(parsed); i++)
|
||||
u->bytes[i] = parsed[i];
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user