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wip: move shared functions to a header file for re-use
Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> init: abstract configuring the root block device Configuring the root block device is a fairly isolated block, so abstract it into its own separate function so it can be re-used. Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: abstract most of the content in init.c to utils.h Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: split utils into .h and .c files Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: move config parsing logic to its own files Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: move fs related code to its own files Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: move timesync related code to its own files Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: do not expose helper functions Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me> wip: remove misc #include directives Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me>
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Lines changed: 1017 additions & 877 deletions

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‎init/fs.c‎

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#include "fs.h"
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static int try_mount(const char *source, const char *target, const char *fstype,
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unsigned long mountflags, const void *data);
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void setup_root_block_device(void)
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{
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int fd;
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char *krun_root;
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char *krun_root_fstype;
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char *krun_root_options;
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krun_root = getenv("KRUN_BLOCK_ROOT_DEVICE");
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if (krun_root) {
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if (mkdir("/newroot", 0755) < 0 && errno != EEXIST) {
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perror("mkdir(/newroot)");
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exit(-1);
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}
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krun_root_fstype = getenv("KRUN_BLOCK_ROOT_FSTYPE");
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krun_root_options = getenv("KRUN_BLOCK_ROOT_OPTIONS");
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if (try_mount(krun_root, "/newroot", krun_root_fstype, 0,
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krun_root_options) < 0) {
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perror("mount KRUN_BLOCK_ROOT_DEVICE");
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exit(-1);
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}
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chdir("/newroot");
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fd = open("/", O_RDONLY);
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if (fd < 0) {
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perror("Couldn't open temporary root directory for removing");
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exit(-1);
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}
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if (ioctl(fd, KRUN_REMOVE_ROOT_DIR_IOCTL) < 0) {
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perror("Error removing temporary root directory");
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}
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close(fd);
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if (mount(".", "/", NULL, MS_MOVE, NULL) < 0) {
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perror("remount root");
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exit(-1);
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}
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chroot(".");
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// we must mount filesystems again after chrooting
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if (mount_filesystems() < 0) {
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printf("Couldn't mount filesystems, bailing out\n");
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exit(-2);
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}
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}
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if (mount(NULL, "/", NULL, MS_REC | MS_SHARED, NULL) < 0) {
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perror("Couldn't set shared propagation on the root mount");
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exit(-1);
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}
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}
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int mount_filesystems()
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{
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char *const DIRS_LEVEL1[] = {"/dev", "/proc", "/sys"};
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char *const DIRS_LEVEL2[] = {"/dev/pts", "/dev/shm"};
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int i;
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for (i = 0; i < 3; ++i) {
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if (mkdir(DIRS_LEVEL1[i], 0755) < 0 && errno != EEXIST) {
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printf("Error creating directory (%s)\n", DIRS_LEVEL1[i]);
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return -1;
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}
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}
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if (mount("devtmpfs", "/dev", "devtmpfs", MS_RELATIME, NULL) < 0 &&
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errno != EBUSY) {
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perror("mount(/dev)");
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return -1;
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}
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if (mount("proc", "/proc", "proc",
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MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
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perror("mount(/proc)");
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return -1;
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}
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if (mount("sysfs", "/sys", "sysfs",
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MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
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perror("mount(/sys)");
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return -1;
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}
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if (mount("cgroup2", "/sys/fs/cgroup", "cgroup2",
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MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
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perror("mount(/sys/fs/cgroup)");
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return -1;
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}
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for (i = 0; i < 2; ++i) {
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if (mkdir(DIRS_LEVEL2[i], 0755) < 0 && errno != EEXIST) {
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printf("Error creating directory (%s)\n", DIRS_LEVEL2[i]);
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return -1;
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}
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}
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if (mount("devpts", "/dev/pts", "devpts",
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MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
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perror("mount(/dev/pts)");
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return -1;
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}
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if (mount("tmpfs", "/dev/shm", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_RELATIME,
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NULL) < 0) {
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perror("mount(/dev/shm)");
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return -1;
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}
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/* May fail if already exists and that's fine. */
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symlink("/proc/self/fd", "/dev/fd");
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return 0;
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}
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static int try_mount(const char *source, const char *target, const char *fstype,
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unsigned long mountflags, const void *data)
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{
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FILE *f;
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char line[129];
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int mount_status = -1;
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if (fstype) {
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return mount(source, target, fstype, mountflags, data);
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}
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f = fopen("/proc/filesystems", "r");
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if (f == NULL) {
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perror("fopen(/proc/filesystems)");
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return -1;
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}
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while (fgets(line, sizeof(line), f)) {
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char fstype[sizeof(line)];
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if (!strncmp(line, "nodev", 5)) {
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continue;
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}
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if (sscanf(line, "%128s\n", fstype) != 1) {
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continue;
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}
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mount_status = mount(source, target, fstype, mountflags, data);
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if (mount_status == 0) {
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break;
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}
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}
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fclose(f);
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return mount_status;
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}
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int is_virtiofs(const char *path)
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{
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struct statfs fs;
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if (statfs(path, &fs) != 0) {
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perror("statfs");
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return -1;
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}
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// virtiofs magic number: 0x65735546
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return (fs.f_type == 0x65735546) ? 1 : 0;
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}
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‎init/fs.h‎

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#ifndef FS_H
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#define FS_H
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <sys/statfs.h>
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#define KRUN_REMOVE_ROOT_DIR_IOCTL 0x7603
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void setup_root_block_device(void);
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int is_virtiofs(const char *path);
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int mount_filesystems();
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#endif

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