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https://git.proxmox.com/git/mirror_lxc
synced 2025-08-12 06:53:50 +00:00
utils: use loop device helpers from LXD
Use the loop device helpers I wrote for LXD in LXC as well. They should be more efficient. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
parent
d435aae15b
commit
c6868a1f81
@ -35,19 +35,9 @@
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#include "lxcloop.h"
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#include "utils.h"
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#ifndef LO_FLAGS_AUTOCLEAR
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#define LO_FLAGS_AUTOCLEAR 4
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#endif
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#ifndef LOOP_CTL_GET_FREE
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#define LOOP_CTL_GET_FREE 0x4C82
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#endif
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lxc_log_define(lxcloop, lxc);
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static int do_loop_create(const char *path, uint64_t size, const char *fstype);
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static int find_free_loopdev_no_control(int *retfd, char *namep);
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static int find_free_loopdev(int *retfd, char *namep);
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/*
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* No idea what the original blockdev will be called, but the copy will be
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@ -174,47 +164,26 @@ int loop_detect(const char *path)
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int loop_mount(struct bdev *bdev)
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{
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int lfd, ffd = -1, ret = -1;
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struct loop_info64 lo;
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char loname[100];
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int ret, loopfd;
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char loname[MAXPATHLEN];
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if (strcmp(bdev->type, "loop"))
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return -22;
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if (!bdev->src || !bdev->dest)
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return -22;
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if (find_free_loopdev(&lfd, loname) < 0)
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return -22;
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ffd = open(bdev->src + 5, O_RDWR);
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if (ffd < 0) {
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SYSERROR("Error opening backing file %s", bdev->src);
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goto out;
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}
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if (ioctl(lfd, LOOP_SET_FD, ffd) < 0) {
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SYSERROR("Error attaching backing file to loop dev");
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goto out;
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}
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memset(&lo, 0, sizeof(lo));
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lo.lo_flags = LO_FLAGS_AUTOCLEAR;
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if (ioctl(lfd, LOOP_SET_STATUS64, &lo) < 0) {
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SYSERROR("Error setting autoclear on loop dev");
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goto out;
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}
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loopfd = lxc_prepare_loop_dev(bdev->src + 5, loname, LO_FLAGS_AUTOCLEAR);
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if (loopfd < 0)
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return -1;
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DEBUG("prepared loop device \"%s\"", loname);
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ret = mount_unknown_fs(loname, bdev->dest, bdev->mntopts);
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if (ret < 0)
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ERROR("Error mounting %s", bdev->src);
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ERROR("failed to mount rootfs \"%s\" onto \"%s\" via loop device \"%s\"", bdev->src, bdev->dest, loname);
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else
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bdev->lofd = lfd;
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bdev->lofd = loopfd;
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DEBUG("mounted rootfs \"%s\" onto \"%s\" via loop device \"%s\"", bdev->src, bdev->dest, loname);
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out:
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if (ffd > -1)
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close(ffd);
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if (ret < 0) {
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close(lfd);
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bdev->lofd = -1;
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}
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return ret;
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}
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@ -266,63 +235,3 @@ static int do_loop_create(const char *path, uint64_t size, const char *fstype)
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return 0;
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}
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static int find_free_loopdev_no_control(int *retfd, char *namep)
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{
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struct dirent *direntp;
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struct loop_info64 lo;
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DIR *dir;
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int fd = -1;
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dir = opendir("/dev");
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if (!dir) {
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SYSERROR("Error opening /dev");
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return -1;
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}
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while ((direntp = readdir(dir))) {
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if (!direntp)
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break;
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if (strncmp(direntp->d_name, "loop", 4) != 0)
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continue;
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fd = openat(dirfd(dir), direntp->d_name, O_RDWR);
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if (fd < 0)
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continue;
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if (ioctl(fd, LOOP_GET_STATUS64, &lo) == 0 || errno != ENXIO) {
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close(fd);
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fd = -1;
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continue;
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}
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// We can use this fd
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snprintf(namep, 100, "/dev/%s", direntp->d_name);
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break;
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}
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closedir(dir);
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if (fd == -1) {
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ERROR("No loop device found");
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return -1;
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}
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*retfd = fd;
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return 0;
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}
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static int find_free_loopdev(int *retfd, char *namep)
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{
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int rc, fd = -1;
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int ctl = open("/dev/loop-control", O_RDWR);
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if (ctl < 0)
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return find_free_loopdev_no_control(retfd, namep);
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rc = ioctl(ctl, LOOP_CTL_GET_FREE);
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if (rc >= 0) {
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snprintf(namep, 100, "/dev/loop%d", rc);
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fd = open(namep, O_RDWR);
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}
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close(ctl);
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if (fd == -1) {
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ERROR("No loop device found");
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return -1;
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}
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*retfd = fd;
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return 0;
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}
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@ -590,95 +590,21 @@ static int mount_rootfs_dir(const char *rootfs, const char *target,
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return ret;
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}
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static int lxc_setup_lodev(const char *rootfs, int fd, struct loop_info64 *loinfo)
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{
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int rfd;
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rfd = open(rootfs, O_RDWR);
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if (rfd < 0) {
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SYSERROR("failed to open '%s'", rootfs);
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return -1;
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}
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memset(loinfo, 0, sizeof(*loinfo));
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if (ioctl(fd, LOOP_SET_FD, rfd)) {
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SYSERROR("failed to LOOP_SET_FD");
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close(rfd);
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return -1;
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}
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loinfo->lo_flags = LO_FLAGS_AUTOCLEAR;
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if (ioctl(fd, LOOP_SET_STATUS64, loinfo)) {
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SYSERROR("failed to LOOP_SET_STATUS64");
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close(rfd);
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return -1;
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}
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return 0;
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}
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static int mount_rootfs_file(const char *rootfs, const char *target,
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static int lxc_mount_rootfs_file(const char *rootfs, const char *target,
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const char *options)
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{
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struct dirent *direntp;
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struct loop_info64 loinfo;
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DIR *dir;
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int ret, loopfd;
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char path[MAXPATHLEN];
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int ret = -1, fd = -1, rc;
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dir = opendir("/dev");
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if (!dir) {
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SYSERROR("failed to open '/dev'");
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loopfd = lxc_prepare_loop_dev(rootfs, path, LO_FLAGS_AUTOCLEAR);
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if (loopfd < 0)
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return -1;
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}
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DEBUG("prepared loop device \"%s\"", path);
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while ((direntp = readdir(dir))) {
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if (!direntp)
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break;
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if (!strcmp(direntp->d_name, "."))
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continue;
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if (!strcmp(direntp->d_name, ".."))
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continue;
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if (strncmp(direntp->d_name, "loop", 4))
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continue;
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rc = snprintf(path, MAXPATHLEN, "/dev/%s", direntp->d_name);
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if (rc < 0 || rc >= MAXPATHLEN)
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continue;
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fd = open(path, O_RDWR);
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if (fd < 0)
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continue;
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if (ioctl(fd, LOOP_GET_STATUS64, &loinfo) == 0) {
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close(fd);
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continue;
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}
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if (errno != ENXIO) {
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WARN("unexpected error for ioctl on '%s': %m",
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direntp->d_name);
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close(fd);
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continue;
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}
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DEBUG("found '%s' free lodev", path);
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ret = lxc_setup_lodev(rootfs, fd, &loinfo);
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if (!ret)
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ret = mount_unknown_fs(path, target, options);
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close(fd);
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close(loopfd);
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break;
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}
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if (closedir(dir))
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WARN("failed to close directory");
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DEBUG("mounted rootfs \"%s\" on loop device \"%s\" via loop device \"%s\"", rootfs, target, path);
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return ret;
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}
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@ -911,7 +837,7 @@ static int mount_rootfs(const char *rootfs, const char *target, const char *opti
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} rtfs_type[] = {
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{ S_IFDIR, mount_rootfs_dir },
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{ S_IFBLK, mount_rootfs_block },
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{ S_IFREG, mount_rootfs_file },
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{ S_IFREG, lxc_mount_rootfs_file },
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};
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if (!realpath(rootfs, absrootfs)) {
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123
src/lxc/utils.c
123
src/lxc/utils.c
@ -2070,3 +2070,126 @@ int lxc_setgroups(int size, gid_t list[])
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return 0;
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}
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static int lxc_get_unused_loop_dev_legacy(char *loop_name)
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{
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struct dirent *dp;
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struct loop_info64 lo64;
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DIR *dir;
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int dfd = -1, fd = -1, ret = -1;
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dir = opendir("/dev");
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if (!dir)
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return -1;
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while ((dp = readdir(dir))) {
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if (!dp)
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break;
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if (strncmp(dp->d_name, "loop", 4) != 0)
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continue;
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dfd = dirfd(dir);
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if (dfd < 0)
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continue;
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fd = openat(dfd, dp->d_name, O_RDWR);
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if (fd < 0)
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continue;
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ret = ioctl(fd, LOOP_GET_STATUS64, &lo64);
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if (ret < 0) {
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if (ioctl(fd, LOOP_GET_STATUS64, &lo64) == 0 ||
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errno != ENXIO) {
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close(fd);
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fd = -1;
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continue;
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}
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}
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ret = snprintf(loop_name, LO_NAME_SIZE, "/dev/%s", dp->d_name);
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if (ret < 0 || ret >= LO_NAME_SIZE) {
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close(fd);
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fd = -1;
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continue;
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}
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break;
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}
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closedir(dir);
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if (fd < 0)
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return -1;
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return fd;
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}
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static int lxc_get_unused_loop_dev(char *name_loop)
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{
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int loop_nr, ret;
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int fd_ctl = -1, fd_tmp = -1;
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fd_ctl = open("/dev/loop-control", O_RDWR | O_CLOEXEC);
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if (fd_ctl < 0)
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return -ENODEV;
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loop_nr = ioctl(fd_ctl, LOOP_CTL_GET_FREE);
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if (loop_nr < 0)
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goto on_error;
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ret = snprintf(name_loop, LO_NAME_SIZE, "/dev/loop%d", loop_nr);
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if (ret < 0 || ret >= LO_NAME_SIZE)
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goto on_error;
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fd_tmp = open(name_loop, O_RDWR | O_CLOEXEC);
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if (fd_tmp < 0)
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goto on_error;
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on_error:
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close(fd_ctl);
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return fd_tmp;
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}
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int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags)
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{
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int ret;
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struct loop_info64 lo64;
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int fd_img = -1, fret = -1, fd_loop = -1;
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fd_loop = lxc_get_unused_loop_dev(loop_dev);
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if (fd_loop < 0) {
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if (fd_loop == -ENODEV)
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fd_loop = lxc_get_unused_loop_dev_legacy(loop_dev);
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else
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goto on_error;
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}
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fd_img = open(source, O_RDWR | O_CLOEXEC);
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if (fd_img < 0)
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goto on_error;
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ret = ioctl(fd_loop, LOOP_SET_FD, fd_img);
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if (ret < 0)
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goto on_error;
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memset(&lo64, 0, sizeof(lo64));
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lo64.lo_flags = flags;
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ret = ioctl(fd_loop, LOOP_SET_STATUS64, &lo64);
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if (ret < 0)
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goto on_error;
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fret = 0;
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on_error:
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if (fd_img >= 0)
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close(fd_img);
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if (fret < 0 && fd_loop >= 0) {
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close(fd_loop);
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fd_loop = -1;
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}
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return fd_loop;
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}
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@ -23,15 +23,19 @@
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#ifndef __LXC_UTILS_H
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#define __LXC_UTILS_H
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/* Properly support loop devices on 32bit systems. */
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#define _FILE_OFFSET_BITS 64
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#include "config.h"
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#include <errno.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include <linux/loop.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "initutils.h"
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@ -164,6 +168,15 @@ static inline int signalfd(int fd, const sigset_t *mask, int flags)
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}
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#endif
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/* loop devices */
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#ifndef LO_FLAGS_AUTOCLEAR
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#define LO_FLAGS_AUTOCLEAR 4
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#endif
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#ifndef LOOP_CTL_GET_FREE
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#define LOOP_CTL_GET_FREE 0x4C82
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#endif
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/* Struct to carry child pid from lxc_popen() to lxc_pclose().
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* Not an opaque struct to allow direct access to the underlying FILE *
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* (i.e., struct lxc_popen_FILE *file; fgets(buf, sizeof(buf), file->f))
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@ -332,4 +345,7 @@ int lxc_safe_long(const char *numstr, long int *converted);
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int lxc_switch_uid_gid(uid_t uid, gid_t gid);
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int lxc_setgroups(int size, gid_t list[]);
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/* Find an unused loop device and associate it with source. */
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int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags);
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#endif /* __LXC_UTILS_H */
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