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Systemd/src/basic/copy.c
Lennart Poettering 9a50e3caab machined: support non-btrfs file systems with "machinectl clone" 
Fall back to a normal copy operation when the backing file system isn't btrfs,
and hence doesn't support cheap snapshotting. Of course, this will be slow, but
given that the execution is asynchronous now, this should be OK.

Fixes: #1308
2016-05-02 11:15:30 +02:00

604 lines
17 KiB
C
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/***
This file is part of systemd.
Copyright 2014 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <sys/xattr.h>
#include <time.h>
#include <unistd.h>
#include "alloc-util.h"
#include "btrfs-util.h"
#include "chattr-util.h"
#include "copy.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "io-util.h"
#include "macro.h"
#include "missing.h"
#include "string-util.h"
#include "strv.h"
#include "time-util.h"
#include "umask-util.h"
#include "xattr-util.h"
#define COPY_BUFFER_SIZE (16*1024u)
static ssize_t try_copy_file_range(int fd_in, loff_t *off_in,
int fd_out, loff_t *off_out,
size_t len,
unsigned int flags) {
static int have = -1;
ssize_t r;
if (have == false)
return -ENOSYS;
r = copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
if (_unlikely_(have < 0))
have = r >= 0 || errno != ENOSYS;
if (r >= 0)
return r;
else
return -errno;
}
int copy_bytes(int fdf, int fdt, uint64_t max_bytes, bool try_reflink) {
bool try_cfr = true, try_sendfile = true, try_splice = true;
int r;
size_t m = SSIZE_MAX; /* that is the maximum that sendfile and c_f_r accept */
assert(fdf >= 0);
assert(fdt >= 0);
/* Try btrfs reflinks first. */
if (try_reflink &&
max_bytes == (uint64_t) -1 &&
lseek(fdf, 0, SEEK_CUR) == 0 &&
lseek(fdt, 0, SEEK_CUR) == 0) {
r = btrfs_reflink(fdf, fdt);
if (r >= 0)
return 0; /* we copied the whole thing, hence hit EOF, return 0 */
}
for (;;) {
ssize_t n;
if (max_bytes != (uint64_t) -1) {
if (max_bytes <= 0)
return 1; /* return > 0 if we hit the max_bytes limit */
if (m > max_bytes)
m = max_bytes;
}
/* First try copy_file_range(), unless we already tried */
if (try_cfr) {
n = try_copy_file_range(fdf, NULL, fdt, NULL, m, 0u);
if (n < 0) {
if (!IN_SET(n, -EINVAL, -ENOSYS, -EXDEV, -EBADF))
return n;
try_cfr = false;
/* use fallback below */
} else if (n == 0) /* EOF */
break;
else
/* Success! */
goto next;
}
/* First try sendfile(), unless we already tried */
if (try_sendfile) {
n = sendfile(fdt, fdf, NULL, m);
if (n < 0) {
if (!IN_SET(errno, EINVAL, ENOSYS))
return -errno;
try_sendfile = false;
/* use fallback below */
} else if (n == 0) /* EOF */
break;
else
/* Success! */
goto next;
}
/* Then try splice, unless we already tried */
if (try_splice) {
n = splice(fdf, NULL, fdt, NULL, m, 0);
if (n < 0) {
if (!IN_SET(errno, EINVAL, ENOSYS))
return -errno;
try_splice = false;
/* use fallback below */
} else if (n == 0) /* EOF */
break;
else
/* Success! */
goto next;
}
/* As a fallback just copy bits by hand */
{
uint8_t buf[MIN(m, COPY_BUFFER_SIZE)];
n = read(fdf, buf, sizeof buf);
if (n < 0)
return -errno;
if (n == 0) /* EOF */
break;
r = loop_write(fdt, buf, (size_t) n, false);
if (r < 0)
return r;
}
next:
if (max_bytes != (uint64_t) -1) {
assert(max_bytes >= (uint64_t) n);
max_bytes -= n;
}
/* sendfile accepts at most SSIZE_MAX-offset bytes to copy,
* so reduce our maximum by the amount we already copied,
* but don't go below our copy buffer size, unless we are
* close the the limit of bytes we are allowed to copy. */
m = MAX(MIN(COPY_BUFFER_SIZE, max_bytes), m - n);
}
return 0; /* return 0 if we hit EOF earlier than the size limit */
}
static int fd_copy_symlink(int df, const char *from, const struct stat *st, int dt, const char *to) {
_cleanup_free_ char *target = NULL;
int r;
assert(from);
assert(st);
assert(to);
r = readlinkat_malloc(df, from, &target);
if (r < 0)
return r;
if (symlinkat(target, dt, to) < 0)
return -errno;
if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
return -errno;
return 0;
}
static int fd_copy_regular(int df, const char *from, const struct stat *st, int dt, const char *to) {
_cleanup_close_ int fdf = -1, fdt = -1;
struct timespec ts[2];
int r, q;
assert(from);
assert(st);
assert(to);
fdf = openat(df, from, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fdf < 0)
return -errno;
fdt = openat(dt, to, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, st->st_mode & 07777);
if (fdt < 0)
return -errno;
r = copy_bytes(fdf, fdt, (uint64_t) -1, true);
if (r < 0) {
unlinkat(dt, to, 0);
return r;
}
if (fchown(fdt, st->st_uid, st->st_gid) < 0)
r = -errno;
if (fchmod(fdt, st->st_mode & 07777) < 0)
r = -errno;
ts[0] = st->st_atim;
ts[1] = st->st_mtim;
(void) futimens(fdt, ts);
(void) copy_xattr(fdf, fdt);
q = close(fdt);
fdt = -1;
if (q < 0) {
r = -errno;
unlinkat(dt, to, 0);
}
return r;
}
static int fd_copy_fifo(int df, const char *from, const struct stat *st, int dt, const char *to) {
int r;
assert(from);
assert(st);
assert(to);
r = mkfifoat(dt, to, st->st_mode & 07777);
if (r < 0)
return -errno;
if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
r = -errno;
if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
r = -errno;
return r;
}
static int fd_copy_node(int df, const char *from, const struct stat *st, int dt, const char *to) {
int r;
assert(from);
assert(st);
assert(to);
r = mknodat(dt, to, st->st_mode, st->st_rdev);
if (r < 0)
return -errno;
if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
r = -errno;
if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
r = -errno;
return r;
}
static int fd_copy_directory(
int df,
const char *from,
const struct stat *st,
int dt,
const char *to,
dev_t original_device,
bool merge) {
_cleanup_close_ int fdf = -1, fdt = -1;
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
bool created;
int r;
assert(st);
assert(to);
if (from)
fdf = openat(df, from, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
else
fdf = fcntl(df, F_DUPFD_CLOEXEC, 3);
if (fdf < 0)
return -errno;
d = fdopendir(fdf);
if (!d)
return -errno;
fdf = -1;
r = mkdirat(dt, to, st->st_mode & 07777);
if (r >= 0)
created = true;
else if (errno == EEXIST && merge)
created = false;
else
return -errno;
fdt = openat(dt, to, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fdt < 0)
return -errno;
r = 0;
FOREACH_DIRENT_ALL(de, d, return -errno) {
struct stat buf;
int q;
if (STR_IN_SET(de->d_name, ".", ".."))
continue;
if (fstatat(dirfd(d), de->d_name, &buf, AT_SYMLINK_NOFOLLOW) < 0) {
r = -errno;
continue;
}
if (buf.st_dev != original_device)
continue;
if (S_ISREG(buf.st_mode))
q = fd_copy_regular(dirfd(d), de->d_name, &buf, fdt, de->d_name);
else if (S_ISDIR(buf.st_mode))
q = fd_copy_directory(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device, merge);
else if (S_ISLNK(buf.st_mode))
q = fd_copy_symlink(dirfd(d), de->d_name, &buf, fdt, de->d_name);
else if (S_ISFIFO(buf.st_mode))
q = fd_copy_fifo(dirfd(d), de->d_name, &buf, fdt, de->d_name);
else if (S_ISBLK(buf.st_mode) || S_ISCHR(buf.st_mode) || S_ISSOCK(buf.st_mode))
q = fd_copy_node(dirfd(d), de->d_name, &buf, fdt, de->d_name);
else
q = -EOPNOTSUPP;
if (q == -EEXIST && merge)
q = 0;
if (q < 0)
r = q;
}
if (created) {
struct timespec ut[2] = {
st->st_atim,
st->st_mtim
};
if (fchown(fdt, st->st_uid, st->st_gid) < 0)
r = -errno;
if (fchmod(fdt, st->st_mode & 07777) < 0)
r = -errno;
(void) copy_xattr(dirfd(d), fdt);
(void) futimens(fdt, ut);
}
return r;
}
int copy_tree_at(int fdf, const char *from, int fdt, const char *to, bool merge) {
struct stat st;
assert(from);
assert(to);
if (fstatat(fdf, from, &st, AT_SYMLINK_NOFOLLOW) < 0)
return -errno;
if (S_ISREG(st.st_mode))
return fd_copy_regular(fdf, from, &st, fdt, to);
else if (S_ISDIR(st.st_mode))
return fd_copy_directory(fdf, from, &st, fdt, to, st.st_dev, merge);
else if (S_ISLNK(st.st_mode))
return fd_copy_symlink(fdf, from, &st, fdt, to);
else if (S_ISFIFO(st.st_mode))
return fd_copy_fifo(fdf, from, &st, fdt, to);
else if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) || S_ISSOCK(st.st_mode))
return fd_copy_node(fdf, from, &st, fdt, to);
else
return -EOPNOTSUPP;
}
int copy_tree(const char *from, const char *to, bool merge) {
return copy_tree_at(AT_FDCWD, from, AT_FDCWD, to, merge);
}
int copy_directory_fd(int dirfd, const char *to, bool merge) {
struct stat st;
assert(dirfd >= 0);
assert(to);
if (fstat(dirfd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
return fd_copy_directory(dirfd, NULL, &st, AT_FDCWD, to, st.st_dev, merge);
}
int copy_directory(const char *from, const char *to, bool merge) {
struct stat st;
assert(from);
assert(to);
if (lstat(from, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
return fd_copy_directory(AT_FDCWD, from, &st, AT_FDCWD, to, st.st_dev, merge);
}
int copy_file_fd(const char *from, int fdt, bool try_reflink) {
_cleanup_close_ int fdf = -1;
int r;
assert(from);
assert(fdt >= 0);
fdf = open(from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fdf < 0)
return -errno;
r = copy_bytes(fdf, fdt, (uint64_t) -1, try_reflink);
(void) copy_times(fdf, fdt);
(void) copy_xattr(fdf, fdt);
return r;
}
int copy_file(const char *from, const char *to, int flags, mode_t mode, unsigned chattr_flags) {
int fdt = -1, r;
assert(from);
assert(to);
RUN_WITH_UMASK(0000) {
fdt = open(to, flags|O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, mode);
if (fdt < 0)
return -errno;
}
if (chattr_flags != 0)
(void) chattr_fd(fdt, chattr_flags, (unsigned) -1);
r = copy_file_fd(from, fdt, true);
if (r < 0) {
close(fdt);
unlink(to);
return r;
}
if (close(fdt) < 0) {
unlink_noerrno(to);
return -errno;
}
return 0;
}
int copy_file_atomic(const char *from, const char *to, mode_t mode, bool replace, unsigned chattr_flags) {
_cleanup_free_ char *t = NULL;
int r;
assert(from);
assert(to);
r = tempfn_random(to, NULL, &t);
if (r < 0)
return r;
r = copy_file(from, t, O_NOFOLLOW|O_EXCL, mode, chattr_flags);
if (r < 0)
return r;
if (replace) {
r = renameat(AT_FDCWD, t, AT_FDCWD, to);
if (r < 0)
r = -errno;
} else
r = rename_noreplace(AT_FDCWD, t, AT_FDCWD, to);
if (r < 0) {
(void) unlink_noerrno(t);
return r;
}
return 0;
}
int copy_times(int fdf, int fdt) {
struct timespec ut[2];
struct stat st;
usec_t crtime = 0;
assert(fdf >= 0);
assert(fdt >= 0);
if (fstat(fdf, &st) < 0)
return -errno;
ut[0] = st.st_atim;
ut[1] = st.st_mtim;
if (futimens(fdt, ut) < 0)
return -errno;
if (fd_getcrtime(fdf, &crtime) >= 0)
(void) fd_setcrtime(fdt, crtime);
return 0;
}
int copy_xattr(int fdf, int fdt) {
_cleanup_free_ char *bufa = NULL, *bufb = NULL;
size_t sza = 100, szb = 100;
ssize_t n;
int ret = 0;
const char *p;
for (;;) {
bufa = malloc(sza);
if (!bufa)
return -ENOMEM;
n = flistxattr(fdf, bufa, sza);
if (n == 0)
return 0;
if (n > 0)
break;
if (errno != ERANGE)
return -errno;
sza *= 2;
bufa = mfree(bufa);
}
p = bufa;
while (n > 0) {
size_t l;
l = strlen(p);
assert(l < (size_t) n);
if (startswith(p, "user.")) {
ssize_t m;
if (!bufb) {
bufb = malloc(szb);
if (!bufb)
return -ENOMEM;
}
m = fgetxattr(fdf, p, bufb, szb);
if (m < 0) {
if (errno == ERANGE) {
szb *= 2;
bufb = mfree(bufb);
continue;
}
return -errno;
}
if (fsetxattr(fdt, p, bufb, m, 0) < 0)
ret = -errno;
}
p += l + 1;
n -= l + 1;
}
return ret;
}
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