/* SPDX-License-Identifier: LGPL-2.1+ */
/***
- This file is part of systemd.
-
Copyright 2014 Lennart Poettering
***/
#include "io-util.h"
//#include "macro.h"
#include "missing.h"
+//#include "mount-util.h"
//#include "string-util.h"
#include "strv.h"
#include "time-util.h"
#include "user-util.h"
//#include "xattr-util.h"
-#define COPY_BUFFER_SIZE (16*1024u)
+#define COPY_BUFFER_SIZE (16U*1024U)
+
+/* A safety net for descending recursively into file system trees to copy. On Linux PATH_MAX is 4096, which means the
+ * deepest valid path one can build is around 2048, which we hence use as a safety net here, to not spin endlessly in
+ * case of bind mount cycles and suchlike. */
+#define COPY_DEPTH_MAX 2048U
+
+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 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)
+ if (have == 0)
return -ENOSYS;
r = copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
- if (_unlikely_(have < 0))
+ if (have < 0)
have = r >= 0 || errno != ENOSYS;
- if (r >= 0)
- return r;
- else
+ if (r < 0)
return -errno;
+
+ return r;
}
enum {
struct stat st;
int flags;
- /* Checks whether the specified file descriptor refers to a pipe, and if so if is has O_NONBLOCK set. */
+ /* Checks whether the specified file descriptor refers to a pipe, and if so if O_NONBLOCK is set. */
if (fstat(fd, &st) < 0)
return -errno;
if (flags < 0)
return -errno;
- return (flags & O_NONBLOCK) == O_NONBLOCK ? FD_IS_NONBLOCKING_PIPE : FD_IS_BLOCKING_PIPE;
+ return FLAGS_SET(flags, O_NONBLOCK) ? FD_IS_NONBLOCKING_PIPE : FD_IS_BLOCKING_PIPE;
}
int copy_bytes_full(
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 (max_bytes <= 0)
+ return 1; /* return > 0 if we hit the max_bytes limit */
- if (m > max_bytes)
- m = max_bytes;
- }
+ if (max_bytes != UINT64_MAX && m > max_bytes)
+ m = max_bytes;
/* First try copy_file_range(), unless we already tried */
if (try_cfr) {
int dt,
const char *to,
dev_t original_device,
+ unsigned depth_left,
uid_t override_uid,
gid_t override_gid,
CopyFlags copy_flags) {
assert(st);
assert(to);
+ if (depth_left == 0)
+ return -ENAMETOOLONG;
+
if (from)
fdf = openat(df, from, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
else
continue;
}
- if (buf.st_dev != original_device)
- continue;
+ if (S_ISDIR(buf.st_mode)) {
+ /*
+ * Don't descend into directories on other file systems, if this is requested. We do a simple
+ * .st_dev check here, which basically comes for free. Note that we do this check only on
+ * directories, not other kind of file system objects, for two reason:
+ *
+ * • The kernel's overlayfs pseudo file system that overlays multiple real file systems
+ * propagates the .st_dev field of the file system a file originates from all the way up
+ * through the stack to stat(). It doesn't do that for directories however. This means that
+ * comparing .st_dev on non-directories suggests that they all are mount points. To avoid
+ * confusion we hence avoid relying on this check for regular files.
+ *
+ * • The main reason we do this check at all is to protect ourselves from bind mount cycles,
+ * where we really want to avoid descending down in all eternity. However the .st_dev check
+ * is usually not sufficient for this protection anyway, as bind mount cycles from the same
+ * file system onto itself can't be detected that way. (Note we also do a recursion depth
+ * check, which is probably the better protection in this regard, which is why
+ * COPY_SAME_MOUNT is optional).
+ */
+
+ if (FLAGS_SET(copy_flags, COPY_SAME_MOUNT)) {
+ if (buf.st_dev != original_device)
+ continue;
+
+ r = fd_is_mount_point(dirfd(d), de->d_name, 0);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+ }
- if (S_ISREG(buf.st_mode))
+ q = fd_copy_directory(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device, depth_left-1, override_uid, override_gid, copy_flags);
+ } else if (S_ISREG(buf.st_mode))
q = fd_copy_regular(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
- else if (S_ISDIR(buf.st_mode))
- q = fd_copy_directory(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device, override_uid, override_gid, copy_flags);
else if (S_ISLNK(buf.st_mode))
q = fd_copy_symlink(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
else if (S_ISFIFO(buf.st_mode))
if (S_ISREG(st.st_mode))
return fd_copy_regular(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
else if (S_ISDIR(st.st_mode))
- return fd_copy_directory(fdf, from, &st, fdt, to, st.st_dev, override_uid, override_gid, copy_flags);
+ return fd_copy_directory(fdf, from, &st, fdt, to, st.st_dev, COPY_DEPTH_MAX, override_uid, override_gid, copy_flags);
else if (S_ISLNK(st.st_mode))
return fd_copy_symlink(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
else if (S_ISFIFO(st.st_mode))
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
- return fd_copy_directory(dirfd, NULL, &st, AT_FDCWD, to, st.st_dev, UID_INVALID, GID_INVALID, copy_flags);
+ return fd_copy_directory(dirfd, NULL, &st, AT_FDCWD, to, st.st_dev, COPY_DEPTH_MAX, UID_INVALID, GID_INVALID, copy_flags);
}
int copy_directory(const char *from, const char *to, CopyFlags copy_flags) {
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
- return fd_copy_directory(AT_FDCWD, from, &st, AT_FDCWD, to, st.st_dev, UID_INVALID, GID_INVALID, copy_flags);
+ return fd_copy_directory(AT_FDCWD, from, &st, AT_FDCWD, to, st.st_dev, COPY_DEPTH_MAX, UID_INVALID, GID_INVALID, copy_flags);
}
int copy_file_fd(const char *from, int fdt, CopyFlags copy_flags) {
~ianmdlvl / elogind.git / blobdiff