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repart: Keep existing directory timestamps intact when copying
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Otherwise, when merging multiple directory trees, the output becomes
unreproducible as the directory timestamps will be changed to the current
time when copying identical directories from the second tree.

We introduce a new copy flag to achieve this behavior.

(cherry picked from commit d850a544bc1f895decb452160c97a884a20b12b7)
(cherry picked from commit d5640c4f8583de2752a7f4e03006a1fa74942da1)
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@DaanDeMeyer @bluca
DaanDeMeyer authored and bluca committed Sep 10, 2024
1 parent 4a86d30 commit 7a3b3ad
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Showing 3 changed files with 29 additions and 22 deletions.
4 changes: 2 additions & 2 deletions src/partition/repart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4667,14 +4667,14 @@ static int do_copy_files(Context *context, Partition *p, const char *root) {
sfd, ".",
pfd, fn,
UID_INVALID, GID_INVALID,
COPY_REFLINK|COPY_HOLES|COPY_MERGE|COPY_REPLACE|COPY_SIGINT|COPY_HARDLINKS|COPY_ALL_XATTRS|COPY_GRACEFUL_WARN|COPY_TRUNCATE,
COPY_REFLINK|COPY_HOLES|COPY_MERGE|COPY_REPLACE|COPY_SIGINT|COPY_HARDLINKS|COPY_ALL_XATTRS|COPY_GRACEFUL_WARN|COPY_TRUNCATE|COPY_RESTORE_DIRECTORY_TIMESTAMPS,
denylist, subvolumes_by_source_inode);
} else
r = copy_tree_at(
sfd, ".",
tfd, ".",
UID_INVALID, GID_INVALID,
COPY_REFLINK|COPY_HOLES|COPY_MERGE|COPY_REPLACE|COPY_SIGINT|COPY_HARDLINKS|COPY_ALL_XATTRS|COPY_GRACEFUL_WARN|COPY_TRUNCATE,
COPY_REFLINK|COPY_HOLES|COPY_MERGE|COPY_REPLACE|COPY_SIGINT|COPY_HARDLINKS|COPY_ALL_XATTRS|COPY_GRACEFUL_WARN|COPY_TRUNCATE|COPY_RESTORE_DIRECTORY_TIMESTAMPS,
denylist, subvolumes_by_source_inode);
if (r < 0)
return log_error_errno(r, "Failed to copy '%s%s' to '%s%s': %m",
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8 changes: 7 additions & 1 deletion src/shared/copy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -981,6 +981,7 @@ static int fd_copy_directory(

_cleanup_close_ int fdf = -EBADF, fdt = -EBADF;
_cleanup_closedir_ DIR *d = NULL;
struct stat dt_st;
bool exists;
int r;

Expand Down Expand Up @@ -1025,6 +1026,9 @@ static int fd_copy_directory(
if (fdt < 0)
return fdt;

if (exists && FLAGS_SET(copy_flags, COPY_RESTORE_DIRECTORY_TIMESTAMPS) && fstat(fdt, &dt_st) < 0)
return -errno;

r = 0;

if (PTR_TO_INT(hashmap_get(denylist, st)) == DENY_CONTENTS) {
Expand Down Expand Up @@ -1124,7 +1128,9 @@ static int fd_copy_directory(

(void) copy_xattr(dirfd(d), NULL, fdt, NULL, copy_flags);
(void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
}
} else if (FLAGS_SET(copy_flags, COPY_RESTORE_DIRECTORY_TIMESTAMPS))
/* If the directory already exists, make sure the timestamps stay the same as before. */
(void) futimens(fdt, (struct timespec[]) { dt_st.st_atim, dt_st.st_mtim });

if (copy_flags & COPY_FSYNC_FULL) {
if (fsync(fdt) < 0)
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39 changes: 20 additions & 19 deletions src/shared/copy.h
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Original file line number Diff line number Diff line change
Expand Up @@ -12,25 +12,26 @@
#include "set.h"

typedef enum CopyFlags {
COPY_REFLINK = 1 << 0, /* Try to reflink */
COPY_MERGE = 1 << 1, /* Merge existing trees with our new one to copy */
COPY_REPLACE = 1 << 2, /* Replace an existing file if there's one */
COPY_SAME_MOUNT = 1 << 3, /* Don't descend recursively into other file systems, across mount point boundaries */
COPY_MERGE_EMPTY = 1 << 4, /* Merge an existing, empty directory with our new tree to copy */
COPY_CRTIME = 1 << 5, /* Generate a user.crtime_usec xattr off the source crtime if there is one, on copying */
COPY_SIGINT = 1 << 6, /* Check for SIGINT regularly and return EINTR if seen (caller needs to block SIGINT) */
COPY_SIGTERM = 1 << 7, /* ditto, but for SIGTERM */
COPY_MAC_CREATE = 1 << 8, /* Create files with the correct MAC label (currently SELinux only) */
COPY_HARDLINKS = 1 << 9, /* Try to reproduce hard links */
COPY_FSYNC = 1 << 10, /* fsync() after we are done */
COPY_FSYNC_FULL = 1 << 11, /* fsync_full() after we are done */
COPY_SYNCFS = 1 << 12, /* syncfs() the *top-level* dir after we are done */
COPY_ALL_XATTRS = 1 << 13, /* Preserve all xattrs when copying, not just those in the user namespace */
COPY_HOLES = 1 << 14, /* Copy holes */
COPY_GRACEFUL_WARN = 1 << 15, /* Skip copying file types that aren't supported by the target filesystem */
COPY_TRUNCATE = 1 << 16, /* Truncate to current file offset after copying */
COPY_LOCK_BSD = 1 << 17, /* Return a BSD exclusively locked file descriptor referring to the copied image/directory. */
COPY_VERIFY_LINKED = 1 << 18, /* Check the source file is still linked after copying. */
COPY_REFLINK = 1 << 0, /* Try to reflink */
COPY_MERGE = 1 << 1, /* Merge existing trees with our new one to copy */
COPY_REPLACE = 1 << 2, /* Replace an existing file if there's one */
COPY_SAME_MOUNT = 1 << 3, /* Don't descend recursively into other file systems, across mount point boundaries */
COPY_MERGE_EMPTY = 1 << 4, /* Merge an existing, empty directory with our new tree to copy */
COPY_CRTIME = 1 << 5, /* Generate a user.crtime_usec xattr off the source crtime if there is one, on copying */
COPY_SIGINT = 1 << 6, /* Check for SIGINT regularly and return EINTR if seen (caller needs to block SIGINT) */
COPY_SIGTERM = 1 << 7, /* ditto, but for SIGTERM */
COPY_MAC_CREATE = 1 << 8, /* Create files with the correct MAC label (currently SELinux only) */
COPY_HARDLINKS = 1 << 9, /* Try to reproduce hard links */
COPY_FSYNC = 1 << 10, /* fsync() after we are done */
COPY_FSYNC_FULL = 1 << 11, /* fsync_full() after we are done */
COPY_SYNCFS = 1 << 12, /* syncfs() the *top-level* dir after we are done */
COPY_ALL_XATTRS = 1 << 13, /* Preserve all xattrs when copying, not just those in the user namespace */
COPY_HOLES = 1 << 14, /* Copy holes */
COPY_GRACEFUL_WARN = 1 << 15, /* Skip copying file types that aren't supported by the target filesystem */
COPY_TRUNCATE = 1 << 16, /* Truncate to current file offset after copying */
COPY_LOCK_BSD = 1 << 17, /* Return a BSD exclusively locked file descriptor referring to the copied image/directory. */
COPY_VERIFY_LINKED = 1 << 18, /* Check the source file is still linked after copying. */
COPY_RESTORE_DIRECTORY_TIMESTAMPS = 1 << 19, /* Make sure existing directory timestamps don't change during copying. */
} CopyFlags;

typedef enum DenyType {
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