shaba/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2025-03-09 12:58:26 +03:00
Code

shared: Copy holes in sparse files in copy_bytes_full()

Browse Source 
Previously, all holes in sparse files copied with copy_bytes_full()
would be expanded in the target file. Now, we correctly detect holes
in the input file and we replicate them in the target file.
This commit is contained in:
Daan De Meyer 2022-01-14 16:41:28 +00:00
parent 9e3e592946
commit 8646b5d6e6
2 changed files with 42 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
src/shared/copy.c
View File

@ -202,6 +202,47 @@ int copy_bytes_full(
if (max_bytes != UINT64_MAX && m > max_bytes)
m = max_bytes;
if (copy_flags & COPY_HOLES) {
off_t c, e;
c = lseek(fdf, 0, SEEK_CUR);
if (c < 0)
return -errno;
/* To see if we're in a hole, we search for the next data offset. */
e = lseek(fdf, c, SEEK_DATA);
if (e < 0 && errno == ENXIO) {
/* If errno == ENXIO, that means we've reached the final hole of the file and
* that hole isn't followed by more data. */
e = lseek(fdf, 0, SEEK_END);
if (e < 0)
return -errno;
} else if (e < 0)
return -errno;
/* If we're in a hole (current offset is not a data offset), create a hole of the same size
* in the target file. */
if (e > c && lseek(fdt, e - c, SEEK_CUR) < 0)
return -errno;
c = e; /* Set c to the start of the data segment. */
/* After copying a potential hole, find the end of the data segment by looking for the next
* hole. If we get ENXIO, we're at EOF. */
e = lseek(fdf, c, SEEK_HOLE);
if (e < 0 && errno == ENXIO)
break;
else if (e < 0)
return -errno;
/* SEEK_HOLE modifies the file offset so we need to move back to the initial offset. */
if (lseek(fdf, c, SEEK_SET) < 0)
return -errno;
/* Make sure we're not copying more than the current data segment. */
m = MIN(m, (size_t) e - c);
}
/* First try copy_file_range(), unless we already tried */
if (try_cfr) {
n = try_copy_file_range(fdf, NULL, fdt, NULL, m, 0u);

1
src/shared/copy.h
View File

@ -24,6 +24,7 @@ typedef enum CopyFlags {
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 */
} CopyFlags;
typedef int (*copy_progress_bytes_t)(uint64_t n_bytes, void *userdata);