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copy: introduce COPY_VERIFY_LINKED flag

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If the flag is set, then copy_file() and friends check if the source
file still exists when the copy operation finished.
This commit is contained in:
Yu Watanabe 2024-02-15 19:37:43 +09:00
parent cb0d5f73e6
commit 72ef2a617f
3 changed files with 67 additions and 2 deletions
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46
src/shared/copy.c
View File

@ -209,6 +209,7 @@ int copy_bytes_full(
r = reflink_range(fdf, foffset, fdt, toffset, max_bytes == UINT64_MAX ? 0 : max_bytes); /* partial reflink */
if (r >= 0) {
off_t t;
int ret;
/* This worked, yay! Now — to be fully correct — let's adjust the file pointers */
if (max_bytes == UINT64_MAX) {
@ -227,7 +228,14 @@ int copy_bytes_full(
if (t < 0)
return -errno;
return 0; /* we copied the whole thing, hence hit EOF, return 0 */
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
return r;
}
/* We copied the whole thing, hence hit EOF, return 0. */
ret = 0;
} else {
t = lseek(fdf, foffset + max_bytes, SEEK_SET);
if (t < 0)
@ -237,8 +245,18 @@ int copy_bytes_full(
if (t < 0)
return -errno;
return 1; /* we copied only some number of bytes, which worked, but this means we didn't hit EOF, return 1 */
/* We copied only some number of bytes, which worked, but
* this means we didn't hit EOF, return 1. */
ret = 1;
}
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
return r;
}
return ret;
}
}
}
@ -484,6 +502,12 @@ int copy_bytes_full(
copied_something = true;
}
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
return r;
}
if (copy_flags & COPY_TRUNCATE) {
off_t off = lseek(fdt, 0, SEEK_CUR);
if (off < 0)
@ -799,6 +823,12 @@ static int fd_copy_regular(
(void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
(void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
return r;
}
if (copy_flags & COPY_FSYNC) {
if (fsync(fdt) < 0) {
r = -errno;
@ -1334,6 +1364,12 @@ int copy_file_fd_at_full(
(void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
}
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
return r;
}
if (copy_flags & COPY_FSYNC_FULL) {
r = fsync_full(fdt);
if (r < 0)
@ -1404,6 +1440,12 @@ int copy_file_at_full(
(void) copy_times(fdf, fdt, copy_flags);
(void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {
r = fd_verify_linked(fdf);
if (r < 0)
goto fail;
}
if (chattr_mask != 0)
(void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);

1
src/shared/copy.h
View File

@ -30,6 +30,7 @@ typedef enum CopyFlags {
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. */
} CopyFlags;
typedef enum DenyType {

22
src/test/test-copy.c
View File

@ -566,4 +566,26 @@ TEST(copy_lock) {
fd = safe_close(fd);
}
TEST(copy_verify_linked) {
_cleanup_(rm_rf_physical_and_freep) char *t = NULL;
_cleanup_close_ int tfd = -EBADF, fd_1 = -EBADF, fd_2 = -EBADF;
tfd = mkdtemp_open(NULL, O_PATH, &t);
assert_se(tfd >= 0);
assert_se(write_string_file_at(tfd, "hoge", "bar bar", WRITE_STRING_FILE_CREATE) >= 0);
fd_1 = openat(tfd, "hoge", O_CLOEXEC | O_NOCTTY | O_RDONLY);
assert_se(fd_1 >= 0);
fd_2 = openat(tfd, "hoge", O_CLOEXEC | O_NOCTTY | O_RDONLY);
assert_se(fd_2 >= 0);
assert_se(unlinkat(tfd, "hoge", 0) >= 0);
assert_se(copy_file_at(fd_1, NULL, tfd, "to_1", 0, 0644, 0) >= 0);
assert_se(read_file_at_and_streq(tfd, "to_1", "bar bar\n"));
assert_se(copy_file_at(fd_2, NULL, tfd, "to_2", O_EXCL, 0644, COPY_VERIFY_LINKED) == -EIDRM);
assert_se(faccessat(tfd, "to_2", F_OK, AT_SYMLINK_NOFOLLOW) < 0 && errno == ENOENT);
}
DEFINE_TEST_MAIN(LOG_DEBUG);