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sysusers: modernize file backup logic a bit

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Let's use _cleanup_ magic to clean up files, let's fully operate by fds
whenever we can.
This commit is contained in:
Lennart Poettering 2020-09-23 17:49:35 +02:00
parent e59d030ff8
commit 62c03398ba
1 changed files with 21 additions and 24 deletions
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45
src/sysusers/sysusers.c
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@ -201,14 +201,16 @@ static int load_group_database(void) {
}
static int make_backup(const char *target, const char *x) {
_cleanup_close_ int src = -1;
_cleanup_(unlink_and_freep) char *dst_tmp = NULL;
_cleanup_fclose_ FILE *dst = NULL;
_cleanup_free_ char *dst_tmp = NULL;
char *backup;
struct timespec ts[2];
_cleanup_close_ int src = -1;
const char *backup;
struct stat st;
int r;
assert(target);
assert(x);
src = open(x, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (src < 0) {
if (errno == ENOENT) /* No backup necessary... */
@ -220,43 +222,38 @@ static int make_backup(const char *target, const char *x) {
if (fstat(src, &st) < 0)
return -errno;
r = fopen_temporary_label(target, x, &dst, &dst_tmp);
r = fopen_temporary_label(
target, /* The path for which to the lookup the label */
x, /* Where we want the file actually to end up */
&dst,
&dst_tmp /* The temporary file we write to */);
if (r < 0)
return r;
r = copy_bytes(src, fileno(dst), (uint64_t) -1, COPY_REFLINK);
if (r < 0)
goto fail;
/* Don't fail on chmod() or chown(). If it stays owned by us
* and/or unreadable by others, then it isn't too bad... */
return r;
backup = strjoina(x, "-");
/* Copy over the access mask */
r = chmod_and_chown_unsafe(dst_tmp, st.st_mode & 07777, st.st_uid, st.st_gid);
/* Copy over the access mask. Don't fail on chmod() or chown(). If it stays owned by us and/or
* unreadable by others, then it isn't too bad... */
r = fchmod_and_chown(fileno(dst), st.st_mode & 07777, st.st_uid, st.st_gid);
if (r < 0)
log_warning_errno(r, "Failed to change access mode or ownership of %s: %m", backup);
ts[0] = st.st_atim;
ts[1] = st.st_mtim;
if (futimens(fileno(dst), ts) < 0)
if (futimens(fileno(dst), (const struct timespec[2]) { st.st_atim, st.st_mtim }) < 0)
log_warning_errno(errno, "Failed to fix access and modification time of %s: %m", backup);
r = fflush_sync_and_check(dst);
r = fsync_full(fileno(dst));
if (r < 0)
goto fail;
return r;
if (rename(dst_tmp, backup) < 0) {
r = -errno;
goto fail;
}
if (rename(dst_tmp, backup) < 0)
return errno;
dst_tmp = mfree(dst_tmp); /* disable the unlink_and_freep() hook now that the file has been renamed*/
return 0;
fail:
(void) unlink(dst_tmp);
return r;
}
static int putgrent_with_members(const struct group *gr, FILE *group) {