[systemd-devel] [PATCH] util: add rename_noreplace
Alban Crequy
alban.crequy at gmail.com
Tue Mar 10 08:16:06 PDT 2015
From: Alban Crequy <alban at endocode.com>
renameat2() exists since Linux 3.15 but btrfs support for the flag
RENAME_NOREPLACE was added later.
This patch implements a fallback when renameat2() returns EINVAL.
EINVAL is the error returned when the filesystem does not support one of
the flags.
---
src/import/import-raw.c | 2 +-
src/import/import-tar.c | 2 +-
src/import/pull-raw.c | 2 +-
src/import/pull-tar.c | 2 +-
src/shared/copy.c | 13 ++++++++++---
src/shared/machine-image.c | 2 +-
src/shared/machine-pool.c | 2 +-
src/shared/util.c | 34 ++++++++++++++++++++++++++++++++++
src/shared/util.h | 2 ++
9 files changed, 52 insertions(+), 9 deletions(-)
diff --git a/src/import/import-raw.c b/src/import/import-raw.c
index 15e5eb2..e354023 100644
--- a/src/import/import-raw.c
+++ b/src/import/import-raw.c
@@ -245,7 +245,7 @@ static int raw_import_finish(RawImport *i) {
(void) rm_rf_dangerous(i->final_path, false, true, false);
}
- if (renameat2(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path, RENAME_NOREPLACE) < 0)
+ if (rename_noreplace(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path) < 0)
return log_error_errno(errno, "Failed to move image into place: %m");
free(i->temp_path);
diff --git a/src/import/import-tar.c b/src/import/import-tar.c
index d5b6dad..dcbe721 100644
--- a/src/import/import-tar.c
+++ b/src/import/import-tar.c
@@ -201,7 +201,7 @@ static int tar_import_finish(TarImport *i) {
(void) rm_rf_dangerous(i->final_path, false, true, false);
}
- if (renameat2(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path, RENAME_NOREPLACE) < 0)
+ if (rename_noreplace(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path) < 0)
return log_error_errno(errno, "Failed to move image into place: %m");
free(i->temp_path);
diff --git a/src/import/pull-raw.c b/src/import/pull-raw.c
index d1d77d5..d4b17e7 100644
--- a/src/import/pull-raw.c
+++ b/src/import/pull-raw.c
@@ -384,7 +384,7 @@ static void raw_pull_job_on_finished(PullJob *j) {
if (r < 0)
goto finish;
- r = renameat2(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path, RENAME_NOREPLACE);
+ r = rename_noreplace(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path);
if (r < 0) {
r = log_error_errno(errno, "Failed to move RAW file into place: %m");
goto finish;
diff --git a/src/import/pull-tar.c b/src/import/pull-tar.c
index 504642f..69df7af 100644
--- a/src/import/pull-tar.c
+++ b/src/import/pull-tar.c
@@ -281,7 +281,7 @@ static void tar_pull_job_on_finished(PullJob *j) {
if (r < 0)
goto finish;
- if (renameat2(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path, RENAME_NOREPLACE) < 0) {
+ if (rename_noreplace(AT_FDCWD, i->temp_path, AT_FDCWD, i->final_path) < 0) {
r = log_error_errno(errno, "Failed to rename to final image name: %m");
goto finish;
}
diff --git a/src/shared/copy.c b/src/shared/copy.c
index 0239a58..458a654 100644
--- a/src/shared/copy.c
+++ b/src/shared/copy.c
@@ -404,9 +404,16 @@ int copy_file_atomic(const char *from, const char *to, mode_t mode, bool replace
if (r < 0)
return r;
- if (renameat2(AT_FDCWD, t, AT_FDCWD, to, replace ? 0 : RENAME_NOREPLACE) < 0) {
- unlink_noerrno(t);
- return -errno;
+ if (replace) {
+ if (renameat(AT_FDCWD, t, AT_FDCWD, to) < 0) {
+ unlink_noerrno(t);
+ return -errno;
+ }
+ } else {
+ if (rename_noreplace(AT_FDCWD, t, AT_FDCWD, to) < 0) {
+ unlink_noerrno(t);
+ return -errno;
+ }
}
return 0;
diff --git a/src/shared/machine-image.c b/src/shared/machine-image.c
index c6d2850..ad5bff4 100644
--- a/src/shared/machine-image.c
+++ b/src/shared/machine-image.c
@@ -440,7 +440,7 @@ int image_rename(Image *i, const char *new_name) {
if (!nn)
return -ENOMEM;
- if (renameat2(AT_FDCWD, i->path, AT_FDCWD, new_path, RENAME_NOREPLACE) < 0)
+ if (rename_noreplace(AT_FDCWD, i->path, AT_FDCWD, new_path) < 0)
return -errno;
/* Restore the immutable bit, if it was set before */
diff --git a/src/shared/machine-pool.c b/src/shared/machine-pool.c
index e7671a3..7e902a3 100644
--- a/src/shared/machine-pool.c
+++ b/src/shared/machine-pool.c
@@ -140,7 +140,7 @@ static int setup_machine_raw(uint64_t size, sd_bus_error *error) {
goto fail;
}
- if (renameat2(AT_FDCWD, tmp, AT_FDCWD, "/var/lib/machines.raw", RENAME_NOREPLACE) < 0) {
+ if (rename_noreplace(AT_FDCWD, tmp, AT_FDCWD, "/var/lib/machines.raw") < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to move /var/lib/machines.raw into place: %m");
goto fail;
}
diff --git a/src/shared/util.c b/src/shared/util.c
index 74f2994..23aabb7 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -8118,3 +8118,37 @@ void cmsg_close_all(struct msghdr *mh) {
if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int));
}
+
+int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath)
+{
+ struct stat buf;
+ int ret;
+
+ ret = renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE);
+
+ /* Even though renameat2() exists since Linux 3.15, btrfs added
+ * support for it later. If it is not implemented, fallback to another
+ * method. */
+ if (ret != -1 || errno != EINVAL)
+ return ret;
+
+ /* The link()/unlink() fallback does not work on directories. But
+ * renameat() without RENAME_NOREPLACE gives the same semantics on
+ * directories, except when newpath is an *empty* directory. This is
+ * good enough. */
+ ret = fstatat(olddirfd, oldpath, &buf, 0);
+ if (ret == 0 && S_ISDIR(buf.st_mode))
+ return renameat(olddirfd, oldpath, newdirfd, newpath);
+
+ /* If it is not a directory, use the link()/unlink() fallback. */
+ ret = linkat(olddirfd, oldpath, newdirfd, newpath, 0);
+ if (ret == -1)
+ return ret;
+
+ ret = unlinkat(olddirfd, oldpath, 0);
+ if (ret != 0) {
+ if (unlinkat(newdirfd, newpath, 0) != 0)
+ log_error("Failed to recover from unlinkat() failure.");
+ }
+ return ret;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index 2de654f..45a8d37 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -1080,3 +1080,5 @@ void sigkill_wait(pid_t *pid);
int syslog_parse_priority(const char **p, int *priority, bool with_facility);
void cmsg_close_all(struct msghdr *mh);
+
+int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath);
--
2.1.4
More information about the systemd-devel
mailing list