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udev-node: use symlink_atomic_full_label() to create devlink

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If the filename of a device symlink is too long, then the temporary
filename may become invalid, and we fail to create symlink.

The function `tempfn_random()` used in symlink_atomic_full() generates
a safe temporary filename.

Note that, thanks to the PR #23043, now only one worker can handle
the same symlink simultaneously. Hence, the device ID based temporary
filename is not necessary.
This commit is contained in:
Yu Watanabe
2022-09-18 23:23:23 +09:00
parent 590d81002b
commit 6d42138593
1 changed files with 8 additions and 27 deletions
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src/udev/udev-node.c
+8 -27
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@@ -14,6 +14,7 @@
#include "format-util.h"
#include "fs-util.h"
#include "hexdecoct.h"
#include "label.h"
#include "mkdir-label.h"
#include "parse-util.h"
#include "path-util.h"
@@ -69,8 +70,6 @@ int udev_node_cleanup(void) {
}
static int node_symlink(sd_device *dev, const char *devnode, const char *slink) {
_cleanup_free_ char *target = NULL;
const char *id, *slink_tmp;
struct stat st;
int r;
@@ -91,34 +90,16 @@ static int node_symlink(sd_device *dev, const char *devnode, const char *slink)
} else if (errno != ENOENT)
return log_device_debug_errno(dev, errno, "Failed to lstat() '%s': %m", slink);
r = mkdir_parents_label(slink, 0755);
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to create parent directory of '%s': %m", slink);
/* use relative link */
r = path_make_relative_parent(slink, devnode, &target);
r = symlink_atomic_full_label(devnode, slink, /* make_relative = */ true);
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to get relative path from '%s' to '%s': %m", slink, devnode);
r = device_get_device_id(dev, &id);
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to get device id: %m");
slink_tmp = strjoina(slink, ".tmp-", id);
(void) unlink(slink_tmp);
r = mkdir_parents_label(slink_tmp, 0755);
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to create parent directory of '%s': %m", slink_tmp);
mac_selinux_create_file_prepare(slink_tmp, S_IFLNK);
r = RET_NERRNO(symlink(target, slink_tmp));
mac_selinux_create_file_clear();
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to create symlink '%s' to '%s': %m", slink_tmp, target);
if (rename(slink_tmp, slink) < 0) {
r = log_device_debug_errno(dev, errno, "Failed to rename '%s' to '%s': %m", slink_tmp, slink);
(void) unlink(slink_tmp);
return r;
}
return log_device_debug_errno(dev, r, "Failed to create symlink '%s' to '%s': %m", slink, devnode);
log_device_debug(dev, "Successfully created symlink '%s' to '%s'", slink, devnode);
return 0;
}