libudev: device - create db file atomically

[elogind.git] / libudev / libudev-device-private.c

diff --git a/libudev/libudev-device-private.c b/libudev/libudev-device-private.c
index 66f0328eb3e7c2d158e42c4fe484cdabe2adba61..07249c3885fe973bb0ef9cba922534e69ae66d31 100644 (file)
--- a/libudev/libudev-device-private.c
+++ b/libudev/libudev-device-private.c
@@ -25,6 +25,7 @@ int udev_device_update_db(struct udev_device *udev_device)
 {
        struct udev *udev = udev_device_get_udev(udev_device);
        char filename[UTIL_PATH_SIZE];
+       char filename_tmp[UTIL_PATH_SIZE];
        FILE *f;
        char target[232]; /* on 64bit, tmpfs inlines up to 239 bytes */
        size_t devlen = strlen(udev_get_dev_path(udev))+1;
@@ -35,7 +36,7 @@ int udev_device_update_db(struct udev_device *udev_device)
 
        util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev), "/.udev/db/",
                      udev_device_get_subsystem(udev_device), ":", udev_device_get_sysname(udev_device), NULL);
-       unlink(filename);
+       util_strscpyl(filename_tmp, sizeof(filename_tmp), filename, ".tmp", NULL);
 
        udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(udev_device))
                if (udev_list_entry_get_flag(list_entry))
@@ -66,21 +67,24 @@ int udev_device_update_db(struct udev_device *udev_device)
                        goto file;
                }
        }
-       info(udev, "create db link (%s)\n", target);
-       udev_selinux_setfscreatecon(udev, filename, S_IFLNK);
-       util_create_path(udev, filename);
-       ret = symlink(target, filename);
+       udev_selinux_setfscreatecon(udev, filename_tmp, S_IFLNK);
+       util_create_path(udev, filename_tmp);
+       ret = symlink(target, filename_tmp);
        udev_selinux_resetfscreatecon(udev);
-       if (ret == 0)
-               goto out;
+       if (ret != 0)
+               goto file;
+       ret = rename(filename_tmp, filename);
+       if (ret != 0)
+               goto file;
+       info(udev, "created db link (%s)\n", target);
+       goto out;
 file:
-       util_create_path(udev, filename);
-       f = fopen(filename, "w");
+       util_create_path(udev, filename_tmp);
+       f = fopen(filename_tmp, "w");
        if (f == NULL) {
-               err(udev, "unable to create db file '%s': %m\n", filename);
+               err(udev, "unable to create temporary db file '%s': %m\n", filename_tmp);
                return -1;
                }
-       info(udev, "created db file for '%s' in '%s'\n", udev_device_get_devpath(udev_device), filename);
 
        if (udev_device_get_devnode(udev_device) != NULL) {
                fprintf(f, "N:%s\n", &udev_device_get_devnode(udev_device)[devlen]);
@@ -105,6 +109,8 @@ file:
                        udev_list_entry_get_value(list_entry));
        }
        fclose(f);
+       rename(filename_tmp, filename);
+       info(udev, "created db file for '%s' in '%s'\n", udev_device_get_devpath(udev_device), filename);
 out:
        return 0;
 }