diff options
Diffstat (limited to 'src/libudev')
| -rw-r--r-- | src/libudev/libudev-device.c | 102 | ||||
| -rw-r--r-- | src/libudev/libudev.h | 1 | ||||
| -rw-r--r-- | src/libudev/libudev.sym | 4 |
3 files changed, 107 insertions, 0 deletions
diff --git a/src/libudev/libudev-device.c b/src/libudev/libudev-device.c index 9fe3d633d4..05c5fbce98 100644 --- a/src/libudev/libudev-device.c +++ b/src/libudev/libudev-device.c @@ -1440,6 +1440,108 @@ out: return val; } +/** + * udev_device_set_sysattr_value: + * @udev_device: udev device + * @sysattr: attribute name + * @value: new value to be set + * + * Update the contents of the sys attribute and the cached value of the device. + * + * Returns: Negative error code on failure or 0 on success. + **/ +_public_ int udev_device_set_sysattr_value(struct udev_device *udev_device, const char *sysattr, char *value) +{ + struct udev_device *dev; + char path[UTIL_PATH_SIZE]; + struct stat statbuf; + int fd; + ssize_t size, value_len; + int ret = 0; + + if (udev_device == NULL) + return -EINVAL; + dev = udev_device; + if (sysattr == NULL) + return -EINVAL; + if (value == NULL) + value_len = 0; + else + value_len = strlen(value); +restart: + strscpyl(path, sizeof(path), udev_device_get_syspath(dev), "/", sysattr, NULL); + if (lstat(path, &statbuf) != 0) { + udev_list_entry_add(&dev->sysattr_value_list, sysattr, NULL); + ret = -ENXIO; + goto out; + } + + if (S_ISLNK(statbuf.st_mode)) { + /* + * Cannot modify core link values + */ + if (streq(sysattr, "driver") || + streq(sysattr, "subsystem") || + streq(sysattr, "module")) { + ret = -EPERM; + } else if (!streq(sysattr, "device")) { + /* resolve custom link to a device */ + strscpyl(path, sizeof(path), udev_device->syspath, "/", sysattr, NULL); + dev = udev_device_new_from_syspath(udev_device->udev, path); + if (dev != NULL) + goto restart; + ret = -ENXIO; + } else { + /* Unhandled, to not try to modify anything */ + ret = -EINVAL; + } + goto out; + } + + /* skip directories */ + if (S_ISDIR(statbuf.st_mode)) { + ret = -EISDIR; + goto out; + } + + /* skip non-readable files */ + if ((statbuf.st_mode & S_IRUSR) == 0) { + ret = -EACCES; + goto out; + } + + /* Value is limited to 4k */ + if (value_len > 4096) { + ret = -EINVAL; + goto out; + } + util_remove_trailing_chars(value, '\n'); + + /* write attribute value */ + fd = open(path, O_WRONLY|O_CLOEXEC); + if (fd < 0) { + ret = -errno; + goto out; + } + size = write(fd, value, value_len); + close(fd); + if (size < 0) { + ret = -errno; + goto out; + } + if (size < value_len) { + ret = -EIO; + goto out; + } + + /* wrote a valid value, store it in cache and return it */ + udev_list_entry_add(&dev->sysattr_value_list, sysattr, value); +out: + if (dev != udev_device) + udev_device_unref(dev); + return ret; +} + static int udev_device_sysattr_list_read(struct udev_device *udev_device) { struct dirent *dent; diff --git a/src/libudev/libudev.h b/src/libudev/libudev.h index bb41532a21..61567b1d67 100644 --- a/src/libudev/libudev.h +++ b/src/libudev/libudev.h @@ -107,6 +107,7 @@ const char *udev_device_get_action(struct udev_device *udev_device); unsigned long long int udev_device_get_seqnum(struct udev_device *udev_device); unsigned long long int udev_device_get_usec_since_initialized(struct udev_device *udev_device); const char *udev_device_get_sysattr_value(struct udev_device *udev_device, const char *sysattr); +int udev_device_set_sysattr_value(struct udev_device *udev_device, const char *sysattr, char *value); int udev_device_has_tag(struct udev_device *udev_device, const char *tag); /* diff --git a/src/libudev/libudev.sym b/src/libudev/libudev.sym index df6a1aeddf..c232fbfdd5 100644 --- a/src/libudev/libudev.sym +++ b/src/libudev/libudev.sym @@ -108,3 +108,7 @@ global: udev_hwdb_unref; udev_hwdb_get_properties_list_entry; } LIBUDEV_189; + +LIBUDEV_199 { + udev_device_set_sysattr_value; +} LIBUDEV_196; |