Adding to Block Drivers the capability of being able to clean up its created files can be useful in certain situations. For the LUKS driver, for instance, a failure in one of its authentication steps can leave files in the host that weren't there before.
This patch adds the 'bdrv_co_delete_file' interface to block drivers and add it to the LUKS driver. The implementation is provided in a new 'bdrv_co_delete_file_generic' function inside block.c. This function is made public in case other block drivers wants to support this cleanup interface as well. Suggested-by: Daniel P. Berrangé <berra...@redhat.com> Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com> --- block.c | 45 +++++++++++++++++++++++++++++++++++++++ block/crypto.c | 2 ++ include/block/block.h | 3 +++ include/block/block_int.h | 6 ++++++ 4 files changed, 56 insertions(+) diff --git a/block.c b/block.c index 0a93ee9ac8..2b632baba2 100644 --- a/block.c +++ b/block.c @@ -547,6 +547,51 @@ int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp) return ret; } +/** + * Helper that checks if a given path represents a regular + * local file. + */ +bool bdrv_path_is_regular_file(const char *path) +{ + struct stat st; + + return (stat(path, &st) == 0) && S_ISREG(st.st_mode); +} + +/** + * Co-routine function that erases a regular file. Its original + * intent is as a implementation of bdrv_co_delete_file for + * the "luks" driver that can leave created files behind in the + * file system when the authentication fails. + * + * The function is exposed here, and with 'generic' in its name, + * because file removal isn't usually format specific and any other + * BlockDriver might want to re-use this function. + */ +int coroutine_fn bdrv_co_delete_file_generic(const char *filename, + Error **errp) +{ + int ret; + + /* Skip file: protocol prefix */ + strstart(filename, "file:", &filename); + + if (!bdrv_path_is_regular_file(filename)) { + ret = -ENOENT; + error_setg_errno(errp, -ret, "%s is not a regular file", filename); + goto done; + } + + ret = unlink(filename); + if (ret < 0) { + ret = -errno; + error_setg_errno(errp, -ret, "Error when deleting file %s", filename); + } + +done: + return ret; +} + /** * Try to get @bs's logical and physical block size. * On success, store them in @bsz struct and return 0. diff --git a/block/crypto.c b/block/crypto.c index 3af46b805f..c604c96c93 100644 --- a/block/crypto.c +++ b/block/crypto.c @@ -639,6 +639,8 @@ static BlockDriver bdrv_crypto_luks = { .bdrv_co_truncate = block_crypto_co_truncate, .create_opts = &block_crypto_create_opts_luks, + .bdrv_co_delete_file = bdrv_co_delete_file_generic, + .bdrv_reopen_prepare = block_crypto_reopen_prepare, .bdrv_refresh_limits = block_crypto_refresh_limits, .bdrv_co_preadv = block_crypto_co_preadv, diff --git a/include/block/block.h b/include/block/block.h index e452988b66..efb77daf9f 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -363,6 +363,9 @@ int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, Error **errp); void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base); +bool bdrv_path_is_regular_file(const char *path); +int coroutine_fn bdrv_co_delete_file_generic(const char *filename, + Error **errp); typedef struct BdrvCheckResult { int corruptions; diff --git a/include/block/block_int.h b/include/block/block_int.h index 01e855a066..74abb78ce7 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -309,6 +309,12 @@ struct BlockDriver { */ int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs); + /* + * Delete a local created file. + */ + int coroutine_fn (*bdrv_co_delete_file)(const char *filename, + Error **errp); + /* * Flushes all data that was already written to the OS all the way down to * the disk (for example file-posix.c calls fsync()). -- 2.20.1