[Qemu-devel] [PATCH v7 1/4] block: introducing 'bdrv_co_delete_file' interface

[Daniel Henrique Barboza <danielhb413@gmail.com>]

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 'file' driver in file-posix.c.The
implementation is given by 'raw_co_delete_file'.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 block/file-posix.c        | 28 ++++++++++++++++++++++++++++
 include/block/block_int.h |  6 ++++++
 2 files changed, 34 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c
index fbeb0068db..52756de522 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2390,6 +2390,33 @@ static int coroutine_fn raw_co_create_opts(const char *filename, QemuOpts *opts,
     return raw_co_create(&options, errp);
 }
 
+/**
+ * Co-routine function that erases a regular file.
+ */
+static int coroutine_fn raw_co_delete_file(BlockDriverState *bs,
+                                           Error **errp)
+{
+    struct stat st;
+    int ret;
+
+    if (!(stat(bs->filename, &st) == 0) || !S_ISREG(st.st_mode)) {
+        ret = -ENOENT;
+        error_setg_errno(errp, -ret, "%s is not a regular file",
+                         bs->filename);
+        goto done;
+    }
+
+    ret = unlink(bs->filename);
+    if (ret < 0) {
+        ret = -errno;
+        error_setg_errno(errp, -ret, "Error when deleting file %s",
+                         bs->filename);
+    }
+
+done:
+    return ret;
+}
+
 /*
  * Find allocation range in @bs around offset @start.
  * May change underlying file descriptor's file offset.
@@ -2942,6 +2969,7 @@ BlockDriver bdrv_file = {
     .bdrv_co_block_status = raw_co_block_status,
     .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
     .bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,
+    .bdrv_co_delete_file = raw_co_delete_file,
 
     .bdrv_co_preadv         = raw_co_preadv,
     .bdrv_co_pwritev        = raw_co_pwritev,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 0422acdf1c..a959ec2d1e 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -314,6 +314,12 @@ struct BlockDriver {
      */
     int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs);
 
+    /*
+     * Delete a local created file.
+     */
+    int coroutine_fn (*bdrv_co_delete_file)(BlockDriverState *bs,
+                                            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()).
-- 
2.21.0