Patchwork block: Don't parse protocol from file.filename

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Submitter Kevin Wolf
Date July 10, 2013, 1:51 p.m.
Message ID <1373464273-7934-1-git-send-email-kwolf@redhat.com>
Download mbox | patch
Permalink /patch/258061/
State New
Headers show

Comments

Kevin Wolf - July 10, 2013, 1:51 p.m.
One of the major reasons for doing something new for -blockdev and
blockdev-add was that the old block layer code parses filenames instead
of just taking them literally. So we should really leave it untouched
when it's passing using the new interfaces (like -drive
file.filename=...).

This allows opening relative file names that contain a colon.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c                    | 17 ++++++++++++-----
 block/sheepdog.c           |  2 +-
 include/block/block.h      |  3 ++-
 qemu-img.c                 |  4 ++--
 tests/qemu-iotests/051     | 12 ++++++++++++
 tests/qemu-iotests/051.out | 14 ++++++++++++++
 6 files changed, 43 insertions(+), 9 deletions(-)
Eric Blake - July 10, 2013, 5:09 p.m.
On 07/10/2013 07:51 AM, Kevin Wolf wrote:
> One of the major reasons for doing something new for -blockdev and
> blockdev-add was that the old block layer code parses filenames instead
> of just taking them literally. So we should really leave it untouched
> when it's passing using the new interfaces (like -drive
> file.filename=...).
> 
> This allows opening relative file names that contain a colon.

Will a protocol prefix ever contain a '/'?  Would it be desirable to
state that relative file names containing a colon should be specified as
'./file:name', with the '/' serving as the escape that means relative
file rather than attempting to use protocol './file:', even when using
legacy options?

> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c                    | 17 ++++++++++++-----
>  block/sheepdog.c           |  2 +-
>  include/block/block.h      |  3 ++-
>  qemu-img.c                 |  4 ++--
>  tests/qemu-iotests/051     | 12 ++++++++++++
>  tests/qemu-iotests/051.out | 14 ++++++++++++++
>  6 files changed, 43 insertions(+), 9 deletions(-)

> 
> @@ -813,7 +817,10 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
>          drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
>          qdict_del(options, "driver");
>      } else if (filename) {
> -        drv = bdrv_find_protocol(filename);
> +        drv = bdrv_find_protocol(filename, allow_protocol_prefix);
> +        if (!drv) {
> +            qerror_report(ERROR_CLASS_GENERIC_ERROR, "Unknown protocol");
> +        }

If you want to allow './' as a forceful non-protocol escape even in
legacy parsing, then this code may need tweaking.  Otherwise, I think
the code looks fine.

Reviewed-by: Eric Blake <eblake@redhat.com>

> +++ b/tests/qemu-iotests/051
> @@ -149,6 +149,18 @@ echo
>  run_qemu -drive file=$TEST_IMG,file.driver=file
>  run_qemu -drive file=$TEST_IMG,file.driver=qcow2
>  
> +echo
> +echo === Parsing protocol from file name ===
> +echo
> +
> +# Protocol strings are supposed to be parsed from traditional option strings,
> +# but not when using driver-specific options. We can distinguish them by the
> +# error message for non-existing files.

Is it also worth testing that we successfully open a file name with a
colon from driver-specific options, or is that harder to do portably
(since windows doesn't allow : in file names except for the drive prefix)?
Kevin Wolf - July 11, 2013, 7:19 a.m.
Am 10.07.2013 um 19:09 hat Eric Blake geschrieben:
> On 07/10/2013 07:51 AM, Kevin Wolf wrote:
> > One of the major reasons for doing something new for -blockdev and
> > blockdev-add was that the old block layer code parses filenames instead
> > of just taking them literally. So we should really leave it untouched
> > when it's passing using the new interfaces (like -drive
> > file.filename=...).
> > 
> > This allows opening relative file names that contain a colon.
> 
> Will a protocol prefix ever contain a '/'?  Would it be desirable to
> state that relative file names containing a colon should be specified as
> './file:name', with the '/' serving as the escape that means relative
> file rather than attempting to use protocol './file:', even when using
> legacy options?

In fact, that already works, but it's kind of non-obvious magic (see
path_has_protocol), whereas file.filename should works in a consistent
way.

> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> >  block.c                    | 17 ++++++++++++-----
> >  block/sheepdog.c           |  2 +-
> >  include/block/block.h      |  3 ++-
> >  qemu-img.c                 |  4 ++--
> >  tests/qemu-iotests/051     | 12 ++++++++++++
> >  tests/qemu-iotests/051.out | 14 ++++++++++++++
> >  6 files changed, 43 insertions(+), 9 deletions(-)
> 
> > 
> > @@ -813,7 +817,10 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
> >          drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
> >          qdict_del(options, "driver");
> >      } else if (filename) {
> > -        drv = bdrv_find_protocol(filename);
> > +        drv = bdrv_find_protocol(filename, allow_protocol_prefix);
> > +        if (!drv) {
> > +            qerror_report(ERROR_CLASS_GENERIC_ERROR, "Unknown protocol");
> > +        }
> 
> If you want to allow './' as a forceful non-protocol escape even in
> legacy parsing, then this code may need tweaking.  Otherwise, I think
> the code looks fine.
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> > +++ b/tests/qemu-iotests/051
> > @@ -149,6 +149,18 @@ echo
> >  run_qemu -drive file=$TEST_IMG,file.driver=file
> >  run_qemu -drive file=$TEST_IMG,file.driver=qcow2
> >  
> > +echo
> > +echo === Parsing protocol from file name ===
> > +echo
> > +
> > +# Protocol strings are supposed to be parsed from traditional option strings,
> > +# but not when using driver-specific options. We can distinguish them by the
> > +# error message for non-existing files.
> 
> Is it also worth testing that we successfully open a file name with a
> colon from driver-specific options, or is that harder to do portably
> (since windows doesn't allow : in file names except for the drive prefix)?

The hard thing is that $TEST_DIR and $TEST_IMG are absolute paths and I
would need relative ones to test this. And I don't want to create files
outside the test directory.

We don't really care about portability in qemu-iotests (and there's
always '_supported_os Linux').

Kevin
Stefan Hajnoczi - July 16, 2013, 5:58 a.m.
On Wed, Jul 10, 2013 at 03:51:13PM +0200, Kevin Wolf wrote:
> One of the major reasons for doing something new for -blockdev and
> blockdev-add was that the old block layer code parses filenames instead
> of just taking them literally. So we should really leave it untouched
> when it's passing using the new interfaces (like -drive
> file.filename=...).
> 
> This allows opening relative file names that contain a colon.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c                    | 17 ++++++++++++-----
>  block/sheepdog.c           |  2 +-
>  include/block/block.h      |  3 ++-
>  qemu-img.c                 |  4 ++--
>  tests/qemu-iotests/051     | 12 ++++++++++++
>  tests/qemu-iotests/051.out | 14 ++++++++++++++
>  6 files changed, 43 insertions(+), 9 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

Patch

diff --git a/block.c b/block.c
index 183fec8..2df65c8 100644
--- a/block.c
+++ b/block.c
@@ -417,7 +417,7 @@  int bdrv_create_file(const char* filename, QEMUOptionParameter *options)
 {
     BlockDriver *drv;
 
-    drv = bdrv_find_protocol(filename);
+    drv = bdrv_find_protocol(filename, true);
     if (drv == NULL) {
         return -ENOENT;
     }
@@ -482,7 +482,8 @@  static BlockDriver *find_hdev_driver(const char *filename)
     return drv;
 }
 
-BlockDriver *bdrv_find_protocol(const char *filename)
+BlockDriver *bdrv_find_protocol(const char *filename,
+                                bool allow_protocol_prefix)
 {
     BlockDriver *drv1;
     char protocol[128];
@@ -503,9 +504,10 @@  BlockDriver *bdrv_find_protocol(const char *filename)
         return drv1;
     }
 
-    if (!path_has_protocol(filename)) {
+    if (!path_has_protocol(filename) || !allow_protocol_prefix) {
         return bdrv_find_format("file");
     }
+
     p = strchr(filename, ':');
     assert(p != NULL);
     len = p - filename;
@@ -784,6 +786,7 @@  int bdrv_file_open(BlockDriverState **pbs, const char *filename,
     BlockDriverState *bs;
     BlockDriver *drv;
     const char *drvname;
+    bool allow_protocol_prefix = false;
     int ret;
 
     /* NULL means an empty set of options */
@@ -800,6 +803,7 @@  int bdrv_file_open(BlockDriverState **pbs, const char *filename,
         filename = qdict_get_try_str(options, "filename");
     } else if (filename && !qdict_haskey(options, "filename")) {
         qdict_put(options, "filename", qstring_from_str(filename));
+        allow_protocol_prefix = true;
     } else {
         qerror_report(ERROR_CLASS_GENERIC_ERROR, "Can't specify 'file' and "
                       "'filename' options at the same time");
@@ -813,7 +817,10 @@  int bdrv_file_open(BlockDriverState **pbs, const char *filename,
         drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
         qdict_del(options, "driver");
     } else if (filename) {
-        drv = bdrv_find_protocol(filename);
+        drv = bdrv_find_protocol(filename, allow_protocol_prefix);
+        if (!drv) {
+            qerror_report(ERROR_CLASS_GENERIC_ERROR, "Unknown protocol");
+        }
     } else {
         qerror_report(ERROR_CLASS_GENERIC_ERROR,
                       "Must specify either driver or file");
@@ -4452,7 +4459,7 @@  void bdrv_img_create(const char *filename, const char *fmt,
         return;
     }
 
-    proto_drv = bdrv_find_protocol(filename);
+    proto_drv = bdrv_find_protocol(filename, true);
     if (!proto_drv) {
         error_setg(errp, "Unknown protocol '%s'", filename);
         return;
diff --git a/block/sheepdog.c b/block/sheepdog.c
index b397b5b..6a41ad9 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1510,7 +1510,7 @@  static int sd_create(const char *filename, QEMUOptionParameter *options)
         BlockDriver *drv;
 
         /* Currently, only Sheepdog backing image is supported. */
-        drv = bdrv_find_protocol(backing_file);
+        drv = bdrv_find_protocol(backing_file, true);
         if (!drv || strcmp(drv->protocol_name, "sheepdog") != 0) {
             error_report("backing_file must be a sheepdog image");
             ret = -EINVAL;
diff --git a/include/block/block.h b/include/block/block.h
index dd8eca1..eeb4816 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -111,7 +111,8 @@  bool bdrv_io_limits_enabled(BlockDriverState *bs);
 
 void bdrv_init(void);
 void bdrv_init_with_whitelist(void);
-BlockDriver *bdrv_find_protocol(const char *filename);
+BlockDriver *bdrv_find_protocol(const char *filename,
+                                bool allow_protocol_prefix);
 BlockDriver *bdrv_find_format(const char *format_name);
 BlockDriver *bdrv_find_whitelisted_format(const char *format_name,
                                           bool readonly);
diff --git a/qemu-img.c b/qemu-img.c
index f8c97d3..c55ca5c 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -240,7 +240,7 @@  static int print_block_option_help(const char *filename, const char *fmt)
         return 1;
     }
 
-    proto_drv = bdrv_find_protocol(filename);
+    proto_drv = bdrv_find_protocol(filename, true);
     if (!proto_drv) {
         error_report("Unknown protocol '%s'", filename);
         return 1;
@@ -1261,7 +1261,7 @@  static int img_convert(int argc, char **argv)
         goto out;
     }
 
-    proto_drv = bdrv_find_protocol(out_filename);
+    proto_drv = bdrv_find_protocol(out_filename, true);
     if (!proto_drv) {
         error_report("Unknown protocol '%s'", out_filename);
         ret = -1;
diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index 8039e23..1cf8bf7 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -149,6 +149,18 @@  echo
 run_qemu -drive file=$TEST_IMG,file.driver=file
 run_qemu -drive file=$TEST_IMG,file.driver=qcow2
 
+echo
+echo === Parsing protocol from file name ===
+echo
+
+# Protocol strings are supposed to be parsed from traditional option strings,
+# but not when using driver-specific options. We can distinguish them by the
+# error message for non-existing files.
+
+run_qemu -hda foo:bar
+run_qemu -drive file=foo:bar
+run_qemu -drive file.filename=foo:bar
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index 3d1ac7b..6b3d636 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -169,4 +169,18 @@  Testing: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2
 QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2: Can't use 'qcow2' as a block driver for the protocol level
 QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2: could not open disk image TEST_DIR/t.qcow2: Invalid argument
 
+
+=== Parsing protocol from file name ===
+
+Testing: -hda foo:bar
+QEMU_PROG: -hda foo:bar: Unknown protocol
+QEMU_PROG: -hda foo:bar: could not open disk image foo:bar: No such file or directory
+
+Testing: -drive file=foo:bar
+QEMU_PROG: -drive file=foo:bar: Unknown protocol
+QEMU_PROG: -drive file=foo:bar: could not open disk image foo:bar: No such file or directory
+
+Testing: -drive file.filename=foo:bar
+QEMU_PROG: -drive file.filename=foo:bar: could not open disk image ide0-hd0: No such file or directory
+
 *** done