Re: [Bug-wget] [PATCH] Implement --keep-badhash to keep Metalink's files with a bad hash

[Matthew White]

On Thu, 04 Aug 2016 17:08:20 +0200
Tim Ruehsen <address@hidden> wrote:

> On Thursday, August 4, 2016 12:40:49 PM CEST Matthew White wrote:
> > On Thu, 04 Aug 2016 12:08:50 +0200
> > 
> > Tim Ruehsen <address@hidden> wrote:
> > > On Wednesday, August 3, 2016 2:40:14 PM CEST Matthew White wrote:
> > > > On Wed, 03 Aug 2016 14:05:06 +0200
> > > > 
> > > > Tim Ruehsen <address@hidden> wrote:
> > > > > On Tuesday, August 2, 2016 11:27:28 AM CEST Matthew White wrote:
> > > > > > On Mon, 01 Aug 2016 16:32:30 +0200
> > > > > > 
> > > > > > Tim Ruehsen <address@hidden> wrote:
> > > > > > > On Saturday, July 30, 2016 9:41:48 PM CEST Matthew White wrote:
> > > > > > > > Hello!
> > > > > > > > 
> > > > > > > > I think that sometimes it could help to keep downloaded
> > > > > > > > Metalink's
> > > > > > > > files
> > > > > > > > which have a bad hash.
> > > > > > > > 
> > > > > > > > The default wget behaviour is to delete such files.
> > > > > > > > 
> > > > > > > > This patch provides a way to keep files which have a bad hash
> > > > > > > > through
> > > > > > > > the
> > > > > > > > option --keep-badhash. It appends the suffix .badhash to the
> > > > > > > > file
> > > > > > > > name,
> > > > > > > > except without overwriting existing files. In the latter case,
> > > > > > > > an
> > > > > > > > unique
> > > > > > > > suffix is appended after .badhash.
> > > > > > > > 
> > > > > > > > I made this patch working on the following branch:
> > > > > > > > master (latest 20cac2c5ab3d63aacfba35fb10878a2d490e2377)
> > > > > > > > git://git.savannah.gnu.org/wget.git
> > > > > > > > 
> > > > > > > > What do you think?
> > > > > > > 
> > > > > > > Hi Matthew,
> > > > > > > 
> > > > > > > good work !
> > > > > > > 
> > > > > > > While your FSF assignment is underway (PM), we can continue
> > > > > > > polishing.
> > > > > > > 
> > > > > > > Didn't test your code yet,  but from what I see, there are just
> > > > > > > these
> > > > > > > peanuts:
> > > > > > > 
> > > > > > > 1.
> > > > > > > +  bhash = malloc (strlen (name) + strlen (".badhash") + 1);
> > > > > > > +  strcat (strcpy (bhash, name), ".badhash");
> > > > > > > 
> > > > > > > Please consider using concat_strings() from util.h.
> > > > > > > And please leave an empty line between var declaration and code -
> > > > > > > just
> > > > > > > for
> > > > > > > readability.
> > > > > > > 
> > > > > > > 2.
> > > > > > > Please add 'link' and 'unlink' to bootstrap.conf. Gnulib will
> > > > > > > emulate
> > > > > > > these on platforms where they are not available (or have a
> > > > > > > slightly
> > > > > > > different behavior). I guess we simply forgot 'unlink' when we
> > > > > > > switched
> > > > > > > to gnulib.
> > > > > > > 
> > > > > > > 3.
> > > > > > > The (GNU) commit messages should ideally look like:
> > > > > > > 
> > > > > > > one line of short description
> > > > > > > <empty line>
> > > > > > > file changes
> > > > > > > <empty line>
> > > > > > > long description
> > > > > > > 
> > > > > > > For example:
> > > > > > > Add new option --keep-badhash
> > > > > > > 
> > > > > > > * src/init.c: Add keepbadhash
> > > > > > > * src/main.c: Add keep-badhash
> > > > > > > * src/options.h: Add keep_badhash
> > > > > > > * doc/wget.texi: Add docs for --keep-badhash
> > > > > > > * src/metalink.h: Add prototypes badhash_suffix(),
> > > > > > > badhash_or_remove()
> > > > > > > * src/metalink.c: New functions badhash_suffix(),
> > > > > > > badhash_or_remove().
> > > > > > > 
> > > > > > >   (retrieve_from_metalink): Call append .badhash()
> > > > > > > 
> > > > > > > With --keep-badhash, append .badhash to Metalink's files with
> > > > > > > checksum
> > > > > > > mismatch, except without overwriting existing files.
> > > > > > > 
> > > > > > > Without --keep-badhash, remove downloaded files with checksum
> > > > > > > mismatch
> > > > > > > (this conforms to the old behaviour).
> > > > > > > 
> > > > > > > [This also applies to to your other patches]
> > > > > > > 
> > > > > > > 4.
> > > > > > > Please not only write 'keepbadhash', but also what you did (e.g.
> > > > > > > remove,
> > > > > > > rename, add, ...), see my example above.
> > > > > > > 
> > > > > > > Those ChangeLog entries should allow finding changes / faults /
> > > > > > > regressions
> > > > > > > etc. even when a versioning system is not at hand, e.g. when
> > > > > > > unpacking
> > > > > > > the
> > > > > > > sources from a tarball. (Not debatable that consulting commit
> > > > > > > messages
> > > > > > > directly is much more powerful.)
> > > > > > > 
> > > > > > > 5.
> > > > > > > You write "except without overwriting existing files", maybe you
> > > > > > > should
> > > > > > > mention appending a counter instead of overwriting existent files
> > > > > > > !?
> > > > > > > 
> > > > > > > 
> > > > > > > Regards, Tim
> > > > > > 
> > > > > > Thanks Tim!
> > > > > > 
> > > > > > I really needed your guidance. I sent the modified patches to
> > > > > > address@hidden
> > > > > > 
> > > > > > I believe there are more things to fix.
> > > > > > 
> > > > > > Consider the following after applying the attached patch:
> > > > > > * src/metalink.c (retrieve_from_metalink): line 124: If the download
> > > > > > is
> > > > > > interrupted (output_stream isn't NULL), and there are more urls for
> > > > > > the
> > > > > > same file (we are still in the download loop), switching to the next
> > > > > > url
> > > > > > should resume the download (instead than start it over).
> > > > > > 
> > > > > > In this patch I added a fix to rename/remove the fully downloaded
> > > > > > file
> > > > > > (output_stream is NULL), but there was an error (probably checksum)
> > > > > > and
> > > > > > we
> > > > > > are still in the download loop (more urls for the same file). But as
> > > > > > said
> > > > > > before, switching to the next url should continue the download: *
> > > > > > src/metalink.c (retrieve_from_metalink): line 131: Rename/remove
> > > > > > fully
> > > > > > downloaded file on error
> > > > > > 
> > > > > > I still have to investigate the problem...
> > > > > 
> > > > > So, I wait with 0001-... !?
> > > > > 
> > > > > 0002-... has been pushed (extended with 'symlink').
> > > > > 
> > > > > Thanks for your contribution.
> > > > > 
> > > > > Tim
> > > > 
> > > > Ok for 0002. Thanks.
> > > > 
> > > > There's no problem applying the 0001.
> > > 
> > > Applied and pushed !
> > > 
> > > > The "if the stream got interrupted, then restart the download with the
> > > > next
> > > > url" (output_stream isn't NULL) was already there before the patch 0001.
> > > > 
> > > > [debug is required to know when output_stream isn't NULL]
> > > > 
> > > > commit 7fad76db4cdb7a0fe7e5aa0dd88f5faaf8f4cdc8
> > > > * src/metalink.c (retrieve_from_metalink): line 124: 'if
> > > > (output_stream)'
> > > > remove file and restart download with next url
> > > > 
> > > > With the 0001, if --keep-badhash is used the file is renamed instead
> > > > than
> > > > removed, even when "output_stream is NULL".
> > > > 
> > > > I have to look through the "stream interrupted" situation.
> > > > 
> > > > I'm guessing that the download is not resumed.
> > > > 
> > > > What do you suggest?
> > > 
> > > We need a  document where we define wanted behavior, create tests and
> > > amend the code.
> > > 
> > > Regards, Tim
> > 
> > Ok, I just documented a test. See the attached tarball.
> > 
> > Also there is a patch attached (there's a copy in the tarball too),
> > providing the suggested bugfix.
> 
> I made that test without your patch => crash due to badhash_or_remove(NULL).
> With your patch, valgrind says:
> 
> ==15068== Syscall param open(filename) points to unaddressable byte(s)
> ==15068==    at 0x6848F40: __open_nocancel (syscall-template.S:84)
> ==15068==    by 0x67DFF7D: _IO_file_open (fileops.c:221)
> ==15068==    by 0x67E009F: _IO_file_fopen@@GLIBC_2.2.5 (fileops.c:328)
> ==15068==    by 0x67D4F03: __fopen_internal (iofopen.c:86)
> ==15068==    by 0x434FAE: retrieve_from_metalink (metalink.c:184)
> ==15068==    by 0x406C63: main (main.c:2025)
> ==15068==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
> ==15068== 
> 
> Can you reproduce this ?
> 
> Tim

Thanks Tim for spotting that out. I did some tests.

Please, don't push the patches, let me understand the bugs first.

Vanilla commit e3fb4c3859d2705fb2de80801b0bba2b64bea1a1:
* Doesn't understand metalink:file "path/file" name format
* Downloads "path/file" as "file" in the working directory
* Fails the "path/file" checksum (cannot find "path/file")

Vanilla commit, test.meta4: name="bash-4.3-patches/bash43-001"
$ wget --input-metalink=test.meta4
$ wget -c --input-metalink=test.meta4
Both the aboves: File OK, checksum fails (cannot find "path/file").

Vanilla commit, test2.meta4: name="bash43-001"
$ wget --input-metalink=test2.meta4
File OK, checksum OK.
$ wget -c --input-metalink=test2.meta4
Segmentation fault (I'm working on it).

Patch 0001 http://lists.gnu.org/archive/html/bug-wget/2016-08/msg00021.html
$ wget --input-metalink=test.meta4
$ wget -c --input-metalink=test.meta4
$ wget --input-metalink=test2.meta4
$ wget -c --input-metalink=test2.meta4
All the aboves: File OK, checksum OK (understands "path/file").

Patch 0002 http://lists.gnu.org/archive/html/bug-wget/2016-08/msg00033.html
$ wget --input-metalink=test.meta4
$ wget -c --input-metalink=test.meta4
Both the aboves: File OK, checksum fails (cannot find "path/file").
$ wget --input-metalink=test2.meta4
File OK, checksum OK.
$ wget -c --input-metalink=test2.meta4
File OK, checksum fails (what?! I'm working on it).

0001 + 0002: All OK.

I posted 0001 and 0002 before (see links above), I attach them here too.

PS: sorry for the boring message.

Later,
Matthew

-- 
Matthew White <address@hidden>

0001-Bugfix-create-download-verify-Metalink-s-files-with-.patch
Description: Text Data

0002-Bugfix-Continue-download-when-retrying-with-the-next.patch
Description: Text Data

test.meta4
Description: application/metalink4

test2.meta4
Description: application/metalink4

pgpEc_XOSTphP.pgp
Description: PGP signature