Using tar to access files

[Gedare Bloom]

On Mon, Jul 13, 2015 at 11:26 AM, Pavel Pisa <pisa at cmp.felk.cvut.cz> wrote:
> Hello Sujay Raj,
>
>
> On Tuesday 30 of June 2015 06:39:28 Sujay Raj wrote:
>> I need to access configurations files the for web server I am porting to
>> rtems.
>>
>> I create a tar archive , that contains the required folders and files ,
>> convert it into c source using rtems-bin2c , ( a header file and a c source
>> ) and link them with my project.
>>
>> In the init, I call
>>
>> sc = Untar_FromMemory((void *)TARFILE_START, (size_t)TARFILE_SIZE);
>>
>> where TARFILE_START is the macro with the name of the array , TARFILE_SIZE
>> is the size of the array.
>>
>> But when I run the program, I get errors of the form
>>
>> "Untar: failed to create file <folder>/<filename>"
>>
>
> I have noticed and reported similar problem and workaround some
> time ago. Problem is, that Untar_FromMemory() function fails
> when it reaches a directory entry in a TAR file and given
> directory already exists. It fails even for existing
> top level directory which has to exists in RTEMS runing
> system and are packed by TAR by default.
>
> My fix is not ideal. Other (more generic option) is to use
> stat(const char *path, struct stat *buf) with check
> that target is already existing direcory. But using stat()
> in really minimal application can lead to unneeded overhead.
> Other option is to ignore directory create errors completelly
> but I do not like something like that in RT system.
>
> There is alternative way to untar file by other RTEMS functions
> but we use Untar_FromMemory() in more projects. If there is no
> objection or opinion for other solution, I prepare and check
> patch with stat().
>
>
> From 4ce027b21cfde5bc6143d51d244345e05dd85cd4 Mon Sep 17 00:00:00 2001
> Message-Id: <4ce027b21cfde5bc6143d51d244345e05dd85cd4.1436800331.git.ppisa at pikron.com>
> From: Pavel Pisa <ppisa at pikron.com>
> Date: Mon, 31 Mar 2014 00:57:12 +0200
> Subject: [PATCH] untar: workaround for fail on top level directory existence.
> To: rtems-devel at rtems.org
>
> Signed-off-by: Pavel Pisa <ppisa at pikron.com>
> ---
>  cpukit/libmisc/untar/untar.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/cpukit/libmisc/untar/untar.c b/cpukit/libmisc/untar/untar.c
> index aed8fed..498fa12 100644
> --- a/cpukit/libmisc/untar/untar.c
> +++ b/cpukit/libmisc/untar/untar.c
> @@ -203,6 +203,8 @@ Untar_FromMemory(
>        }
>      } else if (linkflag == DIRTYPE) {
>        if ( mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) != 0 ) {
> +        if ( !strcmp(fname, "/") || !strcmp(fname, "./"))
> +          continue;
So this just proceeds if the top-level directly already exists? I
don't really have a problem with the patch if there is a test case
that shows the problem case, but I think the reported failure may be
elsewhere since Sujay said the error was "Untar: failed to create
file" and not "directory".

>          printk("Untar: failed to create directory %s\n", fname);
>          retval = UNTAR_FAIL;
>          break;
> --
> 1.9.1
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