Re: [PATCH] read_file: Make it work on tftp servers which do not pass size

[Sascha Hauer <s.hauer@pengutronix.de>]

On Thu, Jun 20, 2013 at 01:15:31PM +0200, Jan Weitzel wrote:
> Am Mittwoch, den 19.06.2013, 22:58 +0200 schrieb Sascha Hauer:
> > Some tftp servers (for example netkit-tftp) do not pass the filesize.
> > Add a workaround for read_file which reads the file into a temporary
> > file which then is copied to a buffer.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  fs/fs.c      | 18 ++++++++++++++++++
> >  fs/tftp.c    |  5 ++++-
> >  include/fs.h |  2 ++
> >  3 files changed, 24 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/fs.c b/fs/fs.c
> > index dc3a6e3..7046f2c 100644
> > --- a/fs/fs.c
> > +++ b/fs/fs.c
> > @@ -38,10 +38,21 @@ void *read_file(const char *filename, size_t *size)
> >  	int fd;
> >  	struct stat s;
> >  	void *buf = NULL;
> > +	const char *tmpfile = "/.read_file_tmp";
> > +	int ret;
> >  
> > +again:
> >  	if (stat(filename, &s))
> >  		return NULL;
> >  
> > +	if (s.st_size == FILESIZE_MAX) {
> > +		ret = copy_file(filename, tmpfile, 0);
> > +		if (ret)
> > +			return NULL;
> > +		filename = tmpfile;
> > +		goto again;
> > +	}
> > +
> >  	buf = xzalloc(s.st_size + 1);
> >  
> >  	fd = open(filename, O_RDONLY);
> > @@ -56,12 +67,19 @@ void *read_file(const char *filename, size_t *size)
> >  	if (size)
> >  		*size = s.st_size;
> >  
> > +	if (filename == tmpfile)
> > +		unlink(tmpfile);
> > +
> >  	return buf;
> >  
> >  err_out1:
> >  	close(fd);
> >  err_out:
> >  	free(buf);
> > +
> > +	if (filename == tmpfile)
> > +		unlink(tmpfile);
> > +
> >  	return NULL;
> >  }
> >  
> > diff --git a/fs/tftp.c b/fs/tftp.c
> > index 98cbb37..1c37acf 100644
> > --- a/fs/tftp.c
> > +++ b/fs/tftp.c
> > @@ -597,7 +597,10 @@ static int tftp_stat(struct device_d *dev, const char *filename, struct stat *s)
> >  		return PTR_ERR(priv);
> >  
> >  	s->st_mode = S_IFREG | S_IRWXU | S_IRWXG | S_IRWXO;
> > -	s->st_size = priv->filesize;
> > +	if (priv->filesize)
> > +		s->st_size = priv->filesize;
> > +	else
> > +		s->st_size = FILESIZE_MAX;
> Maybe we can determine the size here? Commands like "ls -l" and
> "ubiformat" asks about the filesize via stat. I'm not sure how much
> overheat it will be.

How do you want to do that? You would have to transfer the whole file
first and see how big it is. That works for small files we expect to fit
into memory like the ones read_file normally is called with. If you want
to transfer a rootfs image it might happen that it's bigger than the
available memory.

Sascha

-- 
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