libfile: Introduce pwrite_full() ...

Analogous to what we have with write()/write_full(), introduce a
lightweight wrapper around pwrite() that guarantees the either all
data is going to be written or a negative error code would be
returned.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: implement new helper write_file_flash() ...

Compared to write_file() this new function also calls erase() to be
suitable for flash devices.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/tftp-workaround'

libfile: Make write_file buffer const ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: implement a function to cache a file ...

Due to the nature of TFTP which can't lseek and due to the silliness
of our filesystem implementation which can't cache accesses we have to
manually cache files on TFTP filesystems sometimes. Make it easier
for them by providing a cache_file() function which copies the file
from TFTP to RAM.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: implement make_temp ...

Create a make_temp() function which creates a name for a temporary file.
Since we do not have any concurrency in barebox we do not need to create
the file right away and can leave that to the caller. Unlike unix
mktemp the resulting filename is dynamically allocated and must be
freed by the caller.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: Change write_full to be have const buf ...

write() uses a const pointer so write_full should do the same.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

move unlink_recursive declaration to libfile.h ...

unlink_recursive is a file utility function, so move the prototype to
libfile.h

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

move make_directory declaration to libfile.h ...

As a utility function for file handling make_directory() is well
suited for libfile. Move it there.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: move open_and_lseek() to libfile ...

libfile is a collection of helpers for handling files. open_and_lseek()
is a perfect match for this, so move it there.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: Add copy_recursive ...

To recursively copy a directory tree.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

libfile: add compare_file function ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

read_file: introduce read_file_2 ...

read_file has some limitations:

- It is not possible to check the error code since read_file returns
  NULL for failure
- It is not possible to limit the buffer size to sensible limits.

This patch introduces read_file_2 which doesn't have these limitations.
read_file becomes a wrapper around read_file_2.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

move file helper functions to separate file ...

We have our file helper functions in several places. Move them
all to lib/libfile.c.
With this we no longer have file helpers in fs/fs.c which contains
the core fs functions and no functions in lib/libbb.c which are
not from busybox.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>