tests: Add a failed test case for 'fdtoverlay' with long target path

This adds a test case to demonstrate some issue seen when applying
overlays using 'fdtoverlay'. It fails with FDT_ERR_NOSPACE:
- with long target path
- symbols in order to use these nodes in possible subsequent overlay.

This is seen with this patch, by running:
$ make check # Reports a failed test
$ ./fdtoverlay -i tests/overlay_base.test.dtb -o out.dtb \
  tests/overlay_overlay_long_path.fdoverlay.test.dtb
  Failed to apply tests/overlay_overlay_long_path.fdoverlay.test.dtb (-3)

This overlay fails to apply, because dtb size is close to modulo 1024
bytes chunk: utilfdt_read() -> utilfdt_read_err() -> bufsize = 1024.

As there is not much extra space in the blob to resolve symbols (long
target path), it fails with FDT_ERR_NOSPACE. In fdtoverlay, size is :
 /* grow the blob to worst case */
 blob_len = fdt_totalsize(blob) + total_len;

I can see assumption is made that result should be lower than:
- base fdt size + overlay size. Is there a simple way to find to know
what the final size is?
I'm not sure what the correct fix might be, for such (worst) case?
Similar issue is also seen in u-boot/common/image-fit.c that implements
similar approach (e.g. base fdt size + overlay size).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Message-Id: <1538553302-1353-1-git-send-email-fabrice.gasnier@st.com>
[dwg: To avoid breaking bisection, I committed this after a fix, so
 the "failed" description is no longer accurate]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

0 files changed, 0 insertions, 0 deletions