Re: [PATCH v7 16/17] scripts/oss-fuzz: use hardlinks instead of copying

[Darren Kenny]

On Friday, 2020-10-23 at 11:07:45 -04, Alexander Bulekov wrote:
> Prior to this, fuzzers in the output oss-fuzz directory were exactly
> the same executable, with a different name to do argv[0]-based
> fuzz-target selection. This is a waste of space, especially since these
> binaries can weigh many MB.
>
> Instead of copying, use hard links, to cut down on wasted space. We need
> to place the primary copy of the executable into DEST_DIR, since this is
> a separate file-system on oss-fuzz. We should not place it directly into
> $DEST_DIR, since oss-fuzz will treat it as an independent fuzzer and try
> to run it for fuzzing. Instead, we create a DEST_DIR/bin directory to
> store the primary copy.
>
> Suggested-by: Darren Kenny <darren.kenny@oracle.com>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>

Reviewed-by: Darren Kenny <darren.kenny@oracle.com>

> ---
>  scripts/oss-fuzz/build.sh | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/oss-fuzz/build.sh b/scripts/oss-fuzz/build.sh
> index 0c3ca9e06f..0ce2867732 100755
> --- a/scripts/oss-fuzz/build.sh
> +++ b/scripts/oss-fuzz/build.sh
> @@ -62,6 +62,9 @@ fi
>  
>  mkdir -p "$DEST_DIR/lib/"  # Copy the shared libraries here
>  
> +mkdir -p "$DEST_DIR/bin/"  # Copy executables that shouldn't
> +                           # be treated as fuzzers by oss-fuzz here
> +
>  # Build once to get the list of dynamic lib paths, and copy them over
>  ../configure --disable-werror --cc="$CC" --cxx="$CXX" --enable-fuzzing \
>      --prefix="$DEST_DIR" --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" \
> @@ -88,13 +91,16 @@ make "-j$(nproc)" qemu-fuzz-i386 V=1
>  # Copy over the datadir
>  cp  -r ../pc-bios/ "$DEST_DIR/pc-bios"
>  
> +cp "./qemu-fuzz-i386" "$DEST_DIR/bin/"
> +
>  # Run the fuzzer with no arguments, to print the help-string and get the list
>  # of available fuzz-targets. Copy over the qemu-fuzz-i386, naming it 
> according
>  # to each available fuzz target (See 05509c8e6d fuzz: select fuzz target 
> using
>  # executable name)
>  for target in $(./qemu-fuzz-i386 | awk '$1 ~ /\*/  {print $2}');
>  do
> -    cp qemu-fuzz-i386 "$DEST_DIR/qemu-fuzz-i386-target-$target"
> +    ln  "$DEST_DIR/bin/qemu-fuzz-i386" \
> +        "$DEST_DIR/qemu-fuzz-i386-target-$target"
>  done
>  
>  echo "Done. The fuzzers are located in $DEST_DIR"
> -- 
> 2.28.0