Re: [PATCH v2 10/15] scripts/oss-fuzz: Add wrapper program for generic fuzzer

[Darren Kenny]

Just thinking after reading later code, that maybe this should be
renamed to something like target.c.tmpl, target_template.c, or similar
so that it is clearer that this is not used directly, but as a template
for generation of other targets.

Thanks,

Darren.


On Wednesday, 2020-08-19 at 02:11:05 -04, Alexander Bulekov wrote:
> On oss-fuzz we need some sort of wrapper to specify command-line
> arguments or environment variables. When we had a similar problem with
> other targets that I fixed with
> 05509c8e6d ("fuzz: select fuzz target using executable name")
> by selecting the fuzz target based on the executable's name. In the
> future should probably commit to one approach (wrapper binary or
> argv0-based target selection).
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>  scripts/oss-fuzz/target.c | 40 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
>  create mode 100644 scripts/oss-fuzz/target.c
>
> diff --git a/scripts/oss-fuzz/target.c b/scripts/oss-fuzz/target.c
> new file mode 100644
> index 0000000000..4a7257412a
> --- /dev/null
> +++ b/scripts/oss-fuzz/target.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright Red Hat Inc., 2020
> + *
> + * Authors:
> + *  Alexander Bulekov   <alxndr@bu.edu>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <limits.h>
> +#include <libgen.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +
> +/* Required for oss-fuzz to consider the binary a target. */
> +static const char *magic __attribute__((used)) = "LLVMFuzzerTestOneInput";
> +static const char args[] = {QEMU_FUZZ_ARGS, 0x00};
> +static const char objects[] = {QEMU_FUZZ_OBJECTS, 0x00};
> +
> +int main(int argc, char *argv[])
> +{
> +    char path[PATH_MAX] = {0};
> +    char *dir = dirname(argv[0]);
> +    strncpy(path, dir, PATH_MAX);
> +    strcat(path, "/deps/qemu-fuzz-i386-target-general-fuzz");
> +
> +    setenv("QEMU_FUZZ_ARGS", args, 0);
> +    setenv("QEMU_FUZZ_OBJECTS", objects, 0);
> +
> +    argv[0] = path;
> +    int ret = execvp(path, argv);
> +    if (ret) {
> +        perror("execv");
> +    }
> +    return ret;
> +}
> -- 
> 2.27.0