tools: bpftool: add "prog run" subcommand to test-run programs

Add a new "bpftool prog run" subcommand to run a loaded program on input
data (and possibly with input context) passed by the user.

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tools: bpftool: add "prog run" subcommand to test-run programs

Add a new "bpftool prog run" subcommand to run a loaded program on input
data (and possibly with input context) passed by the user.

Print output data (and output context if relevant) into a file or into
the console. Print return value and duration for the test run into the
console.

A "repeat" argument can be passed to run the program several times in a
row.

The command does not perform any kind of verification based on program
type (Is this program type allowed to use an input context?) or on data
consistency (Can I work with empty input data?), this is left to the
kernel.

Example invocation:

# perl -e 'print "\x0" x 14' | ./bpftool prog run \
pinned /sys/fs/bpf/sample_ret0 \
data_in - data_out - repeat 5
0000000 0000 0000 0000 0000 0000 0000 0000 | ........ ......
Return value: 0, duration (average): 260ns

When one of data_in or ctx_in is "-", bpftool reads from standard input,
in binary format. Other formats (JSON, hexdump) might be supported (via
an optional command line keyword like "data_fmt_in") in the future if
relevant, but this would require doing more parsing in bpftool.

v2:
- Fix argument names for function check_single_stdin(). (Yonghong)

Signed-off-by: Quentin Monnet <[email protected]>
Reviewed-by: Jakub Kicinski <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

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