Support JSON output

[david942j]

Introduce a new CLI argument --output-format FORMAT (or -o FORMAT) with FORMAT can be one of pretty, raw, and json.

• --raw is still available but it becomes an alias to -o raw.
• --[no-]raw is removed.

Examples of JSON output:

$ one_gadget -b b417c0ba7cc5cf06d1d1bed6652cedb9253c60d0 -o json -l1
[{"value":324279,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","{\"sh\", \"-c\", r12, NULL} is a valid argv"]},{"value":324286,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, \"-c\", r12, NULL} is a valid argv"]},{"value":324293,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, rax, r12, NULL} is a valid argv"]},{"value":324386,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv"]},{"value":939679,"effect":"execve(\"/bin/sh\", r14, r12)","constraints":["[r14] == NULL || r14 == NULL || r14 is a valid argv","[r12] == NULL || r12 == NULL || r12 is a valid envp"]},{"value":940120,"effect":"execve(\"/bin/sh\", [rbp-0x88], [rbp-0x70])","constraints":["[[rbp-0x88]] == NULL || [rbp-0x88] == NULL || [rbp-0x88] is a valid argv","[[rbp-0x70]] == NULL || [rbp-0x70] == NULL || [rbp-0x70] is a valid envp"]},{"value":940127,"effect":"execve(\"/bin/sh\", r10, [rbp-0x70])","constraints":["[r10] == NULL || r10 == NULL || r10 is a valid argv","[[rbp-0x70]] == NULL || [rbp-0x70] == NULL || [rbp-0x70] is a valid envp"]},{"value":940131,"effect":"execve(\"/bin/sh\", r10, rdx)","constraints":["[r10] == NULL || r10 == NULL || r10 is a valid argv","[rdx] == NULL || rdx == NULL || rdx is a valid envp"]},{"value":1090444,"effect":"execve(\"/bin/sh\", rsp+0x70, environ)","constraints":["[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv"]},{"value":1090456,"effect":"execve(\"/bin/sh\", rsi, [rax])","constraints":["[rsi] == NULL || rsi == NULL || rsi is a valid argv","[[rax]] == NULL || [rax] == NULL || [rax] is a valid envp"]}]

$ one_gadget spec/data/libc-2.27-b417c0ba7cc5cf06d1d1bed6652cedb9253c60d0.so -o json --near exit,mkdir
[{"near":"exit","near_offset":274720,"gadgets":[{"value":324286,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, \"-c\", r12, NULL} is a valid argv"]},{"value":324293,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, rax, r12, NULL} is a valid argv"]},{"value":324386,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv"]},{"value":1090444,"effect":"execve(\"/bin/sh\", rsp+0x70, environ)","constraints":["[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv"]}]},{"near":"mkdir","near_offset":1113008,"gadgets":[{"value":1090444,"effect":"execve(\"/bin/sh\", rsp+0x70, environ)","constraints":["[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv"]},{"value":324386,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv"]},{"value":324293,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, rax, r12, NULL} is a valid argv"]},{"value":324286,"effect":"execve(\"/bin/sh\", rsp+0x40, environ)","constraints":["rsp & 0xf == 0","writable: rsp+0x50","rcx == NULL || {rcx, \"-c\", r12, NULL} is a valid argv"]}]}]

Also confirmed the output can be parsed by Python3:

$ one_gadget spec/data/libc-2.27-b417c0ba7cc5cf06d1d1bed6652cedb9253c60d0.so -o json -l1 | python3  -c 'print(__import__("json").loads(__import__("sys").stdin.read()))'
[{'value': 324279, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', '{"sh", "-c", r12, NULL} is a valid argv']}, {'value': 324286, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, "-c", r12, NULL} is a valid argv']}, {'value': 324293, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, rax, r12, NULL} is a valid argv']}, {'value': 324386, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv']}, {'value': 939679, 'effect': 'execve("/bin/sh", r14, r12)', 'constraints': ['[r14] == NULL || r14 == NULL || r14 is a valid argv', '[r12] == NULL || r12 == NULL || r12 is a valid envp']}, {'value': 940120, 'effect': 'execve("/bin/sh", [rbp-0x88], [rbp-0x70])', 'constraints': ['[[rbp-0x88]] == NULL || [rbp-0x88] == NULL || [rbp-0x88] is a valid argv', '[[rbp-0x70]] == NULL || [rbp-0x70] == NULL || [rbp-0x70] is a valid envp']}, {'value': 940127, 'effect': 'execve("/bin/sh", r10, [rbp-0x70])', 'constraints': ['[r10] == NULL || r10 == NULL || r10 is a valid argv', '[[rbp-0x70]] == NULL || [rbp-0x70] == NULL || [rbp-0x70] is a valid envp']}, {'value': 940131, 'effect': 'execve("/bin/sh", r10, rdx)', 'constraints': ['[r10] == NULL || r10 == NULL || r10 is a valid argv', '[rdx] == NULL || rdx == NULL || rdx is a valid envp']}, {'value': 1090444, 'effect': 'execve("/bin/sh", rsp+0x70, environ)', 'constraints': ['[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv']}, {'value': 1090456, 'effect': 'execve("/bin/sh", rsi, [rax])', 'constraints': ['[rsi] == NULL || rsi == NULL || rsi is a valid argv', '[[rax]] == NULL || [rax] == NULL || [rax] is a valid envp']}]

 one_gadget spec/data/libc-2.27-b417c0ba7cc5cf06d1d1bed6652cedb9253c60d0.so -o json --near exit,mkdir | python3  -c 'print(__import__("json").loads(__import__("sys").stdin.read()))'
[{'near': 'exit', 'near_offset': 274720, 'gadgets': [{'value': 324286, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, "-c", r12, NULL} is a valid argv']}, {'value': 324293, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, rax, r12, NULL} is a valid argv']}, {'value': 324386, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv']}, {'value': 1090444, 'effect': 'execve("/bin/sh", rsp+0x70, environ)', 'constraints': ['[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv']}]}, {'near': 'mkdir', 'near_offset': 1113008, 'gadgets': [{'value': 1090444, 'effect': 'execve("/bin/sh", rsp+0x70, environ)', 'constraints': ['[rsp+0x70] == NULL || {[rsp+0x70], [rsp+0x78], [rsp+0x80], [rsp+0x88], ...} is a valid argv']}, {'value': 324386, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['[rsp+0x40] == NULL || {[rsp+0x40], [rsp+0x48], [rsp+0x50], [rsp+0x58], ...} is a valid argv']}, {'value': 324293, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, rax, r12, NULL} is a valid argv']}, {'value': 324286, 'effect': 'execve("/bin/sh", rsp+0x40, environ)', 'constraints': ['rsp & 0xf == 0', 'writable: rsp+0x50', 'rcx == NULL || {rcx, "-c", r12, NULL} is a valid argv']}]}]

Fixes #224