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ring-transpile-c2rust.py
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ring-transpile-c2rust.py
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#
# 1. Install c2rust dependencies:
# sudo apt install build-essential llvm clang libclang-dev cmake libssl-dev pkg-config python3
# 2. Install c2rust:
# cargo install c2rust:
# 3. Run this program inside the target directory:
# python ring-transpile-c2rust.py
#
# This creates a bunch of `.rs` files with `#[no_mangle] extern "C"` declarations,
# which allow other Rust code to link against it. This program also tries hard to
# fixup the types so that they work without libc.
#
# The resulting code may even compile! But you may need to add more fixes under the
# `massage_line()` function in order to get things working.
#
# The idea behind this program is that you run it once on a project and then begin
# gradually rewriting parts of it.
import subprocess
import os
import re
RING_C_FILES = [
"crypto/fipsmodule/aes/aes_nohw.c",
"crypto/fipsmodule/bn/montgomery.c",
"crypto/fipsmodule/bn/montgomery_inv.c",
"crypto/limbs/limbs.c",
"crypto/mem.c",
"crypto/poly1305/poly1305.c",
# Other libraries
"crypto/crypto.c",
"crypto/curve25519/curve25519.c",
"crypto/fipsmodule/ec_17/ecp_nistz.c",
# "crypto/fipsmodule/ec/ecp_nistz256.c",
"crypto/fipsmodule/ec_17/gfp_p256.c",
"crypto/fipsmodule/ec_17/gfp_p384.c",
"crypto/fipsmodule/ec_17/p256.c",
]
COMMANDS_FILE = "compile_commands.json"
p_sizeof = re.compile(r'(.*)(std::mem::size_of::)(.*)(as u64)(.*)')
def massage_line(line):
line = line.strip()
# Remove various compile-time directives
if line == "#![register_tool(c2rust)]":
return ""
if line == "use core::arch::asm;":
return ""
if line.startswith("#![feature("):
return ""
if line.startswith("#![allow("):
return ""
# Convert types
line = line.replace("std::os::raw::c_int", "i32")
line = line.replace("std::os::raw::c_ulonglong", "u64")
line = line.replace("std::os::raw::c_longlong", "i64")
line = line.replace("std::os::raw::c_uint", "u32")
line = line.replace("std::os::raw::c_char", "u8")
line = line.replace("std::os::raw::c_uchar", "u8")
line = line.replace("std::os::raw::c_schar", "i8")
line = line.replace("std::os::raw::c_void", "u8")
line = line.replace("::std::mem::transmute", "std::mem::transmute")
line = line.replace("libc::c_char", "std::os::raw::c_char")
line = line.replace("libc::c_schar", "std::os::raw::c_schar")
line = line.replace("libc::c_uchar", "std::os::raw::c_uchar")
line = line.replace("libc::c_int", "std::os::raw::c_int")
line = line.replace("libc::c_uint", "std::os::raw::c_uint")
line = line.replace("libc::c_ulonglong", "u64")
line = line.replace("libc::c_longlong", "i64")
line = line.replace("libc::c_ulong", "u32") # this must come after the longlong
line = line.replace("libc::c_long", "i32")
line = line.replace("libc::c_void", "std::os::raw::c_void")
# Fix program-specific oddities
line = line.replace(" bf16", " u128") # fixed in https://github.com/immunant/c2rust/issues/486, but not yet released
if line == "GFp_memcpy(":
line = line.replace("GFp_memcpy(", "let _ = GFp_memcpy(")
if line == "GFp_memset(":
line = line.replace("GFp_memset(", "let _ = GFp_memset(")
if line == "GFp_bn_from_montgomery_in_place(":
line = line.replace("GFp_bn_from_montgomery_in_place(", "let _ = GFp_bn_from_montgomery_in_place(")
line = line.replace("::std::mem::size_of", "std::mem::size_of")
line = line.replace("::std::vec::", "std::vec::")
line = line.replace(": Vec::", ": std::vec::Vec::")
# line = line.replace(") = limbs_mul_add_limb(", ") = GFp_limbs_mul_add_limb(")
line = line.replace("use std::arch::asm;", "")
if p_sizeof.search(line):
line = p_sizeof.sub(r'\g<1>\g<2>\g<3>as u32\g<5>', line)
# Replace this ASM weirdness with a barrier
compiler_fence = (
"core::sync::atomic::compiler_fence(core::sync::atomic::Ordering::SeqCst);"
)
line = line.replace(
'asm!("", inlateout(reg) a, options(preserves_flags, pure, readonly));',
compiler_fence,
)
return line
def lint():
# lint the c2rust using cargo and a cleanup pass
build = subprocess.run(
["cargo", "build", "--target=riscv32imac-unknown-xous-elf"],
stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
state = "SEARCHING"
subs = {}
warntype = ""
token = ""
p_token = re.compile(r'(.*)`(.*)`(.*)')
p_line = re.compile(r'(.*)--> (.*):([0-9]*):([0-9]*)')
for line in build.stdout.decode('utf8').split('\n'):
if line.startswith("warning:"):
if "value assigned to" in line and "is never read":
warntype = "unused init"
token = p_token.search(line).group(2)
state = "FOUND"
elif "unused variable" in line:
warntype = "unused variable"
token = p_token.search(line).group(2)
state = "FOUND"
elif "variable does not need to be mutable" in line:
warntype = "remove mut"
token = 'mut'
state = "FOUND"
elif "function" in line and "is never used in line":
warntype = "unused func"
token = p_token.search(line).group(2)
state = "FOUND"
else:
state = "SEARCHING"
pass
if state == "FOUND":
p = p_line.search(line)
if p:
fname = p.group(2)
fline = int(p.group(3))
fcol = int(p.group(4))
if fname in subs:
subs[fname][fline] = [warntype, token, fcol]
else:
subs[fname] = {fline: [warntype, token, fcol]}
state == "SEARCHING"
warntype = ""
for fname in subs.keys():
if 'src/c2rust' in fname:
# print(fname)
# print(subs[fname])
with open(fname, "r") as src_file:
sfile = src_file.readlines()
with open(fname, "w") as dst_file:
line_no = 1
for line in sfile:
if line_no in subs[fname]:
warn = subs[fname][line_no]
if "unused init" in warn[0]:
if " = 0" in line:
# this is an unused 0-init
line = line.replace(" = 0", "")
else:
# this is an unused assignment
line = line[:warn[2] - 1] + 'let _' + line[warn[2] - 1:]
elif "unused variable" in warn[0]:
line = line[:warn[2]-1] + '_' + line[warn[2]-1:]
# print("DEBUG: {}".format(subs[fname][line_no]))
elif "remove mut":
line = line[:warn[2]-1] + line[warn[2]+3:]
elif "unused func":
line = line[:warn[2]-1] + '_' + line[warn[2]-1:]
else:
print("TODO: {}".format(subs[fname][line_no]))
line_no += 1
print(line, file=dst_file, end="")
def run():
# Generate the `compile_commands.json` file that c2rust uses
cwd = os.getcwd()
with open(COMMANDS_FILE, "w") as cmd_file:
print("[", file=cmd_file)
first_line = False
for file in RING_C_FILES:
rs_file = file.replace(".c", ".rs")
if os.path.exists(rs_file):
os.unlink(rs_file)
if first_line is not False:
print(",", file=cmd_file)
first_line = True
print(" {", file=cmd_file)
print(
f""" "arguments": [
"cc",
"-c",
"-o",
"build/tmp.o",
"-m32",
"-Iinclude",
"-UOPENSSL_X86_64",
"-U__x86_64",
"-D__xous__",
"-D__riscv",
"-D__riscv_xlen=32",
"{file}"
],
"directory": "{cwd}",
"file": "{file}"
}}""",
file=cmd_file,
end="",
)
print("", file=cmd_file)
print("]", file=cmd_file)
subprocess.run(["c2rust", "transpile", COMMANDS_FILE])
if not os.path.exists("src/c2rust"):
os.mkdir("src/c2rust")
print("Add this to the end of `src/lib.rs`:")
print("mod c2rust {")
for file in RING_C_FILES:
mod_name = file.split("/")[-1].split(".")[0]
rs_file = file.replace(".c", ".rs")
# print(f" #[path = \"../{rs_file}\"]")
print(f" mod {mod_name};")
with open(rs_file, "r") as src_file:
with open(f"src/c2rust/{mod_name}.rs", "w") as dest_file:
print("#![allow(non_camel_case_types)]", file=dest_file)
print("#![allow(non_snake_case)]", file=dest_file)
print("#![allow(non_upper_case_globals)]", file=dest_file)
print("extern crate std;", file=dest_file)
#print("use core::ffi::*;", file=dest_file)
for line in src_file:
print(massage_line(line), file=dest_file)
subprocess.run(["rm", rs_file])
subprocess.run(["rustfmt", "src/c2rust/{}.rs".format(mod_name)])
print("}")
# multiple passes of linting are needed to tease out all the unused mut warnings
# each pass removes some muts from the warning tree that propagates backwards...
# we don't loop this but make it individual calls because the depth of this sort of depends
# upon the code itself.
print("linting...")
lint()
print("pass2")
lint()
print("pass3")
lint()
if __name__ == "__main__":
run()