File size: 9,093 Bytes
ab54eb4 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 | """
C preprocessor integration for AMC.
Expands #include directives via `cc -E` so that each source file
becomes a self-contained translation unit that the parser and CBMC
can handle without knowing the original include paths.
Also strips GCC/ARM64 extensions that CBMC does not accept:
__attribute__((...)), __asm__/__asm blocks, _Noreturn, typeof,
and register-asm variable declarations.
"""
from __future__ import annotations
import re
import subprocess
import tempfile
from pathlib import Path
from bmc_agent.logger import get_logger
logger = get_logger("preprocessor")
# ---------------------------------------------------------------------------
# Public API
# ---------------------------------------------------------------------------
def preprocess(
source_file: str | Path,
include_dirs: list[str] | None = None,
defines: list[str] | None = None,
cc: str = "cc",
) -> str:
"""
Return a cleaned, self-contained C source string for *source_file*.
Steps:
1. Run ``cc -E -P`` to expand all #include references.
2. Strip lines that originate from system headers (``/usr/``, ``/lib/``).
3. Strip GCC/ARM64 extensions that confuse CBMC.
4. Prepend standard CBMC-friendly headers.
Parameters
----------
source_file:
Path to the ``.c`` file to preprocess.
include_dirs:
List of ``-I`` paths to pass to the compiler.
defines:
List of ``-D`` macros to pass to the compiler.
cc:
C compiler binary to use for preprocessing (default ``cc``).
"""
source_file = Path(source_file)
include_dirs = include_dirs or []
defines = defines or []
expanded = _run_preprocessor(source_file, include_dirs, defines, cc)
cleaned = _strip_system_content(expanded, source_file)
cleaned = _strip_gcc_extensions(cleaned)
cleaned = _prepend_cbmc_headers(cleaned)
return cleaned
def preprocess_to_file(
source_file: str | Path,
output_file: str | Path,
include_dirs: list[str] | None = None,
defines: list[str] | None = None,
cc: str = "cc",
) -> Path:
"""Preprocess *source_file* and write the result to *output_file*."""
result = preprocess(source_file, include_dirs, defines, cc)
out = Path(output_file)
out.parent.mkdir(parents=True, exist_ok=True)
out.write_text(result, encoding="utf-8")
return out
# ---------------------------------------------------------------------------
# Step 1: run cc -E
# ---------------------------------------------------------------------------
def _run_preprocessor(
source_file: Path,
include_dirs: list[str],
defines: list[str],
cc: str,
) -> str:
cmd = [cc, "-E", "-P"]
for d in include_dirs:
cmd += ["-I", d]
for define in defines:
cmd += ["-D", define]
# Suppress warnings; treat as plain C
cmd += ["-w", "-x", "c", str(source_file)]
try:
result = subprocess.run(
cmd,
capture_output=True,
text=True,
timeout=60,
)
if result.returncode != 0 and not result.stdout.strip():
logger.warning("Preprocessor failed for %s: %s", source_file, result.stderr[:200])
# Fall back to reading the file as-is
return source_file.read_text(encoding="utf-8", errors="replace")
return result.stdout
except (FileNotFoundError, subprocess.TimeoutExpired) as exc:
logger.warning("Cannot run preprocessor (%s): %s — reading file as-is", cc, exc)
return source_file.read_text(encoding="utf-8", errors="replace")
# ---------------------------------------------------------------------------
# Step 2: strip system-header content
# ---------------------------------------------------------------------------
# Marker lines emitted by cc -E (without -P): # <lineno> "<path>" <flags>
# We use them to track which file lines belong to. With -P they are absent,
# but system headers expand inline. We detect system content by checking
# whether it looks like it came from standard paths.
#
# Without -P we get linemarkers; strip content from system paths.
# With -P we don't — fall back to heuristic stripping of known system decls.
_SYSTEM_PATHS = ("/usr/", "/lib/", "/opt/homebrew/", "/Applications/Xcode")
_LINEMARKER = re.compile(r'^# \d+ "([^"]+)"')
def _strip_system_content(source: str, original_file: Path) -> str:
"""Remove content that expanded from system headers."""
lines = source.splitlines(keepends=True)
# Check if preprocessor emitted linemarkers (happens without -P).
has_markers = any(_LINEMARKER.match(l) for l in lines[:50])
if has_markers:
return _strip_by_linemarkers(lines, original_file)
# -P was used (no markers): keep everything — the system headers already
# provided only type declarations that CBMC needs. Just remove duplicate
# blank lines to keep the file manageable.
return _collapse_blanks(source)
def _strip_by_linemarkers(lines: list[str], original_file: Path) -> str:
in_user_file = True
out: list[str] = []
for line in lines:
m = _LINEMARKER.match(line)
if m:
path = m.group(1)
in_user_file = not any(path.startswith(sp) for sp in _SYSTEM_PATHS)
continue # don't emit the marker itself
if in_user_file:
out.append(line)
return "".join(out)
def _collapse_blanks(source: str) -> str:
return re.sub(r'\n{3,}', '\n\n', source)
# ---------------------------------------------------------------------------
# Step 3: strip GCC / ARM64 extensions
# ---------------------------------------------------------------------------
def _strip_attributes_nested(source: str) -> str:
"""Remove __attribute__((...)) handling nested parentheses correctly."""
result = []
i = 0
n = len(source)
marker = "__attribute__"
mlen = len(marker)
while i < n:
if source[i:i+mlen] == marker:
j = i + mlen
# skip whitespace
while j < n and source[j] in ' \t\n\r':
j += 1
if j < n and source[j] == '(':
# consume the outer paren pair with nesting count
depth = 0
while j < n:
if source[j] == '(':
depth += 1
elif source[j] == ')':
depth -= 1
if depth == 0:
j += 1
break
j += 1
i = j # skip entire __attribute__((...))
else:
result.append(source[i])
i += 1
else:
result.append(source[i])
i += 1
return ''.join(result)
_ATTR_RE = re.compile(r'__attribute__\s*\(.*?\)', re.DOTALL) # fallback, unused
_DECLSPEC_RE = re.compile(r'__declspec\s*\([^)]*\)')
_TYPEOF_RE = re.compile(r'\btypeof\s*\(')
# __asm__ volatile ( "..." : ... : ... : ... ) or __asm__ ( "..." )
_ASM_RE = re.compile(
r'__asm__\s*(?:volatile\s*)?\s*\([^;]*\)\s*;',
re.DOTALL,
)
# register uint64_t x asm("reg") — ARM register variable
_REGVAR_RE = re.compile(
r'\bregister\b([^;]+)\basm\s*\([^)]*\)\s*;',
)
# _Noreturn (C11 keyword CBMC may not handle)
_NORETURN_RE = re.compile(r'\b_Noreturn\b')
# __extension__
_EXTENSION_RE = re.compile(r'\b__extension__\b')
# __restrict / __restrict__
_RESTRICT_RE = re.compile(r'\b__restrict(?:__)?(\s)')
# __volatile__ (same as volatile)
_VOLATILE_RE = re.compile(r'\b__volatile__\b')
# __const__ (same as const)
_CONST_RE = re.compile(r'\b__const__\b')
# __signed__ (same as signed)
_SIGNED_RE = re.compile(r'\b__signed__\b')
# __inline__ / __inline (same as inline)
_INLINE_RE = re.compile(r'\b__inline(?:__)?\b')
def _strip_gcc_extensions(source: str) -> str:
source = _strip_attributes_nested(source)
source = _DECLSPEC_RE.sub('', source)
source = _ASM_RE.sub(';', source)
source = _REGVAR_RE.sub(r'/* register-asm variable removed */;', source)
source = _NORETURN_RE.sub('', source)
source = _EXTENSION_RE.sub('', source)
source = _RESTRICT_RE.sub(r'\1', source)
source = _VOLATILE_RE.sub('volatile', source)
source = _CONST_RE.sub('const', source)
source = _SIGNED_RE.sub('signed', source)
source = _INLINE_RE.sub('inline', source)
return source
# ---------------------------------------------------------------------------
# Step 4: prepend CBMC-friendly headers
# ---------------------------------------------------------------------------
_CBMC_PREAMBLE = """\
/* AMC preprocessor preamble — CBMC-friendly type definitions */
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <assert.h>
#ifndef NULL
#define NULL ((void*)0)
#endif
#ifndef true
#define true 1
#define false 0
#endif
"""
def _prepend_cbmc_headers(source: str) -> str:
# Avoid duplicate preamble if preprocessing ran twice
if "AMC preprocessor preamble" in source:
return source
return _CBMC_PREAMBLE + source
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