Subzero: implemented wrapper script to replace calls to calloc()

pydir/sz-clang.py

+#!/usr/bin/env python2
+
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+
+from utils import FindBaseNaCl, shellcmd
+
+def subsToMacros(subs):
+    macros = '#include <stddef.h>\n'
+    for func in subs:
+        args = [('{atype} a{num}').format(atype=atype, num=i) for
+                i, atype in enumerate(subs[func]['sig'][1:])]
+        macros += (
+            '{ftype} {name}({args});\n'
+            ).format(ftype=subs[func]['sig'][0],
+                     name=subs[func]['sub'],
+                     args=', '.join(args))
+        macros += (
+            '#define {func}(args...) ({sub}(args))\n'
+            ).format(func=func, sub=subs[func]['sub'])
+    return macros
+
+def main():
+    """Passes its arguments directly to pnacl-clang.
+
+    If -fsanitize-address is specified, extra information is passed to
+    pnacl-clang to ensure that later instrumentation in pnacl-sz can be
+    performed. For example, clang automatically inlines many memory allocation
+    functions, so this script will redefine them at compile time to make sure
+    they can be correctly instrumented by pnacl-sz.
+    """
+    pnacl_root = FindBaseNaCl()
+    dummy_subs = {'calloc': {'sig': ['void *', 'size_t', 'size_t'],
+                             'sub': '__asan_dummy_calloc'},
+                  '_calloc': {'sig': ['void *', 'size_t', 'size_t'],
+                              'sub': '__asan_dummy_calloc'}}
+    subs_src = (
+        '{root}/toolchain_build/src/subzero/pydir/sz_clang_dummies.c'
+        ).format(root=pnacl_root)
+    clang = (
+        '{root}/toolchain/linux_x86/pnacl_newlib_raw/bin/pnacl-clang'
+        ).format(root=pnacl_root)
+    args = sys.argv
+    args[0] = clang
+    tmp_dir = ''
+    if '-fsanitize-address' in args:
+        args.remove('-fsanitize-address')
+        include_dirs = set()
+        tmp_dir = tempfile.mkdtemp()
+        for i, arg in enumerate(args[1:], 1):
+            if not os.path.isfile(arg):
+                continue
+            src = os.path.basename(arg)
+            ext = os.path.splitext(arg)[1]
+            if ext in ['.c', '.cc', '.cpp']:
+                include_dirs |= {os.path.dirname(arg)}
+                dest_name = os.path.join(tmp_dir, src)
+                with open(dest_name, 'w') as dest:
+                    dest.write(subsToMacros(dummy_subs))
+                    dest.write('#line 1 "{file}"\n'.format(file=arg))
+                    with open(arg) as src:
+                        for line in src:
+                            dest.write(line)
+                args[i] = dest_name

[Karl, 2016/07/14 17:33:50]

Ok. I now understand the following code. I suggest adding a comment to clarify
that you are adding a "dummy" implementation of the substituted calloc, when not
doing (single file) compilation.

[tlively, 2016/07/14 20:26:14]

Done.

+        if not ('-o' in args and
+                ('-c' in args or '-S' in args or '-E' in args)):
+            args.append(subs_src)
+        for d in include_dirs:
+            args.append('-iquote {d}'.format(d=d))
+    err_code = 0
+    try:
+        shellcmd(args, echo=True)
+    except subprocess.CalledProcessError as e:
+        print e.output
+        err_code = e.returncode
+    if tmp_dir != '':
+        shutil.rmtree(tmp_dir)
+    exit(err_code)
+
+if __name__ == '__main__':
+    main()