contrib/fuzz/manifest.cc

discovery: avoid wrong detection of multiple branch heads (issue6256)

This fix the code using obsolescence markers to remove "to be obsoleted" heads
during the detection of new head creation from push. The code turned out to not
use the branch information at all. This lead changeset from different branch to
be detected as new head on unrelated branch.

The code fix is actually quite simple. New tests have been added to covers
these cases.

Differential Revision: https://phab.mercurial-scm.org/D8259

#include <Python.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>

#include "pyutil.h"

#include <string>

extern "C" {

static PYCODETYPE *code;

extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
{
	contrib::initpy(*argv[0]);
	code = (PYCODETYPE *)Py_CompileString(R"py(
try:
  lm = parsers.lazymanifest(mdata)
  # iterate the whole thing, which causes the code to fully parse
  # every line in the manifest
  for e, _, _ in lm.iterentries():
      # also exercise __getitem__ et al
      lm[e]
      e in lm
      (e + 'nope') in lm
  lm[b'xyzzy'] = (b'\0' * 20, 'x')
  # do an insert, text should change
  assert lm.text() != mdata, "insert should change text and didn't: %r %r" % (lm.text(), mdata)
  cloned = lm.filtercopy(lambda x: x != 'xyzzy')
  assert cloned.text() == mdata, 'cloned text should equal mdata'
  cloned.diff(lm)
  del lm[b'xyzzy']
  cloned.diff(lm)
  # should be back to the same
  assert lm.text() == mdata, "delete should have restored text but didn't: %r %r" % (lm.text(), mdata)
except Exception as e:
  pass
  # uncomment this print if you're editing this Python code
  # to debug failures.
  # print e
)py",
	                                      "fuzzer", Py_file_input);
	return 0;
}

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
	// Don't allow fuzzer inputs larger than 100k, since we'll just bog
	// down and not accomplish much.
	if (Size > 100000) {
		return 0;
	}
	PyObject *mtext =
	    PyBytes_FromStringAndSize((const char *)Data, (Py_ssize_t)Size);
	PyObject *locals = PyDict_New();
	PyDict_SetItemString(locals, "mdata", mtext);
	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
	if (!res) {
		PyErr_Print();
	}
	Py_XDECREF(res);
	Py_DECREF(locals);
	Py_DECREF(mtext);
	return 0; // Non-zero return values are reserved for future use.
}
}