Rewrite SIZEOF_* and HAVE_* feature detection.

pyconfig.h shouldn't hard-code values from a 64-bit machine!  Include
_build/detected-config.h instead.

It now compiles on ubuntu32, but it crashes!  There are a few more
hard-coded sizeof() definitions.

Python-2.7.13/pyconfig.h

@@ -1,5 +1,11 @@
/* pyconfig.h.  Generated from pyconfig.h.in by configure.  */
/* pyconfig.h.in.  Generated from configure.ac by autoheader.  */
/* pyconfig.h.
 *
 * OVM Change: Instead of being generated by autoconf, pyconfig.h was frozen
 * from a run of Python's ./configure on Alpine Linux, then deleted lines
 * and modified it to work on many platforms. */

/* From our own ./configure */
#include "../_build/detected-config.h"


#ifndef Py_PYCONFIG_H
@@ -104,9 +110,6 @@
/* Define if `unsetenv` does not return an int. */
/* #undef HAVE_BROKEN_UNSETENV */

/* Define this if you have the type _Bool. */
#define HAVE_C99_BOOL 1

/* Define to 1 if you have the 'chflags' function. */
/* #undef HAVE_CHFLAGS */

@@ -452,12 +455,6 @@
/* Define to 1 if you have the `log1p' function. */
#define HAVE_LOG1P 1

/* Define this if you have the type long double. */
#define HAVE_LONG_DOUBLE 1

/* Define this if you have the type long long. */
#define HAVE_LONG_LONG 1

/* Define to 1 if you have the `lstat' function. */
#define HAVE_LSTAT 1

@@ -996,57 +993,21 @@
/* Define if i>>j for signed int i does not extend the sign bit when i < 0 */
/* #undef SIGNED_RIGHT_SHIFT_ZERO_FILLS */

/* The size of `double', as computed by sizeof. */
#define SIZEOF_DOUBLE 8

/* The size of `float', as computed by sizeof. */
#define SIZEOF_FLOAT 4

/* The size of `fpos_t', as computed by sizeof. */
#define SIZEOF_FPOS_T 16

/* The size of `int', as computed by sizeof. */
#define SIZEOF_INT 4

/* The size of `long', as computed by sizeof. */
#define SIZEOF_LONG 8

/* The size of `long double', as computed by sizeof. */
#define SIZEOF_LONG_DOUBLE 16

/* The size of `long long', as computed by sizeof. */
#define SIZEOF_LONG_LONG 8

/* The size of `off_t', as computed by sizeof. */
#define SIZEOF_OFF_T 8

/* The size of `pid_t', as computed by sizeof. */
#define SIZEOF_PID_T 4

/* The size of `pthread_t', as computed by sizeof. */
#define SIZEOF_PTHREAD_T 8

/* The size of `short', as computed by sizeof. */
#define SIZEOF_SHORT 2

/* The size of `size_t', as computed by sizeof. */
#define SIZEOF_SIZE_T 8

/* The size of `time_t', as computed by sizeof. */
#define SIZEOF_TIME_T 8

/* The size of `uintptr_t', as computed by sizeof. */
#define SIZEOF_UINTPTR_T 8

/* The size of `void *', as computed by sizeof. */
#define SIZEOF_VOID_P 8

/* The size of `wchar_t', as computed by sizeof. */
#define SIZEOF_WCHAR_T 4

/* The size of `_Bool', as computed by sizeof. */
#define SIZEOF__BOOL 1

/* Define to 1 if you have the ANSI C header files. */
#define STDC_HEADERS 1

configure

@@ -12,6 +12,9 @@
# Other settings: LTO, PGO?  Consider moving prefix, LTO, PGO to build and
# install steps.

TMP=${TMP:-/tmp}  # Assume that any system has $TMP set or /tmp exists
readonly TMP  # POSIX sh supports 'readonly'

log() {
  echo "$0: $@" 1>&2
}
@@ -85,6 +88,33 @@ cc_quiet() {
  cc "$@" -o /dev/null >/dev/null 2>&1
}

cc_or_die() {
  if ! cc "$@" >$TMP/cc.log 2>&1; then
    log "Error running 'cc $@':"
    cat $TMP/cc.log
    die "Fatal compile error running feature test"
  fi
}

# Check if a given program compiles
cc_statement() {
  local pp_var="$1"
  local prog="$2"

  cat >$TMP/cc_statement.c <<EOF
int main() {
  $prog
}
EOF
  # Return exit code of compiler
  if cc_quiet $TMP/cc_statement.c; then
    echo "#define $pp_var 1"
    return 0
  else
    return 1
  fi
}

# Write a shell script to standard out with variables, or fail.
detect_readline() {
  if cc_quiet build/detect-readline.c -l readline; then
@@ -106,6 +136,84 @@ detect_and_echo_vars() {
  echo "PREFIX=$FLAG_prefix"
}

# c.m4 AC_LANG_INT_SAVE
cc_print_expr() {
  local c_expr="$1"
  cat >$TMP/print_expr.c <<EOF
#include <stdio.h>
#include <sys/types.h>  /* size_t, pid_t */

int main() {
  printf("%lu", $c_expr);
}
EOF
  cc_or_die -o $TMP/print_expr $TMP/print_expr.c 
  $TMP/print_expr > $TMP/print_expr.out
}

# Shell note:
# - local is not POSIX, but most shells have it.
# C note:
# - autoconf uses ac_fn_compute_int (in sh) aka AC_COMPUTE_INT (in m4).
#   - it uses different tests when cross compiling.
#   - cross-compiling does binary search?
#   - other one does AC_LANG_INT_SAVE
#     - generates a C program that outputs to conftest.val!
#     - well why not use exit code?
# - QEMU configure doesn't do any tests

# Hm, don't bother with cross compiling case for now.

# Check if the size of a type is greater than a certain integer.
check_sizeof() {
  local pp_var="$1"
  local c_type="$2"
  local min_bytes="$3"

  cc_print_expr "sizeof($c_type)"

  local actual_bytes
  actual_bytes=$(cat $TMP/print_expr.out)

  if test "$actual_bytes" -lt "$min_bytes"; then
    die "sizeof($c_type) should be at least $min_bytes; got $actual_bytes"
  fi

  # Echo to stdout!
  echo "#define $pp_var $actual_bytes"
}

detect_c_language() {
  # This is the equivalent of AC_CHECK_SIZEOF(int, 4)
  check_sizeof SIZEOF_INT 'int' 4
  check_sizeof SIZEOF_LONG 'long' 4
  check_sizeof SIZEOF_VOID_P 'void *' 4
  check_sizeof SIZEOF_SHORT 'short' 2
  check_sizeof SIZEOF_FLOAT 'float' 4
  check_sizeof SIZEOF_DOUBLE 'double' 8

  check_sizeof SIZEOF_SIZE_T 'size_t' 4

  # NOTE: This might only be relevant for large file support, which we don't
  # have.
  check_sizeof SIZEOF_FPOS_T 'fpos_t' 4
  check_sizeof SIZEOF_PID_T 'pid_t' 4

  if cc_statement HAVE_LONG_LONG 'long long x; x = (long long)0;'
  then
    check_sizeof SIZEOF_LONG_LONG 'long long' 8
  fi
  if cc_statement HAVE_LONG_DOUBLE 'long double x; x = (long double)0;'
  then
    check_sizeof SIZEOF_LONG_DOUBLE 'long double' 8
  fi
  if cc_statement HAVE_C99_BOOL '_Bool x; x = (_Bool)0;'
  then
    # NOTE: this is mainly used in ctypes.h, which we might not need.
    check_sizeof SIZEOF__BOOL '_Bool' 1
  fi
}

# Another way of working: set detected-config.mk ?
# And set the default target as oil_readline, oil_no_readline, oil_lto,
# oil_pgo, etc.?
@@ -117,9 +225,30 @@ main() {
  # The shell build actions will 'source _build/detected-config.sh'.  And then
  # adjust flags to compiler (-D, -l, etc.)
  mkdir -p _build
  local out=_build/detected-config.sh
  detect_and_echo_vars > $out
  log "Wrote $out"
  local sh_out=_build/detected-config.sh
  local c_out=_build/detected-config.h

  detect_and_echo_vars > $sh_out
  detect_c_language > $c_out

  log "Wrote $sh_out and $c_out"
}

unittest() {
  cc_print_expr 'sizeof(int)'
  local actual
  actual=$(cat $TMP/print_expr.out)
  test "$actual" = 4 || die "Expected 4, got $actual"

  check_sizeof SIZEOF_INT 'int' 4 || die "FAILED"
  # failing test
  #check_sizeof SIZEOF_INT 'int' 8

  cc_statement HAVE_INT 'int x = (int)0;' || die "FAILED"
  cc_statement HAVE_FOO 'foo x = (foo)0;' && die "Expected to fail"

  #detect_c_language
}

main "$@"
#unittest "$@"

scripts/ovm.sh

@@ -0,0 +1,25 @@
#!/bin/bash
#
# Miscellaneous scripts for figuring out OVM.
#
# Usage:
#   ./ovm.sh <function name>

set -o nounset
set -o pipefail
set -o errexit

source build/common.sh  # $PY27

grep-python() {
  find $PY27 -type f | xargs grep "$@"
}

# https://stackoverflow.com/questions/2224334/gcc-dump-preprocessor-defines

# 493 variables.
pp-vars() {
  gcc -E -dM - < $PY27/pyconfig.h
}

"$@"