/**************************************************************************/
/*                                                                        */
/*                                 OCaml                                  */
/*                                                                        */
/*             Sebastien Hinderer, projet Gallium, INRIA Paris            */
/*                                                                        */
/*   Copyright 2016 Institut National de Recherche en Informatique et     */
/*     en Automatique.                                                    */
/*                                                                        */
/*   All rights reserved.  This file is distributed under the terms of    */
/*   the GNU Lesser General Public License version 2.1, with the          */
/*   special exception on linking described in the file LICENSE.          */
/*                                                                        */
/**************************************************************************/

/* Stubs to let OCaml programs use the run library */

#define _GNU_SOURCE

#define CAML_INTERNALS

#ifdef __CYGWIN__
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <string.h>

#include "run.h"

#include "caml/mlvalues.h"
#include "caml/memory.h"
#include "caml/io.h"
#include "caml/osdeps.h"
#include <caml/fail.h>

/* cstringvect: inspired by similar function in otherlibs/unix/cstringv.c */
static array cstringvect(value arg)
{
  array res;
  mlsize_t size;

  size = Wosize_val(arg);
  res = (array) caml_stat_alloc((size + 1) * sizeof(char_os *));
  for (mlsize_t i = 0; i < size; i++)
    res[i] = caml_stat_strdup_to_os(String_val(Field(arg, i)));
  res[size] = NULL;
  return res;
}

static void free_cstringvect(array v)
{
  for (char_os **p = v; *p != NULL; p++)
    caml_stat_free(*p);
  caml_stat_free(v);
}

static void logToChannel(void *voidchannel, const char *fmt, va_list ap)
{
  struct channel *channel = (struct channel *) voidchannel;
  int length, initialTextLength = 512;
  char *text = malloc(512);
  if (text == NULL) return;
  length = vsnprintf(text, initialTextLength, fmt, ap);
  if (length <= 0)
  {
    free(text);
    return;
  }
  if (length > initialTextLength)
  {
    free(text);
    text = malloc(length);
    if (text == NULL) return;
    if (vsnprintf(text, length, fmt, ap) != length) goto end;
  }
  caml_channel_lock(channel);
  caml_putblock(channel, text, length);
  caml_flush(channel);
  caml_channel_unlock(channel);
end:
  free(text);
}

CAMLprim value caml_run_command(value caml_settings)
{
  int res;
  command_settings settings;

  CAMLparam1(caml_settings);
  settings.program =
    caml_stat_strdup_to_os(String_val(Field(caml_settings, 0)));
  settings.argv = cstringvect(Field(caml_settings, 1));
  settings.envp = cstringvect(Field(caml_settings, 2));
  settings.stdin_filename =
    caml_stat_strdup_to_os(String_val(Field(caml_settings, 3)));
  settings.stdout_filename =
    caml_stat_strdup_to_os(String_val(Field(caml_settings, 4)));
  settings.stderr_filename =
    caml_stat_strdup_to_os(String_val(Field(caml_settings, 5)));
  settings.append = Bool_val(Field(caml_settings, 6));
  settings.timeout = Int_val(Field(caml_settings, 7));
  settings.logger = logToChannel;
  settings.loggerData = Channel(Field(caml_settings, 8));
  res = run_command(&settings);
  caml_stat_free(settings.program);
  free_cstringvect(settings.argv);
  free_cstringvect(settings.envp);
  caml_stat_free(settings.stdin_filename);
  caml_stat_free(settings.stdout_filename);
  caml_stat_free(settings.stderr_filename);
  CAMLreturn(Val_int(res));
}

CAMLprim value caml_drop_privilege(value name)
{
#ifdef __CYGWIN__
  LUID privilege_luid;
  DWORD dwReturnLength;

  if (!LookupPrivilegeValue(NULL, String_val(name), &privilege_luid))
    caml_raise_not_found();

  /* Search through the primary token and, if this privilege is found, remove
     it. */
  if (!GetTokenInformation(GetCurrentProcessToken(), TokenPrivileges, NULL, 0,
                           &dwReturnLength)
      && GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
    TOKEN_PRIVILEGES* process_privileges;

    if (!(process_privileges = (TOKEN_PRIVILEGES*)malloc(dwReturnLength)))
      caml_raise_out_of_memory();

    if (GetTokenInformation(GetCurrentProcessToken(),
                            TokenPrivileges, process_privileges,
                            dwReturnLength, &dwReturnLength)) {
      LUID_AND_ATTRIBUTES* privilege = process_privileges->Privileges;

      for (int i = 0; i < process_privileges->PrivilegeCount; i++) {
        if (privilege->Luid.HighPart == privilege_luid.HighPart &&
            privilege->Luid.LowPart == privilege_luid.LowPart) {
          HANDLE hToken;
          if (OpenProcessToken(GetCurrentProcess(),
                               TOKEN_ADJUST_PRIVILEGES | TOKEN_DUPLICATE,
                               &hToken)) {
            TOKEN_PRIVILEGES adjustment;
            adjustment.PrivilegeCount = 1;
            adjustment.Privileges->Luid = privilege_luid;
            adjustment.Privileges->Attributes = SE_PRIVILEGE_REMOVED;
            AdjustTokenPrivileges(hToken, FALSE, &adjustment,
                                  sizeof(TOKEN_PRIVILEGES), NULL, NULL);
            CloseHandle(hToken);
          }

          break;
        }
        privilege++;
      }
    }

    free(process_privileges);
  }
#endif
  return Val_unit;
}